journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.241 for many decades, it has been stated that renewable energy, re, needs subsidy, otherwise it will not be able to compete or sustain. for a certain level, this statement was valid. in this period, the investment costs for both wind and photovoltaic, pv, were high. in other words, production costs of both of them reached around 7.0 and 13.0 cent us$ per kwh. on the other hand, oil and natural gas, ng, prices were low; i.e. less than us$ 30.0 per oil barrel and around us$ 4.0 per million british thermal unit, mmbtu, of ng. also, policies of promoting re were limited; almost there are two main policies, feed-in-tariff, fit, in limited developed countries and international tenders. as a result, investment in re was usually led by developed countries and minor share from the developing countries. this was the scene of re before around 10 years. nowadays, the scene of re totally differs. starting from the policies side, through auctions in both solar and wind energies, new records of prices have been reached. in numbers, in the field of wind energy morocco and egypt already signed contracts with prices lower than 4.0 us$ cents/kwh. for pv, there is a dramatic devaluation in the prices. now we are speaking for less than 0.7 million us$ per mw for turnkey projects. as a result, during the last couple of years, the global re market witnessed a bundle of an outstanding prices, el-sewihan project at abu dhabi, 2.42 us$ cent/kwh. mexico and dubai projects, 3.6 and 3.0 us$ cent/kwh. few days ago, dubai electricity and water authority, dewa, received $9.45 cents per kilowatt-hour for its 200mw concentrated solar power (csp) plant. all these figures, and others, gave us important messages; 1) despite low prices of oil and ng, re is able to compete and offer outstanding prices, 2) wind and pv technologies do not need any kind of subsidy, rather than they need a real free market to compete, 3) csp is a low hanging fruit and it will witness a frog-leap during the coming couple of years, 4) even csp still high, compared with both pv and wind, but is a dispatchable energy. so, it is a game changer. 5) there is a need for more r&d efforts in storage technology. 6) the role of small-scale applications; i.e. biomass and pv, still need further development in the developing countries. 7) most of the outstanding recent prices have been fulfilled by developing countries, which means that their role in promoting re applications, grow year by year. about mohammed mostafa el-khayat dr. mohammed mostafa el-khayat, got his ph.d. from mansoura university egypt, and the business diploma certificate from eslsca school of business, paris, france. he is the chairman of the new and renewable energy authority, nrea in egypt. also, he is the chairperson of renewable energy and energy efficiency committee, league of arab state, las. he has over 25 years of experience in the fields of renewable energy, environment, and academic activities. he is responsible for the wind and solar energy projects. also, he is responsible for the energy efficiency activities. dr. el-khayat shared in drafting pan arab renewable energy strategy issued by league of arab states. also, he is participating in drafting renewable energy laws and regulations. el-khayat received many awards from different countries and worked with different regional and international entities. finally, he issued 5 books and writing a weekly article in al ahram newspaper. 241 resd © 2017 http://apc.aast.edu does renewable energy still need subsidy dr. eng. mohamed mostafa el khayat chairman of the new and renewable energy authority, nrea chair of renewable energy and energy efficiency of arab experts committee, league of arab states, las http://dx.doi.org/10.21622/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.185 efficient use of energy….. as a life style eng. omneya m.k. sabry chairperson of executive committee regional center for renewable energy and energy efficiency, rcreee cairo, egypt email: omneya.sabry@rcreee.org since the early eighties of the last century, the egyptian government considered energy conservation as one of the main pillars of energy planning in egypt, based on the fact that investing in energy efficiency is more cost effective than in constructing new power plants. energy efficiency (ee) programs financed by international financing institutions focused at that time, on energy audits in industrial buildings, power plants, electricity transmission and in some other governmental buildings. recommendations for efficient use of energy and reducing energy consumption at those entities were implemented by the use of efficient lamps, improving power factor, waste heat recovery, thermal insulation, efficient firing in boilers…. consequently, high quality energy efficient products were competing in the market with others not having the same advantage. although the above mentioned ee programs included awareness campaigns for all sectors but the consumption in residential sector remained high and increased more and more ,exceeding even the consumption in industrial sector specially that the prices of electricity were highly subsidized. for that reason, more awareness campaigns (lectures, brochures, audio and visual advertisement) and more incentives were offered by ministry of electricity and renewable energy (moere) to consumers in the residential sector. meanwhile, a program to reduce gradually subsidies on electricity prices started aiming to push consumers to follow energy efficiency instructions and buy efficient appliances especially while they were suffering from electricity cut for about two years. to prepare for market transformation to efficient appliances the government, issued the standard specifications and labeling for energy efficient appliances (lamps, refrigerators, freezers, washing machines, air conditioners, dish washers and others). meanwhile, these standards are supported with accredited testing labs in national entities (nrea,eos,…). in addition, ministerial decisions and resolutions were issued to enforce the standards and labeling and to monitor the industry and the market as well. at the regional level the league of arab states issued the “arab framework for energy efficiency for enduser” supported by the regional center for renewable energy and energy efficiency( rcreee) acting as technical arm. in 2012, moere applied this framework to develop its national plan which has been endorsed by the cabinet in the same year. this plan included ee projects to be implemented by the ministry as well as measures for energy efficiency improvement expected as a result of implementing these projects. efficient use of energy is a life style and culture that should be taught to children in schools and at home. 185 resd © 2017 http://apc.aast.edu http://dx.doi.org/10.21622/ mailto:omneya.sabry@rcreee.org http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.185 about eng. omneya sabry qualification: b.sc. telecommunication engineering, faculty of engineering, ain shams university, 1978 present post: chairperson of executive committee, regional of renewable energy and energy efficiency employment record: 20132015: vice chairman for studies and technical affairs, new and renewable energy authority 20072013: undersecretary of state for international cooperation, ministry of electricity and energy 20012007: general manager of testing department, new and renewable energy authority 1986-2001: database developer then computer network manager at it department, new and renewable energy authority 19791986: maintenance engineer, arab organization for industrialization practical skills and experience were acquired in the field of renewable energy and energy efficiency by participating in several activities including:  wind and solar projects  wind, solar and biomass studies  solar and biomass testing process  quality management system in testing facilities (solar, biomass and energy efficiency)  standard specifications of solar water heaters and pv systems  setting plans and securing finance for developing solar and wind systems or plants in egypt  national energy efficiency plan for electricity sector, energy strategy of egypt 2035.  research projects in solar and biomass  publications in solar, biomass, energy efficiency and leadership development. in addition to three awards of excellence received from minister of electricity and energy 186 resd © 2017 http://apc.aast.edu http://dx.doi.org/10.21622/ http://apc.aast.edu/ microsoft word 249-1181-1-ce.docx journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.242     heavy metals usually referred to those with atomic weights ranging from 63.5 to 200.6. because of natural-mineral dissolution and human activities such as mining, pesticides, fertilizer, metal planting and batteries manufacture, etc., these heavy metals, including zinc, copper, mercury, lead, cadmium and chromium have been excessively released into water courses, like underground water, lake and river, etc. the ingestion of the heavy metals-contaminated water would raise serious health problems to human beings even at a low concentration. for instance, lead can bring human beings about barrier to the normal function of kidney, liver and reproductive system, while zinc can cause stomach cramps, skin irritations, vomiting and anemia. mercury is a horrible neurotoxin that may result in damages to the central nervous system, dysfunction of pulmonary and kidney, chest and dyspnea. chromium (vi) has been proved can cause many diseases ranging from general skin irritation to severe lung carcinoma. accordingly, the world health organization announced the maximum contaminant levels (mcl) for the heavy metals in drinking water. there are numerous processes for eliminating heavy metals from water in order to provide citizens safe drinking water, including precipitation, adsorption, ion exchange, membrane separation and biological treatment, etc. adsorption is considered as a potential process for deeply removing heavy metals, in which the selection of adsorbents plays a predominant role. nano-sheet minerals as the adsorbents are currently the hottest researches in the field. they are obtained from layered minerals, such as montmorillonite, graphite and molybdenite, through the processing of intercalation, electrochemical and mechanical exfoliation, etc. nano-sheet minerals are featured by their large specific surface area, relatively low costs and active adsorbing sites, leading to be effective and potential adsorbents for heavy metals removal from water. montmorillonite was usually pre-interacted with organics to increase the interlayer space, and then exfoliated to single or several layers by using ultrasonic. among the nano-sheets, the surfaces are strongly charged negatively, while the edges are positively charged. this characteristic allows the adsorption of cations or anions, as well as the substances with negative or positive charges. graphite can be oxidized and exfoliated into graphene oxide (go), which has a huge specific surface area and plentiful of functional groups such as carboxyl, epoxy, carbonyl and hydroxyl, leading to high adsorption capacity to heavy metals in water. nano-sheet molybdenite is a novel two-dimensional material with single or several layers of mos2 sheets. the most common method to prepare nano-sheet molybdenite is exfoliated from bulk molybdenite through chemical method based on ion intercalation process. a large quantity of functional groups and s atom on the sheets are the active sites for adsorbing heavy metals in water. 242 resd © 2017 http://apc.aast.edu eliminating heavy metals from water with nanosheet minerals as adsorbents shaoxian song institute de metalurgia, universidad autonoma de san luis potosi, sierra leona 550, san luis potosi, s.l.p., c.p. 78210, mexico tel: +52-444-8254326, e-mail: shaoxian@uaslp.mx journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.242 nano-sheet minerals are used as adsorbents in the form of three-dimension hydrogels. they are featured by the huge specific surface area and high adsorption efficiency. in addition, the clean and smooth surfaces allow heavy metals to adsorb directly by film dispersion. without any barrier of mesopores and micropores, the adsorption rate could be well improved. these characteristics would lead to the extremely large adsorption capacity and high adsorption rate. currently, nano-sheet minerals as adsorbent is a very hot research topic in the field of heavy metal removal. it is expected that nanosheet minerals will be promising adsorbents in the removal of heavy metals from water. about shaoxian song dr. song has been a professor in the universidad autonoma de san luis potosi, mexico, since july of 1996, and is a national researcher level 3 and the member of the mexican academy of science. concurrently, he is a chair professor of the school of resources and environmental engineering, wuhan university of technology, china. he received his ph. d. in mineral engineering in the central-south university, china in 1991. his main fields of interests include water treatment, mineral processing and colloidal stability. he is the author or co-author of over 280 journal articles (in which over 200 articles have been indexed by sci), 3 books, 8 book chapters and over 50 proceedings articles. 243 resd © 2017 http://apc.aast.edu  journal of renewable energy and sustainable development (resd) volume 3, issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.187 how the hbrc contributes to the sustainability in egypt prof. khalid mohamed el zahaby chairman of the housing & building national research center, hbrc cairo, egypt email: kmelzaha99@yahoo.com housing & building national research center, hbrc, is a governmental institute subordinate to the ministry of housing, utilities and urban communities which started in 1954 by 12 employees. hbrc now has more than 1100 employees, 300 of which are m.sc., and/or ph.d. holders. hbrc is the sole entity nationwide responsible for issuing the egyptian codes (30) as well as technical specifications (21), in addition to providing periodical training for these codes and specifications. training also extends to a variety of engineering subjects and it serves both public and private sectors. hbrc is involved in several national scientific research plans as well as researches leading to academic degrees. one of the main activities of hbrc is serving the community through the assessment of mal-functioning structures nationwide, as well as technically refereeing disputes between different parties. moreover, hbrc is taking a substantial role in the quality control and construction supervision of the national projects. it is worth mentioning that all hbrc labs are iso 17025 accredited by the international accreditation services, ias. moreover, hbrc hosts the egyptian green building council, originated back in 2009 by a ministerial decree. several rating systems exist worldwide, .e.g., leed, breeam, casbee, etc. in this capacity, a rating system for new buildings, termed green pyramid rating system (gprs) has been developed. it has been issued back in december 2010. other rating systems have followed since then, including gprs for banks, communities, etc. these rating systems have been applied to several structures / compounds, e.g., the first governmental green building has been designed at hbrc; compounds, club houses and banks have been assessed according to the appropriate gprs. hbrc has carried out some tangible steps towards the application of the green building concept in egypt. the use of traditional construction systems has to be developed so as to coop with the green building concepts. this started back in 2010 when a research team from hbrc visited several countries so as to carry out smooth technology transfer after making the necessary adaptations for the used systems in order to suit the egyptian climate, habits, etc. a sustainable park subordinate to hbrc has been initiated at the city of 6 october in which full scale models have been constructed with non-traditional systems and/or materials of construction. this can be summarized briefly as follows: sandwich panel system in which polystyrene panels are used with wire mesh attached to both sides and covered with shotcrete. this is used for both walls and ceiling. glass reinforced concrete panels (grc) are also used for both walls and ceiling. 187 resd © 2017 http://apc.aast.edu http://dx.doi.org/10.21622/ mailto:kmelzaha99@yahoo.com http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.187 cold formed steel is used for both walls and ceiling. sand sacs, in which sacs are filled with sand or silty sand and stacked together to form the walls of the structure. ceilings can also be built in the same manner with special technique in construction. rammed earth in which soil is mixed with a very low percentage of cement (about 4 to 5%) and the mixture is manually rammed with a hammer to build the walls of the structure. alternatively, the mixture can be used to form blocks with different shapes using a hand operated simple machine which produces several blocks at a time. the blocks are then sprayed with water and treated for 28 days, after which these blocks can be used to construct both the walls and ceiling of the structure. a full scale model is built as such at the premises of the headquarters of hbrc at dokki. all the previously shown methods of construction have a common factor which is that they are all eco buildings, i.e., environmentally friendly structures which help minimize their life time running cost, help in the reduction of harmful emissions, thus supporting the environment, etc. in short, these types of systems can be considered among the future systems to be used rather than the traditional methods which are becoming more expensive and more important some of the constituents of the conventional methods are getting depleted. part of the vision of hbrc is to help create a green environment. about prof. khalid mohamed el zahaby prof. el zahaby is currently the chairman of the housing & building national research center (hbrc) subordinate to the ministry of housing, utilities & urban communities. he is also the chairman of the metropolis® regional branch as well the chairman of urban training institute (uti). he is the vice-chairman of the egyptian green building council. he started as a research assistant and progressed to be a professor of geotechnical engineering then vice chairman of hbrc before being nominated for the post of the chairman. he obtained his b.sc. and m.sc. from cairo university, egypt and his ph.d. from north carolina state university, usa. he authored and co-authored 36 research papers published in national and international journals and/or conferences. he chaired several international conferences and presented invited keynote lectures in several countries. moreover, prof. el zahaby supervised tens of theses and refereed tens of m.sc, ph.d. and scientific papers. he is also a member on several regional and international organizations. in his capacity as a researcher at hbrc or being a geotechnical consultant, prof. el zahaby prepared more than 2000 geotechnical studies in egypt and some arab countries including geotechnical reports, side supporting systems, dewatering, etc. it is worth mentioning that prof. el zahaby is a member on several standing committees as well as a variety of code committees. prof. el zahaby is the recipient of several awards, among which are the icc global award, usa, 2013; the award given by his highness, prince mansur ibn metaab, ksa, 2013. 188 resd © 2017 http://apc.aast.edu http://dx.doi.org/10.21622/resd.2017.03.1.187 http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.183 energy and the city prof. francesco martinico, phd city and regional planning università degli studi di catania deputy president of the school of architecture in siracusa catania, italy email: fmartinico@dau.unict.it spatial planning should have a key role in creating urban environments that support less energy-intense lifestyles. a wise consideration of energy in urban land use policies should play an important role considering that, in spite of having a land occupation of 2% and accommodating 50% of the world population, cities produce 80% of ghg emissions and consume 80 % of the world’s resources. in the building industry, the green economy is already part of the designers’ approach. this has already produced several energy efficient buildings that also feature high architectural quality. now is the turn of cities to take the same direction in developing the capacity of formulating sounded urban policies. this will contribute to develop adequate new tools for achieving the energy efficiency goal. climate change concern, the dominating environmental paradigm, is permeating the political scenario worldwide, producing a plethora of formal documents. the most recent one is the cop21 agreed in paris in december 2015, after the failure of the copenhagen summit in 2009, and formally signed in april 2016 in new york. the challenge for land use planning now is to translate these general commitments into actions that modify planning practices at all levels, from cities to regions. in this field, the current situation is extremely varied. eu has issued several documents focussed mainly at building level but also sustainable transports are considered a key issue. however, a further step is needed in order to increase the level of integration among all land use approaches, including the idea of green infrastructure as a key component of any human settlement. (european commission, 2013). the relationship between urbanisation and climate change has become key worldwide but looking at it from a mediterranean perspective arises some specificities, considering also the political strain that this part of the world is facing. both southern europe and middle east and north africa (mena) countries will face stronger heat waves in the near future (fischer and schär, 2001). their cities, often poorly planned for decades, will be considerably affected by these temperature upsurges. a further complexity arises from the fact that the energy approach in land use plans is not direct. including energy considerations in urban and regional planning is hardly a technological issue. on the contrary, it requires a deep change in the mind-set of urban planners that have to think at the whole city structure wearing the new “energy glasses”. it is possible to trace the energy issue in land use planning back to its history. spatial planning has a long lasting tradition in defining the shape of urban fabric and the layout of buildings, taking into account the role of the sun and the wind. this tradition has evolved from the seminal experiences of modernist planning to the new sustainable districts, recently developed in several countries like germany, the netherlands, france and sweden, including the ones described by peter hall (2014) in his last book. but mediterranean countries have an even longer tradition in building cities and houses that were capable of facing hot temperatures, without any of the electric appliances that are consuming now a considerable share of energy. as part of this long-established tradition, it is worth remembering the inspiring contribution of the egyptian architect hassan fathy. looking back at the city history is not a mere exercise based on nostalgia. making greener mediterranean cities, as they were up to a recent past, is a complex task but it will become unavoidable in order to guarantee forms of sustainable cooling. 183 resd © 2017 http://apc.aast.edu http://dx.doi.org/10.21622/ mailto:fmartinico@dau.unict.it http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.183 this is especially true in those cities that have grown considerably in the second half of the 20th century, according to high-density models. urban planning has been also concerned with defining the proper mix of land uses, taking into account the key role of transports. compact and walkable cites, rich of activities, are naturally energy efficient. the lesson taught by jane jacobs in her seminal book death and life of great american cities remains relevant also assuming the energy approach. more recently, emerging planning themes are including the containment and retrofitting of urban sprawl by integrating transport and land use planning. applying transit oriented development (tod) principles can induce a change in mobility choices of inhabitants of this unsustainable form of urban settlement, by giving them more mobility opportunities. land use planning will also play a relevant role in accommodating new forms of distributed sustainable energy production in the urban fabric. the recent 2015 snapshot of global photovoltaic markets, by the international energy agency, confirms that economic incentives, like feed-in tariffs, are not enough to guarantee a stable diffusion of this type of energy production. after the phasing out of this incentives there diffusion of pv, reduces considerably. this is case of italy that installed only 300 mw of pv systems in 2014, compared to 9,3 gw in 2011, 3,6 gw in 2012 and 1,6 gw in 2013. integrating energy production in the city as part of urban design will increase the opportunity of making sustainable energy production an inherent feature of the city design, including energy production devices in the city realm and using them for retrofitting poor quality buildings. in addition, planning tools have to incorporate incentives aimed at favouring higher energy standards, both for new and existing buildings. the costs of these actions should be covered by planning normative tools. several techniques, like the carbon offset fund in great britain, have been tested but there is a great need of new research in this field, at national and local level, since these tools are not easy to implement without taking into account site-specific norms and approaches. in addition, the exclusive use of the market leverage risks to confine these tools to wealthy communities, excluding the poor ones. these new attitudes require not only new planning tools but also a great capacity of devising urban policies capable of involving communities with different cultural backgrounds and planning traditions. a wise mixture of tradition and innovation is central to innovate the urban planning discipline in the direction of sustainability. a lot of mental energy has to be devoted to the difficult but stimulating objective of improving the energy awareness of our cities. references [1] european commission, building a green infrastructure for europe, luxembourg: publications office of the european union, 2013, doi: 10.2779/54125 [2] fischer e. m., schär c., consistent geographical patterns of changes in high-impact european heatwaves, in «nature geoscience» n. 3, 398-4 3, 2001 [3] hall p., good cities, better lives: how europe discovered the lost art of urbanism, rutledge, oxon 2014. about francesco martinico associate professor in town and regional planning at the university of catania, school of architecture, since october 2005, deputy president of the school of architecture. he has been faculty coordinator of the phd program in "environmental planning and design” at university of catania. in 1987 he graduated in civil engineering at the university of catania. he received his phd in urban and regional planning in 1998. he attended courses at insead, fontainebleau, and at university of surrey. his main fields of interests includes regional and landscape planning, management issues related to land use, the use of gis and planning of industrial estates. he has been part of research teams of several plans and research programs including the following: land use master plan of catania, landscape protection plan in sicily, grabs (green and blue space adaptation for urban areas and eco towns, a program funded by eu interreg ivc), special (spatial planning and energy for communities in all landscapes, a project funded by intelligent energy europe). he is author co-author and editor of over 80 publications (books, book chapters and research papers). 184 resd © 2017 http://apc.aast.edu http://dx.doi.org/10.21622/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.164 this paper has been accepted and presented in the (first international conference on new trends for sustainable energy) 1-3 october, 2016 at pharos university, alexandria, egypt. 164 resd © 2017 http://apc.aast.edu hydrogen through water electrolysis and biomass gasification for application in fuel cells 1department of chemical engineering & technology, kth royal institute of technology, se-100 44 stockholm, sweden 2dipartmento di progettazione e tecnologie, univeristà di bergamo, viale marconi 5, 22044, italy abstract hydrogen is considered to be one of the most promising green energy carrier in the energy storage and conversion scenario. although it is abundant on earth in the form of compounds, its occurrence in free form is extremely low. thus, it has to be produced by reforming processes, steam reforming (sr), partial oxidation (pox) and autothermal reforming (atr) mainly from fossil fuels for high throughput with high energy requirements, pyrolysis of biomass and electrolysis. electrolysis is brought about by passing electric current though two electrodes to evolve water into its constituent parts, viz. hydrogen and oxygen, respectively. hydrogen produced by non-noble metal catalysts for both anode and cathode is therefore cost-effective and can be integrated into fuel cells for direct chemical energy conversion into electrical energy electricity, thus meeting the sustainable and renewable use with low carbon footprint. i. introduction environmentally benign fuels, which can replace today’s fossil based fuels, such as gasoline, oil and coal for combustion either in stationary or mobile applications is of utmost importance. one such fuel is hydrogen, which is considered to be the fuel of the future. hydrogen is an energy carrier maintaining potential applications in many industrial processes such as fertilizers, petroleum refineries, food processing, bulk and specialty chemicals as well as power generation. hydrogen plays an important role as a potential fuel for aviation, vehicles and domestic heating requirements either by direct combustion or in the so-called “cold combustion” as in fuel cells. large scale introduction of hydrogen would mean a paradigm shift as a renewable energy carrier, leading to a substantial decrease of the greenhouse gases. owing to its abundance in the form of compounds and complexes, it is estimated that over 75% of the mass of the universe is primarily hydrogen (1). the combustion product of hydrogen practically being water makes it to be highly important for clean and sustainable energy production. since hydrogen is energy rich on weight basis ( 120 mj/kg) compared to gasoline (44.4 mj/kg) but poor on volumetric basis, large volumes of hydrogen has to be stored, handled and transported for application for example in vehicles with internal combustion engines or fuel cells. therefore one of the daunting challenges for the introduction of hydrogen as a fuel is to find a safe method with high storage capacity and facile generation of the fuel, providing high energy efficiency, light weight and volume, predictable performance, fuel purity and economy. ii. hydrogen production global hydrogen production is estimated to be 50 million tons annually (2,3), where the main feedstock are fossil fuels, such as natural gas, hydrocarbons and coal. these processes are highly endothermic, implying high temperatures (>800 oc) and moderate pressures (20-30 bar), where a set of reaction steps such as desulfurization, high and low temperature shift reactions, methanation and adsorption are required for high purity hydrogen. due to the carbon content contained in the fossil fuels, there is a stoichiometric emission of carbon and thereby increasing the concentration of greenhouse gases (ghg) to the atmosphere. thus, electrochemical process of water splitting (electrolysis), where hydrogen in the cathode and oxygen in the anode are released is a sustainable solution, if electricity is generated from renewable energy resources. the benefit of finding robust, stable and active electrocatalysts instead of the noble metals, which are scarce and highly expensive is a challenge for the production of hydrogen as a “green energy” source yohannes@kth.se y. kiros, s. marini, m. villa and p. nelli 1 222 http://dx.doi.org/10.21622/resd.2017.03.1.164 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ mailto:cpalmen@kth.se renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.164 165 resd © 2017 http://apc.aast.edu for application in industrial processes and fuel cells. demand and supply constraints of ru, ir and pt and platinum group metal alloys for application in largescale electrolyzers would mean a decrease of the loadings by several factors and keeping intact the catalytic activity. thus, there is a growing interest in replacing these electrocatalysts by non-precious and ample reserves of the transition metals. herein we report the sponge-like and highly porous with significant surface area of the ni-al alloys leached out by koh for this purpose. two different electrochemical reactions for cathodic (hydrogen evolution) and anodic (oxygen evolution) configurations were studied by applying alloys of raney-ni catalysts, albeit with different compositions and doped with other metallic species. the gas diffusion electrodes (gde), wet-proofed by ptfe were prepared by the rolling method in thicknesses of 0.5-07 mm and then tested in 6m koh at 60-80 oc, where their polarization curves were assessed in durability tests. the role of catalyst additives is significant for lowering the overpotentials and the intrinsic activities of the respective electrodes to be able to serve for prolonged performances in alkaline electrolyzers. iii. fuel cells for electric generation the high efficiency, high power density, flexibility in size and installation area as well as environmentally friendliness of the fuel cells make them an attractive and alternative power sources for tractionary, portable, hybrid and stationary applications. there are five main types of fuel cells, which have the common advantages but yet are contending in cost, access in materials, performance and stability. although the pros and cons of each type of fuel cell are to a large extent specific to the materials, electrolyte, operation temperature, purity or impurity of the oxidant, there are however, major distinguishing marks among them. common to all fuel cells is, however the electrochemical oxidation of hydrogen at the anode and reduction of oxygen at the cathode resulting in the in the generation of electricity and heat as well as water. the low temperature fuel cells, especially polymer membrane electrolyte fuel cell (pemfc) and alkaline fuel cell (afc) have both a relatively fast start-ups mainly due to the temperature regime in which they operate. pemfc has shown high current densities and small weight and compact stacks due to the incorporation of the electrolyte in the polymer matrix. not excepting that the noble metal price is high and less accessible for mass application in fuel cells, the loss of the activity is ascribed to the agglomeration and corrosion of the catalyst particles and hence decrease of the surface areas. the phosphoric acid (pafc) as an intermediate temperature fuel cell was a frontrunner during the 80s and 90s but due to high loadings of platinum group metals as catalyst, this fuel cell has been phased out. the molten carbon fuel cell (mcfc) and solid oxide fuel cell (sofc) operate at 500-600 oc and 900-1000 oc, respectively, both requiring robust materials and thermal stability. previous work (4) with wood charcoal and agroresidues of a producer gas integrated with fuel processing and gas clean-up laboratory demonstration unit (ldu) showed a successful production of hydrogen for operation in a 250 w afc system. the integrated system was composed of a gasifier to generate producer gas, hydrogen enrichment through high temperature and low temperature shift reactors, gas cleaning units (sulfur, carbon dioxide and oxygen) and preferential oxidation of carbon monoxide. the hydrogen produced after the gasifier, having 3-6% vol.% after these steps increased to 20-30 vol.% to be fed to the fuel cell. electrical efficiency from material and energy balances for the system producer gas to the afc generator, based on lower heating value of wood to direct current was found to be 29% . thus, the study showed that biomass gasification/pyrolysis can be integrated for production of electricity both in decentralized or as stand-alone fuel cell power generators. references [1] contreras, j. capiro, m. molero, t. n. verziroglu, int. j. hydrogen energy, 24 (1999) 1041. [2] c. r. ewan, r. w. k. allen, int. j. hydrogen energy, 30 (2005) 809. [3] report of the hydrogen production expert panel, us doe, washington dc, 20585, 2013. [4] y. kiros, c. myrén, s. schwartz, a. sampathrajan, m. ramanathan, int. j. hydrogen energy, 24 (1999) 549. http://dx.doi.org/10.21622/resd.2017.03.1.178 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.154 154 cad and distributed manufacturing solutions for pellet boiler producers timur mamut1 iuliean hornet2 laurentiu oancea3, camelia bâcu4 1 et innovative solutions ltd., cluster for eco-technologies and alternative energy sources – medgreen, constantza, romania 2 iuliean hornet ,ecohornet ltd., romania. 3 laurentiu oancea, et innovative solutions ltd, romania. 4 camelia bacu et, innovative solutions ltd, romania. 1timur.mamut@et-is.eu, 2president@ecohornet.ro, 3laurentiu.oancea@et-is.eu, 4camelia.bacu@et-is.eu abstract the paper is summarizing the research activities that had been carried out for defining an appropriate manufacturing concept and the system architecture for a manufacturing plant of pellet boilers. the concept has been validated through the implementation of a solution of computer integrated manufacturing that includes a cad platform and a cam facility including laser cutting machines, rolling and welding machines and advanced technologies for assembly, quality control and testing. keywords computer integrated manufacturing, distributed manufacturing, pellet boilers. i. introduction the manufacturing concepts may be considered as the core characteristic of the modern human civilization. at the same time, mankind is now facing a series of social challenges such as non-precedence growth of population, closely related to the increase of consumption, the rise of emission levels, environmental degradation and the scarcity of resources. in the last decades, the manufacturing value chains reached a global scale. it is estimated that 80% of the global manufacturing output is concentrated in just 3 regions [1]. there are many options and there is a convergence of opinions that humanity has to move towards localized, closed loop manufacturing cycles. for the closed loop manufacturing to be considered, it requires a fundamentally paradigm shift, from the current paradigm that starts with design, reacting at a certain scale, mass production and further to product distribution, towards the new paradigm which is called mass customization that means to design for use, to define the economic targets based on scope, to customize products and to manufacture on a distributed base all around the world. experts in this field are considering that researchers have to pass from current 3rd industrial revolution, which is based on extensive use of controls, it and electronics, in order to obtain an automated and highly productive environment, towards the 4th industrial revolution [2], which is considered to be smart and based on integration of virtual and physical production systems. in this context, what the experts call now the industry 4.0 will be based on three basic strategic goals, as convergence of applications which will form conditions of new advancements, energy efficiency and sustainability to gain greater business focus, greater presence of mobility and web-based information systems. from the technology point of view, the 4th industrial revolution will integrate wireless technologies, internet of things, big data and cloud platforms. from the collaboration point of view, it means integrated industries, ip centralization and social innovation. in addition, from the processes perspective, it means sustainable manufacturing, integrating internet of services and life-cycle assessment. http://dx.doi.org/10.21622/resd.2016.02.2.154 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 155 fig .1. the enterprise pyramid [1]. according to the current status of technologies, the architecture of a manufacturing enterprise will be shaped as a pyramid with four layers. the enterprise pyramid is a comprehensive representation of different operational layers at their respective positions. this includes factory floor at level 1, followed by controls and automation in level 2, mes at level 3, and erp at level 4. in a new development, product life cycle management is expected to be included in the future of enterprise hierarchy, between levels 3 and 4. the companies structured following the pattern from figure 1 will be much more flexible and adaptive in integrated enterprise ecosystems. at the factory floor level, the wireless technologies will push for intelligent devices. all the industrial control systems will integrate new smart services based on mobile technologies, enabling intuitive control rooms. the manufacturing execution systems will be pushed by enterprise integration and cloud computing. the enterprise resource planning shall include software as a service and social media integration. ii. evaluation of the current status as a first phase in the implementation of modern enterprise architectures, a comprehensive analysis regarding the enterprise ecosystem and the specific characteristics of the existing value chain should be carried out. for this purpose, in the specific case of the project ecopellet, the analysis has been centered on a company specialized on manufacturing and installing of pellet boilers. the evaluation of the enterprise ecosystem has been initiated with a swot analysis by the evaluation of the internal and external connectivity, including the suppliers of different components and the distribution and market delivery of the final products. in this evaluation the market trends had been analyzed and the growth opportunities identified. the initial status of the infrastructure has been evaluated as well as the requirements for the transition to the journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.154 156 modern architecture, defining optimal alternative solutions to the manufacturing phases and the evaluation of the new solutions from the technical and economical point of view. based on the initial evaluation, the choice for the adopted solution has been substantiated. the project consists of three components as follows: ecopellet soft is the soft component that regards the acquisition procedures, technical assistance and studies, ecopellet core project that includes the upgrade of the manufacturing value chain and the inquiry of infrastructure components, and ecopellet r&d that is the research component. ecopellet soft project is aiming to provide technical assistance for the implementation of the investment project ecopellet and research ecopellet r&d, by contracting specialized firms to carry out feasibility study, technical design, construction documentation and business plan, which will enable the efficient implementation of projects provided above. ecopellet core project is the investment component, aiming to develop a manufacturing line for pelletized biomass incineration system components. the new infrastructure enables accumulation of expertise by r&d activities that provide competitive advantages to the partners. ecopellet r&d is associated with the ecopellet core project. the r&d component includes industrial research, to acquire knowledge allowing the development of a competitive advantage for the partner companies. the objectives also include organizing of research activities in line with market requirements and the exploitation of research results into innovative products and services nationally and internationally competitive. on the short term, the project aims to complete the infrastructure elements required to carry out r&d activities in the field of manufacturing pelletized biomass incinerators thus to offer competitive advantage in developing future business. this infrastructure will enable collaboration with businesses, universities and individual inventors, provision of r&d services and implementing innovation projects. the project is also aiming to increase the performance of the manufacturing processes, the development of competitive advantages through the acquisition of high performance equipment to complement the production line, improve the quality and safety of the operation of systems for burning biomass pelleted, reduce costs and increase product competitiveness of the partner companies. on the medium term, the project will identify specific market segments in eu countries and emerging economies. there will also be prospected emerging markets of azerbaijan and the countries of the caspian region, jordan and the middle east, algeria and north african countries, markets with high growth potential such as turkey, ukraine and countries of the former yugoslav space for the development of an expansion infrastructure. iii. implementation and results in the two years of project implementation, the activities had been carried out by the project team of the two partner companies with no significant delays or setbacks. all the steps had been carried out for the completion of the manufacturing infrastructure that included the inquiry of a laser cutting machine, a rolling machine and an advanced automated welding robot, thus assuring the optimal performance, best quality and competitive production costs. the design department was equipped with state of the art graphic stations, running cad cam software. after commercial solutions have been studied, ptc creo has been adopted as the cad cam software solution, for being versatile and integrating all the elements of the production process, from sketch and design, simulation, manufacturing and assembly. research activities have been carried out, including simulation and optimization of the burning processes, experimental research on the product range, technological planning for the new manufacturing processes. also a test bench have been conceived and certified for the testing of various conditions of load and input of the pellet boilers. as a result, the ecopellet project fulfilled almost all the key point indicators and the project implementation project has ended successfully. http://dx.doi.org/10.21622/resd.2016.02.2.154 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 157 iv. acknowledgment the projects ecopellet, ecopellet cdi and ecopellet soft have been initiated by the national competitiveness pole on modern manufacturing systems for green economy medgreen. the investments are funded through the sectoral operational programme “increase of economic competitiveness” (pos cce 2007-2013) that is co-financed by the european regional development fund. references [1] c. anderson, makers. the new industrial revolution. london: crown business, 2012. [2] d. achuthashankar. “industry 4.0: preparing tomorrow’s digital manufacturing,” in frost & sulivan, deepak achuthashankar, industry analyst industrial automation & process control, 2014. [3] t. mamut. “ecoinnovative methods to exploit secondary energy resources from municipal wastewater treatment plants.” phd thesis, politehnica university of bucharest, bucharest, 2014. renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.019 this paper has been accepted and presented in the (first international conference on new trends for sustainable energy) 1-3 october, 2016 at pharos university, alexandria, egypt 19 development of reliability indices for electric distribution network in egypt eman ahmed, sherein abdualla, kamelia youssef and hatem waheed egyptian electric utility and consumer protection regulatory agency sharino@hotmail.com, white_storm100@yahoo.com abstract reliability indices (ris) are the elemental benchmark used by egyptian electricity holding company (eehc), and the electric utility and consumer protection regulatory agency (egypt era) to evaluate the continuity and compliance of supply, which surpasses the customer's requirements and satisfaction. the power system is very complex, mixing huge different types of generating resources and clusters to supply electric power through transmission and distribution system to a number of customers with varying requirements. the main function of electric system is to supply customers with electric energy that has an acceptable degree of reliability and quality. the power system continuity of supply level is controlled through system indices. the most widely used reliability indices are saifi, saidi and caidi (ieee std. 1366-2000). historical electrical indices, reliability indices threshold and satisfaction index are used as guide for electric network performance, which measure the adequate and secure power supply. the paper presents the reliability indices, relation between indices and satisfaction area to highlight the appropriate guideline values for electric systems, also presents the development of indices since 2011 to now for distribution network in egypt. keywords reliability; power system; benchmark; continuity; indicators. i. introduction the egyptian electricity holding company (eehc) mission towards the society is to supply electricity to all types of consumers according to international performance standards taking into consideration all environmental, social and economic determinates and also the terms and conditions set by the egyptian electric utility and consumer protection regulatory agency (egyptera). eehc has sixteen affiliated companies as shown in “fig. 1” (six generations (epc), nine distributions and the egyptian electricity transmission company (etc)). fig. 1. the relation between eehc and egypt era the main objectives of electricity distribution company (edc) are:  distributing and selling to consumers on medium and low voltages.  managing, operating and maintaining medium and low voltages grids in the company.  ensuring high level of quality, availability and continuity of supply to distribution customers. http://dx.doi.org/10.21622/resd.2017.03.1.019 renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.019 20 resd © 2017 http://apc.aast.edu  the following procedures have been taken to improve  continuity of supply indices:  analysis of the causes in case of increased unplanned interruptions and relate it to network renovation and rehabilitation plans.  follow up the implementation of maintenance programs to insure optimizations of interruption of supply time and at the same time implementation of the maintenance procedures with high quality.  intensive field inspections and data collection for interruptions. each edc consists of number of geographical sectors, have number of districts. the district network consists of mv distributors, distribution transformers (mv/lv), and mv, lv lines, as shown in “fig.2”. eehc and egyptera use ris to trace the performance of edcs. egyptera most commonly uses kpis: saifi, saidi, caidi, ens and cens. ii. performance indices (pis) recommended interruption indices or key performance indices (pis) are those defined in both ieee 1366[1] and the cigre study committee c2 [2]:  saifi (system average interruption frequency index): the average number of sustained interruptions per customer during the year.  saidi (system average interruption duration index): the average time for which customers power supply is interrupted in a year.  caidi (customer average interruption duration index): the average time required to restore service to the average customer per sustained interruption.  ens (energy not supplied): the summation of energy not supplied due to supply interruptions over a year period. its cost is cens (cost of energy not supplied). fig. 2. part of geographical area of an edc iii. system reliability indices (ris) a. system average interruption frequency index (saifi) it measures the average number of interruptions experienced by each customer. all planned and unplanned interruptions are used in calculating the index. saifi can be calculated as follows: saifi = (no. of interruptions during one year)/ (no. of customers). b. system average interruption duration index (saidi) it measures the yearly average interruptions duration per customer. it can be calculated as follows: saidi = (σduration of interruption in min)/ (no. of customers). c. customer average interruption duration index (caidi) it measures the average time required to restore service to the average customer per interruption. the following formula is employed for calculating caidi: caidi = (saidi)/ (saifi). [4], [5] iv. continuity of power supply the main aspects of quality for electric network operation are continuity of supply, safety, technical quality of the commodity, end user service and environmental impact. continuity of supply measures the electric networks ability to supply the end users with electricity. it is generally characterized as the frequency and duration of interruptions in supply. http://dx.doi.org/10.21622/resd.2017.03.1.019 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.019 21 resd © 2017 http://apc.aast.edu  continuity of power supply or sustained outage – an outage that lasts longer than a specified amount of time .saidi, saifi and caidi are all based on sustained outage .the duration of a sustained outage varies from state to state. ieee -1366 defines the duration of sustained outage to be 5 minutes.  power quality – measure of the purity of the electric waveform on power lines. a power quality event, which is not the same as an outage, occurs when one of the waveforms differs from a pure sinusoidal waveform or one or two phases of power are lost. [10] measurements that can quantify power quality are harmonic distortion and peak to peak voltage. power quality events can last from few cycles to a few seconds and can be caused by lightning strikes, falling trees, utility operations and operations from other customers such as disturbances from starting a large motor. a. international example a review of some countries revealed the saidi and saifi performance shown in “table i”. these countries also put greater emphasis on power quality [3], [11] b. variables affecting reliability indices 1. longer circuits lead to more interruptions. it is easier to provide higher reliability in urban areas; line lengths are shorter. 2. the distribution supply configuration greatly impacts reliability. long radial lines provide the poorest service; grid networks are exceptionally reliable. 3. higher primary voltages tend to be more unreliable, mainly because of longer lines. table 1. european reliability performance, with major events country saidi saifi austria 72 0.9 denmark 24 0.5 france 62 1.0 germany 23 0.5 italy 58 2.2 nerthlands 33 0.3 spain 104 2.2 uk 90 0.8 *source: council of european energy regulator asbl (2008) 4th benchmarking report on the quality of electricity supply .brussel ceer. faults and interruptions have significant year-to-year variation because weather conditions vary significantly, age of electrical equipment, or performance of protective systems. these factor variations are translated into variations in the number of faults and in reliability indices. c. relation between saifi & caidi the envelope of “acceptable supply” for relation between frequency of interruptions and longest duration per interruption is shown in “fig.3”.  find optimum and customer satisfied: “a” area, represents the area of biggest reliability, move towards the origin, the performance will be better.  customer dissatisfied: balanced area represents the lower reliability, divided to:  region “b” indicates for the excess number of interruptions but for short time durations.  region “c” indicates for little number of interruptions but for long time durations.  vertical axis “x” and horizontal axis “y” give the reliability indices threshold. d. performance indicators for edc “table 2” and “table 3” represent the development of saifi and caidi during 2011:2014 for edcs. if indicators through the three years are abnormal, (as caidi for edc3 & edc5), the stray number must be dropped out. fig.3. relation between saifi and caidi http://dx.doi.org/10.21622/resd.2017.03.1.019 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.019 22 resd © 2017 http://apc.aast.edu table 2. development of caidi for edcs caidi company 2011 2012 2013 2014 average edc1 102.4 117.761 107.852 97.062 106.269 edc2 31.768 27.12 24.118 21.758 26.191 edc3 54.851 18.483 18.906 9.509 25.437 edc4 143.577 2.094 7.576 67.048 55.074 edc5 40.071 40.416 41.76 36.177 39.606 edc6 67.841 48.567 27.377 28.104 42.972 edc7 23.879 24.474 88.877 106.13 60.84 edc8 152.413 106.931 103.703 108.7 117.937 edc9 77.801 83.167 130.727 171.301 115.749 table 3. development of saifi for edcs saifi company 2011 2012 2013 2014 average edc1 0.435 0.495 0.423 0.341 0.4235 edc2 0.192 0.169 0.134 0.131 0.1565 edc3 0.149 0.934 0.958 0.764 0.70125 edc4 0.452 0.405 0.442 0.445 0.436 edc5 0.66 0.533 1.01 1.009 0.803 edc6 3.01 2.145 0.095 0.081 1.3328 edc7 0.121 0.117 1.388 0.559 0.5463 edc8 0.289 0.169 0.464 0.225 0.287 edc9 1.59 2.237 0.221 0.179 1.0568 the relation between saifi and caidi for 9 edcs during 2011:2014 is presented in “fig. 4”. fig.4. relation between saifi&caidi for edcs (data 2011-20122013-2014) fig.5 relation between saifi and caidi fir edcs in 2014 “fig.5” represents the envelope of “acceptable supply “for relation between saifi and caidi for edcs in 2014. according to ieee1366, 2001 the target of saifi and caidi are 1.0 and 90 minute respectively, they are close to the calculated threshold values notes: 1. saifi and caidi are improved in 2014 for most edcs. 2. edc2 and edc3 are in optimum area v. conclusion there is increasing demand from consumers for more reliable and economical electric power. many factors share to evaluate the reliability of a power network: design, planning, operation and maintenance and faults; which have their contributed input to all power network reliability. the main measures to improve reliability: adequate maintenance, adoption of preventive maintenance rather than break down maintenance, improving power quality and ensuring coordination protection settings. the reliability indicators for electric network in egypt are used by eehc and egypt era to benchmark performance and scenariotize investments in generation, transmission and distribution network, to improve performance. also, these indicators are used by system planners and operators as a channel to improve the level of customer service. reliability level for its delivery facilities and, where appropriate to improve performance. the results are the reliability performance objectives for edcs, etc, and epcs shall have threshold objective designed to help maintain the acceptable envelop. references [1] l.goel, “based reliability studies of a distribution test system,” monte carlo simulation [online]. available: http://www.sciencedirect.com [2] h.haroonabadi, and m.r.haghifam, ”generation http://dx.doi.org/10.21622/resd.2017.03.1.019 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.019 23 resd © 2017 http://apc.aast.edu reliability assessment in power markets using monte carlo simulation and intelligent system,” world applied sciences journal 5(3):302-310, 2008. [3] dennis hesseling en mahir sari, ” the introduction of quality regulation of electricity distribution in the netherlands,” european energy law report ш, 2006. [4] kamelia youssef and hafez el-salmawy,”indices of supply: benchmarking edcs in egypt,” mepcon 2009, assuit university,egypt. [5] kamelia youssef and hafez el-salmawy,”power quality: reliability indices for transmission system in egypt, “the conference of the power quality and harmonics (jcnc),” amman, jordan. [6] mahmud fatuhi , firuzabad, and saeed afshar, ”reliability analysis in electrical distribution system considering preventive maintenance applications on circuit breakers,” world academy of science, engineering and technology 49 2009. [7] math bollen, and anders holm, ”a customer – oriented approach towards reliability indices,” cired, 19th international conference on electricity distribution, vienna, 2007. [8] lina bertling, and roland eriksson, ”impact of maintenance strategy on cost and reliability of distribution systems,”cired 17th international conference on electricity distribution , barcelona, 2003. [9] michael holzenthal, andre osterholt, ”reliability based planned: reducing the reinvestment needs of an urban utility,” cired 17th international conference on electricity distribution , barcelona , 2003. [10] konstantin petrov, and daniel grote, ”quality of supply,” presentation for erra tariff committee, april 2010 [11] “electricity distribution quality of service report2002/2003,” 14 distribution network operators, great britain, july 2004. [12] a. sumper, a. sudria, and f.ferrer, ”international reliability analysis in distribution networks,” citcea, universidad politecnica de catalunya, spain. http://dx.doi.org/10.21622/resd.2017.03.1.019 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.091 91 smart seaports logistics roadmap khaled el-sakty college of international transport and logistics, arab academy for science, technology and maritime transport, cairo, egypt. khaled.sakty@aast.edu abstract in the digital world, a smart concept became an essential feature for port organizations to serve as intelligent hubs in the world transport networks. smart ports are the trend for the future long-term strategies. henceforth, ports aims at contributing to sustainable growth by establishing the appropriate conditions for the adoption of new management energy models based on low environmental impact and triggering innovation of both technologies and processes. the scope of this paper is to examine three main issues of smart ports; smart port arctic logistics roadmap, smart port challenges and obstacles in arctic port areas, and the criteria and key performance indicators (kpi) guiding the assessment of ports against this concept. the main purpose is to develop a smart arctic logistics roadmap for the future. keywords arctic logistics, smart port, logistics roadmap, smart intelligence. i. introduction the importance of the smart port concept is strategically increasing in the last years as a future trend in the maritime industry. the new trend of smart port will lead to rely on the new management energy models, which are based on low environmental impacts and prompting the innovations of both processes and technologies. consequently, smart ports will contribute to sustainable growth. nowadays, most of the countries and unions, such as the european union, have released new transport infrastructure policies. the purpose is to enhance the transport networks around the world, remove bottlenecks and technical barriers, and reachi remote markets in less times. all these trends rely on investing in the new technologies (hamalainen, 2015). the investment in the new technologies will lead to a greener and smarter transport systems, globally. thus, the future trend for governments is to conduct ‘technology platforms’ that contributes to defining the future transport strategies, including integration of the supply chains and providing the needed innovation. on the other hand, the green corridors have become an important feature for denoting the smart transport corridors, where advanced technology and comodality are used to achieve energy efficiency and reduce environmental impact. the characteristics of a green corridor include, for example:  sustainable logistics solutions  high safety  high quality  integrated logistics concepts  optimal utilization of all transport modes  harmonized regulations with openness for all actors  a concentration of national and international freight traffic  efficient and strategically placed trans-shipment points  supportive infrastructure  innovative logistics solutions, including information systems those green corridors will lead to smart corridors where intelligent transport services can be provided. ports are considered the main members within those smart corridors. in other words, smart corridors including a maritime transport leg require smart ports. the aim is to improve the commuter services, enhance the traffic safety and make the traffic flow smoother, especially at the borders. ii. research problem this paper aims to address the following problem:  what is the logistics roadmap for the future smart seaports? this requires discussing those criteria that affect the transformation of seaports to be smart in the future. in turn, the paper will explain the challenges and obstacles facing smart ports. also, smart port and the 2050 visions will be illuminated in order to highlight the required roadmap for both the authorities and stakeholders. http://dx.doi.org/10.21622/resd.2016.02.2.091 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 92 smart port criteria environment management system berth productivity infrastructure productivity capacity technology intermodality energy consumption energy management use of renewable lines callings security safety quality waste management iii. methodology the objective of the smart arctic logistics roadmap in seaports is to formulate a future vision and discuss the required roadmap for the ports. hence, the approach of this paper is including the arctic context; including arctic competence and policy making, environmental informatics and mobile technology, and smart logistics and transport. explanatory methodology will be applied in this paper and the philosophy is objectivist ontology. it aims to discuss the nature of reality, where the objectivist ontology deals with what is physically real, with no regard to the social objects, and where the results are based on the facts of the findings derived from real investigation (maylor and blackmon, 2005). iv. the smart port concept the smart port concept can be displayed as the port where the environmental impacts, operations, and the energy consumption are addressed. the main concern for the future maritime industry is to transform ports into smart sustainable cities (ssc) in the global supply chains. itu (2015, p. 8) defined the ssc as “ is an innovative city that uses information and communication technologies and other means to improve quality of life, efficiency of urban operation and services, and competitiveness, while ensuring that it meets the needs of present and future generations with respect to economic, social and environmental aspects”. this concept can be applied to seaports with certain criteria. v. smart port kpis and criteria med (2015) has discussed 23 criteria and 68 key performance indicators (kpis) against the smart port concept in relative to the environmental impacts, operations, and the energy consumption dimensions. figure 1 displays most of the key criteria in relation to the smart port concept. fig .1. scheme of some criteria in the different topics defined in the smart-port concept source: med (2015) o p e ra tio n e n v iro n m e n t energy journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.091 93 in ports operations, measuring productivity is the most common performance criteria (cullinane et al., 2004). it includes sub measures such as berth productivity , berth efficiency and others which can be used to measure the productivity of the smart ports. the infrastructure productivity is another criterion where it ensures the cost-effective yard operations. also, the combined capacity of infrastructure and equipment is important in order to accommodate an increase of the ships’ sizes. its availability helps enhance the ports’ competitiveness. from the operational point of view, the reliable, accurate and secure flow of information is essential in order to provide quick, reliable services and operations at seaports. for the intermodality criteria, it helps to speed up the flow of goods within the logistics chains, reduces cargo handling and prevents damage or loss of the handled cargoes at ports (matajic, 2010). in terms of energy, the energy consumption presents an important criterion for improving the smart port performance, enhancing the ports’ sustainability and strengthening the competitiveness (cisco, 2003). energy efficiency and savings can take place in ports at the various operations, buildings, equipment and warehouses. hence, renewable energy technologies can be applied to ports such as wind, photovoltaic and marine technologies. in other environmental contexts, different maritime and port activities can lead to pollutions. hence, different environmental performance indicators can be particularly useful for both the authority and a wide range of stakeholders in providing evidence of progress and the achievement of environmental objectives. those indicators include, for example, soil waste, air pollution and water contamination (puig m., 2012). waste management is a highly required philosophy by the new trend of smart ports in the future (and more particularly in the case of recycling processes). smart ports have to adopt their strategies to provide such services that raise the service quality provided at ports, such as repair, replacement and repositioning the equipment at different terminals. also, an attraction towards the investment in port is a mandatory requirement in smart ports, where the investment in research innovation and development will incur an updated the security systems (piniella 2009; trelleborg 2010). vi. challenges facing smart ports applying the smart port concept is facing a number of challenges as the concept has to contribute to the sustainable development of sea and waterways activities, which is known as “blue growth”. this can be achieved by improving the performance levels of navigation and harbour calls, within a transport chain between the sea/waterway and the land and spatial planning between all those activities within the port boundaries. these challenges are:  the first challenge is to enhance the competitiveness of the maritime industry as it involves numerous stakeholders in a wide range of activities such as shipbuilding, equipment, repair, and transformation of ships, offshore technology and the new on-going sector of renewable marine energies. it increases renowned knowledge in complex high-tech ships. this industry must be capable, in an international competitive environment, of remaining competitive in order to meet the demands of various users such as ship owners, importers, exporters, freight forwarders and shipping lines. being a smart port leads to provide safe, secure, environmentally friendly and economic operations.  one additional challenge involves the skills acquired by operators of the sea based (or related) industry. in order to maintain the sea industry attractive, it needs to rely on high-performance staff.  the challenge facing the intermodality and associated cost of transferring goods between different means of transport raises a need for technological improvements on ships and at the port terminals.  the highest challenge is to eliminate the global co2 emissions originating from sea transport.  ship energy efficiency is another challenge due to a future context of rarefaction of oil and power.  smart ports play an indispensable role in providing damage control, security control, and illicit acts control such as theft, piracy, immigration and terrorism. http://dx.doi.org/10.21622/resd.2016.02.2.091 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 94 vii. smart ports parameters there are a number of parameters that should be considered in determining the smart ports roadmap. these parameters are:  the ship use; new generations of ships are released in the maritime industry according to the economic, technological, environmental and regulatory developments.  re-structuring the main world economic centers and the new sources of growth will affect the role of the transshipment ports.  new kind of goods, such as drinking water, hydrogen, captured co2, carried by sea requires developing new specific urban logistics at seaports.  a new need for modular ship is highly required in order to reduce the total operating costs. those modular ships can be used for several purposes such as fishing and scientific usage.  structuring of industrial stakeholders within the maritime industry operating in the same or neighboring port areas.  fragmented and globalized value chains of logistic / supply chain operators, service providers and users.  the industrial ecosystem. viii. smart ports and the 2050 visions for the ports' future, the 2050 visions have been developed to presume long term economic contexts primarily defined by the type and size of ships. in vision 1, ship owners replace orders to build ships with latest innovation and quality and accommodate high capacity. this requires the shipyards to deploy low-labor cost and / to run fast production cycles. this will lead the shipyards to look for countries where they can get lower labor cost, optimized services, and modular maintenance. in turn, this vision explains the optimization of costs and the global fragmentation of the value chains. in vision 2, the ship owners will demand their ships to perform new uses. the purpose is to minimize the purchasing costs and to provide competitive operations.similarly, the switching signals of the lower switches (s2, s4, and s6) can be determined. table 1. the smart ports and the 2050 visions future uses current uses new uses worldwide vision 1 optimizing costs vision 2 new standardized market niches a local-level industrial ecosystem vision 3 high-tech specialization vision 4 complexity and customization source: ademe, 2015 in vision 3, industrialists in the maritime industry aim to utilize renewable energies for the ships’ designs. they aim to reduce the materials costs and operating expenditures, especially when ordering mega ships. extended engine life, energy savings and new energies such as green ships are examples of this vision, which implies new requirements from ports. in vision 4, the maritime transport will move towards global integration. this will lead to improve the quality and performance levels of the ships. sharing port facilities will result in achieving optimal utilization of the available facilities at ports. ix. obstacles facing transformation into smart seaports ademe (2015) discussed a number of obstacles facing the future maritime transport in two main groups as follows: a. lack of technological solutions  to reduce the consumption of fossil energies  to reduce the environmental impacts of the ships  to resolve the safety/security challenges faced by ships, their crews, passengers and goods  lack of permanent monitoring and adaptive maintenance technologies  lack of efficient production methods to increase competitiveness b. socio-economic, organizational and regulatory  loss of national skills in certain key/strategic fields  lack of guarantee funds to support the risk taken by the ship owner  lack of research and testing capacities dedicated to sea transport  restrictions connected to port infrastructures  social acceptability of the new ship uses journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.091 95  adoption of innovations by crews x. conclusion this paper aims to contribute to the development of a logistics roadmap to identify future priority opportunities and capability needs for the ports to be smart in the future. it starts with discussing the most important criteria in relation to smart ports as a roadmap template. the most important challenges and obstacles facing the smart ports were then highlighted, based on the previous defined criteria as adapted to new and future contexts. in conclusion, there is a strong emphasis on a move towards integrated intermodal transport systems, reducing emissions, implementation of track & trace solutions, and focusing on more automation and integration of data. xi. recommendations in reviewing the required kpis for smart ports as a roadmap and discussing the challenges and obstacles facing the transformation of ports to be smartic logistics nodes, it is recommended for both the stakeholders and the authorities at seaports to:  promote quality jobs and working conditions  encourage investment in technology  secure transport  apply a ‘one-stop-shop’ concept  spread over the tracking and tracing technologies  adopt the legislation themes in the maritime industry  enhance the capacity and quality of the infrastructure  improve the environmental and waste management systems  adopt the corridor management strategies  develop and implement sustainable energy action plans references [1] ademe, french environment and energy management agency, ships of the future: strategic roadmap, pp. 6-22, available: http://www.ademe.fr/en/ships-of-the-futurestrategic-roadmap, december, 2015. [2] barometer reports, the smart ship: the future of maritime intelligenc,available:https://www.porttechnology. org/technical_papers/the_smart_ship_the_future _of_maritime_intelligenc, 2010. [3] m. puig, identification and selection of environmental performance indicators (epis) for use in the management of european seaports, thesis in school of earth and ocean sciences, cardiff university, 2012. [4] cisco, seaport of the futureoptimizing and securing cargo movement using network technology, white paper, available: http://www.cisco.com/web/strategy/docs/trans/se aportswp120203.pdf, 2003. [5] m. matajič, , combined transport development study in the republic of slovenia. prometni institut ljubljana. slovenia, 2010. [6] 6. k. cullinane, , d.-w.song, and t.-f. wang, “an application of dea windows analysis to container port production efficiency”. review of network economics, vol. 3 (2), 2004. [7] med, action plan towards the smart port concept in the mediterranean area smartport, european union, 2015. [8] e. peris-mora, j.m diez., a subirats,. and p. alvarez, development of a system of indicators for sustainable port management. marine pollution bulletin, 50, pp. 1649-1660, 2005. [9] e. hamalainen, eu transport policies and infrastructure, aalto university, 2015. [10] itu, smart sustainable cities, itu academy, 2015. "new direct-svm method for mc with main input power factor compensation" in proc. of the 34th annual conference of industrial electronics, iecon 2008, orlando, fl, pp. 1281-1286, 2008. http://dx.doi.org/10.21622/resd.2016.02.2.091 journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 artificial neural network algorithm for condition monitoring of dc-link capacitors based on capacitance estimation hammam soliman, huai wang, ieee member, brwene gadalla, frede blaabjerg, ieee fellow department of energy technology, aalborg university, aalborg 9220, denmark, has@et.aau.dk, hwa@et.aau.dk, bag@et.aau.dk, fbl@et.aau.dk abstract in power electronic converters, reliability of dc-link capacitors is one of the critical issues. the estimation of their health status as an application of condition monitoring have been an attractive subject for industrial field and hence for the academic research filed as well. more reliable solutions are required to be adopted by the industry applications in which usage of extra hardware, increased cost, and low estimation accuracy are the main challenges. therefore, development of new condition monitoring methods based on software solutions could be the new era that covers the aforementioned challenges. a capacitance estimation method based on artificial neural network (ann) algorithm is therefore proposed in this paper. the implemented ann estimated back converter. analysis of the error of the capacitance estimation is also given. the presented method enables a pure software based approach with high parameter estimation accuracy. keywords capacitor condition monitoring; capacitor health status; capacitance estimation. i. introduction condition monitoring is an important strategy to estimate the health condition of power electronic components, converters and systems. it is widely applied in reliability or safety critical applications, such as wind turbines, electrical aircraft, electric vehicles, etc., enabling the indication of future failure occurrences and preventive maintenances. in [1], the condition monitoring of semiconductor devices used in power electronics is well reviewed. besides the power devices, and according to [2], electrolytic capacitors are sharing 60% of the failure distribution for power converter elements as shown in fig.1, therefore, capacitors are another type of reliability critical components. in the last two decades, a large number of research results on condition monitoring of capacitors has been published. the majority of the condition monitoring methods for capacitors are based on estimation of the capacitance c and equivalent series resistance (esr), which are indicators of the degradation of capacitors [3]. for aluminum electrolytic capacitors, the widely accepted end-of-life criteria are 20% capacitance reduction or double of the esr. for film capacitors, a reduction of 2% to 5% capacitance may indicate the reach of end-of-life. therefore, a method which can estimate the c value could be applied on both aluminum electrolytic and film capacitors. however, obtaining the values of c or esr is an important step since it gives an indication of the ageing process and its acceleration. fig. 2(a) shows a simplified equivalent model of capacitors and fig. 2(b) plots the corresponding frequency characteristics. it can be noted that the capacitor impedances are distinguished by three frequency regions dominated by capacitance, esr and the equivalent series inductance (esl), respectively. fig .1. distribution of failure for power converetr elements [2 (a) simplified equivalent model of capacitors c esr esl 294 journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 (b) impedance characteristic of capacitors fig .2. equivalent model and impedance characteristics of capacitors. from the methodology point of view in [4], condition monitoring methods in the literature are classified into three categories as the following: a) capacitor ripple current sensor based methods, b) circuit model based methods, and c) data and advanced algorithm based methods. the following three subsections are defining the principle of each category with its corresponding examples from the literature. a. capacitor ripple current sensor based methods the basic principle of the this category is to estimate the capacitance and/or the esr by using the capacitor ripple voltage and current information at region i and ii (as shown in fig. 2(b)). in [2, 5–7], an external current injection at low fre-quency is the main approach to achieve condition monitoring, it has been applied to pwm ac/dc/ac converter in [2], [5], and [7], while in [6] it has been applied to a submodule capacitor in moulder multilevel converter. b. circuit model based methods this category is based on that instead of injecting external signals, the capacitor current can be obtained indirectly depending on both the circuit model and the operation principle of pwm switching converters. in [8], an on-line condition monitoring based on capacitance estimation is proposed, the capacitor ripple current is calculated using the difference between the input current sensor, and the output current flows to the inverter which is based on the transistor switching statues. c. data and advanced algorithm based methods this category, obtaining a strong correlation between the available parameters and the parameters to be estimated is the main concept. in [9], an external voltage is injected to the reference voltage of the capacitor at low frequency, the obtained capacitor power is used as a training data in sake of finding an identification model based on support vector regression (svr). after using a group of training data, a generated function is used to analyse the correlation between the known capacitor power and its corresponding capacitance value. although the previous mentioned methods have been verified by simulation and experimental work, errors, complex ity, and cost increasing due to extra hardware are common shortcomings. therefore, the developed technologies are rarely adopted in practical industry applications, implying that new condition monitoring methods based on software solutions and existing feedback signals, without adding any hardware cost, could be more promising in practical applications. this paper aims to propose a condition monitoring method based on artificial neural network (ann) that uses existing power stage and control information and existing spare resources of digital controllers. it requires no extra hardware circuitry (e.g., current sensors and corresponding signal condition circuits), no external signal injection, and therefore minimises the increased complexity and cost. main sections in this paper are as the following: section ii gives the basic principle of ann applied for capacitor condition monitoring. section iii fig .3. the structure of the artificial neural network. illustrates the applied ann to a back to back converter study case. section iv presents the results achieved by the proposed method based on ann, followed by the conclusion. ii. ann for capacitor condition monitoring implementation of capacitor condition monitoring 295 journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 using ann is motivated by the shortcomings that have been investigated earlier in this paper. avoiding the usage of direct/indirect current sensors is one of the main advantages of using ann to obtain the estimated value of c. instead of sensing the capacitor current ic, only the input terminal and output terminal information of the power converters are used as inputs to the ann, while the capacitance is the ann’s target, and then the network is responsible for estimating the value of c when using different inputs than the trained ones. normally, during the operation of the power converter, the required terminal information to train the ann is supposed to be available. taking the power level of the applied converter into consideration while the network is trained, is improving the ann’s estimated results by being more robust against dynamic variations of the loading power. fig.3 illustrates the structure of the proposed ann. the basic structure of any neural network consists of three layers, input, hidden, and output layers. the input layer is where the available amount of data n fed to the ann will be stored. the hidden layer job is to transform the inputs into a function that the output layer can use, while the output layer transforms the hidden layer activations into a scale which the operator wanted the output to be on target. iii. capacitance estimation based on ann capacitance estimation based on ann is applied to a back to back converter as shown in fig. 4. the specifications of the converter are listed in table i. capacitance values in the range between (1000µf and 5000µf) with 100µf step are used as targets to the network, each value of these 41 samples corresponds respectively to the single phase rms input/output voltages, currents, and the dc-link voltage. since the different loading condition of the back-to-back converter is also considered, three groups of 41 samples under the respective loading level of 10 kw, 7 kw and 4 kw are used. fig .4. a back-to-back converter. table 1. the specifications of the back-to-back converter parameters. input ac voltage (vl−l) 600 v output ac voltage (vl−l) 380 v rated dc-link voltage (vdc) 780 v full power level (po) 10 kw capacitance (c) 5000 µf fig .5. regression responce of the trained network.. 296 journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 all the 123 samples are fed to a single hidden layer ann consisting of 10 neurons using the neural fitting tool (nftool) in matlab software. this tool is usually used for estimation and prediction of problems in which the neural network maps between a data set of numeric inputs and a set of numeric targets. the iteration algorithm used in this training is levenberg marquardt, which typically takes more memory but less time. the training automatically stops when generalisation stops improving, as indicated by an increase in the mean square error of the validation samples. during the training observing the regression value r is important, since regression values measure the correlation between outputs and targets. an r value of 1 means a close relationship, while 0 means a random relationship. fig. 5 shows the regression response of the trained network in this paper. it can be noted that all the 123 input data are exactly aligned on the fitting line and the values of r are close to 1. based on this result, the network stopped training and the ann is generated to be used. iv. simulation results and discussion in this section, the trained network is tested for verification purpose. the inputs to the ann are stored in the matlab workspace, and they are sent to the ann as a group set every 0.2 seconds. each group set is resulting in one corresponding output (estimated c value). the same group set of inputs is sent until a new set is available in the work-space. the same back to back converter as shown in fig. 4 is used for the simulation test, but with two capacitors c1 and c2 connected in parallel through switches to have the option to switch between them to simulate the degradation of c. at the timing (5 sec) the capacitor c2 will be switched on instead of c1 . fig.6 shows the capacitance value estimated by the trained ann. the simulation results for the estimated parameters and their corresponding errors are shown in table ii. the estimated results verify that the trained ann is responding for the changes in the capacitance value, and the statues of the capacitor could be easily identified. table 2. simulation results for estimated capacitance.. c1actual=5000µf c1estimated=4991µ f error=0.18% c2actual=4000µf c2estimated=3996µ f error=0.1% moreover, to prove the accuracy of the trained ann, the network is tested to identify the reduction of 50µf out of 5000µf and the resulted estimation is shown in fig. 7. for the initial stage, the estimated value is 4991µf and for the degraded case, the estimated value is 4945µf, which gives a 0.18% error as a maximum. to test the robustness of the trained ann against loading power variations, the ann is tested to estimate a capacitance fig .6. tested dc-link capacitor change in a back-to-back converter. fig .7. trained ann accuracy for the capacitance change shown in fig. 6. fig .8. trained ann accuracy for the loading power change. value of 5000µf during a loading power change. the estimated results with their corresponding errors percentage are shown in fig. 8. 297 journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 moreover, for further verification of the ann accuracy, a set of random values of capacitance between the ranges of (1000µf-5000µf) are applied under three different power levels, their actual and estimated values are shown in fig.9. the actual and estimated values of capacitance of the set applied under 70% power level are presented in table iii. in sake of showing the impact of the training data amount on the accuracy of the trained ann, another network (ann2) is trained by using 63 samples instead of 123 samples considering the same conditions of (ann1) which have been trained earlier in this paper. fig. 10 shows that the errors estimated by ann2 are higher than the ones estimated previously by ann1, implying the trade-off between estimation accuracy and required computation resource. fig .9. estimation error analysis under different level of power. table 3. simulation results for estimated capacitance (at 7kw). cactual=1300µf cestimated=1296µf error=0.3% cactual=1743µf cestimated=1747µf error=0.23% cactual=2600µf cestimated=2589µf error=0.4% cactual=3200µf cestimated=3203µf error=0.09% cactual=3854µf cestimated=3850µf error=0.1% cactual=4265µf cestimated=4257µf error=0.18% fig .10. estimation error analysis by different trained anns. the last accuracy analysis is performed to observe the error percentage of the estimated capacitance with respect to different degree of changes of the original value of 5000µf, the results are shown in fig. 11. it can be noted that the estimation errors of the proposed ann are below 0.25%. it can respond and estimate correctly the capacitance values even under a very low level of capacitance reduction of 0.2% changes. the following remarks are given from the results presented in this section:  the simulation results of the proposed method based on ann verify that condition monitoring methods based on software solutions could be an attractive alternative for the practical industry applications.  it can be noted from the results that trained ann is capable to respond to a very small change of capacitance fig .11. estimation error analysis under different level of capacitance reduction at rated power level. and estimate the capacitance value within the range in which the network is trained.  it should be noted that the accuracy of the trained ann strongly depends on the amount, quality, and accuracy of the data used in the training. v. conclusions a new capacitor condition monitoring method based on artificial neural network algorithm is proposed in this paper. it is applied to a back-to-back converter study case to estimate the capacitance value change of the dc-link capacitor. the proposed method requires no additional hardware circuit and could be implemented by using the spare resources of existing 298 journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 digital controllers in most of power electronic systems, implying a minimum increased cost (e.g., only in the research and development part). the error analysis under different dc-link capacitance values and different level of capacitance reduction with respect to the initial value are given, achieving a maximum estimation error that is well below 0.5%, which could be acceptable in many practical applications. the impact of training data amount on the error analysis is also given. references [1] s. yang, d. xiang, a. bryant, p. mawby, l. ran, and p. tavner, “condition monitoring for device reliability in power electronic converters: a review,” ieee transactions on power electronics, vol. 25, no. 11, pp. 2734–2752, nov 2010. [2] x.-s. pu, t. h. nguyen, d.-c. lee, k.-b. lee, and j.-m. kim, “fault diagnosis of dc-link capacitors in threephase ac/dc pwm converters by online estimation of equivalent series resistance,” ieee transactions on industrial electronics, vol. 60, no. 9, pp. 4118–4127, sept 2013. [3] h. wang and f. blaabjerg, “reliability of capacitors for dc-link applications in power electronic converters-an overview,” ieee transactions on in dustry applications, vol. 50, no. 5, pp. 3569–3578, sept 2014. [4] h. soliman, h. wang, and f. blaabjerg, “a review of the condition monitoring of capacitors in power electronic converters,” in electromotion joint inter national conference (acemp optim), 2015 ieee, august 2015, pp. 243–249. [5] d.-c. lee, k.-j. lee, j.-k. seok, and j.-w. choi, “online capacitance estimation of dc-link electrolytic capacitors for three-phase ac/dc/ac pwm converters using recursive least squares method,” in proceedings of electric power applications, vol. 152, no. 6, pp. 1503–1508, nov 2005. [6] y.-j. jo, t. h. nguyen, and d.-c. lee, “condition monitoring of submodule capacitors in modular mul tilevel converters,” in energy conversion congress and exposition (ecce), 2014 ieee, sept 2014, pp. 2121–2126. [7] t. h. nguyen and d.-c. lee, “deterioration monitoring of dc-link capacitors in ac machine drives by current injection,” ieee transactions on power electronics, vol. 30, no. 3, pp. 1126–1130, march 2015. [8] a. wechsler, b. mecrow, d. atkinson, j. bennett, and m. benarous, “condition monitoring of dc-link capacitors in aerospace drives,” ieee transactions on industry applications, vol. 48, no. 6, pp. 1866– 1874, nov 2012. [9] a. abo-khalil and d.-c. lee, “dc-link capacitance estimation in ac/dc/ac pwm converters using voltage injection,” ieee transactions on industry applica tions, vol. 44, no. 5, pp. 1631–1637, sept 2008. 299 vol1 full version_1_e.pdf 5rania abdel galil.pdf 6adam fenech.pdf 7dieter schramm.pdf 8ahmed abou elseoud.pdf 9p55.pdf 10p68.pdf 11p91.pdf 12p92.pdf 13p100.pdf 14p101.pdf journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 191 resd © 2015 http://apc.aast.edu the eco-efficiency and sustaible national projects in egypt khaled el-sakty head of transport logistics department & vice dean of college of international transport and logistics, arab academy for science and technology and maritime transport, cairo, egypt., tel: +2 0100 833 4341, e-mails: khaled.sakty@aast.edu abstract as a national mega project, the suez canal area development project has logistically imposed two main questions. first: how can the project spot an ideal solution for balancing the business and environmental concerns? second: how can the project enhance the trade-off between these two dimensions? in order to answer these two questions, the efficient frontier between the profitability and the environmental impact needs to be investigated. in this paper, the strategic thinking approach will be discussed for improving the ecoefficiency. the main purpose of this paper is to discuss the eco-efficiency solution and to identify the appropriate way for measuring the environmental performance in such a project. keywords eco-efficiency, suez canal area development project , eco-efficiency analysis. i. introduction in a supply chain context, suppliers, customers and governments have recently increased their attention towards the balance between the profitability of establishing mega national projects on one hand and the environmental and societal impacts on the other. hence, governments have changed the ‘end-of-pipe’ laws to more comprehensive one, worldwide. here, one question arises: which trade-offs would be counted for between the environmental impacts of an activity project such as the suez canal area development project, known as “new suez canal project” and the associated costs of the project?. in other words, what are the best solutions balancing between the ecological and economic concerns of such a project? these questions lead to a concept of eco-efficiency as displayed in figure 1. the axes represent the economic value and the environmental quality of economic activity expected from establishing a mega project. the eco-efficiency curve provides either decreasing the environmental pressure without decreasing the economic value added, or increasing economic value without restricting environmental quality. in both cases, the right direction is to move to the efficient frontier. as each point on the efficient frontier is pareto optimal, it is up to the decision makers to decide which improvement path is preferred. in most cases, increasing environmental quality without losing economic value means moving to the right direction when establishing new projects. in other words, increasing economic value without losing environmental quality means moving up (neto et. al., 2007). fig .1. eco-efficiency of mega project source: huppes and ishikawa, 2005 according to a management philosophy, the ecoefficiency aims to combine business excellence with business excellence that can support sustainable development. concerning the strategic framework of economic and social development plan in egypt 2022, the economic value can be realized when the investment policies (including financial, monetary and commercial policies) are directed towards enhancing demand on work in national mega projects. in addition, institutional and legislative reforms should be added to the policies, focusing on developing unorganized labor market. environmentally, the environment should support small and micro projects as well as young http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 192 resd © 2015 http://apc.aast.edu businessmen to improve the chances of having land, loans, and instructional services. in many projects, the quality of environment is affected due to unsustainable use of natural resources, shortage in water resources, and many environmental problems related to different activities in agriculture, industry drinking water, sanitary sewage sectors and other problems. according to a united nation program definition of environment as “green economy”, we understand that environment could be seen as a tool to help modify unsustainable consumption and production attitude resulting in pollution. it can also help modify the overuse of natural resources, especially energy sources and its emissions. accordingly, the national mega projects in egypt such as the suez canal area development project should consider this new attitude that leads to more efficient and diverse economy in terms of usage and production of the resources which preserve environment and create proper job opportunities. such a project must encourage sustainable trade operations in order to limit the rate of poverty and achieve social justice. moreover, the objectives of the suez canal area development project should include the following: creating extended job opportunities, generating investment projects, increasing exportation scale, promoting world trade activities, ensuring long-term economic growth by integrating the existing activities and attracting new foreign investment, using the available resources to find out best practices in the field of sustainable development, and upgrading the efficiency of egyptian laborers to meet the international advanced labor standards. consequently, the potential optimum can be attained by reviewing the economic value together with the quality of the environment as displayed in figure 1. in the next section, the importance of eco-efficiency in improving the performance of any logistic system will be discussed. ii. research problem in national mega projects, a management philosophy often aims at encouraging business to develop and commercialize products with environmental improvements that would yield economic benefits. there are two challenges facing managers in this case. first, they need to know what the potential drivers that affect the environmental performance are. second, they need to have tools that can be applied by them to achieve comprehensive environmental and economic benefits for such projects. this paper is trying to seek out a solution for these two problems. the paper is limited to identify the appropriate methodology for managing an environmental performance in national projects. iii. methodology exploratory approach was conducted in this paper to help understand the research problem and provide significant insights into a given situation. it relies on secondary research such as reviewing available literature, qualitative approach and projective methods. this approach helps build strength around the linkage between process elements, metrics, best practices and opportunities for eco-efficiency in logistics cluster. in this research, the exploratory approach helps to understand the scientific thinking process for improving the eco-efficiency in such a project. iv. eco-efficiency and business case eco-efficiency includes creating economic value and reducing environmental impact and resource use at the same time. this leads to a more significant value to be added to any project. five aspects of ecoefficiency have been identified that make it an indispensable strategic element in business project. these aspects are:  eco-innovation  optimized processes  networks/virtual organizations  new services  waste recycling any project includes a set of activities, where ecoefficiency can be implemented along the entire value chain of a product or service. implementing the ecoefficiency can be achieved through seven key approaches:  reduce material intensity  energy intensity minimized http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 193 resd © 2015 http://apc.aast.edu  dispersion of toxic substances is reduced  undertake recycling  capitalize on use of renewables  extend product durability  service intensity is increased. v. eco-efficiency and logistics network increasing importance of sustainable development has lead eco-efficiency to find a specific position in literature. eco-efficiency means producing goods and delivering services by using lower energy and raw material which together result in lower amount of waste, pollution and cost. hence, eco-efficiency considers two aspects: economic and environmental. as a methodology, using the eco-efficiency concept in assessing the trade-off in logistics networks has recently received attention (neto et al., 2008). determining the eco-efficient frontier regarding business and the environment for the design of sustainable logistics networks in suez region requires using such measures. three measures can be used to describe the eco-efficiency of any project (krikke et al., 2003). these measures are cost, energy/resource usage and waste. on the other hand, consumers and legislators have pushed companies to re-design their logistics networks in order to mitigate negative environmental impacts. the objective in the design of logistics networks has changed, therefore, from cost minimization only, to cost and environmental impact minimization. in general, a logistics network has a number of players that influence business costs and environment impact. suppliers, manufactures, consumers, operators, third parties operating in testing, refurbishing, recycling and energy producers for the end-of-life products are the main players (neto et al., 2008). these players affect both businesses and the environment. these activities are related to manufacturing, transportation, usage and end-of-life products’ and destination as shown in figure 2. the decisions regarding these activities will, therefore, determine the network costs and environmental impact. these decisions are strategic (e.g. location of proposed projects in the new suez canal area development project), tactical (e.g. the destination of end-of-life products), and operational (e.g. the choice of suppliers, third parties, investors, etc.). fig .2. framework for a sustainable logistics network source: neto et al., 2008. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 194 resd © 2015 http://apc.aast.edu hence, it is obvious that choosing the right activities in demonstrating definite logistics nets is fundamental. in the available literature, logistics network design is commonly divided in two approaches: minimizing costs (or maximizing profits) and minimizing environmental impact. however, there is little done integrating these two formulations (bloemhofruwaard et al., 2004). in other words, there is a lack of integration or capturing the trade-offs between the logistics network costs and its respective environmental footprint. thus, the eco-efficiency is applied in this research for this purpose. vi. eco-efficiency and new suez canal project the maritime sector is composed of highly competitive businesses. this is because the industry has often faced governmental mandates for achieving regulatory compliance, including safety, security or environmental requirements. meeting these requirements has been typically perceived as added costs that impede to compete in the sea trade marketplace. with applying the eco-efficiency concept on the new suez canal project and the suez logistics corridor project in order to make a trade-off between business and environment, a set of attributes can be applied for this purpose (adams et al., 2009). vii. business approaches the suez logistics corridor and the new canal projects must comply with their applicable environmental laws and regulations in order to avoid enforcement actions by the responsible government agencies. targeted investors are looking forward to motivating ‘greening’ initiatives. recently, ‘green’ and ‘sustainability’ issues have become essential requirements for improving maritime transport (imo, 2014). on the other hand, there are three potential reasons that a business may invest in improving its environmental performance: 1) social license to operate, 2) corporate conscience, and/or 3) competitive advantage. the most important issue for any business established in the corridor is to avoid water or air pollution problems or congestion problems as this will affect the environment as well as the business itself. viii. drivers for environmental initiatives the drivers for suez logistics corridor investments in environmental performance are many and varied. on top of the list are regulatory compliance and courtordered activities where businesses, ports and logistics adding-value activities are forced to make investment to avoid further legal action. there are other drivers, motivations, and considerations as listed in table 1. table 1. potential essential motives and drivers source: adams et al., 2009 http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 195 resd © 2015 http://apc.aast.edu ix. increasing pressure and motivations port, maritime and shipping industries have become targets for public environmental policy regulations (imo, 2014). proper management of water bodies and sediments, air emissions, waste reception facilities, and modal split of port related hinterland traffic are ‘hot button’ issues in today’s port policy agendas. to a certain extent, ports are being pressured to respond to problems related to environmental harm resulting from shipping activities, whether moved by ships or trucks. also, the rapid growth of cargo volumes over the years and expanding port infrastructure led to an increase in both environmental problems and societal pressures. figure 3. shows the overview of total sea pollution due to an increase in cargo volumes handled at seaports, worldwide. fig .3. overview of total sea pollution source: imo, 2012 x. spillover effects and timelines as an eco-efficiency dynamic, the ‘green’ practices create spillover effects. once a business in the suez region begins to address environmental matters, the interdependent nature of ecological and physical elements inevitably will lead towards ever-broader responses. hence, green suppliers and transporters became a mandatory requirement to any business enterprise and supply chains become greener. xi. results as discussed in table 1, there are many drivers affecting the environmental performance in national mega projects. it is recommended in this paper to apply an eco-efficiency analysis (eea) that provides businesses and organizations with more fullymeasured footprint of their projects or processes. this tool aims at evaluating the economic and environmental impacts of a product or process. it differs from other tools such as the life cycle assessment (lca) tool that eco-efficiency analyses evaluate both environmental burdens and economic costs, whereas lca evaluate only environmental burdens. eea works as follows:  it provides managers with both environmental and economic data around a project.  an eea can accurately analyze those potential drivers in a project relying on the credible baseline data.  from that baseline, an environmental footprint can be prioritized or cost reduction efforts.  it helps to identify broader the optimization targets in a project.  the level of detail and data provided is far beyond that available in a life cycle analysis and can be the basis for attaining higher sustainability goals. as the methodology in this paper is exploratory (inductive in nature) rather than explanatory approach, this paper aims at understanding and finding the appropriate methodology that can be used by managers in such mega projects to measure the environmental performance. as further research in future, it is recommended to apply eea tool in the suez canal area development project when data will be available and accessible. xii. conclusion this research is trying to seek out an answer as to how any project can spot the preferred solution for balancing the business and environmental concerns, and how any project can enhance the trade-off between those two dimensions. answering these two questions, the efficient frontier between the profitability and the environmental impact has been discussed. establishing such new national mega projects such as the new suez canal and the suez canal area development project will certainly affect carrier and shipper market practices. ports, transporters, http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 196 resd © 2015 http://apc.aast.edu investors, businesses and other players in these projects should be prepared to proactively address the environmental issues that are emerging, which may also have a potential impact on costs and carrier market practices. making a balance/trade-off between business and the environment has received little attention in the available literature so far. hence, this research has discussed some attributes that can attain this goal using the eco-efficiency concept. these issues may have even greater impacts on both projects for doing global maritime business, particularly if dealt with reactively. on the other hand, if dealt with from an anticipatory perspective, there may be a possibility of improving a port’s competitive position while reducing costs to shippers and carriers. environmental issues can no longer be considered only as added costs but actively treated as business opportunities. as the purpose of this paper is limited to find the appropriate methodology for managing the environmental performance in national projects, eco-efficiency analysis (eea) is recommended to be applied in the future using explanatory approach when the required data are available. references [1] adams, m., quinonez, p., pallis, a., and wakeman, t. (2009) environmental issues in port competitiveness. dalhousie university: halifax. [2] bloemhof-ruwaard, j.m., krikk, h. and van wassenhove, l.n. (2004) or models for eco– eco closed-loop supply chain optimization. vol. 1, springer, berlin: heiderberg. [3] huppes, g.and ishikawa, m. a. (2005) framework for quantified eco-efficiency analysis. journal of industrial ecology, vol. 9(4), pp. 25–41. [4] krikke, h., bloemhof-ruwaard, j.m. and van wassenhove, l. n. (2003) current product and closed loop supply chain design with an application to refrigerators. international journal of production research, vol. 41(16), pp.3689–3719. [5] quariguasi frota neto, j., bloemhof-ruwaard, j, van nunen, j.a.e.e. and van heck, e. (2008) designing and evaluating sustainable logistics networks. international journal of production economics, pp. 195-208. [6] quariguasi frota neto, j., walther, g.,.bloemhof, j., j.a.e.e van nunen and spengler, t. (2007) methodology for assessing eco-efficiency in logistics networks erim, , pp. 1-37. [7] ministery of planning and international cooperation (june 2012) strategic framework for economic and social development plan 2022 [8] imo, (2014) a concept of a sustainable maritime transportation system. international shipping facts and figures. [9] imo, (2012) information resources on trade, safety, security, environment. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 224 resd © 2015 http://apc.aast.edu economical feedback of increasing fuel enrichment on electricity cost for vver-1000 dwiddar,m. s1., badawi, a1. a., abou-gabal, h. h1. el-osery, i. a.2, badawy, m. r2, 1 faculty of engineering, alexandria university alexandria, egypt., 2nuclear power plants authority, nasr city, cairo, egypt. abstract a methodology of evaluating the economics of the front-end nuclear fuel cycle with a price change sensitivity analysis for a vver-1000 reactor core as a case study is presented. the effect of increasing the fuel enrichment and its corresponding reactor cycle length on the energy cost is investigated. the enrichment component was found to represent the highly expenses dynamic component affecting the economics of the front-end fuel cycle. nevertheless, the increase of the fuel enrichment will increase the reactor cycle length, which will have a positive feedback on the electricity generation cost (cent/kwh). a long reactor operation time with a cheaper energy cost set the nuclear energy as a competitive alternative when compared with other energy sources. keywords front end fuel cycle economics; electricity cost; vver-1000. nomenclature – a: conversion factor for uranium yellow cake (u3o8) af: availability factor cl: cycle length (days) cfab: cost of fabrication (m$) cen: cost of enrichment (m$) cconv: cost of conversion (m$) cyc: cost of yellow cake (m$) ctotal: front-end fuel cycle total cost(m$) celec: direct electricity generated cost (cent/kwh) ef: fraction of u-235 in the uranium feed ep: fraction of u-235 charged in the reactor et: fraction of u-235 in the tails lc: material losses of uranium conversion process lf: material losses in fabrication process mcycle: mass of uranium charged in the reactor mf: mass of uranium feed to the enrichment process mp: mass of uranium in the enriched stream mt: mass of uranium in the tails mconv: mass of uranium for conversion process myc: mass of yellow cake m$: million dollar p1: monetary units per lb u3o8 for uranium purchase ($/lbu3o8) p2: monetary units per kg u for fuel conversion ($/kgu) p3: monetary units per swu for fuel enrichment ($/swu) p4: monetary units per kg u for fuel fabrication ($/kgu) qe: electrical power (mw) qth: thermal power (mw) r: average rate of nuclear fuel burn-up (mwd/mtu) s: separative work unit requirements (swu) vx: value function x subscript for f, p or t i. introduction the economics of nuclear fuel cycle for nuclear power plants depends generally on two main issues, the nuclear fuel cycle components and the reactor core cycle length. the nuclear fuel cycle can be divided into three stages: front-end, at-reactor and back-end. these, in turn, can be sub-divided into more specific components [1].to identify the generating electricity costs from a typical nuclear power plant, the economics of fuel cycle must be clear. actually, most countries study the economics and properties for the first two stages of nuclear fuel cycle; front-end and reactor operation time as there is no clear long term strategy made for the back-end part till now. moreover the large dependency on storage of spent fuels in reactor site increases this foggy vision of the nuclear fuel cycle back-end strategy. over the past decade the discharge irradiation level (burn-up) of both pressurized water reactor (pwr) and boiling water reactor (bwr) fuels has increased steadily. this development is mainly attributable to the increased economic benefit that is associated with higher fuel burn-up. this benefit comes from the reduced throughput of fuel that results from higher burn-up [2]. in this paper, we calculate the generating electricity costs for pwr being the most prevalent reactor type in the world as it represents 274 of the world’s 436 reactors now operating [3]. the calculations are performed considering a typical vver-1000 reactor [4] as a case study. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 225 resd © 2015 http://apc.aast.edu ii. vver-1000 generating electricity cost a. front-end fuel cycle cost the front-end component is composed of uranium purchase, conversion of yellow cake into uranium hexafluoride (uf6), enrichment (isotope separation process to rise the content of fissile materials, u235, in the fuel) and uranium oxide fuel fabrication into assemblies. based on a direct cost analysis for the front-end fuel cycle components, the amount and price of each component can be defined [1]. table 1 gives the magnitude of each front-end component unit price [5]. most fuel contracts are made based on long term contracts not on spot prices so the front-end components unit prices are taken as average values for the past three years. table 1. front-end components unit prices (5) component price* uranium purchase (p1) $45/lbu3o8 conversion (p2) $8/kgu enrichment (p3) $120/swu** fabrication (p4) $260/kgu * average prices over the past 3 years. ** swu: separative work unit based on the vver-1000 reactor core configuration and the plant design parameters [4], the amount of required fuel charged to the reactor each cycle can be calculated using (1) [6]. mcycle = qth∙ cl r (1) within the context of dwiddar, m.s., et al.’s previous work on the vver-1000 reactor core and its improvements to achieve the new design of vver1200reactor core, mcnp-x code was used to calculate the core cycle length and the burn up [7].the vver-1000 validated model showed that for a 3000 mwth, the average value of fuel burn-up is 11800mwd/mtu and the core cycle length is 300 days [7]. using (1) the amount of required fuel is 76.2 tons of uranium. the value of burn-up is assumed to be an average value for the whole core for one cycle length time. the reactor core consists of three batches and only one batch will be replaced each cycle. therefore, the output of (1) will be divided by 3 as it will be 76.2/3 = 25.4 tons of uranium, which represents the amount of required fuel for each cycle length. going backwards through the front-end components, this amount of uranium represents the output of fabrication stage. the mass of uranium, mp, required for the fabrication is slightly more than the mass of uo2in the core, mcycle, due to fabrication losses. to calculate the amount needed for the fabrication stage, the occurring losses must be considered. the loss factor of fabrication stage is 1.0% [1]. thus applying (2) [1], a value of 25.65 tons is obtained for mp. mp = mcycle ∙ (1 + lf) (2) using (3) [1] the cost of this amount is calculated based on the price value in table 1, and is found to be equal to 6.669 m$. cfab = mp ∙ p4 (3) moving to the enrichment stage, to calculate the amount of uranium required for the enrichment process, both the enriched and depleted assays (ep & et) must be well known. the fuel enrichment batch charged for the vver-1000 case study is 3.3% – which will be refueled to the reactor core each cycle – so the enriched assay output for the enrichment process is 3.3%. the depleted assay is assumed to be 0.25% which is the prevalent value for the enrichment process in russia. according to (4) [1] the feed material for the enrichment process is calculated and a value of 169701.73 kg u is obtained. equation (5) [1] gives the amount of depleted uranium from this specific enrichment process and it is equal to 144051.73 kg u. mf = [ ep−et ef−et ] ∙ mp (4) mt = mf − mp (5) since the price of enrichment services is expressed per separative work unit (swu), the quantity of swus necessary to obtain the enriched uranium quantity (mp) at the required enrichment level (3.3%) must be calculated. this quantity can be estimated depending on the 'value' of a mixture (v) which is http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 226 resd © 2015 http://apc.aast.edu estimated on equation (6) as a function of the u235 content. equation (7) [1] gives the swu required for this specific enrichment process. according to (7), the separative work need for this process is equal to 113289 swu. vx = (2 ∙ ex − 1) ∙ ln [ ex 1−ex ] (6) s = mp ∙ vp + mt ∙ vt − mf ∙ vf (7) thus, the cost of enrichment is calculated using (8) [1] and is found to be equal to 13.7m$. cen = s ∙ p3 ∙ (1 + lf) (8) moving to the conversion stage, the amount of uranium required is calculated using (9) [1]. this amount is equal to 170550.24kg u considering the loss factor of conversion stage to be 0.5% [1]. according to the calculated uranium amount and using (10) [1] the cost of conversion process is calculated to be 1.364 m$. mconv = mf ∙ (1 + lc) (9) cconv = mconv ∙ p2 (10) finally, the amount and cost of yellow cake to be purchased for starting the nuclear fuel cycle processes have to be calculated. equations (11) and (12) [1] give the amount and the cost respectively. the amount of yellow cake is equal to 443430.63 lb and the cost is 19.95 m$. myc = mconv ∙ a (11) cyc = myc ∙ p1 (12) fig. 1 summarizes the actual annual front-end fuel cycle requirements for the vver-1000 case study. the total front-end fuel cost is the sum of all its components cost. equation (13) [1] gives the total cost which is equal to 41.69 m$. ctotal = cyc + cconv + cen + cfab (13) fig .1. annual vver-1000 front-end fuel cycle requirements http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 227 resd © 2015 http://apc.aast.edu from the calculated front-end fuel cycle total cost and considering a plant’s availability factor of 82%, (14) estimates the direct fuel cost for the unit electricity generation to be 0.7047 cent/kwh. this value represents the direct electricity generation cost according to the front-end fuel cycle economics. celec = ctotal qe ∙ cl ∙ af ∙ 24 × 100 (cent/$) 1000 (kwh/mwh) (14) b. price sensitivity analysis a sensitivity analysis has been carried out with respect to the unit prices for the front-end fuel cycle components. the sensitivity range for front-end service prices generally reflects the upper and lower bound values seen from the extrapolation of component spot prices in international market [1]. the values used for the sensitivity analysis are shown in table 2. table 2. sensitivity range for the front-end component unit prices component price sensitivity range* uranium purchase 22.5-90 $/lb u conversion 3.75-15 $/kg u enrichment $60-240 $/swu fabrication 130-520 $/kg u fig. 2 gives the results of the front end fuel cycle components prices sensitivity analysis applied on the direct electricity cost. it is clear that although the uranium purchase is the highly significant component, enrichment cost is the most effective because it is the dynamic process that affects all other components. so it may be deduced that the enrichment cost forms a significant component of the front-end fuel cycle costs. fig .2. effect of front end fuel cycle components price change on electricity direct costs c. effects of increasing enrichment and core cycle length for increasing the reactor core cycle length, it is required to increase the fissile material content in the reactor core. this will affect the economics of fuel cycle components. from international practice, the maximum allowable enrichment for pwrs is 5%. for saving the design basis parameters for the vver1000 case study, the minimum enrichment batch of vver-1000 model is increased by a step of 0.1. the enrichments of the other batches are also increased keeping the same ratio of enrichment between the three batches as in the reference case. according to this assumption, the maximum enrichment calculated is 4.95 %. [7] table 3 gives all probable improvements of fuel batches enrichment within the maximum allowable value with the corresponding reactor cycle length and core average burn up. the reactor cycle length and the core average burn up are out data from the mcnp-x code [7]. table 3. changes considered in the enrichment of the fuel batches [7] cases enrichment of fuel batches cycle length (days) average burnup (mwd/ mtu) batch 1 batch 2 batch3 a (ref. case) 2 3 3.3 300 11800 b 2.1 3.15 3.465 336 13213 c 2.2 3.3 3.63 372 14626 d 2.3 3.45 3.795 408 16039 e 2.4 3.6 3.96 444 17452 f 2.5 3.75 4.125 480 18865 g 2.6 3.9 4.29 516 20278 h 2.7 4.05 4.455 552 21691 i 2.8 4.2 4.62 588 23104 j 2.9 4.35 4.785 624 24517 k (max. enrich.) 3.0 4.5 4.95 660 25930 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 variation from reference % c o s ts ( $ /k w h ) uranium purchaseuranium purchase enrichmentenrichment fabricationfabrication conversionconversion http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 228 resd © 2015 http://apc.aast.edu according to the output data given in table 3, fig. 3 shows that the fuel burn-up is directly proportional to the core cycle length. fig .3. relation between core cycle length and fuel burn-up similarly to case a already considered in section a, (1) to (14) were used to calculate the front end fuel cycle economics and its effect on the electricity generation cost for the other cases. calculating the fuel mass required each cycle for the different cases results in a constant value as shown in fig. 4. this can be explained by the proportionality relation obtained between the core cycle length and the fuel burn-up. as (2) and (3) do not depend on the enrichment percentage, this constant value of fuel mass required each cycle will be reflected in a constant value for both the required mass for the fabrication stage and its cost, namely 25.65 tons and 6.669 m$ respectively. fig .4 fuel mass required each cycle for the different cases in table 3 however as fuel enrichment increases, the feed material will increase. consequently the enrichment cost will increase due to the need for more separative work units as seen in fig. 5. fig. 6 shows that the cost of enrichment process is directly proportional to the mass of uranium feed. fig .5 amount of required swu for different fuel enrichments fig .6 enrichment process cost versus the mass of uranium feed the increase in the uranium feed to the enrichment process leads to the need for more uranium for both the conversion and the uranium purchase components resulting in an increase in their costs as illustrated in figs. 7 and 8. fig .7 conversion costs versus the mass of uranium 250 300 350 400 450 500 550 600 650 700 10000 12000 14000 16000 18000 20000 22000 24000 26000 28000 reactor core cycle length (days) a v e ra g e c o re b u rn -u p ( m w d /m t u ) 300 330 360 390 420 450 480 510 540 570 600 630 660 20 21 22 23 24 25 26 27 28 29 30 cycle length (days) f u e l m a s s ( t o n e s ) 3.2 3.4 3.6 3.8 4 4.2 4.4 4.6 4.8 5 120000 135000 150000 165000 180000 195000 210000 enrichment s w u 160000 182000 204000 226000 248000 270000 1.200x10 7 1.400x10 7 1.600x10 7 1.800x10 7 2.000x10 7 2.200x10 7 2.400x10 7 2.600x10 7 mass of uranium feed (kg) e n ri c h m e n t c o s ts ( $ /k w h ) 170000 190000 210000 230000 250000 270000 1.300x10 6 1.400x10 6 1.500x10 6 1.600x10 6 1.700x10 6 1.800x10 6 1.900x10 6 2.000x10 6 2.100x10 6 2.200x10 6 uranium mass (kg) c o n v e rs io n c o s ts ( $ ) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 229 resd © 2015 http://apc.aast.edu fig .8 uranium purchase costs versus the mass of uranium as a consequence of the increase in the costs of the uranium enrichment, the conversion and the uranium purchase components, the total cost of the front end fuel cycle will increase. but since the increase in the uranium enrichment will lead to longer reactor core cycle length due to the higher fuel burn-up, the resulting electricity cost decreases as shown in fig. 9. fig .9 direct electricity cost versus total front-end cost iii. conclusion the effect of increasing the nuclear fuel enrichment on the electricity cost has been considered. a typical vver-1000 reactor has been selected as the case study. the fuel enrichment has been increased up to 5% which is the maximum allowable value for pwrs. excluding the fabrication component, increasing fuel enrichment was found to increase the uranium masses needed for all the front-end components and consequently their costs. a sensitivity analysis was performed with respect to the unit prices for the front-end fuel cycle components and their effects on the electricity direct cost. it was noticed that although the uranium purchase is the most effective component, the uranium enrichment still has the highly priority effect due to its dynamic properties and its consequences on the other frontend fuel cycle components. although increasing the fuel enrichment resulted in a higher total cost of the front end fuel cycle, it was found to extend the reactor core cycle allowing the reactor to operate for more than 12 months. this fact results in a decrease in the electricity generation cost. therefore, increasing the nuclear fuel enrichment within the limit allowable internationally for the pwrs will have a positive economic feedback leading to a cheaper electricity cost. this makes the nuclear energy a strong competitor to the other energy sources references [1] nuclear energy agency, the economical on nuclear fuel cycle (1994) , organization for economic co-operation and development, paris, france. [2] christopher s. (june 1998) economic and fuel performance analysis of extended operating cycles in existing light water reactors (lwrs), handwork, massachusetts institute of technology, [3] pris, iaea,( august 2014) power reactor information system. www.iaea.org/pris/worldstatistics/operational reactorbytupe.aspx [4] iaea, (november 1995) in-core fuel management code package validation for wwers. iaea-tecdoc-847. [5] the ux consulting company (august 2014). www.uxc.com/review/uxcproces.aspx [6] cacuci, d. g. (2010) handbook of nuclear engineering, institute for nuclear technology and reactor safety. karlsruherinstitut fur technologie, germany. [7] dwiddar, m. s. (may 2014) from vver-1000 to vver-1200: investigation of the effect of the changes in core. the third international conference on physics and technology of reactors and applications, tetuan, morocco. 400000 450000 500000 550000 600000 650000 700000 1.800x10 7 2.000x10 7 2.200x10 7 2.400x10 7 2.600x10 7 2.800x10 7 3.000x10 7 3.200x10 7 yellow cake mass (ib) u ra n iu m p u rc h a s e c o s ts 4.100x107 4.600x107 5.100x107 5.600x107 6.100x107 6.600x107 0.48 0.5 0.52 0.54 0.56 0.58 0.6 0.62 0.64 0.66 0.68 0.7 0.72 front-end fuel cycle total costs ($) e le c tr ic it y p ri c e ( c e n t/ k w h ) http://apc.aast.edu/ http://www.iaea.org/pris/worldstatistics/operational%20reactorbytupe.aspx http://www.iaea.org/pris/worldstatistics/operational%20reactorbytupe.aspx http://www.uxc.com/review/uxcproces.aspx journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 184 resd © 2015 http://apc.aast.edu triple –e vessels: tonnage measurement and suez canal dues assessment elsayed hussien galal vice director of suez canal transit department email: galallelsayed@gmail.com abstract container industry is growing faster than gdp; shipping lines always attempt to augment efficiency by reducing cost and by attracting larger volumes of containers. as a result, rising container freight rates leads to an increase of the economic scale of the lines that have been driven, by building mega ships and making more efficient port calls. in 2011 maersk line ordered up to 20 new “triplee “class of container vessels to be delivered between 20132015. this class of mega container vessels has its way through suez canal. other companies like cmaand cgm also ordered this type of mega container vessels in order to reach higher profits due to the achieved economic scale. it is believed that 20000 teu could be the next target size. present mega container fleet of vessels and any future potential vessel capacity demand an expansion for suez canal route to handle vessels larger than 18000 teu. this will put suez canal route in strong competitive position. meanwhile panama canal will not be able to handle vessels larger than 12600 teu even after its expansion in 2015. keywords triple – e vessels – tonnage measurement – suez canal rules. i. introduction various types of vessels transit suez canal. on top of these ships, come container vessels which represent 56% of total suez canal net tonnages and 60% of suez canal total revenues. specifications and characteristics of triple –e vessels have been studied. it is worth mentioning that triple-e vessel pay about one million us dollars as transport dues when transiting suez canal. at the same time the cost of teu transiting suez canal for this type of vessel is less than small types such as new – panamax (12500 teu ) or new –post panamax (15000 teu), thereby achieving high economic scale. this paper mainly highlights various methods of tonnage measurements in general and various methods of tonnage measurements for suez canal in particular. ii. container vessels evolution container ships carry more than 95% of the world’s manufactured goods.in the last decades container vessels became larger carriers trying to achieve high economic scales by increasing the container vessels capacity and consequently the emergence of socalled mega container vessels or ultra-large container vessels has taken place. this new generation of ships is called “triple-e”. “triple-e” vessels have emerged taking into account the following specifications:  energy efficiency.  economics of scale.  environmental improvements, reducing co2 emission by 50% per container carried. fig .1. evolution of container ships fig .2. triple-class http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 185 resd © 2015 http://apc.aast.edu such ships need new ports and container terminals with high specifications and sustainable maritime system. nowadays, this type of vessels uses asia europe lane through suezcanal iii. triplee class in figures its length is approximately 400m, its width is approximately 59m, its draught is about 14.5m and its capacity is 18200 teu (on deck approx. 10600 teu in holds 7600 teu). its displacement is 55000 tons. a reefer container’s capacity is 600 teu. its height is 73m. its maximum speed is 23 knots, average speed is approximately 17-18 knots. rows in hold/ on hatches are about 21/23, tiers in hold/ on hatches are about 11/10. fig .3. triple-class fig .4. longitudinal section of 18000 teu ship the economics of ship size are the driving force for increasing numbers of containers transported. the aforementioned dimensions of “triplee” vessels are outside the ability of panama canal dimensions even after its recent expansion project. also it has 30% less power per ton displacement than the other vessels (emma maersk, marco polo). this is mainly because the “triplee” vessels will be sailing at the utmost power speed because it has a full ushaped body and is more spacious than traditional containerships; accordingly one extra row of containers has to be accommodated. the engine room has been put at the rear of the ship instead of the middle, so it is able to fit in more containers behind the navigation bridge and in the hull. iv. energy efficiency of triple-e vessels a waste heat recovery system helps propel the ship by capturing energy from the engine’s exhaust gas. this cuts fuel by up to 10%. the, energy is also used to produce electricity for the onboard accommodations. the waste heat recovery system on “tripe – e” vessels has allowed to use a smaller and less energy, consuming main engine speeds in the range of 2025 knots. now, these speeds had dropped to 15-17 knots lesser than it was commonplace 5 years ago, v. environmental improvement triple-e” vessels are a combination of carefully thought-of technological and ecological solutions, as well as the result of many years of engineering work. they will enhance the ecological solutions and performance. better fuel efficiency may be the easiest way to cut down on both air pollution and greenhouse gases. thus, “triple-e” vessel innovative design and technological features will help reduce its co2 emissions by more than 50% for every container it moves. also it has a waste heat recovery system that reduces fuel consumption. emissions of air pollutants from the shipping sector have increased substantially in the last two decades, contributing to both climate change and air pollution problems. in 2007 shipping sector was responsible for 3.3% of global carbon dioxide emissions. this sector has contributed to the growing of emissions by 4% per year over the next decade .if ships reduced their speed by 10% , which is known as “ slow steaming “, they could cut and reduce carbon footprint. vi. problems facing triplee vessels the greater outreach required to service the ship’s extra row of containers will mean longer booms. the booms also must be located at a greater height than the height of the ship’s container stacks which also creates a number of new stresses. the wind forces on the crane will be higher which has an impact on wheel loads [1]. the capital cost per teu moved has increased even, considering the increase in slot size of the vessels. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 186 resd © 2015 http://apc.aast.edu furthermore, due to the increase in transportation duration, the capital cost and insurance of goods transported have gone up. furthermore the cost increase could be influenced by the time-length taken by goods that need longer to get from the world’s production centers to the markets. goods that move faster cost less. shipping lines are demanding ever shorter port stay in order to make the economies of scale work. longer vessels of 400 yards (such as maersk line’s “triple-e” class) will lead to more berth wastage to handle efficiently. high port productivity and reliability are essential to enable carriers to operate within schedules. the bigger the ship, the greater the cost of hours lost in port, and an increased port stay is a diseconomy of scale [2]. vii. importance of container ships in suez canal the suez canal plays a pivotal role in today’s global container shipping network, particularly in accommodating vessels that sail on the important. asiaeurope trade lane. container ships accounted for about 56% of suez canal total net tonnages and 60% of total revenues. the charge of containerized cargo also is still rising. the number of teus transiting the suez canal is still growing , it has reached ( 42.1 million teus ) in 2014 , (38.2 million teus ) in 2013 and (37.7 million teus ) in 2012 .the following data illustrates the importance of container vessels traffic through suez canal (as stated on tables 1 & 2). table 1. number of container ships and its net tonnages (20102014) : source: suez canal authority year no. of container vessels container ships net tonnages (million tons) total net tonnages of ships in suez canal (million tons) ratio of net tonnage of container ships% 2010 6852 465.7 846.4 55 2011 7178 519.3 928.5 55.9 2012 6332 507.1 928.5 54.6 2013 6014 508.2 915.5 55.5 2014 6129 536.3 962.7 55.7 table 2. containerized cargo in suez canal : source: suez canal authority year containerized cargo (million tons) total cargo (million tons) ratio of containerized cargo % 2010 367.0 646.1 56.8 2011 397.2 691.8 57.4 2012 398.0 739.9 53.8 2013 406.1 754.5 53.8 2014 435.0 822.3 52.9 comparing containerized cargo with the total cargo in suez canal, we find it ranging between 54% to 57% as stated in table 2. viii. importance of tonnage in maritime world maritime institutes and departments of ship engineering in egyptian universities does not give sufficient importance to the study of ship tonnage measurement rules in spite of its importance in maritime world. the tonnage of a ship has become important as one of its defining characteristics. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 187 resd © 2015 http://apc.aast.edu this paper is intended to define and point out briefly some of the ways that tonnage factors influence ship design. it also sheds light on how tonnage factors affect the financial responsibility of ship-owners who pay dues in accordance with the amount of net tonnage, gross tonnage or net registered tonnage. practically all seagoing merchant vessels operating on the open seas, bays, rivers, lakes and waterways are measured for the assignment of national gross and net registered tonnages. also vessels intending to transit suez canal and panama are measured according to the rules of the respective canal authorities. imo rules refer always to tonnage base to its laws. harbors and waterways dues are depending on net tonnage base or gross tonnage. light house dues, pilotage dues, dry dock dues, wharves dues and similar facilities throughout the life of the vessel depend on its tonnage. also, there is a correlation between tonnage and the balance and the safety rules of a ship. the tonnage figures are used for statistics in maritime trade and for charging taxes. they are also used for comparison of national fleets, framing of policies on trade of shipping, granting of subsidies, comparison of shipbuilding, scrapping, regulatory application basis for manning, registration and survey charges, insurance premium and limitation liability in cases of pollution. for vessel registration, tonnage indicators must be offered. shipping tonnage was a useful indicator of a country’s commercial strength. it also indicates the physical carrying capacity of a ship as well as the comparison of trade and movement of goods. tonnage has been used to indicate the relative magnitude of ships for centuries. ix. evolution of tonnage measurement system a. moorsom’s system 185 traditionally, tonnage was related to the carrying capacity of the ship. moorsom’s [3] concept related tonnage to the total volume of enclosed spaces. being the colonial power, the british maritime legislation spread throughout the world. during the second half of the 19th century, moorsom’s system was the basis for tonnage measurement around the world, though the rules varied from one jurisdiction to another [4]. b. suez canal rules 1873[5] initially the net register tonnage was used as a basis for suez canal company tolls. since the revenue of suez canal was inadequate to meet the expenses and owing to the questionable propelling power deduction for steamers, gross register tonnage was adapted as the basis from july 1872, leading to higher charges. shipping companies and owners opposed this change. thus, an international tonnage commission, formed to resolve the issue, adopted separate rules for suez canal tonnage in 1873 at constantinople. it was expected that the 1873 rules would be adopted by the countries represented at constantinople leading to a universal system. separate rules for suez canal tonnage came into existence. it is important here to cite the text of annex 2 regulation for the measurement of tonnage recommended by the international tonnage commission assembled at constantinople 1873: “general principles: the gross tonnage or total capacity of ships comprises the exact measurement of all spaces (without any exception) below the upper deck, as well as of all permanent covered and closed in erections on that deck”.n. b. by permanent covered and closedin erections on the upper deck are to be understood all those which are separated off by decks or coverings, or fixed partitions and therefore represent an increase of capacity which might be used for the stowage of merchandises, or for the berthing and accommodation of the passengers or of officers and crew[6].this text in the constantinople convention is the philosophical basis for estimating the suez canal tonnage so far. c. panama canal ad measurement system the tonnage measurement system used in the panama canal is known as: panama canal universal measurement system (pc/ums), following the rules of itc1969, using its parameters to determine the total volume of a vessel with the additional variations established by the authority. the acp ad measurement system for a full container vessel reflects the international standard for a container teu. this measurement considers the full container carrying capacity of vessels (above and below deck). in october 2002, the panama canal authority decided to charge container vessels in a new method based on teu, since the pc/ums net tonnage was not representing the earning or economic capacity of http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 188 resd © 2015 http://apc.aast.edu container vessels[7]. d. international convention on tonnage measurement of ships, 1969 (itc69) the efforts for a uniform method materialized when the convention on tonnage measurement of ships (itc69) was adopted at an international conference held in london from 27th may to 23 june 1969. it was the second successful attempt to introduce a universal tonnage measurement system. the first attempt in 1873, when the maritime powers assembled at constantinople and adopted the rules of suez canal measurement system. itc 69 applies to ships above 24 meters long and came into force on 18th july 1982. a phase in period was given for the ships built before that date to retain the existing tonnage figures up to 18th july 1994, for a smooth transition to the new system. the suez canal and panama canal company continued with their separate methods for tonnage measurement even after adopting (itc69).150 states amounting to 98.9% of world tonnage have ratified the convention, as of 31th july 2010 [8]. under itc-69 the overall size and useful capacity of a ship are indicated by dimensionless figures, gt and nt respectively (instead of grt and nrt under moorson’s system). calculated based on the total molded volume of enclosed spaces and volume of cargo spaces[9]. therefore, gt= k,1 v, whereby v= total volume of all enclosed spaces in cubic meters, and k1= a coefficient as tabulated in appendix 2 (of the convention). this coefficient ranges from 0.22 to 0.32 for the smallest to the largest volumes and cares for results being similar to the former tonnage figures based on 100 cubic feet. for the calculation of nt, same coefficient is used together with the volume of cargo spaces, the depth and the draught. nt shall not be taken as less than 0.30 gt. thus gt and nt are calculated independently[10]. x. suez canal transit fees of triple-e vessels the tonnage on which all dues and charges to be paid by vessels are assessed, is the net tonnage resulting from the system of measurement laid down by the international commission held in constantinople in 1873, and duly entered, on the special tonnage certificate issued by the competent authorities in each country[11]. the containers on upper deck are considered as closed in spaces increasing the carriage capacity of the ship when situated over the main deck[12]. tolls are calculated on the basis of suez canal net tonnage plus a ratio specified for the number of tiers on the upper deck according to circular no. 3/2014 of suez canal are as follows: 1. northbound container vessels  4% for vessels carrying one tier.  6% for vessels carrying two tiers.  8% for vessels carrying three tiers.  11% for vessels carrying four tiers.  15% for vessels carrying five tiers.  21% for vessels carrying six tiers. an increase of 2% shall be applied for each tier in excess of six tiers, which means that a surcharge of 23% shall be applied on vessels carrying seven tiers and 25% surcharge if vessels carrying 8 tiers…etc.: south bound vessels, circular no. 2/2007 shall remain in force, for example container vessel carrying 8 tiers on deck shall pay 20% surcharge [13]. 2. southbound container vessel  2% for vessels carrying one tier.  4% for vessels carrying two tiers.  6% for vessels carrying three tiers.  8% for vessels carrying four tiers.  12% for vessels carrying five tiers.  16% for vessels carrying six tiers.  18% for vessels carrying seven tiers. an increase of 2% shall be applied for each tier in excess of seven tiers, which means that a surcharge of 20% shall be applied on vessels carrying 8 tiers on deck….etc. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 189 resd © 2015 http://apc.aast.edu 3. example  northbound transit triple– e” class transited suez canal from its gross tonnage= 200532 tons. net tonnage= 180528 tons. carrying 8 layers of containers on upper deck. so additional dues 25% are taxed, plus extra dues for escorting tugs and pilots. the total canal dues were 932741 u.s $. that means the transfer cost of teu in suez canal is 64.4 u.s. $. so the more teu the ship carry the less cost are realized. another triplee class vessel’s cost of teu through the suez canal is 58.8 u.s $.  southbound transit cost of teu transiting suez canal ranges between 56 and 59 u.s $, according to the number containers the ship were transporting.  emmamaersk class vessel this type of container vessel capacity 15000 teu, the cost of teu for transiting suez canal was 71.8 u.s. $ in case of 68% utilization. table 3. teu fees in suez canal teu cost u.s. $. utilization a triplee direction (northbound): 67.5 76.0% 64.5 80.4% 58.8 88.9% b triplee direction (southbound): 56.1 88.4% 59.1 86.0% 59.5 85.0% c emma maersk class (southbound): 68.0% teu transport cost through suez canal decrease, the higher the numbers of teu can the ship carry. xi. advantages granted to container vessels  allow to the vessel carrying 10 teus on the higher tier without calculating it as tier.  if protuberance part of open teus on the last tier exceeds half height of container, then consider one tier.  if the ship carries empty containers only, then suez canal dues shall be calculated as ballast, provided that containers carried be belonged to the owner or charters v. conclusion  container vessels represent the bulk of the suez canal revenues.  there is correlation between mega projects and economics of scale.  varying utilization of mega container ship affect the cost of teu transiting suez canal.  the slot cost increase for diminishing utilization.  the importance of tonnage measurement of a container ship in particular for its operating economics.  the need to pay attention to the rules of tonnage measurement of ships in the maritime institutes and colleges of engineering (departments of ship engineering).  new suez canal will cut time of transiting, consequently affecting “triple-e” economics by saving time. references [1] the journal of commerce, march 4, vol. 14, no.5, 2013. [2] cullian, k & khanna, ‘economies of scale in large container ships. journal of transport economics and policies, march 2000, vol. 33. pp. 185207 e-journal: www.bath.ac.uk. [3] george moorsom, secretary board of trade in britain, the 1854 british tonnage rules, british merchant shipping act of 1854. [4] corkhill, michael, andrew moysa, ‘the tonnage measurement of ships’, fairplay publication. london, 1980. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 190 resd © 2015 http://apc.aast.edu [5] lane, frederic, tonnage medieval and modern. the economic history review. second series, pp.17 (2) (213233) electronic version. [6] elsayed hussein galal,’the international conflict over the exploitation of suez canal (18691882) arabic edition’, 1979, pp. 197292, general egyptian book organization. [7] suez canal authority: rules of navigation (2007), part. 4, p. 169. [8] aji vasudevan, ‘tonnage measurement of ships: historical evolution, current issues and proposals for the way forward’, 2010, p. 21. world maritime university, malmo. sweden. [9] architecture of instruction and delight, ibid, pp. 4344. [10] international maritime origination issues, imo, 1982. [11] international maritime origination issues, imo, 1982. op. cit. [12] suez canal authority, rules of navigation (1995) p. 190. [13] architecture of instruction and delight, ibid, art. 98, pp. 194. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.244 244 resd © 2017 http://apc.aast.edu synthesis, characterization and performance of cu2snse3 for solar cell application mostafa sh. eraky, atef y. shenouda and ibrahim a. ibrahim electrochemical metallurgy department, central metallurgical research & development institute (cmrdi), helwan, egypt mostafashawki87@yahoo.com abstract cu2snse3 (ctse) powders were prepared by solvothermal (sr) and solid state reactions (ssr) using low cost starting materials. the crystal structure, morphology, uv-vis absorbance, electrochemical and solar energy properties were investigated using x-ray diffraction (xrd), field emission scanning electron microscopy (fesem), electrochemical impedance spectroscopy (eis) and solar energy applications using i-v characteristics measurements. a single cubic cu2snse3 was obtained for the two methods of preparations. the calculated crystallite size (l) values for ctse prepared by sr and ssr are 24.1 and 30.3 nm, respectively. uv-vis. spectra for sr and ssr preparations showed maximum absorbencies at 240 nm with band gap (eg) values of 0.9 and 1.4 ev, respectively. the charge transfer resistances (rct) were equal to 3.5 and 24  for photoelectrochemical cells (pec) and the calculated conductivities were equal to 3x10-2 and 2x10-2 s.cm-1 for samples that prepared by sr and ssr methods, respectively. a good photoelectrochemical cell (pce) has accomplished power conversion efficiency per unit area of about 0.84 and 0.64 % for cells prepared by sr and ssr, respectively. keywords ctse; solvothermal; solid state reaction; optical properties; photoelcetrochemical cell (pec). i. introduction solar cell energy applications have become widely important in the last few decades. this is because of the energy crisis and pollution caused by the traditional energy sources like fossil fuels. so, it is important to develop newer low cost light absorber materials for thin film solar cell energy applications. recently, relatively high efficient materials were discovered and investigated, for example copper indium gallium diselenide (cigs) and cdte [1]-[3]. such materials encounter the problems of being expensive and unavailable, especially indium, tellurium and gallium. also, the toxicity of elements like cadmium makes these materials less applicable. copper-containing calcogenides, especially compounds of groups (i–iv–vi) have been reported to have wide applications in photovoltaic thin film solar cell devices, light emitting diodes, non linear optical materials [4]. these materials have a suitable band gap range: 0.96-1.35 ev. meanwhile, they have a relatively high absorption coefficient ≥ 104 cm-1 [5],[6]. these advantages make them a promising candidate for thin film solar cell absorbing materials. copper tin selenide compounds were prepared mainly in the 2:1:3 elemental ratio i.e cu2snse3[7][8] and 2:1:4 ratioi.ecu2snse4 [9]. recently, cu2snse3 (ctse) have gained a great attention in many applications, especially the field of thin film solar cell application. ctse material is suitable for solar cell energy application because it is environmentally friendly, cheap in preparation, nontoxic, inexpensive and earth-abundant. ctse was prepared with different methods such as vertical bridgman–stockbarger technique [10],[11], direct current sputtering technique [12]-[14], coevaporation process[15]-[17], colloidal synthetic process[18]-[19], and solvothermal process[7],[9],[20]. it was prepared with different crystal structures, e.g cubic[7],[9],[15],[17]-[20] and monoclinic [10],[11]. the crystallite size range is 12-30 nm [7],[18]. the band gap values range is (0.84-2.1 ev) [7],[12],[15]. all these previous parameters affect the efficiency of a definite prepared phase. this work was done to study the preparation of cu2snse3 (ctse) using solvothermal reaction (sr) in comparison with the traditional solid-state reaction (ssr). furthermore, there are only a are not enough data available about the electrochemical and photovoltaic properties of ctse such as impedance, resistivity and conductivity, and solar power conversion efficiency so that this work was conducted to study these properties. in addition to that, a photoelectrochemical cell will be fabricated for the current-voltage measurements. http://dx.doi.org/10.21622/resd.2017.03.3.244 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.244 245 resd © 2017 http://apc.aast.edu ii. experimental 1. synthesis of cu2snse3 by solvothermal (sr) and solid-state (ssr) reactions cu2snse3 was prepared by solvothermal reaction as follows:a mixture of 3.03 gm cu(no3)2 .3h2o, 2.1 gm of seo2,1.2 gm of sncl2 was added to 250 ml autoclave then about 200 ml ethylenediamine (ed) was added to the mixture then put in the oven at about 205 °c for about 24 hours (overnight). a black precipitate was obtained which was filtered and washed with distilled water and ethanol three times then put in the dryer at about 60 °c for about 4 hours; a black cu2snse3 powder was obtained and kept for characterization and further investigation the role of ethylene diamine (en) in the preparation of cu2snse3 by sr can be illustrated by the following equations: cu2snse3 was also synthesized by solid-state process using stoichiometric ratios of cu, sn and se powders that were mixed and ground well in a mortar. then, the mixture was put in a boat crucible in a tube furnace at 600 °c for three hours under argon with 5 % h2 atmosphere. it was cooled to the room temperature under the argon atmosphere. a black powder was obtained, which was ground and kept for further investigations. 2. samples characterization samples compositions were identified by an x-ray diffractometer (xrd), model: brukur advanced d8 kristalloflex (ni-filtered cu k radiation; 1.5406 å). the microstructure was examined by backscattered electron (bse) in the field emission scanning electron microscopy (fesem quantafeg 250). the optical measurements were performed using uv–vis–nir scanning spectrophotometer (perkinelmer lambda 1050 spectrophotometer, usa) using 1 cm path length quartz cell. eis measurements were done using potentiostat (parastat 4000 princeton, usa). the impedance measurements amplitude was 20 mv and the frequency range was 1mhz-10 mhz. 3. photoelectrochemical cell fabrication and measurements the prepared samples were coated on indium tin oxide (ito) conducting glass as working electrode the resistivity of the ito is 30 /cm2. the cell configuration was: ito/cu2snse3/0.5 m ki + 0.5 m i2/c. it was fabricated and characterized through current–voltage (i–v) measurements [21].xenon arc lamp 150 w was used as a light source with solar simulator sciencetechss150waaa. the cell was exposed to light intensity 1 sun (100 mw cm-2) using air mass 1.5 global filter. i-v tester is 2400 keithley source meter ssivt-60wc. the calibrated reference cell consists of a 20 x 20 mm monocrystalline silicon (model sc-lt) photovoltaic cell encased in a 92 x 70 x 16 mm metal enclosure with a protective quartz window. the reference detector (ssivt-refl) is effective in sensing wavelengths between 190 nm and 1100 nm and is calibrated with the 1 sun. parameters measured by i-v software wereopen circuit voltage (voc), short circuit current (isc), maximum power (pmax), and filling factor (ff). iii. results and discussion 1. cu2snse3 samples characterization the cu2snse3 compound prepared by sr and ssm is characterized by xrd as shown in fig. 1. the pattern of the xrd shows main three peaks at 2 equal to 27°, 45°, and 53°. the crystal structure of this compound is cubic phase for both samples prepared by sr and ssr methods with miller indices of (111), (220) and (311) planes. the obtained results are in agreement with jcpds data (01-089-2879) [7],[9],[15],[17]. furthermore, the crystallite size was calculated from scherer equation: (1) where; (l) is the crystallite size (nm), () is wave length of the target (1.5406 å for cu), () is full width half maximum (fwhm) in radians, and () is the chosen diffraction angle [22]. the calculated crystallite size values for ctse prepared by sr and ssr are 24.1 and 30.3 nm, respectively 0.94   cos  l = http://dx.doi.org/10.21622/resd.2017.03.3.244 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.244 246 resd © 2017 http://apc.aast.edu fig .1. xrd pattern of cu2snse3 prepared by (a) sr and (b) ssr the morphology of the prepared samples is characterized by sem inspection as shown in fig. 2.the sample prepared by sr has homogenous spherical particles with a particle size of about 40 nm. on the other hand, the sample prepared by ssr shows agglomerate bulked shape. the particle size of the sample prepared by ssr is about 100 nm. fig .2. sem photo for (a) ctse prepared by sr (b) ctse prepared by ssr 2. optical measurements uv–vis. absorbance measurements are used to reveal the energy structure and optical properties of the as-prepared cu2snse3 architecture as shown in fig. 3. cu2snse3 crystal gives maximum absorbance wavelength of 240 nm that is somewhat near the visible region for both samples prepared with sr and ssr. the absorbance characteristics of the samples obey the model equation αh = a (h-eg)0.5 for the direct transition, where () is the optical absorption coefficient, (h) is planck’s constant, () is the photon frequency, (a) is a constant, and (eg)is the energy gap [23].the energy band gap of cu2snse3 is obtained from the plot of (αh) 2 vs. h (photon energy) by extrapolation as shownalso in fig. 3. the energy gab of sr sample equals 0.9 ev that is smaller than the ssr one, 1.4 ev and this is attributed to the small particle and crystallite sizes of the ctse prepared by sr. also, the obtained value agrees with the previously reported values [7], [24]. it has been reported that ctse thin films have a wide range of band gap energies, 0.7–1.38 ev [25], [26]. http://dx.doi.org/10.21622/resd.2017.03.3.244 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.244 247 resd © 2017 http://apc.aast.edu fig .3. uv-vis. absorbance and band gap diagrams for ctse prepared by (a) sr and (b) ssr atse 3. electrochemical impedance spectroscopy (eis) measurements eis is applied for pellets of dimensions: radius (r) 0.675 cm and thickness (t) 0.35 cm of the prepared ctse powder to measure the resistance of the material itself. nyquist plot for ctse pellets prepared by ssr and sr is shown in fig. 4. the conductivities of ctse powders materials prepared by sr and ssr are 3x10-2 and 2x10-2 s.cm-1, respectively. fig .4. nyquist plot for ctse pellets prepared by (a) sr and (b) ssr the eis is also applied for photoelectrochemical cell (pec) containing the sample plated on ito glass as working electrode against glassy carbon counter electrode in electrolyte of iodine in potassium iodide. cell configuration is: ito/ctse/ 0.5 m ki + 0.5 m i2 /c. the double layer capacitance (cdl) is calculated using equations: cdl = 1/ rct (2)  =2f (3) where; (cdl) is the double layer capacitance (farad), () is the radial frequency (radians/second), (f) is the frequency (hertz) and (rct) is the charge transfer resistance (). nyquist plots for ctse photo electrochemical cell (pec) are shown in fig. 5. for the ctse sample prepared by sr two semicircles are presented with two values of charge transfer resistances rct and two values of double layer capacitance (cdl). the charge transfer resistances (rct) are equal to 32.2 and 6  for the sample prepared by sr. and while, rct of ctse prepared by ssr is 40.1 . the two semicircles can be attributed to the bulk and grain boundary resistances of ctse [27],[28]. double layer capacitances (cdl) for photo electrochemical cells (pec) and for the sample prepared by sr are equal to 7.8x10-9 and 6.67x10-5 f and for the sample prepared by ssr cdl is equal to 2.51x10-8f. eis results show higher conductivity of ctse prepared by sr than that prepared by ssr with higher double layer capacitances (cdl) for photo electrochemical cells (pec) because electron transfer through double layer interface for cell prepared by sr is higher than that prepared by ssr which may be attributed to the fine structure of the samples obtained from sr as explained previously[29]. fig .5. nyquist plot for ctse photo electrochemical cell (pec) prepared by (a) sr and (b) ssr http://dx.doi.org/10.21622/resd.2017.03.3.244 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.244 248 resd © 2017 http://apc.aast.edu 4. photovoltaicproperties to obtain the power output characteristics of the photo electrochemical cell (pec), voc and isc are recorded for the prepared cts samples. the semiconductor | liquid junction proposed operating mechanism is illustrated in fig. 6 diagram. fig .6. representation of photoelectrochemical cell proposed operating mechanism table 1. i-v characteristics results of cu2snse3 which was prepared with the two methods i–v curves are shown in fig. 7. the power conversion efficiency ( %) and fill factor (ff %) are given by the following equations: (4) (5) where: voc: open circuit potential for working electrode, isc: short circuit current measured at zero voltage, vmax, and imax are the optimum maximum voltage and current, respectively of the i-v characteristic relation, a: area of the working electrode, 1 cm2 and pin is the incident intensity of the light (1sun = 100 mw cm-2). photovoltaic i-v characteristics results are summarized in table i. this study is considered one of the priority researches reported about the solar efficiency for cu2snse3[30]. fig .7. i-v characteristics curve for cts prepared by (a) sr (b) ssr under 1 sun and am 1.5 iv. conclusions cu2snse3(ctse) compound has been prepared with two different ways, solvothermal (sr) and solid state reactions (ssr). single cubic cu2snse3 phase was obtained. ctse sample papered with sr present better morphological, optical, electrochemical and photoelectrochemical measurements in comparison with the sample prepared with ssr. the crystallite size (l), eg,rct, conductivities and power conversion efficiency per unit area values for ctse prepared by sr and ssr are 24.1 & 30.3 nm, 0.9 & 1.4 ev, 3x10-2 & 2x10-2 s.cm-1 and 0.84 & 0.64 %, respectively.this demonstrates the advantage of the sr method for the preparation of such compounds over the ssr method. the results also show the ability for the development of such compound for the application in solar cell fabrication. • acknowledgements the cmrdi research team would like to thank prof. dr. el-sayed el-shereafy, professor of physical chemistry, faculty of science, menofia university as he was the university supervisor for the m.sc. thesis of mr. mostafa sh. eraky.the financial and technical support for this work was provided by metallurgical r preparation method voc (v) isc (ma.cm-2) ff %  % solvothermal reaction (sr) 0.47 7.2 25 0.85 solid state reaction (ssr) 0.42 4.6 24 0.64 vmax imax voc isc 100 ff = ff voc isc pin a 100  = http://dx.doi.org/10.21622/resd.2017.03.3.244 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.244 249 resd © 2017 http://apc.aast.edu & d institute (cmrdi), egyptian ministry of higher educationand scientific research. references [1] j.j. scragg, p.j. dale, l.m. peter, g. zoppi and i. forbes."synthesis and characterization of cu2znsns4 absorber layers by an electrodeposition annealing route,"physica status solidi(b), vol. 245, pp 1772, 2008. 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"effect of post-deposition annealing on the performance of d.c. sputtered cu2snse3 thin films,"surface and coatings technology,vol. 205, no. 1, pp.196–200, 25 december 2010. [15] k.m. kim, h. tampo, h. shibata and sh. niki. “growth and characterization of co evaporated cu2snse3 thin films for photovoltaic applications," thin solid films, vol. 536, pp. 111– 114, 2013. [16] g.s. babu, y.b. kishore, y.b. kumar and v.s. raja. "growth and characterization of cu2snse3 thin films," materials chemistry and physics, vol. 96, pp. 442–446, 2006. [17] k.m. kim, h. tampo, h. shibata and sh. niki. "temperature induced phase transformation in coevaporated cu2snse3 thin films,"materials letters, vol. 116, pp. 61–63, 2014. [18] m. ibanez, d. cadavid, u.a. tamburini, r. zamani, s. gorsse, w. li, a.m. lo´pez, j.r. morante, j. arbiold and a. cabot."colloidal http://dx.doi.org/10.21622/resd.2017.03.3.244 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.244 250 resd © 2017 http://apc.aast.edu synthesis and thermoelectric properties of cu2snse3 nanocrystals," journal of materials chemistry a, vol. 1, pp. 1421-1426, 2013. [19] j. wang, a. singh, p. liu, sh. singh, c. coughlan, y. guo and k. ryan. "colloidal synthesis of cu2snse3 tetrapod nanocrystals," journal of the american chemical society, vol. 135, no. 21, pp. 7835–7838, 2013. 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[24] p.u. bhaskar, g.s. babu, y.b. kumar and v.s. raja."investigations on co-evaporated cu2snse3 and cu2snse3-znse thin films," applied surface science, vol. 257, pp 8529–8534, 2011. [25] g.h. chandra, o.l. kumar, r.p. rao, s.uthanna. "colloidal synthesis and thermoelectric properties of cu2snse3 nanocrystals,"journal of materials science, vol. 46, pp 6952–6959, 2011. [26] a. astam.“structural and optical characterization of cu2snse3 thin films prepared by silar method,”thin solid films, vol. 615, pp 324–328, 2016. [27] a. prasad and a. basu."dielectric and impedance properties of sintered magnesium aluminum silicate glass-ceramic," journal of advanced ceramics, vol. 2, pp. 71–78, 2013. [28] a. chaouchi and s. kennour."impedance spectroscopy studies on lead free (ba0.85ca0.15) (ti0.9zr0.1) o3 ceramics," processing and application of ceramics, vol. 6, pp. 201–207, 2012. [29] m. david, b.j. marc, a. cyril, b. annelise, d. laurentand d. elisabeth. "influence of crystallinity and particle size on the electrochemical properties of spray pyrolyzed nd2nio4+δ powders,"electrochimica acta, vol. 87, pp. 330-335, 2013. [30] k.prasad, a. rao, k. tyagi, n. chauhan, b. gahtori, s. bathula, a. dhar."enhanced thermoelectric performance of pb doped cu2snse3 synthesized employing spark plasma sintering,"physica b, vol. 512, pp 39–44, 2017. http://dx.doi.org/10.21622/resd.2017.03.3.244 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.147 147 environmental compensation for port extension: the case of rotterdam harbour and nature compensation, policy and practice f. van der meulen frank van der meulen consultancy, de ruytersingel 56, 2253 tx voorschoten, the netherlands frank.vandermeulen@hetnet.nl abstract the paper focuses on two aspects often forgotten when dealing with smart ports: ecology and compensation of damage. the port of rotterdam (the netherlands) recently built a large extension, maasvlakte 2. it was built in an area with valuable coastal ecosystems belonging to the eu natura 2000 network of european conservation areas. the construction and use of maasvlakte 2 causes considerable damage to existing natura 2000 sites. according to eu regulations, this damage should be compensated by creating new nature. in the case of rotterdam, the compensation was twofold: a marine and a terrestrial part. the paper describes the design and the actual lay-out of the compensation works. it also reports on the monitoring that is ongoing to assess the damage to existing nature and the quality of the new (compensated) nature. keywords port extension, environmental damage and compensation, eu natura 2000, building with nature. i. introduction the dutch government decided in 2003 to develop a policy which enabled a new harbour extension (called maasvlakte 2), in order to receive and handle the world's largest containerships, starting from 2015. maasvlakte 2 (net 1000 ha, which is 20% of the already existing harbour area) was build between 2008 and 2014 by reclaiming part of the north sea with foreshore nourishment (365 mm3). it is expected that the new harbour will be in full operation by 2030. maasvlakte 2 extends in the middle of an environment with valuable coastal and marine ecosystems. they are under protection of the eunatura 2000 network. in such a case, eu-regulations state that construction is only allowed when there are imperative reasons of overriding public interest to carry out the plan, when there is no alternative, and when the submitter of the plan commits himself to compensate for the damage it causes. it concerns the environmental damage to natura 2000 sites that will be caused by the new harbour and its activities. it is important to understand that the compensation activities should start at the same time and parallel with the activities for the new harbour, and not, if at all, afterwards. to convince possible opponents it was decided by the eu-permits to start with the compensation measures before or at least at the moment of beginning the extension. compensation is realized at other locations nearby the port extension (figure 1). it involves marine ecosystems (fish, sea bottom fauna and bird communities) as well as land ecosystems (beach and dune ecosystems). marine compensation is necessary because the new harbour was reclaimed from the sea, causing loss of habitats and foraging areas. beach and dune compensation was necessary because the eia predicted that important existing dune ecosystems nearby will be damaged by the use of the new harbour (extra air pollution by more harbour traffic). in order to assess whether the predicted environmental damage indeed will occur and whether, in the future, the quality of the new nature indeed will compensate for this damage, an extensive monitoring program is running. the case of rotterdam is of importance to mirror with harbour development worldwide to achieve innovative smart solutions in a more sustainable way. key concepts are compensation of irreversible damage to nature and building with nature. http://dx.doi.org/10.21622/resd.2016.02.2.147 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 148 fig .1. the netherlands (inset) and part of the south western delta coast of the north sea. in the middle the new harbour extension (maasvlakte 2) in outline. the dunes of voorne's duin, kapittelduinen and solleveld are nearby natura 2000 areas that will suffer expected environmental damage. spanjaards duin, in the north, is the new dune and beach compensation area. in the south in the voordelta (a shallow sea in front of the coast, also a natura 2000 area) is the area where marine compensation measures are taking place (yellow boundary). image: google earth.. ii. methodology monitoring of the compensation was done using the latest techniques. in the case of dune compensation: terrain morphology (gps transects and laser altimetry), groundwater (piezometers and chemical analyses), vegetation (vegetation samples and individual species records) and in the case of marine compensation: sea bottom fauna, hyperbenthos and fish, countings of indicator sea birds, countings of trawl activities, and countings of water recreation activities. for both compensation activities a special monitoring scheme was developed. this contains main evaluation questions with factsheets per question. each factsheet contains sub questions, the kind of information required to answer the sub question and the strategy needed to acquire this information 8  eu natura 2000 natura 2000 is a network of specially protected areas, both on land and sea, in the 28 member states of the eu, meeting the requirements of the euhabitat directive. it is the largest coordinated network of protected areas in the world. when natura 2000 sites are predicted to be damaged by construction of a project, and the project is of outstanding national economic importance ("imperative reason of overriding public interest, without a proper alternative"), the damage needs to be compensated (article 6.3 and 6.4 of the euhabitat directive)(ec.europe.eu/environment/nature2000). iii. dune compensation (project being carried out with dr bert van der valk, deltares, delft, the netherlands)  damage to existing dunes and compensation targets the eia1 for the extension of maasvlakte 2 predicted that the use of the new harbour would damage important dune ecosystems in the nearby existing dunes. these ecosystems belong to the eu natura 2000 network and, under european habitat directive regulations, have to be compensated. they are: h 2190 (nutrient poor calcareous moist dune valleys, or dune slacks) and h 2130 (nutrient poor, more or less calcareous dry dunes, so-called "grey dunes") 2 in the european context, the netherlands have a special requirement when it comes to maintaining the surface and improving the quality of these nutrient poor (n, p) dune environments. the predicted damage in existing dunes and the compensation targets in the new dunes are given in table 1. table 1. dune compensation targets in new constructed dunes of spanjaards duin in relation to predicted losses in existing natura 2000 dunes. see also figure 2. dune compensation targets loss (ha) compensate (ha) moist dune valley (h 2190) 1,3 6,5 (x5) grey dune (h2130) 4,2 9,6 (x2) species: fen orchid liparis loeselii 1 population 1 population loss of nutrient poor habitats compensate nutrient poor habitats the damage to these ecosystems occurs because the use of the new harbour will cause an increase in traffic and industrial activities. this will raise the level of nox emissions. the extra airborne n-load will affect the nutrient household of the nutrient poor dune ecosystems. the higher nutrient level will cause some common plant species to encroach and take over the space of several rare plants that are journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.147 149 characteristic of h2190 and h2130.  dune compensation and nourishment in order to compensate for this loss, a new dune and beach area was constructed by beach and foreshore nourishment. the work was done in 2008 in combination with a larger regular nourishment works along the dutch delfland coast. the new area covers 35ha and involves 6,5 x 10million m3 of sand. the nourishment was done by dredging the sand some 19km offshore and piping it onshore from a close-by connection point (figure 1). subsequent shovel work formed the basic shape according to its design (fig 2): an elevated (5-7m above msl) dry and undulating ridge, the new frontal dune, and a flat depression (ca. 2.5m above msl) or dune valley, later to become moist due to rising fresh groundwater level. because of sand mobility (see paragraph below), part of the nourished material had to have a specific grain size (180-250μ), which is slightly smaller than the average sea bottom sediment in front of the coast. however, earlier surveys showed that there was enough material present in the neighbourhood. fig .2. top left: construction of the compensation area in front of the existing coastal fore dunes (at right) by beach and foreshore nourishment. the contours of the designed elongated moist dune valley, a flat depression, are already visible in the middle (photograph courtesy nico bootsma, rijkswaterstaat). top right: design of the new dune area in front of the delfland coast. grey=existing dune, yellow=new beach, orange=new dry dune, green=new moist dune valley. from veeken et al.3 bottom: compensation targets grey dune (left) and moist dune valley (right). the fen orchid occurs in the latter.  dune compensation and building with nature building with nature is a technique that is being used more and more when constructing, restoring or reshaping landscapes, also at the coast. applying this technique means that the characteristics and spontaneous forces, materials and elements of the local environment are used as much as possible 4. for example, to strengthen a sandy coast with sand nourishment and not with hard materials like concrete or basalt, can be considered building with nature. in the case of the compensation area, building with nature was applied 4, 5.  phases of new dune development the ecosystems that have to be compensated take time to develop. grey dunes take 15-20 years. a moist dune valley about five years (partly because http://dx.doi.org/10.21622/resd.2016.02.2.147 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 150 of settlement of the appropriate groundwater dynamics and quality). the development of the area was foreseen in four phases (table 2) and started from the design (figure 2). some phases run successively, like the development of the abiotic habitat conditions first, followed by the biotic elements. first the basic foundation was laid out by sand nourishment. after this basic foundation, free movement of sand and spontaneous sand transport (erosion and accumulation by wind) were allowed to take place. this causes some remodelling of the basic shape and also the formation of appropriate aeolian initial dune soils, the appropriate condition for colonisation and growth of vegetation. during this phase, the salt/brackish sand material has gradually been desalinated by precipitation; and consequently a fresh groundwater lens will develop in the subsoil, also fed by infiltration of freshwater from the (thin row of) mainland dunes (fig 2, right). after some time (expected 4-6 years in this case), the phreatic level of this lens will rise up to the valley floor, creating habitat requirements for a moist dune valley, and, eventually, moist dune slack vegetation (h2190). because of sand mobility, part of the nourished material had to have a specific grain size (180-250μ), which is slightly smaller than the average sea bottom sediment in front of the coast. table 2. phases of dune development and building with nature phases of development natural elements and processes involved construct basic foundation sand that is characteristic of the region remodelling of sand by wind transport development of appropriate groundwater dynamics and quality building of natural dunes and valleys by erosion and accumulation desalinisation of sand by precipitation successive colonisation of plants and development of plant (and animal) communities allow spontaneous, natural colonisation, no active, deliberate planting of dune species management to steer if needed aim at compensation targets  monitoring in order to assess whether the dune area develops in the right direction of the target habitats, a monitoring program was established. it concerns dune geomorphology, groundwater and vegetation. also, there are monitoring activities in the existing dunes especially concerning their nutrient (n,p) status.  overall results about seven years after construction, the area is still very dynamic (figure 3). vegetation is scarce. however, the abiotic conditions for the development of the compensation targets, the nutrient poor dune grasslands, are nearly in place. signs of the development towards grey dunes can be seen. the area functions in a number of ways: for coastal defence, nature conservation and also recreation. in the densely populated environs of rotterdam harbour in the dutch delta, this is regarded as a very positive situation. to ensure that nature development can take place, free access is not allowed. the new area is already under natura 2000 protection. fig .3. the new area development of spanjaards duin (2013). wind activity is clearly visible. former (existing) coastal fore dunes are to the left. new embryo dunes formed by wind and sand captured by marram grass are in the middle. prospective wet dune valley and new fore dune ridge are to the right. harbour of rotterdam (maasvlakte 1) is in background. north sea is (just visible) to the right. iv. marine compensation  damage and compensation targets maasvlakte 2 was reclaimed from the sea, in this case the voordelta, a shallow marine environment of high nature value, belonging to the eu natura 2000 network (h1110, shallow seas with sand flats permanently inundated and tidal inundations). journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.147 151 maasvlakte 2 has taken away 2,000ha of sea. rather than creating more new sea, it was decided to improve the quality of existing waters nearby in the voordelta with ca 10%. besides the loss of sea environment and sea (bottom) fauna (fish, benthos), there was also an expected damage to resting and foraging areas of seabirds (common scoter, sandwich tern, and common tern). these birds are most sensitive to disturbance in their habitats. in time after the construction of maasvlakte 2, it was expected that currents will create a sea bottom pit (near the sea defense wall surrounding the harbour) of 500 ha, which also needs to be compensated. the following marine compensation targets were set: (i) create a marine protection area of 2,500x10 = 25,000ha in the voordelta and within the protected area, and (ii) establish resting places for the three most sensitive seabird species, common scoter, sandwich tern and common tern (figure 4) (table 3). fig .4 top: marine compensation in the voordelta (orange boundaries) and the marine protection area (red) and the resting areas for seabirds (yellow). bottom: from left to right common scoter, sandwich tern and common tern. table 3. marine damage and compensation targets. see figure 4. damage compensation target 2,500ha sea(bottom) lost establish 25,000ha marine protection area to restore sea bottom (communities) and fish. resting and foraging places for seabirds lost create new resting places within protection area to restore sea bird populations http://dx.doi.org/10.21622/resd.2016.02.2.147 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 152  compensation measures and monitoring 6 ,7 in the protection area bottom trawling with vessels >260 hp were stopped. it was expected that this would improve the numbers of fish and of sea bottom fauna. and that this would favor the bird numbers because of an increase in food source. in the resting areas all human activity was banned. monitoring was set up to see whether the predicted damage could be sufficiently compensated. the monitoring concentrated on (i) benthos (sea bottom fauna), (ii) birds, (iii) fish, (iv) abiotics and (iv) human use of the area. the first phase (t1) of the monitoring period was from 2009-2013. before this, a t0 period was monitored between 2004 and 2007. during t1 the reference area was the voordelta area outside the protection area.  monitoring results the following results have been obtained after four years of measuring. (i). it was not possible to find a significant correlation between the stopping of fisheries activities and trends in the sea bottom. one possible reason for this is that already in 2004 fisheries activities were reduced by 80%. (ii) it was not possible to find a significant correlation between numbers of the three bird species (and their spatial distribution) and the establishment of new resting places. these results are valid for comparison of the compensation areas both with the reference area and with the t0. as a consequence, at the moment a clear sign that the damage to the marine environment is sufficiently compensated cannot yet be seen. v. discussion there are several factors that can play a role to explain the results in the voordelta. since the closing of the large sea inlets in this delta area (1960-70ies) as part of the dutch delta plan, this area has not yet reached its new equilibrium. because of this and by the nature of the environment itself, the area has a high degree of hydrodynamics. there are great autonomous spatial and temporal changes in abiotic conditions of water and soil. these may cause differences in benthos and fish per time lap, which are larger than the consecutive monitoring differences. also, the data on numbers of birds and their spatial distribution show large differences between the years, larger than those between the compensation and the reference. in this case, also the monitoring period (four years) is too short to detect significant effects. another important factor is that birds and fish do not stay in the same protected area and reference area. they move to other areas and (may) come back. so, their population dynamics is influenced, not only by ecosystem changes in the area itself, but also in other areas (far away). thus, it is difficult to attribute changes only to the compensation measures in the marine protected area. finally, monitoring is being done not only to assess whether the compensation is going to be sufficient, but also to understand more about the relationship between the various elements (birds, fish, benthos, nutrients, and water conditions) in this marine ecosystem. the monitoring will continue for at least another 4year period. this will give more insight in the ecosystems itself (life strategies, carrying capacity, food chains, and resilience). it is expected that new answers can be given to evaluate the compensation efforts. vi. conclusions large-scale technical activities for harbour extension always damage coastal nature. the eu compensation principle can contribute to restoration and new nature development and to more sustainable overall coastal solutions. key concepts are compensation and building with nature. success of a project like this depends on a multidisciplinary cooperation and patience. close cooperation between civil engineers, policy makers and ecologists is necessary. time should be given to nature to develop itself. this time is often longer that politicians can wait. area protection is necessary to allow for undisturbed developments of new nature. the case of rotterdam harbour is of importance to mirror with harbour development worldwide. it is a case that considers, at the same time and right from the beginning, economic development and ecological quality. journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.147 153 vii. acknowledgements mr gerard van der kolff and mr theo prins (deltares, delft, the netherlands), project leaders of the marine compensation project, supplied literature and data on their project. this help is kindly acknowledged. references [1] roal haskoning nederland. milieueffectrapportage (eia) en strategische milieubeoordeling bestemming maasvlakte 2. a)hoofdrapport,b) effectrapport. 2006. in opdracht van projectorganisatie maasvlakte 2. port of rotterdam. in dutch. [2] f. meulen, b. van der, van der valk, k., vertegaal and m. van eerden. "building with nature' at the dutch dune coast: compensation target management in spanjaards duin at eu and regional policy levels." j coast conserv., 2015 . doi 10.1007/s11852-014-0368-2 [3] l. veeken, j. ter hoeven and j. fiselier . ontwerpplan duincompensatie delflandse kustkustvisie zuidholland.. dhv/h+n+s/alterra , 2007, 141 pp. in dutch. [4] f. meulen, b. van der, l. van der valk, e. baars schoor and h. van woerden. "development of new dunes in the dutch delta: nature compensation and 'building with nature." j coast conserv., 2014, doi 10.1007/s11852-0140315-2. [5] r.e. waternan. integrated coastal policy via building with nature. opmeer drukkerij, den haag, 2008. [6] t.c. prins, a.r. boon, j. reinders, c. kuijper, g. hendriksen, h. holzhauer, v.t. langenberg, j.m.a. craeijmeersch, i.y.m. tulp, m.j.m. poot, h.c.m. seegers, j. ademaand g.h. van der kolff. (2014) monitoring natuurcompensatie voordelta: eindrapport 1e fase 2009-2013 deel a. deltares rapport 1200672-000 zks-0042 http://kennisonline.deltares.nl/product/30731 in dutch. [7] prins, t. c. and van der kolff, g. h. ( eds)(2014) monitoring natuurcompensatie voordelta: eindrapport 1e fase 2009-2013 deel b". deltares rapport 1200672-000-zks-0043, in dutch http://kennisonline.deltares.nl/product/30737. [8] plan van aanpak meetstrategie mep duinen, duinen en effectivteit compensatieproject delflandse kust, deltares 2009. 99pp + app in dutch. http://dx.doi.org/10.21622/resd.2016.02.2.147 journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.234 234 resd © 2017 http://apc.aast.edu the application of solar energy in agricultural systems mohammad vahedi torshizi and atefeh hosseini mighani department of bio-system mechanical engineering, gorgan university of agricultural sciences and natural resources, gorgan, iran. mohammadvahedi4130@gmail.com abstract given that one day fossil fuels will end, a need arises to find alternative fuels. renewable energy is considered an alternative to fossil fuels and nowadays it attracts much attention. among renewable energy sources, solar is the most important because it is available in all parts of the world. also, this energy source is used in various industries including agriculture and it can be used in cultivating crops in the farthest corners of the world. in addition, this fuel does not cause pollution, like the other fossil fuels. using the solar energy can be active in all agricultural areas. that will definitely help meet the increasing need for agricultural products with the increasing population. however, it is known that the agricultural land has a fixed area and, sometimes, agricultural products cannot be cultivated. that greenhouse is a method that is used nowadays and using the solar energy can help build solar greenhouses in areas far away from the city. other applications of solar energy include irrigation, drying products, and ventilation niches. in this study, the researchers discuss some of the benefits of solar energy in agriculture. keywords fossil fuels, solar energy, agriculture. i. introduction the energy sector has a direct impact on the economic development of a country [1]. nowadays, 85-90% of the world's primary energy is produced from fossil fuels [2]. there is a limited storage of fossil fuels and one of the important reasons for recession in world’s economy is the continuously increasing prices of these fuels [3]. to solve the problem of the decreasing economy and the energy sector’s related issues, all the world is focusing on an effective utilization of renewable energy resources like solar, wind, thermal and hydro [4,5]. fossil energy supplies became available about 200 years ago [6]. in addition, shortages of cropland, fresh water, fossil energy (fertilizers and irrigation), and biological resources now plague agricultural production in many parts of the world [7]. however, resources of fossil energy have begun to decline and this trend intensified after the year 2000 [8]. the use of renewable energy in the farming systems have several different applications. applications of renewable energy also include generation of power to do a number of farm works: pumping water for irrigation, for keeping livestock, or for domestic use; lighting farm buildings; powering processing operations, and other uses. these forms of renewable energy include solar energy, wind and water power, oil from plants, wood from sustainable sources, other forms of biomass (plant material), and biogas (gas produced from fermentation of manure and crop residues) [9]. the foundation of all agricultural production rests on the unique capability of plants to convert solar energy into stored chemical energy [8]. solar energy is the most appropriate option among other renewable energy sources because the solar energy level is in line with the air condition demand [10]. also, solar energy technologies have a long history. between 1860 and the first world war, a range of technologies developed to generate steam by capturing the sun’s heat to run engines and irrigation pumps [11]. taking into consideration the importance of solar energy and the increased attention humans are paying to renewable energy, this paper investigates the solar energy system in farming. ii. solar energy technologies there are two ways to convert solar energy into electrical energy; a system using photovoltaic technology and another that uses solar capture heating systems [12]. in the photovoltaic system, the sun rays are converted directly to electricity by semiconductors. in addition, in the method of heating, electrical power via the thermodynamic processes, with help of heat exchange equipment, can be converted to mechanical energy. these two methods are centralized and non-centralized. the photovoltaic method leads to more investments. however, in recent years with advances in the field of solar energy, thermal methods are used for power supply. http://dx.doi.org/10.21622/resd.2017.03.2.234 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.234 235 resd © 2017 http://apc.aast.edu fig .1. use of solar energy in agriculture iii. photovoltaic technology solar photovoltaic (pv) cells were invented at bell labs in the united states in 1954, and they have been used in space satellites for electricity generation since the late 1950s [12]. in this technology, solar rays collected via small plates that are semiconductor photovoltaic, are converted into electricity. photovoltaic cells can be built in two ways: concentrator and flat panel. solar cells are the most common type of flat panels where the light is immediately brought to semiconductor and is converted to electricity. yet, in the concentrator cells, first the sunlight is guided via the reflector, concentrated, and then the solar cell connects together. the solar cells are formed by solar modules. power cells and solar modules may be enough only to charge the battery and to build a system with output significantly requires that modules (figure.3) that work together and at same time. given that solar cells are connected together and making modules, also the modules for creating the appropriate voltage and current, are connected in series and parallel to that unit made in this way is called the solar array [13]. fig.2. solar photovoltaic panels providing green energy for agricultural growth iv. solar dryer preservation of food through drying is one of the oldest and the most widespread methods that can be used to enhance the strength of the food. drying food is removing the moisture so that the product can be stored for a long time and be protected against corruption [14]. by reducing the microbial enzyme activity and reducing the speed of chemical reactions, drying increases shelf life of the product. in addition, reducing the weight and volume of materials and packaging, facilitates transportation and storage of products and decreases the cost of these procedures [15]. in the case of drying, in addition to preventing the loss, the marketing can be controlled at sensitive times and potatoes required by many consumers (such as barracks, restaurants, etc.) can be delivered in a dried form [16]. using the sun for dry crops and grain is one of the oldest used applications of solar energy. solar dryers protect grain and fruits and vegetables, reduce losses, dry faster and more uniformly, and produce a better quality product than open-air methods [17]. solar-drying technology offers an alternative, which can process the vegetables and fruits in sanitary conditions to national and international standards and with zero energy costs. it saves energy, time, occupies less area, improves product quality, makes the process more efficient and protects the environment. [18] much research has been conducted about the dryer that kiebling has listed 66 different solar dryers, their (continue from the coming line) configurations, capacity, the products dried and their cost. [19] fuller (fuller, 1995) [20] and ekechukwu et al. [21] have reviewed many solar dryers, and compared their performance and applicability in rural areas. sharma [18] has presented a comprehensive review of the various designs, details of construction and operational principles of the wide variety of practically realized designs of solar-energy drying systems and a systematic approach for the classification of solarenergy dryers has been evolved. a review of new technologies, models and experimental investigations of solar driers has been presented by ramana [22]. http://dx.doi.org/10.21622/resd.2017.03.2.234 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.234 236 resd © 2017 http://apc.aast.edu fig.3. classification of solar dryers and drying modes solar dryers are conventional dryers so that supplementary equipment is added to enable a significant proportion of the thermal energy required for drying to be replaced by solar energy. in these types of dryer, a planned, and generally optimized drying process can be achieved to obtain superior product quality and good economic performance. any influence of the weather conditions on product quality and on the performance of the dryer can be eliminated by using an independent energy source, if needed, and proper control facilities [23]. the construction of the solar assisted dryers is relatively complex compared to other dryers. they usually consist of a solar collector, a fan, a heat storage system, a burner/heater, and a control system. they can handle large quantities and deliver good product quality [24]. v. ventilation systems for agricultural applications therefore, the application of pv can be the best choice because in the event of a grid power break down, pv will take over to supply power, hence potentially saving thousands of birds. direct current motors can also operate directly with pv power and eliminate the use of an expensive inverter. the taiwanese government increases benefits for livestock farmers who use solar energy to generate electricity specifically for pig farms to attract other farmers to build solar farms. a final report on delaware’s poultry farms reveals the economic and technical aspects of pv application for poultry farming. it also reports that pv offers additional benefits, such as security of supply, and economic and environmental advantages over grid electricity supply and conventional energy sources [25, 26]. vi. use of solar energy in farm houses electrification to farm is difficult in some places and the cost is very high and for the sake of reducing costs, solar energy can be used because it is available in all locations and can provide the electricity and fuel needed, for a home can provide home lighting lamps and other appliances, with using solar energy. but the question is for cooking and heating water heaters: what should one do? it is true to fix such problems by using solar cookers and water heaters. vii. solar home seamlessly photovoltaic building that has been worn and has become one of the most popular homes. and it is used more in areas where there is not electrical grid. photovoltaic panels are installed on the roof or walls to get sunlight. solar energy is produced in the same location and can also save additional energy. this technology is cheaper and promising and more power can be produced for home. figure below is a model configure to indicate buildings with photovoltaic energy. for areas where electricity grids are not very useful, it helps the region supply with the fewest problems of electricity [27] fig.4. building integrated photovoltaic system viii. solar cooker solar cookers are systems of clean energy, available and inexpensive sun that is used for cooking food. a solar cooker inhabited radiant heat by rays focusing it on a surface or locking it in a greenhouse space. rather it should be used for cooking [28]. given that in developed countries about 90% of household http://dx.doi.org/10.21622/resd.2017.03.2.234 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.234 237 resd © 2017 http://apc.aast.edu energy consumption is devoted to cooking [29]. these systems can do almost everything like an electric rice cooker or gas stove, such as roasting, brewing, cooking, frying or reheating refrigerated cool foods, including cases that are possible with the solar cookers [30], hence solar cookers are in two forms, direct and indirect. the direct solar cooker consists of an insulated box with transparent window, through which the sunlight enters. it is the most developed and it is for home cooking [27]. in the indirect stove fluid is used for heat transfer from the collector to a baking sheet [31]. fig.5. schematic solar cooker ix. solar water heater systems water heaters are one of the most common applications of solar energy for home and industrial applications and similar solar dryers, water heating systems are also available in natural convection and forced convection scheme and figure (6) shows one water heater [9]. solar water heaters are divided into two categories: direct and indirect. in direct water heaters, water is consumed in the current collector, becomes hot and then is consumed, but in the indirect water heater, the water consumed is used for heating a fluid. the disadvantage of direct solar water heaters is that after a while the collector is blocked with a crime. also, the thermal energy transfer to the water consumed is wasted [32]. fig.6. a sample of a solar water heater in general, in solar water heaters, in order to use hot water when not benefitting from the sun, the hot water is stored in the reservoir. in some solar water heaters, a water tank is installed above the collector and hot water for natural convection is stored in the tank. to the water heater said thermo syphon. in figure (7) shows a direct solar water heater [33]. fig.7.schematic direct solar water heaters in the indirect solar water heaters, a tank is installed in a separate space in order to provide power to flow in the collector by the used pump. that is why this water heater is said to be under pressure. in figure (8) a indirect solar water heater is shown [33]. fig.8. schematic indirect solar water heaters x. solar greenhouse the greenhouse is a structure that nowadays is used in agriculture to grow plants with the best quality. recently, solar energy is used for heating greenhouses so that such greenhouses are known as solar greenhouses (figure 9) and the solar energy can be used to provide light to the greenhouse. a very good step would be to reduce the need for fossil fuels used for heating [34]. after the oil crisis in 1973, researchers tried find to a convenient and simple solution for the use of solar energy in the greenhouse. overall, solar energy is used in greenhouses in three forms. the first type is famous http://dx.doi.org/10.21622/resd.2017.03.2.234 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.234 238 resd © 2017 http://apc.aast.edu as the inactive greenhouse (passive), and it uses thermal energy from radiation solar heated greenhouse. in the greenhouse, the construction method is carried out so as to provide the maximum use of solar radiation during the day and lead to the lowest energy losses during the night in greenhouses. the second type greenhouse is called greenhouse active (active), and it uses the pickers and transfer heated fluid, in heating greenhouses. in the third kind of greenhouses photovoltaic cells are used so that the solar radiation energy becomes electrical and then it is used in greenhouses [35, 36]. fig.9. a sample of a solar greenhouse xi. conclusion the solar energy can be found in the farthest corners of the world and it can be developed to electric power production and agriculture. one reason that, agriculture is not anywhere, and is lack of energy. but using solar energy can do the majority of cases related to agriculture. in addition, due to the reduced fossil fuel energy and also with using solar energy in agriculture can land, that is unusable into them, created the greenhouse or place for breeding animals converted in areas outside city. on foregoing, the use of solar energy is an investment for the future because we can use it for a long time. in addition, a company can use this method to create, build panels and install them. this creates jobs and helps the economy. references [1] aqeel and m.s. butt. “the relationship between energy consumption and economic growth in pakistan.” 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[33] h. dehghani pur. solar water heaters. islamic azad university of qazvin.2012. http://dx.doi.org/10.21622/resd.2017.03.2.234 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.234 240 resd © 2017 http://apc.aast.edu [34] givoni. . “climate considerations in building and urban design.” ny, van nostrand reinhold, pp 175-176, 1998. [35] m. grafiadellis and s. kyritsis. “heating greenhouses with solar energy.” acta hort. vol. 115, pp. 553-560 ilo, 1986. [36] m. santamouris a. argiriou and m. vallindras. “design and operation of a low energy consumption passive solar agricultural greenhouse“. solar energy, vol. 52, no. 5, pp. 371-378, 1994. http://dx.doi.org/10.21622/resd.2017.03.2.234 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ 182-1054-1-ce-69-1 182-1054-1-ce-69-2 journal of renewable energy and sustainable development (resd) volume 2, issue 1, june 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.1.030 30 soil inertia and shallow basement envelope impact on cellar internal temperature naima sakami1, lahcen boukhattem1, hassan hamdi2 1 enr2e, cneree, cady ayyad university, marrakech, morocco 2 lmfe urac27-cnrst, fs, cady ayyad university, marrakech, morocco sakami.na3@gmail.com abstract this study deals with a three dimensional numerical study of heat transfer by conduction between the soil and the shallow basement in the city of marrakech (morocco). the heat transfer equation is solved by the finite difference method using the implicit alternative direction (adi). the internal temperature of the cellar is computed by using energy balance equation in the cellar. the objective of the study is to evaluate the effects of the nature of the soil, the nature of the walls, the thickness of the walls of the cellar, the distance l far from the cellar on the internal temperature, and the heat exchanged between the soil and the shallow basement. keywords adi scheme; internal temperature; nature of soil; basement; heat flow. nomenclature l distance delimiting the disrupted area along x axis, m d distance delimiting the disrupted area along y axis, m h depth of the water table, m e thickness, m t temperature, °c cp specific heat, j kg-1 k-1 ρ density, kg/m3 λ thermal conductivity , w/mk ds internal elementary surface of the wall, m2 t time, s hc the overall exchange coefficient, wm-2k-1 v volume of shallow basement, m3 α thermal diffusivity , m2/s 𝑞 mass flow rate of fresh air, kg/s subscripts – a air amb ambient m wall p floor s soil w water table wall wall surface int inside shallow basement i. introduction the interest of the study of the heat transfer in the basement is to show the importance of the soil inertia in the hot regions such as marrakech. owing to the very high thermal capacity of the soil, the temperature of the ground is lower than that of the outdoor air in the summer and higher in the winter. consequently, the heating and cooling energy of a building considerably sunk into ground is lower than that one above the ground. thus, accurate estimation of loads and energy consumption due to thermal interactions between a building and the ground is needed. this is a difficult task since this analysis needs to include the multidimensional nature of most earth-coupled heat transfer processes, large phase lags caused by soil thermal mass, limited practical ability to model soil thermal proprieties and the variability of soil temperature with ground surface conditions [1]. it is difficult to derive analytical solutions for 3d transient ground-coupled heat transfer even for the simple rectangular slab-on-ground problem. the only available 3d analytical expression is the steady-state solution derived by delsante et al. [2] for a rectangular slab-on-ground with the assumption of a linear temperature distribution along the base (wall/ground interface) of the external walls. a semianalytical method inter-zones temperature profile estimation (itpe) has been developed by krarti et al. [3]. it combines analytical solutions for regularshaped components and numerical techniques to connect these components to construct the ground model. the itpe method is used to calculate the approximate analytical solutions for the threehttp://dx.doi.org/10.21622/resd.2016.02.1.030 journal of renewable energy and sustainable development (resd) volume 2, issue 1, june 2016 issn 2356-8569 31 dimension heat transfer between slab-on-grade floors and rectangular basements under steady-periodic conditions. w.r. bahnfleth developed a detailed three-dimensional finite difference model for heat conduction from slab-on-grade floors and basements, including a detailed ground surface energy balance. [4]. m. p. deru [5] used the two dimensional finite element to study the effects of moisture on the heat transfer from two basic types of building foundations, a slab-on-grade and a basement. a two-dimensional finite element heat and moisture transfer program is used to show the effects of precipitation, soil type, foundation insulation, water table depth, and freezing on the heat transfer from the building foundation. recently m. staniec and h. nowak [6] determined the earth sheltered building’s heating and air-conditioning energy demand depending on the type of soil in which it is founded. for comparison, the corresponding results for the above ground building are presented. in marrakech, several studies have been made to analyze the heat exchange between the ground and a building. a. abdelbaki generated a two-dimensional transfer function coefficients (tfc) for a slab-ongrade floor [7]. later, tfc have been derived successfully for shallow basement [8, 9] and earthsheltered building [10]. it has been shown [7, 9] that the results obtained using the transfer functions method fully agree with those obtained using the itpe technique and the adi technique. recently l. boukhattem [11, 12] used the adi method to study the effects of the parameters of mortar on the heat exchange between the soil and the two buildings: buried building and semi-buried building. in this work, the researchers have developed a computer code that allows them to study the effect of the nature of the soil, the nature of the walls of the underground building, the thickness of the walls, the distance l of the disrupted area on the internal temperature, and the heat exchanged between the soil and the shallow basement. ii. mathematical formulations and boundary conditions a. configuration of the studied shallow basement the configuration treated in this work is illustrated in figure 1. the basement has a rectangular shape with a width of 2b, a length of 2a and a depth of c. the wall and the floor are assumed to have identical thermal conductivity and thermal diffusivity. the results presented in this section are obtained for: a=2 m; b=2 m; c=2 m and em =0.26 m the overall heat transfer coefficient [3, 8, 11] is: hc=8.30 wm-2k-1. fig .1. building with a shallow basement because of the symmetry of the studied configuration, the study is reduced to a quarter of the shallow basement (figure 2) fig .2. shallow basement configuration b. mathematical model the unsteady three-dimensional heat transfer equation can be written as follows: 2 2 2 2 2 2p t t t t c t x y z                 (1) this equation was solved by an improved alternatingdirection-implicit (adi) finite-difference numerical method. a fortran program was built for this analysis. soil i shallow basement journal of renewable energy and sustainable development (resd) volume 2, issue 1, june 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.1.030 32 minimum cell dimensions were established in accordance with the accuracy and stability criteria set forth by the numerical method employed in the study. grid spacing in the present model in the vicinity of the building foundation ranged from 0.2 m to 0.3 m, while spacing at far-field and deep-ground boundaries was as large as 1.3 m. c. real climate of marrakech the simulation by the adi method is made by considering the real ambient temperature of marrakech. this temperature was measured by the weather station of agdal marrakech. figure 3 shows the variation of medium ambient temperature during one year (2008). the water table at a depth of 13 m below the soil surface is maintained constant at 20 °c. fig .3. external air temperature the boundary conditions of the studied problem are:  in the two planes of symmetry: 0)(int    0x tz,y,x, x t (2) for 0d y   and 0h z   0)(int    0y tz,y,x, x t (3) for 0l x   and 0h z    far from building: ( ) 0s x l t x, y, z,t x     (4) for 0d y   and 0h z   ( ) 0s y d t x, y, z,t y     (5) for 0l x   and 0h z    interfaces internal air-side of the building : int ( ) ( ( ) )s scs x a t λ x,y,z,t t -a,y,z,t t x h       (6) for 0b y   and 0c z   int ( ) ( (x ) )s scs y b t λ x, y,z,t t ,-b,z,t t y h       (7) for 0a x   and 0c z   int ( ) ( (x ) )s scs z c t λ x,y,z,t t ,y,-c,t t z h       (8) for 0a x   and 0b y    interfaces soil-external walls of building : mm ( )( ) ( , , z, ) ( , , z, )m s s x a ex a e m t t λ x y t λ x y t xx         (9) for 0 m b e y    and mm (b )(b ) ( , , z, ) ( , , z, )m s m s y ey e t t λ x y t λ x y t xx         (10) for 0 m a e x    and 0 m c e z    mm (c )(c ) ( , , z, ) ( , , z, )m s m s z ez e t t λ x y t λ x y t xx         (11) for 0 m a e x    and 0mb e y     air temperature and water table temperature: ( , , 0) amb t x y t and ( , , h) w t x y t  (12) for 0l x   and 0d y   the heat flow is calculated by the following equation: 0 10 20 30 40 j f m a m j j a s o n d t(°c) t(°c) 0 m c e z    http://dx.doi.org/10.21622/resd.2016.02.1.030 journal of renewable energy and sustainable development (resd) volume 2, issue 1, june 2016 issn 2356-8569 33  intc wallheat flow h ds t t  (13) d. the local heat balance the energy conservation law for the internal medium of the shallow basement, which is considered as an open system is: de q w dt t t       (14) e is the total internal energy of the medium; q is the heat crossing the system boundary; w is the total work that is a sum of the work done by the pressure forces on the control surface and the flow work. thus, the volume v of the control volume remain constant, and as a result, the boundary work is zero. the kinetic and potential energies of air in the cellar are neglected. the air is considered as an ideal gas and the temperature of this one is uniform in the studied cellar, from the above assumptions, the equation 14 reduces to: 3 int int int 1 ( ) ( ) a aa p p amb c wall i t c v qc t t h ds t t t          (15) iii. results and interpretation a. code validation the researchers have elaborated a code that calculates the exchanged heat flow between a soil and shallow basement in 2d and 3d configurations. for computer code validation, they compared the results obtained by the present code and those of m. krarti [10] carried out for the same geometric which is characterized by depth b=3 m, width a=2 m, total width l=9 m and for thick walls e=0.4 m in 3d configuration. a non-uniform mesh in both directions, constructed using a geometric progression, was adopted with 36×38 grid dimension. figure 4 shows good agreement between the results obtained by the proposed code and those of s. amjad. the heat flow is calculated by the following equation:  intc wallheat flow h ds t t  fig .4. variation of the monthly heat flux. b. effect of the distance l at a large distance from the foundation, the effect of the shallow basement on the ground becomes negligible. to determine this distance, the researchers recognized several simulations by varying the distances l each time. table 1 shows the monthly heat flows for each distance. this result indicated that little or no change in predicted heat flow occurs when the far-field boundary is at 8 m or more away from the building. table 1. heat flow for different distances l. months heat flow l=2 m heat flow l=4 m heat flow l=6 m heat flow l=8 m j 297.18 312.74 317.30 315.86 f 214.30 225.51 228.80 227.76 m 129.04 135.79 137.77 137.15 a 100.70 105.97 107.51 107.03 m -7.49 -7.89 -8.00 -7.97 j -1.00e+02 -1.06e+02 -1.07e+02 -1.07e+02 ju -205.34 -216.10 -219.24 -218.24 a -163.57 -172.14 -174.65 -173.85 s -31.26 -32.90 -33.38 -33.22 o -19.81 -20.85 -21.15 -21.06 n 118.40 124.60 126.41 125.84 d 193.23 203.34 206.31 205.37 -40 -30 -20 -10 0 10 20 30 40 1 2 3 4 5 6 7 8 9 10 11 12 present work s.amjad month s heat flow(w) journal of renewable energy and sustainable development (resd) volume 2, issue 1, june 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.1.030 34 c. effect of soil types to evaluate the soil type effect on the cellar internal temperature sensitivity to changes in the external environment, the researchers have performed simulations for three different soil types whose characteristics are presented in table ii. table 2. characteristics of the studied soils. types of soil type 1 type 2 type 3 thermal conductivity w/mk 2.00 1.15 0.32 thermal diffusivity (10-7) m2/s 1.100 0.613 0.267 figure 5 shows the change in the internal temperature of the cellar for three types of studied soil. the thermal conductivity and thermal diffusivity of wall and floor are λm=1.73 w/mk, and m=9.3.10-7 m2/s, respectively. in general, it is observed that there is stability in the internal temperature of the cellar throughout the year that can be explained by the considerable effect of inertia of the soil. this stability is even more important for soil 3 which is characterized by low conductivity and low thermal diffusivity. fig .5. daily variation of the external temperature and the internal temperature for three types of soil during a year. in summer time, the outside temperature increases to 45 °c while that of the interior does not exceed 25 °c for sand and 23 °c for clay with 0.27% moisture content. one can see a difference in indoor temperature between soil 2 and soil 3. this is due to the moisture content that influences the internal temperature of the shallow basement (figure 6). fig .6. hourly variation of indoor and outdoor temperature for one week of the summer period for three soil types. during the winter period, the researchers found out that the cellar temperature does not descent below 16 °c for the three soil types, while the outer temperature recorded negative values in the range of -1 °c. they also found out that the internal temperature provides stability throughout the day with a small amplitude of 2 °c for soil type 1(clay) and 3 °c for soil type 3 (sand) for a weather temperature that have an amplitude of 12 °c (figure 7). fig .7. hourly variation of indoor and outdoor temperature for one week of the winter period for three soil types. therefore, when analyzing the type of soil surrounding the building one should use accurate measurements of soil thermal proprieties (conductivity and diffusivity). d. effect of the material type of the walls the determination of effect of construction materials on the internal temperature simulations was made for soil type 2 and for two building materials: reinforced 4 8 12 16 20 24 28 32 36 40 j f m a m j j a s o n d soil 1 soil 3 soil 2 tamb months t(°c) 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 1 16 31 46 61 76 91 106 121 136 151 166 181 soil 3 soil 1 soil 2 tamb t(°c) t(h) -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 1 16 31 46 61 76 91 106 121 136 151 166 181 soil 1 soil 3 soil 2 tamb t(°c) t(h) http://dx.doi.org/10.21622/resd.2016.02.1.030 journal of renewable energy and sustainable development (resd) volume 2, issue 1, june 2016 issn 2356-8569 35 concrete and hollow brick (table iii). the researchers observed that there is no significant difference between estimated temperatures for both materials. it can be deduced later that there is no effect on the nature of the walls of the internal temperature of the cellar for the studied cases (figure 8). table 3. characteristics of the studied walls. fig .8. hourly variation of indoor and outdoor temperature for one week of the summer period for two wall types. e. effect of the thickness of the walls figure 9 and figure 10 are obtained for a soil type 2, reinforced concrete wall and for different wall thicknesses in the real climate of marrakech. these results show that the influence of the wall thickness is not important; this is mainly due to the predominance of the thermal inertia of the soil compared to the walls cavity. fig .9. hourly variation of the internal temperature for two thicknesses of the wall for a week during the winter period. fig .10. hourly variation of the internal temperature for two thicknesses of wall for a week during the summer period iv. conclusion in this study, the researchers have developed a detailed fortran code to calculate three dimensional heat transfers for an envelope in contact with the ground. it allowed them to calculate the exchange of heat between the soil and the basement through the use of finite difference method in three dimensions and also calculate the internal temperature of the cellar, in the real climate of marrakech. we demonstrated the significant effect of the inertia of the soil on the stabilization of the internal temperature of the cellar. indeed, the average temperature inside the shallow basement varies between 16°c and 24°c throughout the year, with a magnitude of 8°c. on the other hand, the ambient temperature is between 4°c and 34°c with the amplitude of 30°c. this inertia is largely influenced by the thermal characteristics of the soil. in fact; the internal temperature is more stable with the ground having a low thermal conductivity and thermal diffusivity. during the summer season, the internal temperature does not exceed 24°c (soil 1) and 25°c (soil 3) when the ambient temperature reaches 44°c. during the winter season, the ambient temperature descend down to -2°c, while the internal temperature did not descend below 15°c (soil 1) and 16°c (soil 3). the study of the effect of the thickness of the wall and the wall-type shows that there is a difference of less than 1°c between the different studied situations (thickness and type of wall). so we can conclude that 15 16 17 18 19 20 1 16 31 46 61 76 91 106 121 136 151 166 181 t(h) t(°c) hollow brick reinforced concrete 14 15 16 17 18 19 20 21 1 16 31 46 61 76 91 106 121 136 151 166 181 t(°c) e=0,26m e=0,4m 19 20 21 22 23 24 25 26 27 1 16 31 46 61 76 91 106 121 136 151 166 e=0,26m e=0,4m t(°c) t(h) material type of the walls hollow brick reinforced concrete thermal conductivity w/mk 0.35 2.30 thermal diffusivity (10-7) m2/s 3.90 9.58 journal of renewable energy and sustainable development (resd) volume 2, issue 1, june 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.1.030 36 the type of wall and its thickness has little influence on the internal temperature of the cellar. in conclusion, we deduce that the semi-buried building reduces the cooling and the heating loads through the stabilization of the internal temperature. on the other hand, the thermal characteristics of the ground are a great influence on the temperature inside the building in comparison to the type and thickness of the walls. v. acknowledgements this study is a part of the rafribat project financially supported by a grant from the hassan ii royal academy of sciences and techniques, morocco. references [1] d. chen, “dynamic three-dimensional heat transfer calculation for uninsulated slab-onground constructions”, energy and buildings, no 60, pp. 420–428, 2013. [2] a.e. delsante, a.n. stokes, and p.j. walsh, “application of fourier transforms to periodic heat flow into the ground under a building“, international journal of heat mass transfer, vol. 26, no.1, pp.121–132, 1983. [3] s. choi, m. krarti, “thermally optimal insulation distribution for underground structures”, energy and buildings, no.32, pp. 251-265, 2000. [4] w.p. bahnfleth, “a three-dimensional numerical study of slab-on-grade heat transfer”, ashrae transactions, no. 96, pp. 61–72, 1990. [5] m.p. deru, “ground-coupled heat and moisture transfer from buildings”, national renewable energy laboratory. nrel/cp-550-29694, february 2001. [6] m. staniec and h. nowak, “analysis of the energy performance of earth-sheltered houses with southern elevation exposed”, eleventh international ibpsa conference glasgow, scotland july 27-30, 2009. [7] a. abdelbaki, “contribution à la modélisation des transferts thermiques à travers le plancher d’un habitat sur terre-plein” , des thesis, faculty of sciences semlalia, marrakech, morocco, 1993. [8] a. abdelbaki, s. amjad, and z. zrikem, “prediction of heat transfer from shallow basements to the soil by the two-dimensional transfer functions method”, in: proceedings of the 3rd renewable energy congress, reading, uk, 1994. [9] s. amjad, “contribution à l’étude du comportement thermique des bâtiments semienterrés”, des thesis, faculty of sciences semlalia, marrakech, morocco, 1997. [10] s. amjad, a. abdelbaki, and z. zrikem, “adaptation de la méthode des fonctions de transfert à une cavité enterrée”, in: proceedings of the 3rd mechanical congress, tétouan, morocco, pp. 497–502,1997. [11] l. boukhattem, a. bendou, r. mir, and m. kourchi, “simulation et optimisation des transferts de chaleur entre un bâtiment complètement enterré et le sol”, revue internationale d'héliotechnique, energie – environnement, no 36, pp. 27-35, 2007. [12] l. boukhattem, a. bendou, h. hamdi, and d.r. rousse, “simulation bidimensionnelle du transfert d’énergie entre un bâtiment semienterré et le sol en régime variable”, revue internationale d'héliotechnique, n°.44, pp. 23-29, 2012. http://dx.doi.org/10.21622/resd.2016.02.1.030 journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 11 resd © 2015 http://apc.aast.edu adaptive artificial intelligence based fuzzy logic 1 unité de recherche appliquée en energies renouvelables, uraer, centre de développement des energies renouvelables, cder, 47133, ghardaïa, algeria layachi40@yahoo.fr i. introduction in order to obtain an adequate output voltage, pv cells are connected in series to form a pv module. if higher voltages or currents are not available from a single module, modules must be connected into arrays. series connections result in higher voltages, while parallel connections result in higher currents (fig 1).the maximum power point tracking, mppt technique, not only enables an increase in the power delivered from the pv module, but also enhances the operating lifetime of the pv system [2]. various mppt methods have been developed and implemented [3][4]. these methods can be differentiated based on various features including the types of sensors required, convergence speed, cost, range of effectiveness, implementation hardware requirements, and popularity [4]. mppt techniques, such as the perturb & observe and the fuzzy logic methods, will be compared using matlab tool simulink, considering different types of irradiation and temperature variations. the partially shaded condition will not be considered in the simulation: the irradiation is assumed to be uniformly spread over the pv array [4]. fig 1. example of pv arrays ii. modelling and characteristic of pv array 1. modeling of pv array a solar pv array is developed in simulink. this array is used as a source for the maximum power point tracker system. the pv array makes use of the equations of a typical solar cell. the typical model of a solar cell is shown in fig. 2. the current and voltage of the solar cell is given as follows [01]: (1) (2) fig.2. simplified equivalent circuit of solar cell where and are the cell output current and voltage. the definitions of the parameters are keywords solar photovoltaic; mppt; p&o; fuzzy logic controller; pv array; dc/dc buck-boost converter abstract— there is an increased need for analysing the effect of atmospheric variables on photovoltaic (pv) production and performance. the outputs from the different pv cells in different atmospheric conditions, such as irradiation and temperature, differ from each other, evidencing knowledge deficiency in pv systems. maximum power point tracking (mppt) methods are used to maximize the pv array output power by tracking continuously the maximum power point (mpp). among all mppt methods existing in the literature, perturb and observe (p&o) is the most commonly used for its simplicity and ease of implementation; however, it presents drawbacks, such as slow response speed, oscillation around the mpp in steady state, and even tracking in wrong way under rapidly changing atmospheric conditions. in order to allow a functioning around the optimal point mopt, we have inserted a dc-dc converter (buck– boost) for a better matching between the pv and the load. in this paper, we study the maximum power point tracking using adaptive intelligent fuzzy logic and conventional (p&o) control for stand-alone photovoltaic array system. in particular, the performances of the controllers are analyzed under varying weather conditions with constant temperature and variable irradiation. the proposed system is simulated by using matlab-simulink. according to the results, fuzzy logic controller has shown better performance during the optimization. mpptcontrol for stand-alone photovoltaic system under different atmospheric conditions 2 electrical engineering department, university of biskra, algeria l. zaghba 1,2 , n.terki 2, a .borni 1, a.bouchakour 1 journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 12 resd © 2015 http://apc.aast.edu given in table 1.the equivalent circuit for the solar cells arranged in parallel and series is shown in fig.3. array current and array voltage become: (3) : represents the number of parallel modules. it should be noteded that each module is composed of cells connected in series. corresponds to the short circuit current of the solar array. fig.3. electrically equivalent of solar array circuit ( np parallel ns series) the output of simulink model is shows first; the v-p characteristics of pv module, for various irradiation levels (fig.7), and then v-i characteristics, reference to the key specifications of the msx60 array are illustrated in table 2 [01]. the results of simulink pv module show the excellent correspondence to the model. table 1. electrical specifications of the -60 w mono-crystalline photovoltaic module msx60 parameter value maximum power ppv 200w tension at pmax vmpp 26.3 v current at pmax impp 7.61a open circuit voltage voc 32.9v short circuit current isc 8.21a ideality factor a 1.3 table 2. electrical specifications of the 6kw mono-crystalline photovoltaic array of 100 module of msx60 parameter value maximum power ppv 60x100 = 6000w tension at pmax vmpp 17.1x20 = 342 v current at pmax impp 3.5x5 = 17.5a open circuit voltage voc 21.1 x20 = 422v short circuit current isc 3.8x5 = 19 a 0 50 100 150 200 250 300 350 0 5 10 15 20 25 30 voltage (v) c u rr e n t (a ) t = 0 c° t = 25 c° t = 50 c° t = 75 c° t = 100 c° g=1000 w/m² t =25 c° ,g=1000 w/m² pv array = 6 kw fig .4. v-i, characteristics of pv array (6kw) at constant insulations and varying temperature 0 50 100 150 200 250 300 350 0 1000 2000 3000 4000 5000 6000 7000 voltage (v) p o w e r (w ) t =0 c° t =25 c° t =50 c° t =75 c° t =100 c°g = 1000 w/m² t =25 c° ,g=1000 w/m² pv array = 6 kw fig.5.p-v characteristics of pv array (6kw) at constant insulations and varying temperature. 0 50 100 150 200 250 300 350 0 10 20 30 40 voltage (v) c u rr e n t (a ) g=200 w/m² g=400 w/m² g=600 w/m² g=800 w/m² g=1000 w/m² t =25 c° ,g=1000 w/m² pv array = 6 kw t =25 c° fig .6. v-i characteristics of pv array (6kw) at constant temperature and varying insulations 0 100 200 300 400 0 1000 2000 3000 4000 5000 6000 7000 voltage (v) p o w er ( w ) g=200 w /m² g=400 w /m² g=600 w /m² g=800 w /m² g=1000 w /m² t = 25 c° at g=1000 w/m² and t = 25 c° pv array = 6kw fig .7. v-p characteristics of pv array (6kw) at constant temperature and varying insulations 2. dc-dc buck-boost converter the dc-dc converter is an electronics circuit, which is used to provide a loss less transfer of energy between different circuits at different dc voltage levels. there are many dc-dc converters. one of the popular types of dc-dc converters is buckboost converter. the buck-boost converter is used to step down and step up the dc voltage by changing the duty ratio of the mosfet. if the duty ratio is less than 0.5, the output voltage is less than the input voltage; however, if the duty ratio is greater than 0.5, the output voltage will be greater than the input voltage. duty ratio is the time at which the mosfet is on to the total switching time. the buck-boost converter is shown in figure 8.the relation between the input and the output voltages of the buck-boost converter is given as follows: [7]. (4) journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 13 resd © 2015 http://apc.aast.edu table 3. buck-boost converter parameters buck-boost converter parameters l 1mh c1 1000 µf c2 330 µf fs 40khz resistive load r 5ω when applying kirchhoff's laws, we find:             r v id dt dv c vdvd dt di l d c i c i dt dv pv pvpv pvpv )1( .).1( (5) i is the current through the inductance; v is the voltage across the capacitor; d is the duty ratio and vpv is the voltage measured from the photovoltaic panel fig 8. fig. 8. the buck-boost converter circuit fig. 9. block diagram of pv module with mppt controller a. mppt using perturbation & observe this technique introduces a slight perturbation by decreasing or increasing the pwm duty cycle of the buck converter. this perturbation changes the power of the solar module. if the power increases due to the perturbation, the perturbation is continues in that direction [06]. after the peak power is reached, the power at the next instant decreases and hence that the perturbation reverses. when the steady state is reached, the algorithm oscillates around the peak point. to keep the power variation small, the perturbation size is kept very small. the flow chart of algorithm has 4 cases as shown in fig.10 [06]. fig .10. configuration of fuzzy logic controller in matlab/simulink b. mppt using fuzzy logic control fuzzy logic controllers have been introduced recently in the tracking of the mpp in pv systems. they have the advantage to be robust and relatively simple to design as they do not require complete knowledge of the exact model and can handle nonlinearity. the proposed fuzzy logic mppt controller, shown in figure 11, has two inputs and one output. the two input variables are the error e and change of error ce at sampled times k defined by eq. 6 and 7, where p and v are the pv panel power and voltage respectively at instant k: [8][9] [10][11] (6) (7) where: and are the power and the voltage of the pv generator respectively at instant k. the power of the pv system: start mesure v(i),i(i) p(i) = v(i)*i(i) p> 0 v(i)<v(i1) v(i)>v(i1) d(i) = d(i-1) d d(i) = d(i-1) d d(i) = d(i-1) d d(i) = d(i-1) d update v(i-1) = v(i) ;i(i-1) =i(i) retur n 3. maximum power point tracking maximum power point tracking controller is basically used to operate the photovoltaic modules in manner that allows the load connected with the pv module to extract the maximum power, which the pv module is capable to produce at given atmospheric conditions. pv cells have a single operating point, where the value of the current and voltage of the cell results in a maximum power output. with the varying atmospheric condition and because of the rotation of the earth [4], the irradiation and temperature keeps on changing throughout the day. so it is a big challenge to operate a pv module consistently on the maximum power point and for which many mppt algorithms have been developed [1]. the most popular among the available mppt techniques is perturb and observe (p&o) method. this method is having its own merits and demerits. the aim of the present work is to develop the simulink model of p&o mppt controller and then the fuzzy intelligent control has introduced on it to improve its overall performance journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 14 resd © 2015 http://apc.aast.edu (8) the input e(k) shows the following: the operation point at the instant k is located on the right or on the left of the mpp on the pv characteristic curve as shown in figure 12, while the input ce(k) shows moving the direction of this point. where the control action d is duty cycle of pwm signal that control the buck boost converter [5] [6][7][8]. fig.11. block diagram of the fuzzy controller the fuzzy controller design contains the three following steps:  fuzzification the fuzzification is the process of converting the system actual inputs values e and ce into linguistic fuzzy sets using fuzzy membership function. these variables are expressed in terms of five linguistic variables (such as ze(zero), pb (positive big), ps (positive small), nb (negative big), ns (negative small)), using basic fuzzy sub sets as shown in fig.13  rule base & inference engine fuzzy rule base is a collection of if-then rules that contain all the information for the controlled parameters. it is set according to professional experience and the operation of the system control. the fuzzy rule algorithm includes 25 fuzzy control rules listed in table 3 [5] [6][7][8]. fuzzy inference engine is an operating method that formulates a logical decision, based on the fuzzy rule setting and transforms the fuzzy rule base into fuzzy linguistic output. in this paper, mamdani’s fuzzy inference method, with max-min operation fuzzy combination, has been used [9][10][11]. (b) (c) fig.12. membership function of e, ce and d  defuzzification defuzzification of the inference engine evaluates the rules, based on a set of control actions, for a given fuzzy inputs set. this operation converts the inferred fuzzy control action into a numerical value at the output by forming the union of the outputs resulting from each rule. the center of area (coa) algorithm is used for defuzzification of output duty control parameter, i.e. if e is nb and ce is zo, then crisp d is pb. this means that if the operating point is far away from the mpp by the right side, and the variation of the slope of the curve is almost zero, this will increase the duty cycle. the output of duty cycle d is expressed by [10][11][12][13]: (9) table 4. fuzzy rules table e/ce ng np ze pp pg ng ze ze pg pg pg np ze ze pp ze pp ze pp ze ze ze np pp np np np ze ze pg ng ng ng ze ze fig. 13.the input-output surface waveform of the flc inferen ce fuzzificati on deffuzificati on rules e ce d (a) journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 15 resd © 2015 http://apc.aast.edu iii. simulink model of pv system with p&o and fuzzy logic controller the performance of the tow systems, namely perturb &observe (p&o) and fuzzy logic controller, are analyzed. the performances of the controllers are analyzed in the following conditions: constant temperature and variable irradiation fig 14.simulation block diagram of mppt pv systems for maximum using p&o and fuzzy logic controller a. operation under constant conditions in this case, the temperature and irradiation are considered constant. the values are taken under standard conditions: temperature25°cand irradiation in 1000w/m2. b. operation with variable conditions in this case the temperature and irradiation are changing with time under different weather condition. fig. 9 shows how the irradiance is changing for the pv solar panel. the voltage and the current vary depending on irradiance. the curve of variable irradiance is plotted using a signal builder, where the irradiance is not very realistic, because these are instantaneous changing irradiances. the simulation results are shown in the next figures. : fig.15. variation of irradiance used in simulation. c. p&o mppt controller fig.16. input and output current of the buck boost converter with p&o mppt controller at constant temperature (t=25 c°) and varying insulation fig.17. input and output voltage of the buck boost converter with p&o mppt controller at constant temperature (t=25 c°) and varying insulation 0 0.2 0.4 0.6 0.8 1 -4000 -2000 0 2000 4000 6000 8000 time(s) p o w e r (w ) output of the pv array output of the buck boost converter 600 w/m² 800 w/m² 300 w/m² 1000 w/m² fig.18. input and output power of the buck boost with p&o mppt controller at constant temperature (t=25 c°) and varying insulation d. fuzzy logic mppt controller 0 0.2 0.4 0.6 0.8 1 0 10 20 30 40 50 60 70 time (s) c u rr e n t (a ) output of the buck boost converter output of the pv array 600 w/m² 300 w/m² 1000 w/m² 800 w/m² fig.19. input and output current of the buck boost converter with fuzzy logic mppt controller at constant temperature (t=25 c°) and varying insulation pv array continuous powergu scope scope scope scope saturatio product product product vi insolatio tem vou ip i ip d vp p_p ipv pv voltage i v d p & o output voltage outout power manual p v d mppt fuzzy logic mod a fc u ml control input voltage 2 constant2 e d i ic vc buck_boost non_inverse ad 0 0.2 0.4 0.6 0.8 1 -200 -100 0 100 200 300 400 500 time (s) v o lt a g e ( v ) output of the pv array output of the buck boost converter 300 w/m² 800 w/m² 600 w/m² 1000 w/m² 0 0.2 0.4 0.6 0.8 1 0 5 10 15 20 25 30 35 40 time (s) c u rr e n t (a ) output of the pv array output of the buck boost converter 600 w/m² 800 w/m² 300 w/m² 1000 w/m² journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 16 resd © 2015 http://apc.aast.edu 0 0.2 0.4 0.6 0.8 1 -100 0 100 200 300 400 500 time (s) v o lt a g e ( v ) output of the buck boost convertert output of the of the pv array 1000 w/m² 600 w/m² 300 w/m² 800 w/m² fig.20. input and output voltage of the buck boost with fuzzy logic mppt controller at constant temperature (t=25 c°) and varying insulation 0 0.2 0.4 0.6 0.8 1 -2000 0 2000 4000 6000 8000 10000 time (s) p o w e r (w ) output of the pv array output of the buck boost converter 1000 w/m² 600 w/m² 300 w/m² 800 w/m² fig.21. input and output power of the buck boost converter with fuzzy logic mppt controller at constant temperature (t=25 c°) and varying insulation as shown, fuzzy controller gives smother power signal line, less oscillation and better stable operating point than p&o. from the simulation results, it can be deduced that the fuzzy controller gives better performance than p&o, and it has more accuracy for operating at maximum power point. iv. conclusion this paper presents the performance of tow mppt algorithms for tracking the maximum power available in pv array system, with fuzzy logic controller and p&o. the algorithms works as a direct method of mppt through a buck-boost converter placed in parallel with the pv array. based on the simulation results with matlab/simulink, it can be observed that all of the tow mppt controllers can be used to track the mpp under variable changes of solar irradiance and cell temperature. the tow controllers regulate the pv array voltage to operate at mpp operating voltage in order to produce the maximum power. however, it can be concluded that fuzzy logic has a better steady state, less oscillation around the mpp and dynamical performance than traditional p&o. references [1] aurobinda panda,.pathak, m.k., and srivastava, s.p.« fuzzy intelligent controller for the maximum power point tracking of a photovoltaic module at varying atmospheric conditions ». journal of energy technologies and policy. vol.1, no.2. pp.18-27, 2011. [2] mahammad, abd kadir, saon, sharifah and chee, wong swee. «development of optimum controller based on mppt for photovoltaïque system during shading condition, procedia engineering 53 ( 2013 ) 337 – 346 . [3] salas, v., olias, e., làzaro, a. , and. barrado, a “review of the maximum power point tracking algorithms for stand-alone photovoltaic systems,” solar energy material solar cells, 2006, 90:1555–78. [4] esram, t., and chapman, p. “comparison of photovoltaic array maximum power point tracking techniques,” ieee transactions on energy conversion, 2007, 22:2. [5] h.e.a. ibrahim, comparison between fuzzy and p&o control for mppt for photovoltaic system using boost converter, journal of energy technologies and policy. vol. 2, no.6. 2012. [6] fares, ahmed m., belal, a. abo zalam, el nashar, salwa g.,and aka1, haitham. « comparison between different algorithms for maximum ppt in photovoltaic systems and its implementation on microcontroller ». journal of energy technologies and policy, vol.3, no.5, 2013. [7] abdullah m., noman,khaled e. addoweesh, and hussein m. mashaly, « dspace real-time implementation of mppt-based flc method”. hindawi publishing corporation international journal of photoenergy. vol. 2013, article id 549273, 11. pages: [8] rahmani, r., fard, m., shojaei, a. a., othman, m. f., and yusof, r. “a complete model of stand-alone photovoltaïque array in matlab-simulink environment.” ieee student conference on research and development 2011. [9] singh,s., mathew,l. , shimi, s. l, “ design and simulation of intelligent control mppt technique for pv module using matlab/ simscape”. international journal of advanced research in electrical electronics and instrumentation engineering . vol. 2, issue 9, september 2013. [10] rahmani, r., seyedmahmoudian, m., mekhilef, s. and yusof, r. “ implementation of fuzzy logic maximum power point tracking controller for photovoltaic system”. american journal of applied sciences. 10 (3): 209-218, 2013. [11] messai, a., mellit a., guessoum, a. and kalogirou, s.a. 2011. “maximum power point tracking using a ga optimized fuzzy logic controller and its fpga implementation”. solar energy. 85: 265-277. doi:10.1016/j.solener.2010.12.004 [12] hari prasad, k.v., uma maheswar rao, ch. “design and simulation of a fuzzy logic controller for buck & boost converters”. international journal of advanced technology & engineering research (ijater). vol. 2. issue 3. may 2012. [13] aït cheikh, c. larbes, g.f., kebir, t and zerguerras, a. “maximum power point tracking using a fuzzy logic control scheme”. revue des energies renouvelables vol. 10 n°3 (2007). [14] jardine, c. n., conibeer, g. j. and lane, k. “pvcompare: direct comparison of eleven pv technologies at two locations in northern and southern europe”. in 17th european conference on photovoltaic solar energy conversion. munich. vol. 17th . europ, 2001. journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.224 224 resd © 2017 http://apc.aast.edu a new controller to enhance pv system performance based on neural network roshdy abdelrassoul, sm, ieee, yosra ali and mohamed saad zaghloul arab academy for science, technology and maritime transport (aastmt), alexandria, egypt roshdy@ieee.org, yosra_alii@hotmail.com, dr_mszaghloul@yahoo.com abstract in recent years, a radical increase of photovoltaic (pv) power generators installation has taken place because of the increased efficiency of solar cells, the growth of manufacturing technology of solar panels, in addition to the government support policy. this paper shows the operation and modeling of photovoltaic systems, particularly designing neural controller to control the system. neural controller is optimized using particle swarm optimization (pso), which leads to getting the best performance of the designed pv system. by using neural network, the maximum overshoot and rise time obtained become 0.00001% and 0.1798 seconds, respectively. also, this paper strikes a comparison between some kinds of controller for the pv system. keywords particle swarm optimization, neural network and photovoltaic. i. introduction the study of renewable energy sources has been an inclusive concern to the world, and has drawn the attention of many institutions, like the european commission and others. renewable energy is a clean energy system that has no effect during or after generation on the environment and this has grabbed the attention of researchers to make continuous improvement in solar energy. renewable energy is numerous, abundant, sustainable, and can be utilized from different origins such as wind, solar, tidal, hydro, geothermal and biomass. solar energy could be one of the important sources as substitution energy for the hereafter. there are two kinds of technology that has anticipated solar energy, solar thermal and solar pv. a pv cell (solar cell) transforms sunlight into electrical energy by the photovoltaic effect. the solar pv system exhibits various advantages, such as, it needs little maintenance and produces no environmental pollution. pv module presents the fundamental power conversion unit of a pv generator system. ii. literature review many papers have presented different simulations of pv system. in [1], a procedure for the simulation of photovoltaic modules with matlab/simulink is presented. one-diode equivalent circuit is employed in order to investigate i-v and p-v characteristics of solar module. the final model takes irradiation, operating temperature in celsius and module voltage as input and gives the output current ipv and output voltage vpv. also, in [2], a one-diode equivalent circuit-based versatile simulation model in the form of the masked block pv module is proposed. by using the model, it is allowed to estimate the behavior of pv module with respect to changes in irradiance intensity, ambient temperature and parameters of the pv module. in another study [3], a fractional-order pid (fopid) controller [4-6] is designed to control a dc-dc boost converter in a pv-system. in order to obtain the best system performance, parameters of the proposed controller are tuned by using particle swarm optimization (pso) algorithm. in another paper [7], the effect of uniform and non-uniform irradiance on a series of connected solar pv array is presented in detail under matlab-simulink environment. the proposed simulation model helps the researchers to investigate the characteristics of a pv array under different irradiance and temperature conditions [7]. this paper is framed around three major parts. first, an overview of mathematical model of the pv system is summed up. second, a neural controller is designed to enhance the performance of the system. finally, in order to obtain the best system performance, neural network of the proposed controller is optimized using the pso. the system response is tested under various solar irradiation and constant temperature. percentage overshoot (mp) and rise time (tr) are measured and compared with http://dx.doi.org/10.21622/resd.2017.03.2.224 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.224 225 resd © 2017 http://apc.aast.edu other papers. the comparison shows that the system with the neural controller performs better than other systems with different kinds of controller. iii. mathematical model of the pv system 1. mathematical model of pv panel the first part of the system is the solar cell. solar cells are in fact large area semiconductor diodes. due to the photovoltaic effect, energy of light (energy of photons) is converted into electrical current. the equivalent circuit for the simplest solar cell consists of a diode and a current source connected in parallel, as shown in figure 1 [8]. the source current is directly proportional to the solar radiation and diode represents the pn junction of a solar cell. fig.1. one diode model of pv cell equation of the load current is: 𝐼 = [(𝐼𝑝ℎ ×𝑁𝑝) − 𝐼𝑑 − 𝐼𝑠ℎ ] (1) where: (iph) is photocurrent (a); (id) is diode current; (ish) is the current loss because of the shunt resistance; and (np) the parallel connected pv cell number that effects the module current. the thermal voltage equation is: 𝑉𝑡 = 𝑘𝑇 𝑞 (2) where: (k) is boltzmann constant, 1.38×10-23 j/k ; (t) is solar cell temperature (k ); and (q) is charge of electron, 1.6×10-19 c. the researchers represent the reverse saturation current equation for the proposed pv system using simulink on matlab as shwon in figure. 2: fig.2. reverse saturation current 𝐼𝑠 = [( 1 𝑇 − 1 𝑇𝑟𝑒𝑓 ) × ((𝑞2×𝐸𝑔 )/(𝑘×𝑛)) 𝑒 𝑢 [ 𝐼𝑟𝑠 (𝑇 𝑇𝑟𝑒𝑓⁄ ) 3]] (3) where: (t) the temperature of the pv panel; (tref) the refrence temperature of the pv panel; the researchers represent the reverse saturation current at top equation for the proposed pv system using simulink on matlab as described in figure. 3: http://dx.doi.org/10.21622/resd.2017.03.2.224 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.224 226 resd © 2017 http://apc.aast.edu fig. 3. reverse saturation current at the top equation 𝐼𝑟𝑠 = [(𝑉𝑜𝑐 ∗ 𝑞)/(𝐾 ∗ 𝑐 ∗ 𝑇 ∗ 𝑛)] [ 𝐼𝑠𝑐 (𝑒 𝑢 − 1) ⁄ ] (4) where: (voc) open circuit voltag; and (isc) short circuit current. shunt current equation: 𝐼𝑠ℎ = (𝑉 + 𝐼 𝑅)/𝑅𝑝 (5) where: (ish) shunt current; (rs) the series resistance of the pv panel; and (rp) the parallel resistance of the pv panel. diode current equation for the proposed pv system is described in figure.4 as the researchers present it using simulink on matlab: fig. 4. diode current 𝐼𝑑 = [[( 𝑉 𝑁𝑠 ⁄ ) + ( 𝐼 ∗ 𝑅𝑠 𝑁𝑠 ⁄ )] /[𝑛 ∗ 𝑉𝑡 ∗ 𝑐]] [(𝑒 𝑢 − 1) ∗ 𝐼𝑠 ∗ 𝑁𝑝 ] (6) where: (id) diode current; (ns) the series connected pv cell number that effects module voltage; and (vt) thermal voltage; phase current equation: 𝐼𝑝ℎ = [((𝑇 − 𝑇𝑟𝑒𝑓 ) ∗ 𝐾) + 𝐼𝑠𝑐 ] ∗ 𝐼𝑟𝑟 (7) where: (irr) irradiation. 2. converter model the second part of the system is the converter. a boost dc-dc converter is used as a power electronic interface between the load and pv panels in the p-v system. the converter is a powerful electronic device used to produce a higher regulated output voltage from a lower unregulated input voltage [3]. the circuit of the converter consists of an inductor l, a power switch s, a diode, d, a filter capacitor c and a load resistor r, as shown in figure 5 [3]. fig. 5. boost converter circuit the working principle of the converter is cleared as follows: when the switch is in the on mode, the diode is reverse biased (off). in this mode, the inductor is directly connected to the input voltage source and stores energy. meanwhile, the load is powered by the capacitor. when the switch is off mode, the diode is forward biased (on). in this mode, both the stored energy of the inductor and the input voltage source supply power to the load. the capacitor and the inductor values of the converter are calculated respectively by using the formulas [8]: 𝐶𝑚𝑖𝑛 = 𝐷𝐼𝑜𝑢𝑡(max) 𝑓𝑠∆𝑉𝑜𝑢𝑡 (8) 𝐿𝑚𝑖𝑛 = (𝑉𝑜𝑢𝑡−𝑉𝑖𝑛)𝑉𝑖𝑛 ∆𝐼𝐿𝑓𝑠𝑉𝑜𝑢𝑡 (9) where: (cmin) and (lmin) are the minimum capacitor and inductor values; (vin ) and(vout) are the input and output voltage of the http://dx.doi.org/10.21622/resd.2017.03.2.224 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.224 227 resd © 2017 http://apc.aast.edu converter; (fs) is the switching frequency; (∆vout) is the output voltage ripple; (∆il ) is the inductor current ripple; and (d) is the duty cycle, which is the ratio between the pulse duration and period of a rectangular waveform. 3. neural network controller the third part in the system is the controller. there are numerous controllers that can be used to control dynamic systems like the pv systems. in this paper, neural network controller is used because neural networks are mostly used for fuzzy, difficult problems that do not yield to traditional algorithmic approaches. many algorithms can be used to optimize the controller, such as genetic algorithms (ga) [9], differential evolution (de) algorithm [10] and pso algorithm [11]. in this paper, particle swarm optimization (pso) will be used because it does not have genetic operators like crossover and mutation, since particles update themselves with the internal velocity. they also have memory, which is important to the algorithm, as will be explained later in the algorithm. many papers used proportional integral derivative controller (pid) instead of neural network. neural network is more complex than pid controller but neural network gives a better response than the pid controller and some other kinds of controllers. in this paper, the neural network controller supported the designed model of the pv system. a neural network is a method of computation modeled after the brain [12]. they contain a series of mathematical equations that are used to emulate biological processes such as learning and memory. what makes the artificial neural network unique from many other computer algorithms is its primitive ability to learn. through a process of training and being told what the correct output is when given a set of inputs, the artificial neural network eventually learns the correct behavior, and can reproduce correct outputs on its own when given a set of inputs. a neural network can predict an outcome based on the values of some predictor variables. networks are programmed to adjust their internal weights based on the mathematical relationships identified between the inputs and outputs in a data set. fig. 6. diagram of an artificial neural network table 1 is a brief glossary showing some common terms in the field of neural networks and their equivalent in statistics. neural networks are known to be universal function approximates. various architectures are available to approximate any nonlinear function. different architectures allow for generation of functions of different complexity and power. those different architectures are: • feedforward networks • feedback networks • lateral networks table 1. common terms in neural networks and their equivalent in statistics neural networks statistics input independent (predictor) variable output dependent (outcome) variable, predicted value connection weights regression coefficients bias weight intercept parameter error residuals learning, training parameter estimation training case, pattern observation cross-entropy maximum likelihood estimation http://dx.doi.org/10.21622/resd.2017.03.2.224 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.224 228 resd © 2017 http://apc.aast.edu in a neural network, the weights connecting two nodes are usually represented as where i and j are subscripts for the two nodes being connected. estimating the optimal values of these connection weights is the major purpose behind training a neural network model. the network training algorithm is used to gradually adjust the weight and in the network to minimize the difference between the predicted output of the network op and the known value of the outcome variable tp. this difference is known as the error of a neural network and is similar to the concept of minimizing the residuals in statistical regression. the total error (e) of a neural network is usually determined over the whole data set and may be calculated as shown in equation (10): (10) where e is the total error of the network op and is the desired or known neural networks versus logistic regression. iv. particle swarm optamization (pso) the particle swarm optimization (pso) method, suggested by kennedy and eberhart [13], is a computational search algorithm used to optimize a problem iteratively [14]. the algorithm is based on imitating the behaviors of a bird flock (particles) with the help of the mathematical velocity and position formulas of the particles. each particle in the population has a memory to keep its previous best position called pbest (candidate solutions, local minima) and fitness value. also, the particle with minimum fitness value is called gbest (global minima). the flowchart of the algorithm is given in figure 7. mathematical representations of the velocity and position of the particles are given below, respectively. where i is the number of the particle, d is the dimension, c1 and c2 are the acceleration constant of the velocity, w is the inertia weight, and r1 and r2 are the uniformly random numbers. optimum values for these parameters are needed to reach robust transfer function for pv system. pso is used widely in many applications due to its many advantages including its simplicity and easy implementation. pso has no crossover and mutation process; however, the search can be done by the speed of the particle. only the optimum particle can transmit information to the other particles, and the speed of searching is very fast. thereby, the researchers used pso as an optimization tool to find the optimum values for those parameters. the basic pso algorithm consists of three steps generating positions of particles and velocities, velocity update, and position update. each particle represents a possible solution to the problem that changes its position from one iteration to another based on velocity updates. first, the positions, xid, and velocities, vid, of the initial swarm of particles are randomly generated. the pso consists of many particles which form a swarm, design space. at each step, each particle updates its velocity and distance according to equation (8) and equation (9), respectively. fig. 7. a general flowchart of pso (11) (12) the algorithm is ended when the stopping criteria are met. v. simulation results according to the case study which is getting the best performance of a pv system by reducing rise time and the percentage overshoot, a neural controller is used as shown in figure 8. figures 9 and 10 represent the i-v and p-v characteristics of the system, respectively, with a solar irradiation input of 800w/m2. table 2 shows the system parameters. http://dx.doi.org/10.21622/resd.2017.03.2.224 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.224 229 resd © 2017 http://apc.aast.edu fig. 8. simulink/matlab architecture for the pv system with neural controller fig. 9. current – voltage (i-v) characteristics of pv system fig. 10 power– voltage (p-v) characteristics of pv system table 2. parameters of pv system parameters of boost converter 20khz sampling frequency (ts) 5khz switching frequency (fs) 24v output voltage (vo) 5% max. output voltage ripple (∆vc) 5% max. input current ripple (∆i) 6.8mf input capacitor (cin) 11.5mf output capacitor (cout) 1.25mh inductor (l) 12.5-25-50ohm load (r) pv panel parameters 1 nsc 5 npc 17v vr 3a ir 3.10-3ma/oc -73.10-3mw/oc β 3.5 isc 1000w/m2 gr 25oc tcr http://dx.doi.org/10.21622/resd.2017.03.2.224 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.224 230 resd © 2017 http://apc.aast.edu there are a lot of types and training algorithms for neural network. in the proposed case, the researchers do not know which one will fit the best performance therefore, they used the pso to obtain the best neural type, training algorithm, number of hidden layers, and number of perceptions per layer. in this case, four parameters have to be determined. these parameters are shown in table 3. table 3. input parameters of pso parameters description constrains 𝑘1 neural type from 1 to 4 𝑘2 training algorithm from 1 to 12 k3 number of layers from 1 to 10 𝑘4 number of perception from 1 to 10 in equation 12, the d represents the dimension number while the pid represents the best previous position and the global best position is stored in pg. to ensure good coverage of the design space, the velocity update formula includes some random parameters, represented by the uniformly distributed variables, rand. the three terms of the velocity update equations represent current motion, particle own memory, and swarm influence. accordingly, the original pso algorithm used the value of 2 for both constants c1 and c2. in the proposed problem, the objective function is minimizing the overshoot, rise time for the pv system. also, the researchers used a swarm size of 49 in their proposed algorithm. in each iteration of pso, the best parameters is stored as the global minimum. the parameters that should be optimized are summarized in table 3. once the pso chooses the optimum parameter k1, k2, k3, and k4, those parameters are set as the final parameters for setup the neural network to operate as a controller instead of pid. hence, the number of dimensions, d, in equation 12 is equal to 12. all the possible types and algorithms for k1 and k2 are mentioned in table 4. according to pso, the optimum parameters are 2, 1, 1 and 10 for k1, k2, k3 and k4, respectively. this result reflects that the best type which fits the best performance for pv system is feed forward neural network with levenberg-marquardt training method, train lm. the upcoming figure 11 will illustrate the overshoot 0.00001% and that rise time equals 0.170 seconds. fig. 11. structure of the proposed neural network fig. 12. the value of mse fig. 13. step response of process with neural controller unig simulink http://dx.doi.org/10.21622/resd.2017.03.2.224 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.224 231 resd © 2017 http://apc.aast.edu table 4. all possible values and types for k1 and k2 vi. comparison with previous work figure 14 [15] shows the output voltage versus the time and the maximum overshot almost is zero. the simulation results clearly show that the pid controller gives a much better control of pv system rather than the fopid controller. when pid tuned by a genetic algorithm is used as a control for the pv system, the rise time was 0.175 second and percentage overshoot was almost zero. in comparison to [3], this work reduced the overshoot with 0.7% and the rising time by 0.545 seconds. also, the neural network has better impact on the pv system rather than pid and fopid [3] controllers. for neural network controller, the overshot was 0.00001, meanwhile the rise time was 0.170 seconds and table 4 shows a comparison between all the controller types for pv system. in table 4, the first parameter is the maximum overshoot and the second parameter is the rise time. figure 15 shows the result of the three different types of the controller that used to enhance the performance of our pv system. the line by the red circles represents the result of pid controller tuned by ga algorithm, the line by the blue crosses represents the results of the neural pso controller and the line by the black dashes represents the results of a previous work [3]. figure 16 shows the same result as figure 15 but with zoomed x-axis and y-axis. fig. 14. output voltage versus time fig. 15. output voltage versus time. fig. 16. output voltage versus time with zoomed x-axis and y-axis table 5. comparison between this work and previous work [3,14] parameters pid with genetic algoritm [3] neural network controller mp 0.1 0.8 0.00001 tr 0.175 0.72 0.170 p 1.7130 19.22 i 3.8 8.32 d 0.001 0.056 parameters value type k1 1 cascade forward net 2 feed forward net 3 pattern net 4 fit net k2 1 trainlm 2 trainbr 3 trainbfg 4 trainrp 5 trainscg 6 traincgb 7 traincgf 8 traincgp 9 trainoss 10 traingdx 11 traingdm 12 traingd http://dx.doi.org/10.21622/resd.2017.03.2.224 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.224 232 resd © 2017 http://apc.aast.edu vii. conclusion and future work pv system is one of vital renewable energies in the present world. therefore, researchers made a lot of research on pv panels to enhance its performance. this paper introduces a mathematical model for pv system with neural controller. the neural controller is used to enhance the output of pv system. the pso is used to optimize the neural controller, which led to minimum overshoot and minimum rise time. the overshoot is reduced to be 0.00001% and the rise time is set to 0.170 seconds. the results show that neural controller has a better response compared with some other kind of controllers. for future work, different kinds of controller can be used to control the pv system and different algorithms can be replaced instead of pso to optimize the neural network controller. the following points may be considered: • using different algorithms to tune the neural network (nn) controller. • using other kinds of controllers to control the pv system and comparing it with the other types used. • using a combination of back propagation and neural network hybrid pso-bp. • to reach a real time system, the different types of controllers can be implemented on field programmable gate array (fpga). references [1] n. pandiarajan and r. muthu. “mathematical modeling of photovoltaic module with simulink,” in: proc. of international conference on electrical energy system, pp. 3-5, 2011. [2] c. qi and z. ming. “photovoltaic module simulink model for a stand-alone pv system.” physics procedia, vol. 24, pp. 94-100, 2012. [3] e. sahin, erol, m. s. ayas and i. h. altas. “a pso optimized fractional-order pid controller for a pv system with dc-dc boost converter,” in power electronics and motion control conference and exposition (pemc), 2014 16th international. ieee, pp. 477-481, 2014. [4] c. a. monje et al. “proposals for fractional piλdµ tuning,” in the first ifac symposium on fractional differentiation and its applications, pp. 369-381, 2004. [5] r. singhal, s. padhee and g. kaur . “design of fractional order pid controller for speed control of dc motor.” international journal of scientific and research publications, vol. 2.6, pp. 1-8., 2012. [6] k. sundaravadivu, b. arun and k. saravanan. “design of fractional order pid controller for liquid level control of spherical tank,” in control system, computing and engineering (iccsce), 2011 ieee international conference on. ieee, pp. 291-295, 2011. [7] a. s. k. chowdhury, k. m. a. salam and m. a. razzak. “modeling of matlab-simulink based photovoltaic module using flyback converter,” in strategic technology (ifost), 2014 9th international forum on. ieee, pp. 378-381, 2014. [8] b. hauke. “low power dc-dc application/basic calculation of a boost converter’s power stage,” texas instrument application report, pp. 1-9, july, 2010. [9] l. y. chang and h. c. chen. “tuning of fractional pid controllers using adaptive genetic algorithm for active magnetic bearing system.” wseas transactions on systems, vol. 8, pp. 226-236, 2009. [10] a.biswas, s. das, a. abraham and s. dasgupta. “design of fractionalorder p iλdµ controllers with an improved differential evolution.” engineering applications of artificial intelligence, vol. 22, pp. 343350, 2009. [11] m. zamania, m. karimi-ghartemanib, n. sadatib and m. parnianib. “design of a fractional order pid controller for an avr using particle swarm optimization.” control engineering practice, vol. 17, pp. 1380-1387, 2009. [12] j. v. tu. “advantages and disadvantages of using artificial neural networks versus logistic regression for predicting medical outcomes.” journal of clinical epidemiology, vol. 49, no. 11, pp. 1225-1231, 1996. http://dx.doi.org/10.21622/resd.2017.03.2.224 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.224 233 resd © 2017 http://apc.aast.edu [13] j. kennedy and r. eberhart. “particle swarm optimization,” proc. ieee international conference on neural networks, vol. 4, pp. 1942 – 1948, 1995. doi: 10.1109/icnn. 488968, 1995. [14] m. settles. an introduction to particle swarm optimization. department of computer science, university of idaho, pp. 1-8, 2005. [15] r. a. abdelrassoul , y. ali and m. zaghloul. “genetic algorithm-optimized pid controller for better performance of pv system,” internationalconference on artificial intelligence (iccai’2016), 2016 world symposium on computer applications & research, wscar 2016, cairo, egypt, 12-14 march, 2016, pp. 1822, 2016. http://dx.doi.org/10.21622/resd.2017.03.2.224 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 106 resd © 2015 http://apc.aast.edu aerodynamic optimization of a wind turbine blade designed for egypt's saharan environment using a genetic algorithm khaled yassin, aya diab, zakaria ghoneim mechanical power engineering dept. faculty of engineering, ain shams university cairo, egypt aya.diab@eng.asu.edu.eg abstract – this work aims to optimize the aerodynamic parameters (airfoil chord lengths and twist angles smoothed using bezier curves) of the nrel 5mw wind turbine and a wind turbine designed for site-specific wind conditions to increase the wind turbine's annual energy production (aep) under this site conditions. this optimization process is carried out using a genetic algorithm (ga) developed in matlab and coupled with nrel's fast modularization framework. the results showed that after optimizing the nrel 5mw wind turbine design, the aep was improved by 5.9% of the baseline design aep, while a site-specific designed wind turbine using schmitz equations showed 1.2% improvement in aep. these results show that optimization of wind turbine blade aerodynamic parameters for site-specific wind conditions leads to improvement in aep and hence decreasing cost of energy generated by wind turbines. keywords wind turbine, aerodynamics, optimization, genetic algorithm, site-specific wind turbine. i. introduction wind energy is the fastest growing source of energy in the world today, with an average growth rate of nearly 30% per year over the past 10 years. with global warming, energy security, and rising fuel prices being main public concerns, it is reasonable to assume that the growth of the wind energy industry will continue at an unprecedented pace. the global energy challenge is certainly not foreign to egypt whose developmental needs mandate the addition of 2000-3000 mw of installed capacity each year. luckily, egypt is endowed with an excellent wind energy potential, especially in the red sea coast area where a capacity of 20,000 mw could be achieved, as the annual average wind speed is around 10 m/s. egypt's national energy planning incorporates a target of 1,050 mw wind capacity to be installed by the end of the sixth five-year plan period (2007-2012). on the long term, the government envisages 20% of electricity to come from renewable energy by 2020. to meet this target, it is expected that 12% will be satisfied by wind power. with egypt’s wind energy potential and its ambitious plan to expand wind energy contribution in electric energy production, the need to develop its own technology in wind turbine becomes vital. in egypt, while viable wind farm locations with high quality wind resources exist in the gulf of suez region (for example zaafarana, and jabal el-zeit), improved blade design optimized for a particular location can significantly reduce the unit cost of electricity, amortized over the turbine lifetime. this is expected to expand the number of locations that are economically viable, such as the east and the west of the nile. in the last few years, the topic of developing and optimization of wind turbine rotors attracted a lot of attention. maheri et al [1] applied a combined analytical/fea coupled fsi to design and optimize bend-twist adaptive blades to increase average generated power over the operation wind speed. in their work, shell thickness, ply angles, and pre-twist distribution were optimized to increase the energy generated at this wind speed. xiong et al.[2] presented an optimization model of hawt blade using weibull frequency distribution function (to simulate wind speeds around the year) and extended compact genetic algorithm (ecga) to optimize airfoil shapes, chord lengths and twist angles of a 1.3 mw turbine blade to maximum annual energy production. xudong et al. [3] presented optimization procedure of wind turbine blade. this procedure includes both structural dynamics and blade element momentum theory (bem) to optimize annual energy production and cost of the rotor by variation of chord, twist and relative thickness. these procedures are applied on http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 107 resd © 2015 http://apc.aast.edu three different wind turbines: 25 kw mexico experimental rotor, tjaereborg 2mw rotor and nrel 5 mw rotor to compare between original and optimized performance of the mentioned three rotors. the main goal of this work is to design an optimized utility scale wind turbine as a step towards the ultimate long term goal of indigenously fabricating a utility scale wind turbine suitable for operation in the egyptian harsh operating environment, particularly of high temperature, high humidity and the existence of sand and wind speeds that may reach 10-11 m/sec and a capacity factor of 60%. realization of this goal is a major task and has to be carried out progressively. two of the main components of the turbine, the rotor blades, and the tower are obvious candidates. the present work concentrates on the use of genetic algorithm for the aerodynamic design optimization of the rotor blades of a utility scale wind turbines, which, according to mohamed and wetzel [4], is a major contributor to the wind turbine cost. ii. aerodynamic blade design the blade element momentum theory is well known and has been widely used. blade element momentum (bem) is an extension of the simple 1d momentum theory. the low computational cost of the relatively good accuracy has led to its widespread use in the wind turbine industry, both for design analysis and design optimization. the models based on bem method are robust and simple to use but limited to simple boundary conditions, specifically limited to nonyaw and steady cases, where the upstream velocity is constant and perpendicular to the rotating plane. the rotor extracts kinetic energy from the wind and decelerates the airflow passing through the rotor plane. consequently, the relative velocity between the blade element and the air is not equal to the geometric sum of the wind and peripheral velocities. thus, the true velocity experienced by the elements from the air must be obtained after accounting for the slipstream. in this case, it is assumed that the axial and tangential induced velocities are distributed evenly and can be obtained by means of correction models. the bem theory is used to study the behavior and the properties of the wind turbine. the blade is divided to a number of elements, each having the same length. at each element, the generated forces are calculated for the middle of this element as its representative station. these forces combined with the radius at each station and the rotational speed of the rotor are summed to get the produced power and thrust. in the bem theory, the blade is assumed to be divided into n sections which are called the blade elements. it is assumed that there is zero aerodynamic interaction between the blade elements and there is negligible spanwise velocity component on the blade. the forces on the blade element are solely determined by the lift and drag characteristics of 2d airfoils of the blade element; lift and drag components are defined perpendicular and parallel to the relative wind speed direction. the total tangential velocity experienced by the blade element is (1+a´)ω r and the axial velocity is (1-a)u∞. the relative wind velocity at the blade is given by [5]: 𝑊 = 𝑈∞(1−𝑎) 𝑠𝑖𝑛𝜑 (1) where a is the axial induction factor, a’ is the rotational speed in the wake and u∞ is the wind speed. the angle between the relative wind velocity and the plane of rotation is given by: 𝑡𝑎𝑛𝜑 = 𝑈∞(1−𝑎) 𝑟(1−𝑎′) = (1−𝑎) (1−𝑎′)𝑟 (2) where λr is the local tip speed ratio at radius r from the rotation axis and ω is the rotational speed of the rotor. the net force normal to the plane of rotation for each blade element and the resulting torque on each blade element can be written as: 𝑑𝐹 = 𝑑𝐿𝑐𝑜𝑠𝜑 + 𝑑𝐷𝑠𝑖𝑛𝜑 (3) 𝑑𝑄 = 𝑟(𝑑𝐿𝑠𝑖𝑛𝜑 − 𝑑𝐷𝑐𝑜𝑠𝜑) (4) where dl and dd are the lift and drag forces on the blade elements respectively. they are defined as follows: 𝑑𝐿 = 1 2 𝐶𝐿 𝜌𝑊 2𝑐𝑑𝑟 (5) 𝑑𝐷 = 1 2 𝐶𝐷 𝜌𝑊 2𝑐𝑑𝑟 (6) where cl is the lift coefficient of the airfoil at radius r, cd is the drag coefficient at this radius and w is the relative velocity. for a multi-bladed wind turbine with b number of blades and φ is the angle between the plane of rotation and the relative velocity, the http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 108 resd © 2015 http://apc.aast.edu equation becomes: 𝑑𝐹 = 𝐵 1 2 𝜌𝑊 2(𝐶𝐿 𝑐𝑜𝑠𝜑 + 𝐶𝐷 𝑠𝑖𝑛𝜑)𝑐𝑑𝑟 (7) 𝑑𝑄 = 𝐵 1 2 𝜌𝑊 2(𝐶𝐿 𝑠𝑖𝑛𝜑 − 𝐶𝐷𝑐𝑜𝑠𝜑)𝑐𝑑𝑟 (8) defining the local solidity as such: 𝜎 ′ = 𝐵𝑐 2𝜋𝑟 (9) replacing w, the thrust and torque can be written as: 𝑑𝐹 = 𝜎′𝜋𝜌 𝑈∞ 2 (1−𝑎)2 𝑠𝑖𝑛𝜑2 (𝐶𝐿 𝑐𝑜𝑠𝜑 + 𝐶𝐷𝑠𝑖𝑛𝜑)𝑟𝑑𝑟 (10) 𝑑𝑄 = 𝜎′𝜋𝜌 𝑈∞ 2 (1−𝑎)2 𝑠𝑖𝑛𝜑2 (𝐶𝐿 𝑠𝑖𝑛𝜑 − 𝐶𝐷𝑐𝑜𝑠𝜑)𝑟 2𝑑𝑟 (11) although the bem theory does not include 3d characteristics of the flow and viscous losses due to separation and turbulence, some modification can be applied to the theory to take into account these losses. the first modification includes the tip-loss and glauert corrections. the tip-loss model serves to correct the induced velocity resulting from the vortices shed from the blade tips into the wake on the induced velocity field, while the hub-loss model corrects the induced velocity resulting from a vortex being shed near the hub of the rotor. these losses are calculated as: 𝐹𝑡𝑖𝑝 = 2 𝜋 𝑐𝑜𝑠−1 (𝑒𝑥𝑝 (− 𝐵 2 ( 𝑅−𝑟 𝑟𝑠𝑖𝑛𝜑 ))) (12) 𝐹ℎ𝑢𝑏 = 2 𝜋 𝑐𝑜𝑠−1 (𝑒𝑥𝑝 (− 𝐵 2 ( 𝑟−𝑟ℎ𝑢𝑏 𝑟ℎ𝑢𝑏 𝑠𝑖𝑛𝜑 ))) (13) hence, the total tip loss term can be calculated as follows: 𝐹 = 𝐹𝑡𝑖𝑝𝐹ℎ𝑢𝑏 (14) a glauert correction factor as well as a prandtl tip and hub loss correction factor need to be applied to the equations. the solution is obtained using a fixed point iteration scheme until both the axial and tangential induction factors converge to within a specified tolerance. 𝐶𝑇 = 8 9 + (4𝐹 − 40 9 ) 𝑎 + ( 50 9 − 4𝐹) 𝑎2 (15) 𝑎 = 18𝐹−20−3√𝐶𝑇(50−36𝐹)+12𝐹(3𝐹−4) 30𝐹−50 (16) 𝑑𝐹 = 4𝐹𝜌𝑈∞ 2 𝑎(1 − 𝑎)𝜋𝑟𝑑𝑟 = 𝜎′𝜋𝜌 𝑈∞ 2 (1−𝑎)2 𝑠𝑖𝑛𝜑2 (𝐶𝐿 𝑐𝑜𝑠𝜑 + 𝐶𝐷𝑠𝑖𝑛𝜑) (17) 𝑄 = 4𝐹𝜌𝑈∞𝑎 ′(1 − 𝑎)𝑟3𝜋𝑑𝑟 = 𝜎′𝜋𝜌 𝑈∞ 2 (1−𝑎)2 𝑠𝑖𝑛𝜑2 (𝐶𝐿 𝑠𝑖𝑛𝜑 − 𝐶𝐷 𝑐𝑜𝑠𝜑)𝑟 2𝑑𝑟 (18) where ct is the coefficient of thrust. by equating the thrust force relation and torque relation, the axial induction factor and the angular induction factor a' can be calculated iteratively. when the iteration converges, the induction factors can be determined and are then used to calculate the angles of attacks and thrust for each blade element separately for the wind turbine performance analysis. usually wind turbine rotors are designed at specific conditions; however with more and more wind penetration, the optimized design that minimizes the cost of energy becomes mandatory. several studies have been motivated by this need, focusing on rotor optimization by considering blade chord and twist optimization. particularly for countries in the mena region, like egypt, additional cost benefits can be achieved by considering site specific (wind conditions dictated by the histogram of the specific location under consideration) designs with low surface contamination sensitivity. in this work, we considered zaafarana site wind conditions for our optimization process and comparison of aep with different designs. the aep is calculated according to wind frequency distribution calculated by weibull distribution [5]: fw(v) = k a ( v a ) k−1 . e (−( v a ) k ) (19) where fw is the frequency of wind velocity v. according to mortensen et al. [6], zaafarana site has a weibull distribution shape factor k=3.19 and 𝐴 = 𝑈𝑚𝑒𝑎𝑛 𝛤(1+1 𝑘⁄ ) = 10.2 𝑚/𝑠 (20) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 109 resd © 2015 http://apc.aast.edu this represents a very attractive site for wind farms. fig .1. weibull frequency distribution at k=3.19, a=10.2 the aep of both nrel and site-specific wind turbine is calculating by using the equations: aep = ∑ (pvi − pvi−1 n−1 i=1 ). (f(vi < v < vi+1). 8760 (21) umean@hub height umean@ref. height = ( 90 24.5 )α (22) where pv is power generated by this wind turbine at wind velocity v, umean is the mean wind velocity at this site, α (wind shear exponent) = 0.2, hub height = 90m and ref. height=24.5m (anemometer height above ground level). iii. genetic algorithm (ga) in general, optimization techniques fall into one of two main categories: gradient based methods and gradient free methods. gradient free methods include genetic algorithms (ga), the nedler-mead simplex, and particle swarm optimization (pso). typical examples of gradient based methods include the conjugate gradient method the method of feasible decent and sequential quadratic programming. one of the modern optimization techniques that are used widely in research, especially in wind turbine rotor optimization, is genetic algorithm. unlike gradient based optimization methods, where objective function has to be continuous and differentiable to be solved, ga is a heuristic optimization method that the search for the optimum solution starts from a random set of solutions. these random solutions are then evaluated and the best solutions are then re-entered to the process several times until an optimum solution is found [7]. in this work, ga was used in the optimization process because it fits the wind turbine parameters optimization process more than other heuristic optimization methods. for example, simulated annealing (sa), despite its simplicity and flexibility, is not useful in problems where many local optimum values exist. another example is the ant system optimization method that mimics the behavior of ant colony in finding the shortest route to food. despite the high reliability of this method, it is computationally more demanding than other methods since its generation complexity increases as the generation number increases. more information about heuristic optimization methods can be found in maringer [7]. to avoid the high time consumption of the ga, the variables chord lengths and twist angles distribution along the blade were generated using bezier curves with only five control points for each curve to decrease the complexity of the problem and at the same time to ensure smooth distribution of chord lengths and twist angles along the blade. genetic algorithm was first invented by holland [8] in the 1970s to mimic the evolution that happens in nature. this technique is achieved by generating a number of random individuals (called initial population); each consists of randomly chosen string of parameters to be optimized (called genes) and each individual is given a parameter that measures its proximity to the objective of the optimization process. this parameter is called fitness. after that, crossover (or mating) is achieved by splitting each two individuals (called parents) at a random point of the string and exchanging its half with the other to form a new string of genes called offspring or child. the choice of parents from the initial population is achieved by tournament selection technique that compares each two randomly chosen individuals. the one which wins this comparison, i.e. has more fitness than the other, is promoted to the mating pool of parents. that is to say, the higher the fitness the higher the chance of the individuals genes to reach the next generations. more details about this technique can be found in deb [9]. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 110 resd © 2015 http://apc.aast.edu fig .2. ga main procedure the used technique in this work is called multiple elitism (me) genetic algorithm presented by soremekun et al. [10]. the difference between the me technique and the technique described above is that after each crossover process, all parents and offspring are assembled in one pool and individuals with higher fitness are chosen to ensure fast conversion towards the optimum individual. iv. design of site specific wind turbine in this design, the nrel s818, s830 and s831 were used to replace du-91-w2-250, du-93-w-210 and naca-64-618 airfoils respectively in the baseline nrel 5mw wind turbine design. according to diab et al. [11], the s-airfoil family showed less deterioration in aerodynamic performance in dusty environments and hence this design will be suitable for mena region, specially egypt. in this design, the nrel s818, s830 and s831 were used to replace du-91-w2-250, du-93-w-210 and naca-64-618 airfoils respectively in the baseline nrel 5mw wind turbine design. according to diab et al. [11], the s-airfoil family showed less deterioration in aerodynamic performance in dusty environments and hence this design will be suitable for mena region, specially egypt. in the new design, the root airfoils (namely du-99-w-405, du-99-w-350 and du-97-w-300) were not changed in the s-airfoil family design for the following reasons:  there are no corresponding airfoils in the s-airfoil family to the root du-family airfoils (having the same thickness to chord ratio. root sections with high thickness to chord ratio are used in the wind turbine rotor to withstand bending moment. hence, it cannot be replaced with other sections with low thickness to chord ratios.  according to rooij and timmer [12], du airfoils give the lowest roughness sensitivity for airfoils with thickness to chord ratios between 30% and 40%.  the root section of the wind turbine blade has a little effect on the overall generated power of the rotor. hence, performance deterioration due to dust accumulation on root airfoils will not have significant effect on generated power. after selecting the airfoil shapes, the aerodynamic parameters (lift, drag and moment coefficients) are calculated using xfoil software and hence the design angle of attack was selected to have the max cl/cd value. the twist angle and chord lengths were calculated using schmitz equations [13]: 𝛽(𝑟)𝑆𝑐ℎ𝑚𝑖𝑡𝑧 = 2 3 tan−1 𝑅 𝑟𝜆 − 𝛼 (23) 𝑐(𝑟)𝑆𝑐ℎ𝑚𝑖𝑡𝑧 = 1 𝐵 16𝜋𝑟 𝐶𝐿 𝑠𝑖𝑛2( 1 3 𝑡𝑎𝑛−1( 𝑅 𝜆𝑟 )) (24) where β(r) is the twist angle at radius r, r is the blade tip radius, λ is the tip speed ratio, α is the design angle of attack of the airfoil section, c(r) is the chord length of the airfoil section at radius r and cl is the design lift coefficient of the airfoil sections.since the root airfoils in the baseline nrel 5mw wind turbine are already designed for max cl/cd twist angles, these angles are not changed in the s-airfoil family design. the baseline design was simulated at wind velocities ranges from cut-in to cut-out speed, using fast modularization framework [14] to calculate aep at specified weibull distribution. v. results and discussions the simulation and optimization process includes simulation of four wind turbine designs:  case 1: nrel 5mw baseline design (described in [15]).  case 2: optimized nrel 5mw wind turbine.  case 3: baseline site-specific wind turbine design using the s-airfoil family.  case 4: optimized site specific wind turbine design. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 111 resd © 2015 http://apc.aast.edu the baseline design (case 1) power curve at each wind speed was verified against the power curve provided in the definition report of the nrel 5mw [15]. after that, the aep was calculated for all cases. after calculation of the aep of the four cases and running optimization processes of cases 2 and 4 using a matlab optimization code coupled to fast modularization framework to run the optimization process, the results were as follow. fig .3. twist angle distribution along the rotor blade for cases 1 to 4 fig .4. chord length distribution along the rotor blade for cases 1 to 4 table 1. aep of cases 1 to 4 case no. aep (gwh) improvement from baseline case (%) improvement from case 1 (%) 1 32.88 2 34.83 5.9 5.9 3 32.18 -2.13 4 32.57 1.2 -0.94 the previous results show that a 5.9% improvement can be achieved on a baseline design after optimization for zaafarana wind distribution. this highlights the importance of tailoring design and optimization of wind turbine aerodynamic parameters on specific wind distribution along the year and attracts attention towards the need of designing and manufacturing special wind turbines that serve in specific sites to increase the ability of energy extraction from wind. on the other hand, for s-airfoil wind turbine rotor, the aep is less than the optimized baseline design. this is a result of replacing du airfoils with nrel airfoils because du airfoils have better aerodynamic characteristics than nrel airfoils. however, the nrel airfoil family is still recommended for zaafarana wind farm since it is less surface contamination sensitive, according to diab et al. [11]. according to roughness sensitivity data found in [11,12 and 16], the new aerodynamic performance of the rough airfoils of du-91-w2-250, du-97-w-300, s818, s830 and s831 were used to calculate the aep of optimized wind turbine after dust accumulation, while the other airfoils were assumed to maintain the same aerodynamic performance as clean airfoils due. the optimized nrel 5mw wind turbine shows a drop in aep form 34.83 to 29.75 gwh (-14.6% in aep), while the s-airfoil family design shows a drop in aep form 32.571 to 32.497 gwh due to dust accumulation on the blade surface. hence, the loss in aep along the year due to using nrel s-airfoil family airfoils will decrease the loss in aep due to deterioration of aerodynamic characteristics of the du and naca airfoil sections in the baseline nrel 5mw rotor. v. conclusion from the previously mentioned results, we can conclude that the new s-airfoil design and optimization resulted in a new design that is suitable for saharan areas (like areas found in egypt and many countries in the mena region) with higher aep than the baseline design. this work also concludes that design and optimization of site-specific wind turbine design play a very important role in increasing the wind turbine’s aep and hence decreasing the cost of energy generated from the wind turbine. such techniques along with consideration of the conditions in which the turbine operates, such as dust, must be taken into consideration during the process of design or selection of wind turbines to be installed in a specific wind farm. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 112 resd © 2015 http://apc.aast.edu references [1] maheri, a., noroozi, s. and. vinney, j. “application of combined analytical/fea coupled aero-structure simulation in design of wind turbine adaptive blades”. renewable energy. volume 32. issue 12, october 2007. pages: 2011-2018. [2] xiong, l., yan, c. and zhiquan, y. “optimization model for rotor blades of horizontal axis wind turbines”. frontiers of mechanical engineering in china. pages: 483488. [3] xudong, w., jin, ch., zhongshen, w., jun zhu, and nørkærsørensen, j. “shape optimization of wind turbine blades” . wind energy. pages: 781-803. [4] mohamed, m. and wetzel, k.. “3d woven carbon/glass hybrid spar cap for wind turbine rotor blade”. tran. of asme. journal of solar energy engineering. issue 128 (2006). pages:562-573. [5] hansen, m. aerodynamics of wind turbines, 2nd ed. london: earthscan. 2008. [6] mortensen, n., et al. “wind atlas for egypt: measurements, microand mesoscale modellin”. european wind energy conference ewec 2006. 2006. [7] maringer, d. “portfolio management with heuristic optimization”. dordrecht: springer, 2005. [8] holland, j. adaptation in natural and articial systems. ann arbor, mi: the university of michigan press. 1975.ann arbor, mi: the university of michigan press. 1975. [9] deb, k. multi-objective optimization using evolutionary algorithms. john wiley and sons ltd. 2001. [10] soremekun, g., gürdal, z., haftka, r.and watson, l. “composite laminate design optimization by genetic algorithm with generalized elitist selection”. computers & structures. volume 79. issue 2. january 2001. pages: 131-143. [11] diab, a., alaa, m., hossam el-din, a. , salem, h.and ghoniem, z. “performance degradation of wind turbine airfoils dust contamination: a comparative numerical study”. asme turbo expo. 2015 (2015). [12] rooij, r. and timmer, w. "roughness sensitivity considerations for thick rotor blade airfoils." journal of solar energy engineering 125.4 (2003). 468. web. [13] gasch, r. and twele j. “wind power plants: fundamentals, design, construction and operation”. berlin: springer berlin. 2011. [14] jonkman, j. and, buhl, m. “fast user’s guide”. tech. rep. golden, colorado: national renewable energy laboratory. 2005. [15] jonkman, j. , butterfield, s., musial, w. and scott, g. “definition of a 5 mw reference wind turbine for offshore system development” (2009) [16] buhl, m. "wind turbine airfoil list.". wind turbine airfoil list. nwtc. 6 july 2012. web. 02 may 2015. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.277 277 resd © 2017 http://apc.aast.edu production and management of energy: the interdisciplinary approach of enea to concentrated solar power domenico de martinis1,* and alberto giaconia2,§ enea italian national agency for new technologies, energy and sustainable economic development 1 international relations unit 2 thermal and thermodynamic solar division * current address: ministry of education, university and research -miurdepartment for higher education and research dg coordination, promotion and valorisation of research national office for the planning and promotion of italian research in international spheres § corrisponding author: alberto.giaconia@enea.it abstract clean and efficient energy generation by environmental friendly methods and technologies is now one of the major challenges worldwide. new and heterogeneous methods to produce energy pose the challenge of how to guarantee energy security, storage of exceeding production and distribution. in addition to that, the exploitation of next generation energy sources must consider the impact it may have on other productive systems and on rural areas (e.g. solar vs agriculture, biomass vs food production). enea has got and follows an interdisciplinary approach to “challenge the challenge” of a sustainable energy production, merging together materials science, agronomy and biotechnology, solar energy studies, energy efficiency management and more, in collaboration with industries and often in collaboration with the other stakeholders in the mediterranean area. this paper describes the state of the art technology and how concentrating solar power (csp) technology could be modulated to meet different energy needs, both spatial needs (e.g. off grid use vs dispatchability) and temporal needs (day vs night and energy on demand). keywords concentrating solar power ;csp; solar energy; renewable energy; energy security; mediterranean; italy; egypt; eu; engineering; solar plans; nanomaterials; materials science; energy; efficiency;industry i. introduction • setting the scene the conversion of the energy system to a new one which maximizes the use of renewable energy sources as alternative to fossil fuels is a major objective effecting science, technology and policy choices nowadays. yet, despite the global political will of exploiting clean and sustainable energy sources, the energy conversion depends on energy price market since few countries and their citizens in general are willing to bear production costs for the sake of an environmental friendly label1. thus, performance and availability of the energy sources in terms of costs and security represent a must to ensure the appropriate penetration of any kind of energy source2. to date, 19.2% of global energy consumption is fuelled by renewables3 , and renewable energy could represent the fastest growing power source over the next decades4; however, limits and challenges of such new age of energy generation must be considered, such as cost and security as already mentioned, but also distribution, storage and often complementarity with existing production and consumption systems and compatibility with future ones. among renewable energy approaches, concentrating solar power (csp) holds a significant promise for adoption as an utility-scale. different from many other direct renewable http://dx.doi.org/10.21622/resd.2017.03.3.277 http://dx.doi.org/10.21622/resd.2017.03.3.277 http://dx.doi.org/10.21622/resd.2017.03.3.277 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ mailto:alberto.giaconia@enea.it journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.277 278 resd © 2017 http://apc.aast.edu technologies, by the use of cost-effective thermal energy storage, csp is easily dispatchable, and exhibits versatility in its output capability (heat, steam, chemical energy, mechanical work, or electric power). additionally, csp enables integration with conventional power stations, by producing steam with quality standards to drive a conventional turbine 5. in a nutshell the technology enables to capture the solar heat by using mirrors or lenses to concentrate the sun rays captured on a wide area onto a much smaller surface like a solar receiver tube with high photothermal efficiency and mechanical reliability to produce high temperature heat, similar to the heat recovered from traditional fuel combustion. as a result, the same technology usually applied for thermal conversion processes (e.g. steam turbines) can be applied for several energy applications (e.g. electrical power production). a conceptual scheme of the csp basic components is represented in fig. 1. 1. the csp technology a csp plant is basically composed of a “solar field”, i.e. a large area covered with a number of solar collectors, each made of a supporting structure (anchored to the ground) for reflective panels (mirrors) and a solar tracking drive to continuously move and orient the mirrors in the direct normal ray direction. the shape and orientation of the mirrors in the solar field allow focusing the solar rays captured by the reflective panels on the surface of the so-called “solar-receiver”. the ratio between the overall mirrors’ area and the solar receiver area represents a measure of the number of times the solar radiation is concentrated: depending on the csp technology and application, the solar radiation is generally concentrated from tens to thousands times. clearly, for a given solar field and a receiver configuration, the effective captured heat flux depends on the overall efficiency which, in turn, depends on several efficiency factors like optical efficiency, tracking efficiency, mirrors’ reflectance and cleanness, receiver’s efficiency, etc. all these efficiency factors must be optimized in order to get the best overall performance of the csp pant (e.g. annual production). a “heat transfer fluid” (htf) flows inside the solar receiver to remove the high-temperature heat from the receiver and transfers it, through a specific piping system, to the final heat loads and users. depending on the csp technology and conversion process requirements, the htf can be pressurized water/steam, gas, oil, or molten salts. at the end of the cycle, the htf transfers its heat directly to the heat load, such as a steam generator for the production of super-saturated steam to drive a turbine in a rankine cycle for electrical power production. alternatively, the high-temperature heat can be used to drive purely thermal duties, like industrial thermochemical conversion reactors and processes for the production of the so-called “solar fuels”. when the power load is lower than the available heat carried by the htf, the excess heat is stored in a thermal energy storage (tes) system, to be used when necessary. after heat transfer to the thermal load(s), during hours with satisfactory direct solar radiation, the htf is pumped to re-start the heat collection loop. the solar field and the tes system can be integrated with a suitable “back-up” unit. the back-up unit is a device specifically designed to replace the solar field when the solar radiation is not adequate and the tes system is completely discharged, in order to sustain the heat demand (e.g. after extended cloudy periods). the back-up unit usually consists of a fuel combustor contributing to usually less than 10-15% of total energy production per year. clearly, the above mentioned elements and units comprising a csp plant have to be operated using suitable control tools and procedures to maximize the solar power production and the security of power supply. the development of the above mentioned units requires an extensive wide multi-disciplinary approach primarily aiming at innovation and the overall system improvement. this includes structural and mechanical engineering (e.g. for solar collectors and tracking drives), expertise in optics and materials coating (e.g. for efficiency improvements, qualification, reflective panels and solar-receivers development and maintenance), material science (e.g. for the heat transfer fluid and the tes), chemical engineering (for the thermochemical conversion), heat transfer skills (e.g. for the back-up unit, steam generator, etc.), hydraulics and fluid-dynamics (e.g. for the piping system), electronics skills (for the http://dx.doi.org/10.21622/resd.2017.03.3.277 http://dx.doi.org/10.21622/resd.2017.03.3.277 http://dx.doi.org/10.21622/resd.2017.03.3.277 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.277 279 resd © 2017 http://apc.aast.edu control and automation system), astronomical expertise (for the solar collectors’ tracking system), etc. enea’s staff covers all the above mentioned expertise required for the full development of the csp technology, from the individual components to the integrated plant design, construction and operation. concentrating solar technologies are divided in point and linear focusing systems. point focusing systems include solar towers and parabolic dishes6. linear csp technologies are parabolic troughs or linear fresnel reflectors which concentrate the solar radiation on receiver tubes. since the ‘80s several hundred mw have been installed worldwide mainly in parabolic trough csp plants typically using thermal oil htf up to 400°c and a two-tank tes using molten salts as heat storage medium operating in the temperature range between 290°c and 380°c. more recently, large solar tower csp plants have been installed, commonly with direct heating of molten salts up to 565°c: thus, compared to traditional parabolic trough csp plants typically using thermal oil htf up to 400°c, the overall efficiency of the conversion process in tower plants with direct molten salts is increased by increasing the upper temperature of the power cycle. since 2001 enea has developed a new csp concept which benefits of the main advantages of solar troughs and tower systems: solar parabolic troughs are applied for the direct use of molten salts as htf and tes medium up to 550°c. this development was made possible by the above mentioned wide interdisciplinary potentials of enea in applied research. hence, each component has been individually developed in laboratory and then tested in a prototype test plant at enea-casaccia (fig. 2). after performance assessment and qualification, the developed components are made ready for replication in csp plants on the demonstration and commercial scale. the first commercialsize plant (5 mw electrical) has been commissioned in 2010 in sicily. based on the preliminary experience, in the forthcoming years enea’s research on concentrating solar technology has been focused on further improvements of the technology with respect to individual components, plant integration, process optimization and new application scenarios. fig. 3 represents a general process scheme conceived by enea for the application of this concentrating solar technology to heat and power production. accordingly, the htf consisting of a molten salts mixture (usually the binary mixture nano3/kno3 60%wt/40%wt, though different formulation are under investigation) in the solar field is heated from about 290°c up to 550°c and then stored in a thermal energy storage tank to be used for different applications: steam generation, electrical power production, thermochemical conversion and residual heat for heating/cooling of buildings or sea water desalination; in fig. 3 a biomass-based back-up unit integrated in the plant scheme is also shown. 2. current projects and future studies on csp the csp technology can be considered a mature technology for the market and, besides public research, several initiatives are on-going worldwide7. therefore, the value of the approach is not questionable, but since the start of manufacturing plans the challenge is now how to improve the performance in different terms: construction costs, economy of production, training, easiness of use, flexibility of the system and integration with traditional and new technologies. alternative molten salts mixture is under investigation at enea to ease operation and management of the plant (e.g. lower melting temperature). the molten salts at 550°c are collected in a storage tank. enea has conceived an innovative tes system based on a single tank directly integrated with the steam generator, as represented in fig. 3. moreover, csp technology results in many products at different stages towards energy production (fig. 3) that could be used alternatively; the first product of solar concentration is heat, namely concentrated solar thermal (cst) energy that could be either stored or used for those industrial processes that traditionally need to burn a fuel (the explanatory case of methane steam reforming is shown in fig. 3). this use would lead to the deployment of greener industrial plants where combustion driven facilities, chimneys and combustion products would be minimized. therefore, the produced heat at 550°c can then be used to power a heat demanding thermochemical process like steam reforming and/or the produced steam used for electrical power production in a steam rankine cycle (fig. 3) for power generation to feed the electric grid or used http://dx.doi.org/10.21622/resd.2017.03.3.277 http://dx.doi.org/10.21622/resd.2017.03.3.277 http://dx.doi.org/10.21622/resd.2017.03.3.277 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.277 280 resd © 2017 http://apc.aast.edu locally (e.g. off-grid networks). finally, residual heat can be used for district heating and cooling or for sea water desalination, a by-product which represents an extremely high added value to the process8. when the solar radiation is not adequate to heat the molten salts up to 550°c, a molten salts heater is applied; this back-up unit can be fed by waste biomassderived fuels in order to obtain a 100% renewable energy conversion process to satisfy the heat and power demand with high flexibility. such energy conversion schemes based on csp are developed by enea in the framework of national and international projects. among these are the projects mats9 (power, heating/cooling and desalination from a csp plant based on enea’s technology) and comethy10 (steam reforming assisted by solar molten salts at 550°c). specifically, in mats (multipurpose application by thermodynamic solar) a plant with the specifications reported in table 1 is developed, built and demonstrated in the city of borg el arab (egypt). in comethy a molten salts heated steam reforming technology for hydrogen production has been developed and successfully proved with a pilot plant at enea-casaccia research centre in rome. table 1. main features of mats plant built as in borg el-arab, egypt. solar field type linear parabolic collectors (solar trough) size ca. 10,000 m2 active mirrors’ surface thermal energy storage type single tank integrated with steam generator size ca. 14 mwh (thermal), equivalent ca. 4 hours back-up unit type gas burner size ca. 2.3 mw thermal electric power unit type steam rankine cycle power 1.0 mwe desalting unit type med: multi-effect desalinator capacity 250 m 3 per day 3. technological transfer and social impact of industrial csp technological transfer to industry is a key moment to ensure that the performance obtained at the research and development stage can be translated in cost effective/efficient energy production. as mentioned in the previous section, enea was the first organization in the world that developed to the prototype and commercial level (12.5 mw thermal, about 5 mw electrical equivalent) the linear focusing csp technology with solar salts htf (up to 550°c)11. this process lasted about a decade (fig. 4) and requested a role of the government, in fostering the public research into csp, from project start-up to prototyping and an industrial role, that involved both the manufacturers and the distributor of energy and resulted in the construction of a demonstrative plan12. this “best practice” enabled the creation of a complete new high technology manufacture plant and merged together inter-disciplinary public research, component manufacturing and energy production and dispatch actors. to date, industry is fostering csp technology in italy and worldwide13,14 , and the forecast is that csp will contribute to global energy production with 90 gw (worst scenario15) to 266 gw (best scenario16) by 2030 and for a total share of about 28% of all renewable generation by 2060 (the highest growth potential10). the path therefore seems to be defined, and future challenges will focus on increasing the technological and economical value of the system. the social impact of investing in csp must not be underestimated when capacity is built in countries that are growing in demographical and/or economical terms; in short, the realization of e.g. 50 mw with thermal storage system would employ about 1,500 people during the construction phase of the components and construction of the plant (about 2-3 years). to this figure, 50 permanent jobs must be considered for the management and maintenance of the power station. moreover, it is worth to underline that about 65% of the new jobs would be located in the regions where the plants will be located17,18,19,20. 4. csp as example of technology integration and the role in the smart energy generation and management a sustainable energy production is globally considered a core objective in a historical moment of demographic growth, increasing welfare trends and environmental problems. the simple paradigm “increased population/decreased sources” is nowadays more articulated and solutions must match apparently opposite needs, such as the urbanization and the need of cultivated land, the change in population composition (e.g. the ageing http://dx.doi.org/10.21622/resd.2017.03.3.277 http://dx.doi.org/10.21622/resd.2017.03.3.277 http://dx.doi.org/10.21622/resd.2017.03.3.277 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.277 281 resd © 2017 http://apc.aast.edu society) and the different diets in different parts of the society around the globe21,22. generation and management of renewable energy implies several technological challenges at input and output levels; energy may be generated by different sources and at different times, and enter the electric distribution grid in different places. while renewable energy systems are capable of powering houses and small businesses without any connection to the electrical grid, any excess electricity production shall be stored. these aspects, if one considers the electric grid as traditionally conceived, are revolutionary. thus, transition to renewable energies poses various levels of technological complexity. concentrated solar power is a key technology that solves many of the issues mentioned above; the flexibility of the system is important also in terms of societal impact, as the possibility to work in different scenarios and deliver different products may provide answers to the different needs; to make a specific example, in sub-saharan africa (ssa) unreliable power supply poses a major impediment to reduce extreme poverty and boost shared prosperity. “low density/long distance” human settlements and rural areas are lacking access to the grid and this makes costly the distribution of electrical power. this results in poor quality, environmental unfriendly and often unhealthy systems to produce power, that could be overcome if off-grid energy is locally provided23; this issue can be solved by the introduction of small csp plants with single-tank thermal energy storage systems like the one shown in fig. 3, which could feed small communities with local “mini” distribution grids, together with the production of desalted water and other co-generation services (e.g. heating and cooling of buildings). enea is the first organization in the world that developed to the prototype and commercial level an high performance (550°c) linear focusing csp technology and is now implementing alternative applications of these technologies; this implies a strong interdisciplinary approach of far related disciplines, from material science and nanotechnology to engineering and ict to energy management, smart grid concept, climatology, agronomy, etc. all together, this is needed to create the know-how for an efficient use of energy, which would complement csp with other generations system (e.g. biomass and photovolatics) and should be embedded in the energy and social context of the region where it is implemented. a technology to deliver clean, sustainable energy, and with energy, information, education, health, food production, in industrialized areas as well as in small, isolated communities is the approach enea uses also in the framework of strong international cooperation and in collaboration with industries in order to avoid the risk of taking the technology development far away from the societal needs. fig .1. conceptual scheme of the basic components of a csp plant. fig .2. csp components test plant at enea-casaccia. fig .3. general process scheme of a co-generative csp plant by enea. fig .4. the basic step of the development of the csp technology over time and future outlook. http://dx.doi.org/10.21622/resd.2017.03.3.277 http://dx.doi.org/10.21622/resd.2017.03.3.277 http://dx.doi.org/10.21622/resd.2017.03.3.277 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.277 282 resd © 2017 http://apc.aast.edu references [1] s. osborne “costa rica powered by renewable energy for over 100 days.”independent . [on line] available: http://www.independent.co.uk/news/world/americ as/costa-rica-renewable-energy-100-days-powerclimatechange-a7217441.html [august., 2016]. [2] “levelized cost and levelized avoided cost of new generation resources” annual energy outlook 2016, u.s. energy information administration (eia). [on line] available: http://www.eia.gov/forecasts/aeo/pdf/electricity_g eneration.pdf [august 2016] [3] ren21 “renewables 2016 global status report,” paris: ren21 secretariat. isbn 978-3-98181070-7 available: http://www.ren21.net/wpcontent/uploads/2016/06/gsr_2016_full_report .pdf [march 2016]. [4] b.hulac. “strong future forecast for renewable energy,” scientific americanclimate wire available: https://www.scientificamerican.com/article/strongfuture-forecast-for-renewable-energy/ [apr. 27, 2015]. [5] m.t. dunham and b.d. iverson. “high-efficiency thermodynamic power cycles for concentrated solar power systems,” renewable and sustainable energy reviews, vol. 30, pp 758770, 2014. available: http://dx.doi.org/10.1016/j.rser.2013.11.010 [6] k. lovengrove and w. stein. (eds.). concentrating solar power technology – principles, developments and applications. woodhead publishing ltd., 2012. ebook isbn: 9780857096173 [7] nrel national renewable energy laboratories concentrating solar power projects available: http://www.nrel.gov/csp/solarpaces/index.cfm. [8] h. hashem . “can solar power produce freshwater in the middle east? csp today,” available: http://social.csptoday.com/markets/can-solarpower-produce-freshwater-middle-east [oct. 11, 2013]. [9] mats project (multipurpose applications by thermodynamic solar) available: www.mats.enea.it [in progress]. [10] “compact multifuel-energy to hydrogen converter project,” available: http://cordis.europa.eu/result/rcn/144091_en.html [in progress]. [11] “archimede solar energy (ase),” available: http://www.archimedesolarenergy.it/index.htm [in progress]. [12] “archimede solar power plant,” wikipedia available:https://en.wikipedia.org/wiki/archimede _solar_power_plant [last update 8 july 2017 ]. [13] s.stark .“this hybrid power plant combines 3 clean energy sources in one,” energy.gov newsletters available: http://energy.gov/articles/hybrid-powerplant-combines-3-clean-energy-sources-one [oct. 19, 2016]. [14] t. tsanova. “to-the-point: 50-mw csp park produces 1st power in china,” news-renewables available: http://renewables.seenews.com/news/to-thepoint-50-mw-csp-park-produces-1st-power-inchina-544154# [oct. 24, 2016]. [15] m. fawer and b. magyar “solar industry – entering new dimensions” bank sarasin & cie ag eds. available:http://www.esocialsciences.org/downlo ad/repecdownload.aspx?fname=document11012 2010400.3811609.pdf&fcategory=articles&aid=3 298&fref=repec [novembre 2010]. [16] iea, technology roadmap 2014 technology roadmap: solar photovoltaic energy 2014 edition https://www.iea.org/publications/freepublications/ publication/technology-roadmap-solarphotovoltaic-energy---2014-edition.html [september 2014]. http://dx.doi.org/10.21622/resd.2017.03.3.277 http://dx.doi.org/10.21622/resd.2017.03.3.277 http://dx.doi.org/10.21622/resd.2017.03.3.277 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://dx.doi.org/10.1016/j.rser.2013.11.010 http://www.nrel.gov/csp/solarpaces/index.cfm journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.277 283 resd © 2017 http://apc.aast.edu [17] fraunhofer project: middle east and north africa region assessment of the local manufacturing potential for concentrated solar power (csp) projects available: https://www.ise.fraunhofer.de/en/researchprojects/assessment-the-local-manufacturingpotential-of-csp [december 2010] [18] anest associazione nazionale energia solare termodinamica (in italian) available: http://anest-italia.it/wpcontent/uploads/2014/03/presentazione-anestgennaio-2014.pdf [january. 2014]. [19] estela european solar thermal electricity association, press release “how solar thermal electricity creates jobs and improves energy security in europe,” available: http://www.estelasolar.org/wpcontent/uploads/2015/11/2015.03.17-pressrestela-position-paper final.pdf?x66361 [march, 2015]. [20] mesia-middle east solar industry association: “middle east solar outlook for 2016,” available: http://www.mesia.com/wp content/uploads/mesia-outlook-2016-web.pdf [january 2016]. [21] “renewable energy in the water, energy & food nexus,”international renewable energy agency (irena) report available: http://www.irena.org/documentdownloads/public ations/irena_water_energy_food_nexus_2015 .pdf [january 2015]. [22] various authors (2014): “moving forward for an ageing society: bridging the distances,” italian position paper. isbn 978-88-6060-649-5. available: http://attiministeriali.miur.it/media/246231/moving _forward_for_an_ageing_society.pdf [november 2014]. [23] lighting africa benefits of off-grid solar products available: https://www.lightingafrica.org/about/why-off-gridenergy/ [in progress]. http://dx.doi.org/10.21622/resd.2017.03.3.277 http://dx.doi.org/10.21622/resd.2017.03.3.277 http://dx.doi.org/10.21622/resd.2017.03.3.277 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.189 189 resd © 2017 http://apc.aast.edu production of biodiesel from locally available spent vegetable oils m. m. al naggar, f. h. ashour, r. s. ettouney and m. a. el rifai chemical engineering department, faculty of engineering, cairo university, egypt m_anagar@hotmail.com, fhashour@eng.cu.edu.eg abstract the depletion of fossil fuels prompted considerable research targeting the development of alternative fuel sources. biodiesel production has acquired increasing importance owing to its renewable nature and milder environmental impacts. to this end, alternative sources of feedstock have been sought and studies aiming at the optimization of the production procedure have been carried out. millions of liters of waste frying oil are produced from local restaurants and houses every year, most are discarded into sewage systems damaging networks and complicating the treatment process. this study is intended to consider aspects related to the feasibility of the production of biodiesel from waste frying oils in order to alleviate the waste frying oil pollution problems as well as to reduce the cost of biodiesel production. locally available spent vegetable oils have been collected from different sources and accordingly have somewhat different chemical compositions. the conducted experiments involved the production of biodiesel from the different feed stocks using the base catalyzed trans-esterification process. the quality of the produced biodiesel is compared to petro-diesel in terms of established standard specifications. i. introduction increase of energy usage in the industrialized world entails rapid depletion of nonrenewable fossil fuels and is associated with pollution problems [1]. renewable resources of energy include solar energy, wind energy, geothermal energy, tidal energy, ocean thermal energy, hydropower, and alternative combustible fuels [2]. production of alternative fuels should be technically feasible, economically competitive, environmentally acceptable, and readily available [1]. diesel engines are the main engines used in industrial, transport and agricultural applications due to their high efficiency and reliability [3]. diesel engines operate via compression ignition where the fuel is injected in the engine’s cylinder with compressed air at high pressure and temperature. the fuel self-ignites and burns rapidly when it enters the cylinder forcing the piston back down and converting the chemical energy in the fuel into mechanical energy. the fuel used in the first diesel engine, developed by dr. diesel in 1895, was vegetable oil. this, however, poses socio-economic arguments arising from the conflict between food shortage and the demand for energy. due to the availability and low cost of petroleum diesel fuel, vegetable oil-based fuels are not used widely except in times of high oil prices and shortages as in world war ii and the oil crisis of the 1970’s. at present, vegetable oils are not directly used as alternative fuels due to their high viscosity, incomplete combustion, injection and ring coking and may ultimately cause engine failure [4, 5]. vegetable oils, as a source of biodiesel production, include sunflower, safflower, soybean, cottonseed, rapeseed, and peanut oils. vegetable oil based fuels are the attractive alternative for diesel fuel due to their renewable nature, better ignition quality, comparable energy content, high density, higher flash point, nontoxic emissions, cleaner burning, nearly zero sulfur content, high cetane number and high calorific value close to diesel fuel [6, 7]. there are many reasons that encourage search for alternative compression ignition engine fuels. conventional diesel engine fuels are associated with smoke and nitric oxide (nox) emissions. more stringent governmental regulations targeting cleaner combustion have been imposed to reduce diesel engine emissions. this can be done by engine development with fuel reformulation and use of alternative fuels [3]. the alternative sources considered include oils of plant origin [1]. bio-fuel, namely biodiesel and ethanol, is predicted to replace petroleum diesel fuel [8]. the ethanol is used for gasoline engines and biodiesel for compression ignition engines [9]. many countries such as brazil, the united states, germany, australia, italy and austria are currently using bio-fuel; however, its economic feasibility should be improved before it could be widely used. in most countries, the governments support biodiesel usage by reducing its http://dx.doi.org/10.21622/resd.2017.03.2.189 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ mailto:m_anagar@hotmail.com mailto:fhashour@eng.cu.edu.eg journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.189 190 resd © 2017 http://apc.aast.edu cost through tax rebates [10]. according to the american society for testing and materials (astm), biodiesel is defined as mono-alkyl esters of long chain fatty acids derived from vegetable oils and animal fats. "bio" represents its biological and renewable source, and "diesel" implies its use as a fuel on diesel engines [11]. biodiesel is derived from renewable biomass sources thus it represents a closed carbon dioxide cycle (approximately 78%) [12]. the chemical structure of methyl esters depends on the length and degree of un-saturation of the fatty acid alkyl chains. the degree of un-saturation of methyl esters affects the carbon to hydrogen ratio which is slightly different from conventional diesel fuel. the oxygen content is the important difference between conventional diesel fuel and biodiesel because biodiesel contains 10-12 wt% oxygen [13, 14, 15]. the burning efficiency of biodiesel is improved due to its high oxygen content; thus, it corresponds to lower particulate matter (pm), carbon monoxide (co), and hydrocarbon (hc) emissions, however, and it produces higher nox emissions [16]. the purpose of this work is to conduct a laboratory scale study for production of biodiesel using locally gathered waste vegetable oils from different origins. the processing requirements for the different feed stocks are to be compared. the final product specifications are to be also compared with those of petro diesel. ii. experimental conditions trans-esterification reactions have to be carried out under vigorous mixing conditions owing to the immiscibility of the oil and methanol phases. since trans-esterification is a relatively slow process, intense mixing is required both because of the relatively high oil viscosity and in order to ensure sufficient interfacial area between the two reactants present in different phases. the optimum operating temperature for this reaction is 65c, which is slightly above the boiling point of methanol (64.7c)[17]. when the reaction temperature exceeds the boiling point of methanol, the methanol will vaporize and form a large number of bubbles which may inhibit the reaction. the experimental conditions for the different feed stocks have been fixed at an agitation rate of 400 rpm and at a temperature of 65c. iii. materials and methods: waste oil was collected from three different sources: (1) waste frying palm oil (wpo) from a local fast food restaurant, (2) mixed waste home frying oil used only once or twice (who), (3) waste mixed oils, sunflower, palm oil and soya oil (wto) collected after 48 working hours from a controlled food court. the chemicals used in the experiments were: methanol procured from el-nasr pharmaceutical chemicals co. (adwic) with a molecular weight of 32.04 and an assay of 99.8%, koh purified pellets from thannfransu, analar grade isopropyl alcohol, and phenolphthalein. a small-scale laboratory setup was used for pretreatment and trans-esterification experiments. the waste oil is first heated to 60c in a water bath to ensure complete melting. it is then filtered using a standard buchner funnel connected to a vacuum pump in order to ensure complete solids removal. the filtrate is then heated in a water bath up to 110c to ensure vaporization of any residual water since the presence of water negatively affects the reaction by promoting saponification and increasing the viscosity. trans-esterification experiments were conducted in triplicate using 100g of used frying oil. methanol and koh catalyst were poured into a clean reaction flask provided with a magnetic stirrer and a reflux condenser. the oil, methanol, and koh mixture was stirred for 120 min at 60-70c and 400 rpm. the trans-esterification reaction was carried out for different ratios of oil to methanol (10, 15, 20, 30, and 40g). the amount of catalyst had a pronounced influence on the conversion to esters. various amounts (0.75g, 1g, and 1.5g) of koh catalyst were used in the experiments: after the trans-esterification reaction, the biodiesel was separated from glycerol using a separating funnel where the reaction mixture was allowed to cool. clear separation was observed after 12-24 hours of settling. the ester was then washed three times with warm distilled water. the product was then dried by heating at 110oc for 30 min to remove the moisture content and the methyl ester is filtered to remove any residual soap. the effects of catalyst content, methanol to oil molar ratio, and reaction time were determined. it is recognized that the production of waste cooking oil will be a function of the frying temperature and length of use as well as the material used for frying. the free fatty acid (ffa) analysis for the raw oil http://dx.doi.org/10.21622/resd.2017.03.2.001 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.189 191 resd © 2017 http://apc.aast.edu should be lower than 0.5%. the oil has been treated and the ffa content was determined by standard titration while the fatty acid composition was determined using chromatographic analysis (gc). iv. results and discussion: • yield and conversion the effect of base-catalyzed trans-esterification process variables on biodiesel yield from the different waste frying oils was investigated by changing the (koh) catalyst to oil ratios (% w/w) and the methanol to oil ratios (% w/w). table 1.yield and conversion of trans-esterification reaction of all waste frying oils run# koh (g) meth. (g) yield % conversion % wpo wto who wpo wto who 1 0.75 10 63.69 32.41 2 0.75 15 81.41 67.25 78.22 76.92 55.56 61.38 3 0.75 20 76.21 86.35 87.71 61.54 55.56 61.03 4 0.75 30 87.05 75.73 85.14 76.92 77.78 62.07 5 0.75 40 90.26 88.06 87.25 76.92 66.67 31.72 6 1 10 34.53 71.18 69.23 60.34 7 1 15 77.53 54.2 91.06 61.54 55.56 42.07 8 1 20 87.18 80.04 91.41 69.23 55.56 80.69 9 1 30 84.66 83.27 88.01 84.62 77.78 42.76 10 1 40 88.26 84.08 68.96 84.62 55.56 42.17 11 1.5 10 45.9 69.23 12 1.5 15 70.66 73 83.89 38.46 55.56 50.35 13 1.5 20 78.19 79.4 72.37 61.54 66.67 42.41 14 1.5 30 88.59 77.12 67.85 76.92 77.78 60.21 15 1.5 40 81.64 89.6 54.48 53.85 83.33 42.05 table 1 presents the calculated yield and conversion obtained from the experimental data for the different waste frying oils under different reaction conditions. previous results reported in the literature [17] on the effect of catalyst and methanol to oil ratio on biodiesel production suggest that biodiesel with the best properties was obtained using 1 % koh by weight as the catalyst. methanolysis with this catalyst produced the best yields and viscosities of the resulting esters. a. b. chhetri et al. [12] used 0.4%, 0.6%, 0.8%, 1.0% and 1.2% sodium hydroxide as a catalyst and observed that no reaction took place with the 0.4% naoh. with catalyst concentrations of 0.6%, 0.8% and 1.0%, ester yields were approximately 50%, 94% and 40%, respectively. it was also observed that the ester yield decreased with the increase in naoh concentration. with 1.2% catalyst concentration, soap formation was pronounced. increased soap formation caused the ester to dissolve into the glycerol layer. the findings obtained in the present work may be compared with the above literature data by considering the experimental results presented in figures (1-3) below. figure (1) presents the yields obtained for wpo, who, and wto respectively for different amounts of ch3oh and koh. it is seen that the highest yield for wpo ranged between 87.05% to 90.26% (runs 4, 5, 8, 10, and 14). in these runs, the dominant catalyst amount ranged between (0.75 – 1g) except for run 14 which used 1.5g koh. two runs (runs 6, 11) gave a very low yield (34.53%, 45.9%) and no yield was obtained for run (1). all of these runs were carried out using 10g ch3oh, and as such the amount of methanol is not sufficiently in excess to increase the rate of the forward reaction towards ester production. the maximum yield for (who) was found in runs (7, 8, 9) where the amount of catalyst was (1g) and the amount of methanol was (20, 15, 30g), respectively. no yield was obtained from run number (11) while the lowest yield was obtained in runs (1, 10, 14, and 15), where the high amount of koh (1.5g) reduced the yield due to saponification (runs 14, 15) and the low amount of methanol caused incomplete reaction (run 1). also the increase of methanol reduced the yield because it diluted the reaction mixture (runs 10, 14 and 15).thus the optimum trans-esterification reaction conditions for (who) were 1g koh and 20g methanol. the maximum yield for (wto) was in runs (3, 5, 9, 10, and 15) with koh ranging between 0.75g and 1g except for run 15 which used 1.5g koh. the lowest yield was in runs (2, 7) and no reaction took place in runs (1, 6, and 11). all of these runs were carried out with methanol ranging between (10 – 15g), and this means that the amount of ch3oh should not be lower than (20g) to push the reaction in the forward direction. thus, in the case of using (wto) the optimum amount of ch3oh required to achieve a high yield is (20g). comparison of the yields of the three types of oil showed that the highest yield was obtained for (who) in runs (8, 7) reaching 91.41% and 91.06%, respectively. this is attributable to that (who) had the lowest ffa content and thus it gave higher yields http://dx.doi.org/10.21622/resd.2017.03.2.189 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.189 192 resd © 2017 http://apc.aast.edu under the same conditions. the second highest yield was obtained in run (5) for (wpo). yields for both (wpo) and (wto), at low amounts of ch3oh (10 – 15g), were very low and sometimes no reaction occurred. the highest conversion of 84.62% was obtained for (wpo). the second highest conversion of 83.33% was for (wto) while the highest conversion using (who) was 80.69%. fig .1. effect of catalyst content on yield (a) wpo, (b) who and (c) wto • density and viscosity table 2 presents the density and viscosity of the produced fatty acid methyl ester (fame) from wpo, who, and wto respectively for different amounts of koh and ch3oh. the fame density should lie between 0.86 and 0.9 kg/m3 [11]. all the (wpo) densities were within the above specified range except for run (10) which gave a lower density (0.849 kg/m3). all the measured (wto) and (who) densities were equal to or higher than the upper limit of the specification. figure (2) displays the measured kinematic viscosities (kv) for the fame produced from wpo, who, and wto, respectively. the range for biodiesel kinematic viscosity is (1.9 – 6 mm2/s) according to astmd 6751 standard and (3.5 – 5 mm2/s) accords to en14214 standard. the measured (kv) at 40c for (wpo) was 52.9 mm2/s, for (who) was 33.5 mm2/s, and for (wto) was 52.1 mm2/s. most of the produced fame was within the astm range except for run (1) for (who) and runs (2, 3, 7, and 12) for (wto). in these runs, low amounts of methanol were used and as such (wto) require more methanol to improve fame characteristics. for (wpo) the out of specification runs were (2, 6, 7, 11, and 12). all of these runs were carried out using low amounts of methanol and, accordingly, their viscosities were higher than the standards. palmitic acid was the major saturated fatty acid found in this waste oil which is the major factor that determines the viscosity of biodiesel. finally, the recorded decrease in density and viscosity after trans-esterification indicates that good trans-esterification has been achieved under appropriate experimental conditions. table 2.density and viscosity of fame from all waste frying oils run# koh (g) meth. (g) density kg/m3 viscosity mm2/s wpo wto who wpo wto who 1 0.75 10 0.91 6.6 2 0.75 15 0.889 0.92 0.91 6.14 9.2 5.6 3 0.75 20 0.8924 0.91 0.91 5.63 6.7 4.8 4 0.75 30 0.8856 0.90 0.90 4.88 5.2 4.6 5 0.75 40 0.8844 0.90 0.90 5.05 4.9 4.5 6 1 10 0.899 0.90 8.31 5.1 7 1 15 0.891 0.91 0.91 6.11 8.7 4.9 8 1 20 0.8818 0.90 0.90 5.08 4.9 4.4 9 1 30 0.885 0.90 0.90 4.53 4.9 4.2 10 1 40 0.849 0.90 0.91 4.88 5.1 4.7 11 1.5 10 0.896 7.37 12 1.5 15 0.894 0.90 0.91 6.4 6.6 4.7 13 1.5 20 0.8832 0.90 0.91 4.84 4.9 5.7 14 1.5 30 0.8838 0.90 0.89 4.74 5.1 5.2 15 1.5 40 0.891 0.91 0.90 4.62 5 5 fig .2. viscosity of fame at 40c, (a) wpo, (b) who and (c) wto http://dx.doi.org/10.21622/resd.2017.03.2.001 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.189 193 resd © 2017 http://apc.aast.edu • cloud point and pour point figure (3) reveals that the cloud point for (who) ranged between (-2 – 2.5c), for (wto) between (1.75–5c) and for (wpo) between (15–25c). the pour point results presented in figure (4) revealed that it ranged between (-8 – -3c) for (who), between (-5.5– -0.5c) for (wto) and between (4– 14c) for (wpo). it may be concluded that (wpo) is solid at room temperature because its main constituent is palmitic acid. the fame produced from (wpo) would not be suitable for cold weather as it will block vehicles' hoses and pipes. the cloud point and pour point limits of egyptian petro-diesel are 9c and 6c, respectively. thus most esters produced from who and wto would conform to the egyptian specifications, however all esters produced from wpo would not be suitable for local use in cold conditions. fig .3. cloud point of fame, (a) wpo, (b) who and (c) wto fig .4. pour point of fame, (a) wpo, (b) who and (c) wto v. saponification value: the saponification value is defined as the milligrams of koh required to saponify one gram of oil. the obtained saponification value for biodiesel produced from all the tested waste frying oils (wfo) was higher than that of the wfo feed. this is not the case when virgin vegetable oil is used for biodiesel production. this is attributable to the chemical degradation during frying when reactions such as cyclization and polymerization take place. the saponification value of wpo was160.78 mg koh/g oil, while that of its esters ranged between 162.69 and 201.96mg koh/g oil. the saponification value of who was150.66mg koh/g oil, while that of its esters ranged between140.25 and 252.45mg koh/g oil. the saponification value of wto was135.25mg koh/g oil, while that for its esters ranged between145.86 and 238.43mg koh/g oil. the obtained saponification values for the different oils are presented in figure (5). fig .5. saponification value of fame, (a) wpo, (b) who and (c) wto i. gas chromatography (gc) analysis: table (3) presents the results of the gc analysis of the produced fame from wpo. the fatty acid content is the major factor affecting the properties of biodiesel. the biodiesel derived from the sample of waste cooking oil subjected to gc contained palmitic acid, stearic acid, oleic acid, and linoleic acid. the saturated fatty acid content of the waste cooking oil was approximately 60% corresponding to a cold filter plugging point (cfpp) of (6-14 oc). http://dx.doi.org/10.21622/resd.2017.03.2.189 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.189 194 resd © 2017 http://apc.aast.edu table 3. gc results of fame produced from wpo ii. conclusion laboratory trans-esterification experiments have been carried out to determine the effect of the amount of catalyst and methanol on the fame yield produced from different waste frying oils at a reaction temperature of 60 -70oc), a reaction time of 120 min and at an agitation speed of 400 rpm. since the feedstock has been collected from different sources, there was a significant difference in the chemical and physical properties of the produced biodiesel. the yield, conversion, density, viscosity, cloud point, pour point and saponification value of the produced fame have been experimentally determined for different koh and methanol to oil ratios. the optimum amount of catalyst and methanol for the three types of waste oils investigated are respectively(1g koh – 40g methanol) for (wpo), (1.5g koh – 40g methanol) for (wto), and (1g koh – 20g methanol)for (who). the highest yield was obtained from (who) due to its relatively low ffa content. the densities and viscosities of the biodiesel produced from the three waste cooking oils lie within the astm standard except for the runs using low amounts of methanol. the cold flow properties of the (wto) and (who) conform to the egyptian specifications; however, all the esters produced from wpo were not suitable for use in cold conditions. the best biodiesel properties were obtained from (who), followed by that obtained from (wto) and then (wpo) owing to its high palmitic acid content. references [1] l.c. meher, d.v. sagar and s.n. naik. “technical aspects of biodiesel production by transesterification: a review.” renewable and sustainable energy reviews, vol.10, pp. 248268, 2006. [2] k.m. shereena and t.thangaraj. “biodiesel: an alternative fuel produced from vegetable oils by transesterification.” electronic journal of biology, vol.5 3, pp. 67-74, 2009. [3] m. s. kumar, a. kerihuel, j. bellttre and m. tazerout. “ethanol animal fat emulsions as a diesel engine fuel; part 2: engine test analysis.” fuel, vol. 85, pp. 2646-2652, 2006. [4] “pacific biodiesel – recycle used cooking oil & grease trap waste.” available: www.biodiesel.com/biodiesel/history. :[ march 3, 2016]. [5] c.y.may, y. c. liang, c. s. foon, m. a. ngan, c. c. hook and y. basiron. “key fuel properties of palm oil alkyl esters.” fuel, vol. 84, pp. 1717-20, 2005. [6] k. anand, a. ranjan and p. s. mehta. “estimating the viscosity of vegetable oil and biodiesel fuels.” energy fuels vol. 24, pp. 664672, 2010. koh (g) ch3oh (g) a palmitate b linoleate c oleate d stearate saturated unsaturated 0.75 20 49 5.939 38.8 6.202 55.241 44.758 0.75 30 52.7 4.687 36.6 6.008 58.677 41.323 0.75 40 53.2 5.123 35.8 5.878 59.042 40.958 1 20 50 5.913 38.3 5.787 55.745 44.256 1 30 51.8 5.427 37.1 5.744 57.5 42.501 1 40 52.9 5.333 35.8 5.928 58.84 41.161 1.25 20 47.7 6.058 40.2 6.073 53.737 46.264 1.25 30 64.8 4.152 26.6 4.432 69.226 30.775 1.25 40 53 5.232 35.8 6.024 58.982 41.018 1.5 20 57.1 4.854 32.1 5.857 62.996 37.003 1.5 30 53.4 5.31 35.4 5.915 59.294 40.706 http://dx.doi.org/10.21622/resd.2017.03.2.001 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.189 195 resd © 2017 http://apc.aast.edu [7] m. s. kumar, a. ramesh and b. nagalingam. “an experimental comparison of methods to use methanol and jatropha oil in a compression ignition engine.” biomass and bioenergy, vol. 25, pp. 309-18, 2003. [8] n. ozsezen, m.canakci, a.turkcan and c.sayin. “performance and combustion characteristics of a di diesel engine fueled with waste palm oil and canola oil methyl esters.” fuel, vol. 88, pp. 629636, 2009. [9] r. k. pandey, a. rehman, r.m. sarviya and s. dixit. “automobile emission reduction and environmental protection through use of green renewable fuel.” hydro nepal, vol. 7, pp. 6570, 2010. [10] s. behzadi and m. m. farid. “production of biodiesel using a continuous gas–liquid reactor.” bioresource technology, vol. 100, pp. 683-689, 2009. [11] m. canakci and a. n. ozsezen. “evaluating waste cooking oils as alternative diesel fuel.” gu journal of science, vol. 18, pp. 81-91, 2005. [12] b. chhetri, k. c. watts and m. r. islam. “waste cooking oil as an alternate feedstock for biodiesel production.” energies, vol. 1 pp. 3-18, 2008. [13] z. utlu and m. s. kocak. “the effect of biodiesel fuel obtained from waste cooking oil on direct injection diesel engine performance and exhaust emissions.” renewable energy, vol. 33, pp. 1936-41, 2008. [14] m. a. hess, m. j. haas, t. a. foglia and w. n. “marmereffect of antioxidant addition on nox emissions from biodiesel.” energy fuel, vol. 19(4), pp. 1749-54, 2005. [15] j. p. szybist, s. r. kirby and a. l. boehman. “nox emissions of alternative diesel fuels: a comparative analysis of biodiesel and ft diesel.” energy fuel, vol. 19(4), pp. 1484-92, 2005. [16] c. a. sharp, s. a. howell and j. jobe. “the effect of biodiesel fuels on transient emissions from modern diesel engines – part i: regulated emissions and performance.” sae paper. 2000; vol. 1, pp. 1967-85. [17] s. a. el sherbiny, a. a. refaat and s. t. el sheltawy. “production of biodiesel using the microwave technique.” journal of advanced research, vol.1, pp. 309-314, 2010. http://dx.doi.org/10.21622/resd.2017.03.2.189 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 2, issue 1, june 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.1.037 37 lithium-ion battery degradation assessment and remaining useful life prediction in hybrid electric vehicle nabil laayouj *, hicham jamouli * * lgii laboratory, national school of applied sciences, ibn zohr university, agadir, morocco e-mail: nabil.laayouj@gmail.com abstract prognostic activity deals with prediction of the remaining useful life (rul) of physical systems, based on their actual health state and their usage conditions. rul prediction gives operators a potent tool in decision making by quantifying how much time is left until functionality is lost. in addition, it can be used to improve the characterization of the material properties, that govern damage propagation for the monitored structure. rul can be predicted by using three main approaches, namely model-based, datadriven and hybrid approaches. prognostic methods used later in this paper are hybrid and data-driven approaches, which employ the particle filter in the first one and the autoregressive integrated moving average in the second. the performance of the suggested approaches is evaluated in a comparative study on data collected from lithium-ion battery of hybrid electric vehicle. keywords remaining useful life; prognosis; particle filter; arima. i. introduction prognosis and health management (phm) [1] will have significant impact on increasing safety as well as reducing operating and maintenance costs. this can be achieved by providing an accurate quantification of degradation and damage at an early stage to reduce or eliminate malfunctions. furthermore, phm consists of three main routines: fault detection, diagnosis and prognosis. a prognosis has recently attracted a lot of research interest due to the need of models for accurate rul prediction [2]. numerous methods and tools can be employed to evaluate the size of damage by predicting the rul value. prognosis techniques can be categorized under three approaches based on the usage of information: model-based, data-driven and hybrid approaches. the model based approach [3], assumes that a model of system behavior is available and uses this model to predict the future of the system behavior. some recent developments in the model-based approach have been reported in the literature. such as lumped parameter model [4], functional models [5] and first principal models [6]. the data-driven approach [7] aims at transforming the data provided by sensors into relevant models. in the literature, there are the following works: relevance vector machine [8] and neural network [9]. the hybrid approach [10] combines the two approaches cited earlier and includes bayesian techniques [11][12]. in this work, the researchers will study two main approaches to predict rul. the first approach is a hybrid prognosis using a particle filter method, which employs both, state dynamic model and a measurement data. the second approach is a datadriven prognosis based on routinely collected data, using autoregressive integrated moving average (arima) model to estimate the system degradation. the application of particle filters to prognosis has been reported in the literature. for example, prediction of lithium-ion battery capacity depletion [13], degradation prediction of a thermal processing unit in semiconductor manufacturing [14], and remaining useful life prediction of a mechanical component subject to fatigue crack growth [15]. the reported application results have shown that particle filters represent a potentially powerful prognosis tool due to its capability in handling non-linear dynamic systems and non-gaussian noises, using efficient sequential importance sampling [16][17] to approximate the future state probability distributions. many works around arima model have been developed. among these are mechanical deterioration prognosis [18] [19] and economic forecasts [20][21]. in the present study, the researchers will use the arima model to predict http://dx.doi.org/10.21622/resd.2016.02.1.037 journal of renewable energy and sustainable development (resd) volume 2, issue 1, june 2016 issn 2356-8569 38 degradation by computing rul. this paper is organized as follows: section 2 contains the descriptions of the approaches at the basis of rul prediction; in section 3, the results of the application of the methods are presented, and an evaluation of their performance is given; and finally, some conclusions on the advantages and limitations of the approaches are given in section 4. ii. suggested approaches based on the rul prediction a. prognosis of degradation and remaining useful life the term prognosis is originally used in medicine for the prediction of a course of an illness. but, later on it has been introduced to industry to predict the future operating status of equipments, and to set an efficient treatment. the practitioner uses the results of the forecast models to determine the most appropriate treatment. these forecast models based on simple mathematical tools (e.g. decision tree, conditional probability) [22], or on more sophisticated (e.g. markov processes, neural networks, and genetic algorithms) [23]. as mentioned earlier, the main objective of prognosis is to determine the time before failure. note that the data prognosis is important information that may be used in the decision process. for example, this data prognosis can be used to delay the maintenance interventions, or stop a machine before its future maintenance due to earlier default. b. methods of prognosis 1. particle filter for prognosis the particle filter method [24] is a monte carlo technique for the solution of the state estimation problem. the key idea is to represent the required posterior density function by a set of random samples (particles) with associated weights, and to compute the estimations based on these samples and weights. as the number of samples becomes very large, this monte carlo characterization becomes an equivalent representation of the posterior probability function, and the solution approaches the optimal bayesian estimation. 2. particle filter model consider the dynamic system described by the following discrete time model [15]: ),( 1 kkkk vxfx   (1) ),( kkkk xhz  (2) where: kf : is the state transition function (damage model) kv : is state noise vector of known distribution k h : is the measurement function k  : is the measurement noise vector the goal of tracking is to recursively estimate k x by using the set of all available measurements ),...,( 1:1 kk zzz  up to time k, and to create a conditional state pdf (probability density function). like any bayesian estimation, two steps are employed: prediction and update. in the prediction step, the researchers consider that the pdf 1:11  kk zxp previous state estimate at time 1k and the process model (1), both are used to obtain the prior pdf of the state at time k as shown in chapman-kolmogorov equation. 11:1111:1   kkkkkkk dxzxpxxpzxp (3) in the update step, at time , a measurement becomes available (from the likelihood function defined by the measurement model (2)), and this may be used to update the prior distribution to generate the posterior state pdf via bayes rule (4). 1:1 1:1 :1    kk kkkk kk zzp zxpxzp zxp (4) in order to obtain exact state estimation solutions for equations (3) and (4), the actual distributions are approximated by a set of samples and their normalized weights. consider   sn i i k i k wx 1:0 ,  a random measure that characterizes the posterior pdf journal of renewable energy and sustainable development (resd) volume 2, issue 1, june 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.1.037 39 kk zxp :1 , where i k x :0 and i k w are, respectively a set of support points and associated weights. the weights are normalized such that 1i i k w . then, the posterior density at time k is approximated [24] as    sn i i kk i kkk xxwzxp 1 :0:0:1 )( (5) the weight process based on importance sampling [24], such that the weight update equation is given by k i k i k i k i k i kki k i k zxx xxpxzp ww :11:0 1 1      (6) when  s n the importance density function kkk zxx :11:0   can be approximated by the prior pdf 1kk xxp , and weight becomes [16] i kk i k i k xzpww 1  (7) another problem arises is the degeneracy phenomenon, where after a few iterations, all but one particle will have negligible weight. this degeneracy explains that a large number of updating particles is around zero. to overcome this problem, considering resampling procedure [25] at each step, the researchers assign s k n w 1 1   for all the particle weights so they have i kk i k xzpw  (8) to implement sir (sequential importance resampling) filter, as in (7) and (8), the researchers need to know process model, measurement model and likelihood function kk xzp 3. rul prediction using particle filter once the estimated parameter is obtained, the future damage state and rul can be predicted by progressing the damage state until it reaches the threshold (fig. 1). the pdf curve represents the progress of damage state until it reaches the threshold. the distribution of rul can be obtained by subtracting this pdf from the threshold fig .1. illustration of rul calculation 4. arima model for prognosis one of the important and widely used time series model is the autoregressive integrated moving average (arima) model, which is a generalization of arma model. it requires only the historical time series data. these models are fitted to time series data to predict future points in the series (forecasting). 5. arima forecasting method arima is a forecasting technique, noted as arima (p,d,q), the general model was introduced by box and jenkins [26]. it is a method which allows both autoregressive (ar) and moving average (ma). it explicitly includes differencing in the formulation of the model. where, p and q are, respectively, autoregressive parameter and moving average parameter, while d is the number of non-seasonal differences. the autoregressive part of the model of order p is written: t p i itit xcx      1 (9) where t x is a stationary series, it x  represents lag i of t x , the i  , pi ,...,1 are the parameters of the model, c is a constant and t  is a white noise. the moving average part of the model of order q is written: t q i itit x      1 (10) http://dx.doi.org/10.21622/resd.2016.02.1.037 journal of renewable energy and sustainable development (resd) volume 2, issue 1, june 2016 issn 2356-8569 40 where the i  , qi ,...,1 are the parameters of the model,  is the expectation of t x , which is often assumed to equal zero, and the qttt   ,...,, 1 are white noise error terms. after an initial differencing step (corresponding to the integrated part of the model), the researchers can present the arima (p,d,q) as arma (p,q) process:       q i iti p i ititt xcx 11  (11) the estimation of the arima model corresponding to some learning data is done through box and jenkins methods [26]. a procedure of the forecasting can be summarized as:  check stationary: if the data are not stationary, they need to be transformed into stationary data using the differencing technique.  identification: to specify the appropriate number of autoregressive term p, and moving average term q from the autocorrelation function (acf) and partial autocorrelation function (pacf) correlograms.  forecasting: based on the forecasting model, multi-step-ahead prediction is then conducted to forecast the final failure time.  verification: if the predictions result in an unexpected trend, repeat steps 2 and 3 until the model fits the historical data appropriately. 6. rul prediction using arima prediction of lifetime using arima can be expressed in two parts: construction of model and prediction of state. in the first step, the researchers construct the corresponding coefficients (differencing, autoregressive and moving average terms) and they obtain an arima model. next step, when the model is built, a sample is selected to be estimated. remaining useful life (rul) is defined as the number of predictions from current state until the failure states reached the threshold. the following fig. 2 shows the forecasting method for rul prediction. 7. hybrid electric vehicle (hev) an electric car is powered by an electric motor instead of a gasoline or diesel engine. the electric car (also known as electric vehicle ev) uses energy stored in its battery (or series of batteries), which are recharged by different sources. there is a variety of electric vehicles available in the world, among these hev (hybrid electric vehicle), the phev (plug-in hybrid electric vehicle) and bev (battery electric vehicle). the researchers have oriented their work towards the hev (fig. 3), where a small battery is placed on board, and when the vehicle brakes, the energy is stored in the battery and it can later be used to power the electric motor which assists the gasoline engine. hev typically provides better fuel economy than similar conventional vehicles. this is why it is necessary to develop a prognosis of battery degradation, in order to ensure a proper functionality. the cell (or battery) studied in this work [27] is a lithium-ion with 1ah capacity and 3.75 v. the cell is part of a battery pack (battery pack= 15 cells) which is used to collect and distribute electric power (direct current power), mainly to the electrical drive. the researchers use the 25°c as the baseline for measurement. a simple form of the empirical degradation model is expressed by an exponential growth model as follows [28] degradation data differencing lags selection ar and ma coefficients arima model forecasting accurate remaing useful life no yes fig .2. arima prediction algorithm )exp( bta  (12) where a, b are model parameters, t is the time, and  is internal cell performance. the equivalent electrical model is introduced as shown in fig. 4. where, dl c is the double layer capacitance, ct r is journal of renewable energy and sustainable development (resd) volume 2, issue 1, june 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.1.037 41 the charge transfer resistance, w r is the warburg impedance and er is the electrolyte resistance. the internal cell performance is observed instead of the capacity. additionally, there is a relationship between and 1/c capacity; is inversely proportional to the 1/c [28]. also, the observed data are assumed to be given as a capacity. and dl c showed negligible change over the ageing process and are excluded from further analysis. the threshold for fault declaration has arbitrarily been chosen. fig .3. plan of hybrid electric vehicle fig .4. equivalent circuit diagram of a li-ion cell table 1. data of degradation time (t) intial,1 2 3 4 5 c/1 (ah) 1,000 0.981 0.859 0.811 0.788 time(t) 6 7 8 9 10 c/1 (ah) 0.714 0.680 0.612 0.56 0.568 8. rul prediction and results the particle filter uses the exponential growth model (12) to obtain the prior pdf (1). the measurement and process noise variance k  and k v respectively were modeled as gaussian densities. in the particle filter, a and b are incorporated as internal cell parameters e r and ct r . the values of a and b in the actual state are used as initial estimations. then, the resampling of particles is applied to each iteration to solve the degeneracy problem. the predictions are progressed until they reach the threshold to get the rul. the failure threshold is defined when the capacity fades by 35%. fig .5. autocorrelation and partial autocorrelation plots for arima model fig .6. trajectory of degradation for the cell of battery pack using particle filter arima (p,d,q) model uses simply the capacity data measurement to predict the future degradation. in our case, the data are roughly exponential in nature; d is cte rr  cte rr  1/c w r e r w r ct r dl c http://dx.doi.org/10.21622/resd.2016.02.1.037 journal of renewable energy and sustainable development (resd) volume 2, issue 1, june 2016 issn 2356-8569 42 chosen to be 2 in order to remove the non-stationarity, both p and q are chosen to be 1 (fig. 5). the capacity data measurement at every 100 charge/discharge cycles are given in table 1, where 1t=100 charge/discharge cycles. fig. 6 shows the real and the estimated values of the cell degradation using particle filter. although the predicted results are close to the real values throughout the prediction area. in fig. 7, the estimated data of the cell degradation obtained by arima model are far off the real values after t=15. fig .7. trajectory of degradation for the cell of battery pack using arima model the performance of both methods has been evaluated by the mean absolute scaled error (mase) [29] and root mean square error (rmse). definition of mase: a scaled error is defined as        n i ii kk k yy n yy q 2 1 1 1 ˆ (13) where y is the real value of testing cell, ŷ is the prediction value and n is the number of prediction data set. the mase is simply )( k qmeanmase  (14) definition of rmse:    n t yy n rmse 1 2 ]ˆ[ 1 (15) the detail results are shown in table 2. table 2. mase and rmse measurement of the cell prognosis predictive approach particle filter arima model mase 0,7345 2,6163 rmse 0,0253 0,0719 from table 2, one can find that the calculation of mase and rmse for arima model is superior to the particle filter. consequently, the particle filter is more accurate than the arima model. in this study, the researchers have illustrated how the particle filter method can provide accurate predictions of the rul, as presented in [28][30] over conventional data-driven methods without physical model. iii. conclusion in this study, the researchers interested here in two approaches for health prognostics using particle filter and arima model. the goal in applying these methods is to calculate rul. in addition, the rul gives the best idea about the degradation of each system. the results showed that the particle filter was more faithful to the simulated data. the researchers considered different frequencies of inspection for the measurement. this study highlights the value of having a physical failure model to improve the accuracy of results. in contrast, the arima needs great possible historical data in order to give proper results without the need for physical model. however, the disadvantage of the particle filter compared to arima model is the degradation model requirement, which is not always easy in the case of a large-scale system. remember that both approaches require a knowledge of a threshold corresponding to the physical system failure to plan the actions of preventive maintenance, and expect to benefit from the opportunistic maintenance. finally, the obtained results in this paper show that the particle filter is more efficient than the arima model. journal of renewable energy and sustainable development (resd) volume 2, issue 1, june 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.1.037 43 references [1] k. medjaher, tobon-mejia and n. zerhouni, “remaining useful life estimation of ceritical components with application to bearings beliability”, ieee transactions on, vol.61, no.2, 2012, pp.292-302. [2] a. mosallam, k. medjaher and n. zerhouni, “bayesian approach for remaining useful life prediction”, chemical engineering transactions, vol. 33, 2013, pp. 139-144. [3] a. heng, a. c. tan, j. mathew, n. montgomery, d. banjevic, and a. k. jardine, “intelligent condition-based prediction of machinery reliability”, mechanical systems and signal processing, vol. 23, no. 5, 2009, pp. 1600–1614. [4] c. j. and h. lee, “gear fatigue crack prognosis using embedded model, gear dynamic model and fracture mechanics”, mechanical systems and signal processing, vol. 19, 2005, pp. 836846. [5] p. toguyeni, a. k. a and e. craye “structural and functional approach for dependability in fms”, ieee international conference on systems, man, and cybernetics, 1999. [6] jaw, j.c, inc, s. m. and tempe, a. z., “neural networks for model-based prognostics”, ieee aerospace conference, 1999. [7] m. dong and d. he, “a segmental hidden semimarkov model (hsmm)-based diagnostics and prognostics framework and methodology”, mechanical systems and signal processing, vol. 21, no. 5, 2007, pp. 2248–2266. [8] m. tipping, the relevance vector machine. in advances in neural information processing systems, mit press, cambridge, 2000. [9] a.n. srivastava and s. das, “detection and prognostics on low dimensional systems”, ieee transactions on systems, man, and cybernetics, part c: applications and reviews, vol. 39, 2009, pp. 44-54. [10] j. yan and j. lee, “a hybrid method for on-line performance assessment and life prediction in drilling operations”, ieee international conference on automation and logistics, 2007. [11] j. w .sheppard, m. a. kaufman, a. inc and m. d. annapolis, “bayesian diagnosis and prognosis using instrument uncertainty”, ieee autotestcon, 2005, pp. 417 423. [12] b. saha and k. goebel, “uncertainty management for diagnostics and prognostics of batteries using bayesian techniques”, ieee aerospace conference, 2008. [13] b. saha, k. goebel, s. poll, and j. christophersen, “prognostics methods for battery health monitoring using a bayesian framework”, ieee transactions on instrumentation and measurement, vol. 58, no. 2, 2009, pp. 291-296. [14] s. butler and j. ringwood, “particle filters for remaining useful life estimation of abatement equipment used in semiconductor manufacturing”, proceedings of the first conference on control and fault-tolerant systems, nice, france, 2010, pp. 436 441. [15] e. zio and g. peloni, “particle filtering prognostic estimation of the remaining useful life of nonlinear components”, reliability engineering and system safety, vol.96, 2011, pp. 403409. [16] b. ristic, s. arulampalam, n. gordon, beyond the kalman filter, artech house, boston, 2004. [17] a. kong, j.s. liu and w.h. wong, “sequential imputations and bayesian missing data problems”, journal of the american statistical association, vol. 89, no. 425, 1993, pp. 278-288. [18] p. kosasih, w. caesarendra, a. k.tieu, a. widodo & moodie, c. a. s, “degradation trend estimation and prognosis of large low speed slewing bearing lifetime”, applied mechanics and materials, 493, 2014, pp. 343-348. [19] a. guclu1, h. yılboga1, o. f. eker, f. camci, i. jennions, “prognostics with autoregressive moving average for railway turnouts”, annual conference of the prognostics and health management society, 2010. http://dx.doi.org/10.21622/resd.2016.02.1.037 journal of renewable energy and sustainable development (resd) volume 2, issue 1, june 2016 issn 2356-8569 44 [20] g. peter zhang, “time series forecasting using a hybrid arima and neural network model”, neurocomputing 50, 2003, pp. 159 – 175. 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[25] n. j. gordon, d. j. salmond, a. f. smith, “novel approach to nonlinear/non-gaussian bayesian state estimation”. ieee proceedings f (radar and signal pro-cessing) (vol. 140, no. 2), 1993, pp. 107-113. [26] g.b.p. box, g.m. jenkins, g.c. reinsel, “time series analysis, forecasting and control”, 3rd ed., prentice hall,englewood cliffs, nj, 1994. [27] k. smith, m. earleywine, e. wood, j. neubauer and a. pesaran, “comparison of plug-in hybrid electric vehicle battery life across geographies and drive”, sae international, 2012. [28] b. saha1, k. goebel and j. christophersen, “comparison of prognostic algorithms for estimating remaining useful life of batteries”, transactions of the institute of measurement & control, vol. 31, no. 3-4, 2009, pp. 293-308. [29] r. j. hyndman et a. b. koehler, “another look at measures of forecast accuracy”, international journal of forecasting, 22, 2006, pp. 679-688. [30] d. an, j. choi and n. ho kim, “a tutorial for model-based prognostics algorithms based on matlab code”, annual conference of prognostics and health management society, 2012. renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.155 this paper has been accepted and presented in the (first international conference on new trends for sustainable energy) 1-3 october, 2016 at pharos university, alexandria, egypt. 155 resd © 2017 http://apc.aast.edu green building between tradition and modernity study comparative analysis between conventional methods and updated styles of design and architecture processors elshimy .h1 samir. n2 associate professor, architectural engineering department, pharos university, alexandria, egypt assistant lecture, architectural engineering department, pharos university, alexandria, egypt abstract green house concept appeared from the ancient to the modern age ages and there is a tendency to use a traditional architecture with a pristine ecological environment areas and through sophisticated systems arrived to modern systems of the upgraded systems by treatment architectural achieve environmental sustainability in recent years, sustainability concept has become the common interest of numerous disciplines. the reason for this popularity is to perform the sustainable development. the concept of green architecture, also known as "sustainable architecture” or “green house,” is the theory, science and style of buildings designed and constructed in accordance with environmentally friendly principles. green house strives to minimize the number of resources consumed in the building's construction, use and operation, as well as curtailing the harm done to the environment through the emission, pollution and waste of its components. to design, construct, operate and maintain buildings energy, water and new materials are utilized as well as amounts of waste causing negative effects to health and environment is generated. in order to limit these effects and design environmentally sound and resource efficient buildings; "green building systems" must be introduced, clarified, understood and practiced. this paper aims at highlighting these difficult and complex issues of sustainability which encompass the scope of almost every aspect of human life. keywords greenhouse; sustainable buildings; natural buildings; living architecture; renewable resources-eco-design; eco-friendly architecture; earth-friendly architecture; environmental architecture; natural architecture. i. introduction sustainability is comprehensive therefore a complex subject. it is of vital importance to all because it deals with the survival of human species and almost every living creature on the planet. sustainable and eco-friendly architecture is one of the main aims thans for creating a better life have made as the ultimate model for all their activities. for this reason, moving towards a greener architecture is well-thought-out the main goal of the present architecture of our time [1] at the rate the development needs of this world is using the scarce and limited resources found on the earth, it is becoming obvious that unless there are major changes to man's thinking and behavior, the future of civilization as known today is dubious. this complex subject has no straight forward solution, especially considering that sustainability is a goal for all to reach as they continually strive to reach towards it. green architecture produces environmental, social and economic benefits. environmentally, green architecture helps reduce pollution, conserve natural resources and prevent environmental degradation. economically, it reduces the amount of money that the building's operators have to spend on water and energy and improves the productivity of those using the facility [2] and, socially, green buildings are meant to be beautiful and cause only minimal strain on the local infrastructure. the buildings in which we live, work, and play protect us from nature's extremes, yet they also affect our health and environment in countless ways. as the environmental impact of buildings becomes more http://dx.doi.org/10.21622/resd.2017.03.1.155 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.155 156 resd © 2017 http://apc.aast.edu apparent, a new field called "green building" is gaining momentum. green, or sustainable, building is the practice of creating and using healthier and more resource-efficient models of construction, renovation, operation, maintenance and demolition [3]. ii. proplem statement there is no clear approach to design the green architecture iii. 2. aim of study access to appropriate methodology for egypt correspond to different levels of design in terms of ecological techniques to advanced one iv. methodology in order to achieve the stipulated aim, the study presented in this paper, traces the following steps: 1. general overview on applying “green architecture“ as a concept of sustainability. 2. analytical study to ecological project (adrar amlal) 3. analytical study to advanced project (tenth of ramadan city) v. general overview on applying “green architecture “as a concept of sustainability a. green architecture green architecture, or green design, is an approach to building that minimizes harmful effects on human health and the environment. the "green" architect or designer attempts to safeguard air, water, and earth by choosing eco-friendly building materials and construction practices [3]. b. green architecture and green design green architecture defines an understanding of environment-friendly architecture under all classifications, and contains some universal consent [4]; it may have many of these characteristics:  ventilation systems designed for efficient heating and cooling  energy-efficient lighting and appliances  water-saving plumbing fixtures  landscapes planned to maximize passive solar energy  minimal harm to the natural habitat  alternate power sources such as solar power or wind power  non-synthetic, non-toxic materials  locally-obtained woods and stone  responsibly-harvested woods  adaptive reuse of older buildings  use of recycled architectural salvage  efficient use of space while most green buildings do not have all of these features, the highest goal of green architecture is to be fully sustainable. also known as: sustainable development, ecodesign, eco-friendly architecture, earth-friendly architecture, environmental architecture, natural architecture [5]. c. consideration for green building green building involves consideration in four main areas: site development, material selection and minimization, energy efficiency, and indoor air quality  consider site development to reduce the impact of development on the natural environment. for example, orient the buildings to take advantage of solar access, shading and wind patterns that will lessen heating and cooling loads.  carefully select materials that are durable, contain recycled content, and are locally manufactured to reduce negative environmental impacts. a growing market exists of quality recycled products at affordable prices.  incorporate energy-efficient design into buildings to create an efficient and comfortable environment. take advantage of the natural elements and technologies to conserve resources and increase occupant comfort/productivity while lowering long-term operational costs and pollutants [6].  design for high indoor air quality to promote occupant health and productivity. http://dx.doi.org/10.21622/resd.2017.03.1.155 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.155 157 resd © 2017 http://apc.aast.edu  minimize the waste in construction and demolition processes by recovering materials and reusing or recycling those [7]. d. the principles of green building design the green building design process begins with an intimate understanding of the site in all its beauties and complexities. an ecological approach to design aims to integrate the systems being introduced with the existing on-site ecological functions performed by mother nature. these ecological functions provide habitat, respond to the movements of the sun, purify the air as well as catch, filter and store water. designers can create features in their buildings that mimic the functions of particular eco-systems. species that thrive in natural ecosystems may also utilize habitats created in manmade structures. creating new habitat on structures in urbanized areas is especially important to support bio-diversity and a healthy ecosystem [2]. the following points summarize key principles, strategies and technologies which are associated with the five major elements of green building design which are: sustainable site design; water conservation and quality; energy and environment; indoor environmental quality; and conservation of materials and resources. this information supports of the use of the usgbc leed green building rating system, but focuses on principles and strategies rather than specific solutions or technologies, which are often site specific and will vary from project to project (usgbc). fig. 1. elements of green building design by author (usgbc). e. green building benefits green building is not a simple development trend; it is an approach to building suited to the demands of its time, whose relevance and importance will only continue to increase (usgbc)  comfort. because a well-designed passive solar home or building is highly energy efficient, it is free of drafts. extra sunlight from the south windows makes it more cheerful and pleasant in the winter than a conventional house [8].  economy. if addressed at the design stage, passive solar construction doesn’t have to cost more than conventional construction, and it can save money on fuel bills [9].  aesthetics. passive solar buildings can have a conventional appearance on the outside, and the passive solar features make them bright and pleasant inside.  environmentally responsible. passive solar homes can significantly cut use of heating fuel and electricity used for lighting. if passive cooling strategies are used in the design, summer air conditioning costs can be reduced as well [10]. vi. analytical study to ecological project (adrar amlal) an applied analytical study on a project of "adrar amlal" hotel in "gaafar oasis"at siwa in egypt. the mechanism of choosing the construction system is considered as an important stage in urban projects due to its relation with a group of limits forming the building technology, the mechanism of choice is related to the engineering method of decision support system used in construction system through building technical analysis and its application limits which passthrough a group of consecutive stages related to the project nature and the surrounding environment especially in the distinguished sites environmentally to assure the environmental resource conservation for humanity secure in his environment which needs from him to know the ecological dimensions (capacity-dependence-recycling). the research aims to achieve a group of goals, the most important of them is to reach a mechanism to choose the suitable construction system matching http://dx.doi.org/10.21622/resd.2017.03.1.155 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.155 158 resd © 2017 http://apc.aast.edu with sustainable development forming harmony between the design and the construction system and the sustainable development to reach the best economic efficiency of the project encouraging the environment sustainability as one of affecting sustains for a balanced environmental urbanism. fig. 2. run harmonic reciprocal approach on the study a. the research is sequenced as follows  a study and analysis of the decision support system stages to choose the architectural project construction system as a primary stage.  a study of factors and limits fuming the sustainable development and confirming it in an activated developed way.  a study of the harmony relation between the construction system and the sustainable development and the exchangeable effects between them.  a comparison and ordering the construction system priorities' and sustainable development priorities’.  concluding a mechanism of choosing the best construction system in harmony with the sustainable development. the "adrar amlal" hotel in "gaafar oasis"at siwa in egypt is considered the best example of applying the mechanism of choosing the construction system in harmony with sustainable development, the oasis is a distinguished site environmentally at siwa ,it is centralized around (the white mountain),the project criteria is there use of the old oasis method of construction again to build environmental houses of a new view using building technology by using building materials which are suitable for siwa environment such as (karsheef (salted masses)-clay-cured palm cores) fig .3. siwa site for a map of natural reserves [11]. fig.4.natural determinants of the problem of site [12]. fig.5.architectural character of the siwa oasis [13]. b. the research conclusions first: the choice of the best construction system suitable for the project environment is the first step to achieve sustainable development. second: the abundance of the environmental building materials is the most important factor to choose the environmental construction system. third: to make a relation between construction rates and "replacement and exchange "rates of projects in site to achieve the environmental sustainable development. http://dx.doi.org/10.21622/resd.2017.03.1.155 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.155 159 resd © 2017 http://apc.aast.edu fourth: studying and developing the traditional construction systems of projects in sustainable sites which helps to make the project more economic efficient and in harmony with environmental sustainability fifth: the architectural integration together with knowledge between different stages in study and construction helps to achieve the environmental sustainability for the built environment vii. analytical study to advanced project (tenth of ramadan city) this part has concentrated on the neighborhood sustainability evaluation and its efficiency in improving the decision-making for sustainable development, it plans to provide a better understanding of the sustainability assessment at the neighborhood level and provide a critical analysis of both the theory and practice of neighborhood sustainability evaluation. this project aim to introduce a case study for new application of the microclimate of urban open spaces is affected by several factors such as the urban form and geometry, urban density, the vegetation, the water levels and the properties of surfaces. both climatic and physical factors are combined in order to attain sustainable human thermal comfort conditions. a. materials & method to design the form of a village, town or city, we should understand the outline design principles of the urban form.  the concept of sustainability in urban design to residential communities and housing.  urban microclimate the main purpose of climatic design, on a macro (settlement) and micro (building) scale, is to reduce uncomfortable conditions created by an excess of heat and dryness. buildings must be adapted to extreme summer and winter, day and night conditions to achieve a well-balanced indoor climate. not only cooling is required; passive heating may also be required in winter and during cold nights. protection is required from the intense radiation from the sun, ground and surrounding buildings, from dust, sandstorms and insects (flies). glare has to be reduced and dust penetration prevented. settlements and buildings, therefore, have to be compact, providing shade and controllable ventilation. the urban microclimate plays an important role in building energy consumption and thermal comfort in outdoor spaces. nowadays, cities need to increase energy efficiency, reduce pollutant emissions and mitigate the evident lack of sustainability [14].  human comfort thermal comfort is the most important factor that human comfort depends on. thermal comfort is affected by six major factors which can be classified into two categories: personal factors because they are characteristics of the occupants and environmental factors that are related to the conditions of the thermal environment. the former consisting of clothing level and metabolic rate, while the latter is mean radiant temperature, air temperature , air speed and humidity. even if all of these factors may change with time, standards usually refer to a steady state to study thermal comfort, just allowing a change in temperature by small scale. air temperature is also governed by solar radiation. b. urban design improvement methods for thermal comfort there are a lot of urban microclimate moderation approaches parameters like air temperature, relative humidity, mean radiant temperature, and wind velocity can be modified by the effect of urban interventions, which may improve the outdoor thermal comfort conditions [15].  cool reflective materials  water surfaces  green spaces and vegetation  building arrangements with wind movement http://dx.doi.org/10.21622/resd.2017.03.1.155 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.155 160 resd © 2017 http://apc.aast.edu c. simulation tools in urban design decisions there are a few studies have indicated that a good neighborhood sustainability assessment frameworks and tools should have the following characteristics sustainability coverage— consideration of the major themes of sustainability of neighborhoods based on which their performance to be measured in a comprehensive and integrated way [16]. several simulation tools related to urban design such as ecotect, urbanism, gis, envi-met and others. each simulation tool deals with a specific area for instance. urbanism is concerned with transportation, environmental planning, and metropolitan land use; while envi-met is concerned with surface-plant-air interaction inside urban environments. all simulation tools have an unlimited number of points from the model that can be analyzed, whereas, in a measurement study, only the results derived from the measured spots are reliable. on the other hand ecotect software is designed to improve the analysis, simulation, and optimization of highperformance buildings and systems. by using this software architects and engineers can test, evaluate and respond to a variety of strategies because it has a special use in the design and delivery of sustainable 'green' projects. 3d spatial models are one of the most advantages of the design and performance analysis tools because of the property of cutting edge that helps users to visualize simulation output, smoothing the translation of simulation results into the project design. using simulation software, design professionals are able to continuously study and predict how decisions will impact the performance of the building from the early phases of design through occupancy without significant investment in mockups or manual calculations. simulation tools such as ecotect and other similar software can improve the building industry by giving architects and engineers the power to use performance-based criteria in the design of projects. fig. 6. ecotect (building performance simulation software) (http://www.zigersnead.com/current/blog/post/ecotect-building performance-simulation-software) d. tenth of ramadan city (case study) el asher city or tenth of ramadan city is located in the sharqia governorate of egypt close to the city of cairo and follows the urban communities authority. it is one of the first generation cities in egypt, and also one of the largest new industrial cities. it was constructed to provide job opportunities for youths as well as to attract the population increase to the outside of cairo and the narrow valley, its climate classified as hot desert as the rest of egypt. 1. design concept of the project design concept of project (figure 7) based on meeting the determinants architectural device “el asher city or tenth of ramadan city” functional requirements in line with the principles sustainable neighborhood planning to (figures 8, 9):  achieve the functional requirements of the project according to the structural and architectural determinants.  reduce waste entrances of apartment buildings in the movement areas (roads) role habitation and what reduces the cost of the housing unit.  designed muscat approved symmetric to afflict balance in marketing and reduce differences to distinguish between the blanks in order to achieve special layers housing average and exterior distribution quality takes into account the nontypical after the concept of housing people's abhorrent to rush to  the building was used major traffic battery different their positions to ensure optimal routing and compatibility with the gradient vacuum spaces planning (figures 10, 11). http://dx.doi.org/10.21622/resd.2017.03.1.155 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://www.zigersnead.com/current/blog/post/ecotect-building-%20%20%20%20performance-simulation-software http://www.zigersnead.com/current/blog/post/ecotect-building-%20%20%20%20performance-simulation-software renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.155 161 resd © 2017 http://apc.aast.edu  the idea of assembling buildings to reduce the blanks rely on among themselves to provide spaces of the inner shadows. fig. 7. design concept of the project fig. 8. residential neighborhood layout fig. 9. site perspective fig. 10. hierarchy of spaces fig. 11. solid and void diagram e . c a s e s t u d y e v a l u a t i o n the simulation was run on neighboring residential in tenth of ramadan city in order to investigate the local microclimate (solar radiation, air temperature, relative humidity) in the climate of egypt, egypt as a proposed area. readings of the microclimatic parameters were run consecutively currently, expected and proposed then compared on each indicator.(figures 12, 13, 14 and 15). fig. 12. the stereographic diagrams represent the range of maximum temperature in between (40-45) °c on june and observed that the highest day temperature is on 7 july. fig .13. the stereographic diagrams represent the direct solar radiation (w/m2) & diffuse solar radiation (w/m2). http://dx.doi.org/10.21622/resd.2017.03.1.155 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.155 162 resd © 2017 http://apc.aast.edu fig .14. the stereographic diagrams represent the relative humidity. fig .15. the stereographic diagrams represent the prevailing winds. viii. conclusion this paper presents a review on urban sustainability with the aim of understanding key technical principles to be considered while planning for new neighborhoods. sustainable neighborhoods evolution and initiatives are described, several design concepts related to sustainable urban forms are defined and their sustainability characteristics investigated. (focusing on sustainability concepts under the triple bottom line of environmental, economic, and social dimensions) and practitioners. rapid urbanization has brought environmentally, socially, and economically great challenges to cities and societies. to build a sustainable neighborhood, these challenges need to be faced efficiently and successfully. in this regard, the first step of action is to determine the sustainability levels of neighborhoods. from this perspective, the literature points to a number of nsa tools. however, as the critique of these tools suggests they have limitations in their indicator systems and adaptation in the developing country context is challenging. there are many approaches that aim to achieve sustainable urban forms. different approaches use different scales of concepts, as well as emphasizing some concepts over others. in practice, many local governments, planning consultants, landscape architects, and so on are grappling much more specifically with aspects of sustainable urban form through a variety of planning and design approaches and policies. different urban forms give differently to sustainability. moreover, different planners and scholars may develop different combinations of design concepts to achieve sustainable development goals. they might come with different forms, where each form emphasizes different concepts. however, all should be forms that environmentally contribute beneficially to the planet for the present and future generations. the ideal sustainable urban form according to the design concepts of sustainable urban form is that which has a high density and adequate diversity, compact with mixed land uses, and its design is based on sustainable transportation, greening, and passive solar energy. ultimately, sustainable urban forms aim to achieve different objectives. the most prominent among them are decreased energy use, reduced waste and pollution, reduced automobile use, preservation of open space and sensitive ecosystems, and livable and community-oriented human environments. the five principles are highly interrelated and support each other. high density provides the population and activity basis for a sustainable neighborhood; adequate street density is the material basis; mixed land-use and social mix shape the land use and social life in the neighborhood, and limited land use specialization is the first step towards mixed neighborhoods. the five principles balance population growth, economic growth, rapid urbanization, sustainable urban development and other factors, and try to establish a new urban system. in this system, population and urban infrastructure accomplish economies of scale; diversified social networks and the diversity of land uses to support each other and develop together and urban space and urban dwellers live and develop in harmony. http://dx.doi.org/10.21622/resd.2017.03.1.155 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.155 163 resd © 2017 http://apc.aast.edu besides good planning and design decisions, the application of these principles also requires supporting legal frameworks, an analysis of the local society and economy, appropriate infrastructure technology and capacity, and the institutional capacity to enforce decisions. references [1] mohammadjavad, m., arash, z., airya, n., setareh, g., narjes, e., 2014 “dilemma of green and pseudo green architecture based on leed norms in case of developing countries” international journal of sustainable built environment (2014) 3, 235–246. [2] thomas rettenwender, 2009, m.a., mag. arch., leed ap, architect and niklas spitzmonterey peninsula college intd62 spring 2009”the principles of green building design” spring 2009. [3] roy madhumita, 2008, dept. of architecture, jadavpur university, kolkata, india, “importance of green architecture today”. [4] “burcu, g., 2015, “sustainability education by sustainable school design” dokuz eylul university, department of architecture, turkey procedia social and behavioral sciences 186 (2015) 868 – 873. [5] usgbc, 2002, u.s. green building council, building momentum: “national trends and prospects for high-performance green buildings," prepared for the u.s. senate subcommittee on environmental and public works by the u.s. green building council, november 2002. [6] cbfee, 1999, "skylighting and retail sales: an investigation into the relationship between daylighting and human performance," the heschong mahone group, on behalf of the california board for energy efficiency third party program, 1999. [7] cgb, 2009, center for green building, “building the green garden state”, new jersey municipalities magazine. vol. 86, no. 6, june 2009. [8] kats, gregory h.2006, "greening america's schools costs and benefits," capital e. [9] kats, gregory h. 2003, "green building costs and financial benefits." massachusetts technology collaborative. [10] woolley t. 2006. “natural building: a guide to materials and techniques”. crowood press. محميةة 2002 اعالن( "2002)الطبيعية للمحميات المركزية االدارة [11] مصر, القاهرة" , مطروح بمحافظة الطبيعية سيوة الحاملة الحوائط وحكاية مصر فى التقليدى البناء( "2008) عماد,فريد [12] مصر, القاهرة, المصرى المقاول مجلة, . رقم البيئة لقانون التنفيذية الالئحة(, 2002)البيئة لشئون الدولة وزارة [13] مصر, القاهرة, 1995 سنة الصادر 338 . [14] ragheb g., el-shimy h. and ragheb a., 2015; “land for poor: towards sustainable master plan for sensitive redevelopment of slums”, issn 18770428, social and behavioral science, part 1, 212-228. [15] el-darwish i.; ragheb a and ahmed sh., 2015 “the role of simulation in urban design decisions: microclimate and human comfort considerations in planning”, issn 2079-4096, architecture and planning journal – faculty of architecture engineering (bau). [16] yigitcanlar, t., kamruzzaman , md., and teriman, s., (2015), “neighbourhood sustainability assessment: evaluating residential development sustainability in a developing country context” sustainability, 7, 2570-2602; doi:10.3390/su7032570. http://dx.doi.org/10.21622/resd.2017.03.1.155 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 214 resd © 2015 http://apc.aast.edu self shielding treatment to perform cell calculation for seed fuel in thorium/uranium pwr using dragon code ahmed amin abd el-hameed1, mohammed nagy2, hanaa abou-gabal3 1 bsc in nuclear engineering and msc degree researcher, nuclear engineering department, alexandria university, egypt 2 professor emirates, nuclear engineering department, alexandria university, egypt, 3 professor and head, nuclear engineering department, alexandria university, egypt abstract time and precision of the results are the most important factors in any code used for nuclear calculations. despite the high accuracy of monte carlo codes, mcnp and serpent, in many cases their relatively long computational time causes difficulties in using any of them as the main calculation code. monte carlo codes are used mainly to benchmark the results. ideally, the flux distribution in the lattice would be determined by solving the transport equation in the exact geometry of the lattice using continuous energy cross sections, the way a monte carlo code might. but because of time constraints, the calculation scheme within a lattice physics code is intended to reduce the overall computation time without sacrificing too much accuracy. the nuclear deterministic codes have limited precision due to the approximations made to solve the multi-group transport equation. self –shielding treatment is responsible for the biggest error in any deterministic code; it is an algorithm that produces an average cross-section defined over the complete energy domain of the neutrons in a nuclear reactor. the inaccuracy in deterministic codes is increased dramatically in the resonance period, where a small change in the neutron’s energy may lead to a great change in the corresponding microscopic cross section. there are mainly two resonance selfshielding models commonly applied: models based on equivalence and dilution and models based on subgroup approach. the fundamental problem with any self-shielding method is that it treats any isotope as there are no other isotopes with resonance present in the reactor. the most practical way to solve this problem is to use multi-energy groups (50-200) that are chosen in a way that allows us to use all major resonances without self-shielding. this paper offers the best use of a known international program (dragon code) for nuclear reactor fresh cell calculations by using different methodologies, hypothesis and different nuclear data library, with comparison of other well-known international codes, particularly mcnp5 code and wims-d5 nuclear data. similar self-shielding methodologies were tested in other studies. however, all of these studies are concentrated on the low enriched nuclear fuel (3%) which is the standard fuel enrichment of most of nowadays nuclear power reactors. however, there are new designs which propose the use of higher enriched fuel for economical and safety purposes. in higher enriched fuel the effect of resonance interference of uranium isotopes is expected to change. hence, it is important to test the validity of these self-shielding methodologies and hypothesis in such case. one of these new designs introduces the idea of developing thorium/uranium fueled pwrs. this design has been characterized by its good economics, wide safety margins, minimal waste burden and high proliferation resistance. in such design whole assembly seed and blanket are used, where individual seed and blanket regions each occupy one full size pwr assembly. the seed fuel pin in this design has enrichment close to those used in research reactors (about 20%). in this paper, we selected the fresh seed fuel pin, which is used in thorium/uranium reactors, to be our physical model. then, we performed cell calculations by solving 172 energy group transport equation using the deterministic dragon code. two types of selfshielding models (equivalence and dilution models and subgroup models) are used. the data libraries used are wims-d5 and dragon libraries. to obtain the accuracy of the self –shielding treatments, the results are compared with the result obtained from the stochastic mcnp5 code. we also tested the sensitivity of the results to a specific change in selfshielding method implemented, for example the effect of applying livolant-jeanpierre normalization scheme and rimman integration improvement on the http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 215 resd © 2015 http://apc.aast.edu equivalence and dilution method, and the effect of using ribbon extended approach on sub-group method. keywords nuclear cell calculation; self-shielding treatment; precision of nuclear deterministic codes, dragon, mcnp5. i. introduction nuclear fuel cell calculation is one of the most complicated steps of neutron transport problems in the reactor core [1]. broadly speaking, neutron physics problems need to be solved at three levels of precision with respect to the energy variable:  in the epithermal domain, the many resonances of heavy nuclei such as uranium 238 typically require a few tens of thousands of energy groups in order to properly describe each of the resonances. it is not essential to handle the heterogeneities very precisely at this level; in fact, by using equivalence we can relate the real geometry to a homogeneous geometry.  handling the spectrum requires about a hundred energy groups; this can be done at the assembly constituting the elementary “mesh” of the core of a nuclear reactor, but it requires “microscopic” heterogeneity to be taken into account; this means on the scale of the fuel element or assembly.  in practice, the multiplication factor of a core and the power distribution in it can be calculated to a few energy groups only, e.g. two groups for the usual calculations for pressurized water reactor cores. this calculation takes “macroscopic” heterogeneity into account, i.e. the differences between assemblies and axial variations. these three types of calculation must be performed one after the other: when calculations have been carried out at a given level, the mean values in space (homogenization) and energy (condensation) must be taken in order to prepare for the calculation at the next level. [8] the first step in building lattice physics code is to create an energy group-dependent cross section library. this is the first approximation – which we assume we can accurately represent cross sections over a range of energies using constant values as opposed to point-wise data. the number of energy groups needed and the location of the group boundaries are determined by the lattice physics code’s range of application. for example, analysis on mixed-oxide fuel requires different energy detail than does analysis on uranium-oxide fuel; analysis on fast reactors requires different energy detail than does analysis on thermal reactors; analysis on light water reactors requires different energy detail than does analysis on heavy water reactors, and so on. from the early wims days through the1980s, the cross section libraries associated with production-level lattice physics codes were limited to 100 energy groups or fewer. the original wims library contained 69 energy groups and many early lattice physics codes replicated that structure. in the early 1990s, helios was released with a master library containing 190 energy groups, although this group structure was rarely used for analysis. instead, a smaller library with 35 groups was routinely utilized. today, it is common for libraries to contain hundreds of energy groups. [10] there are two generations of physical codes used to solve neutron transport problems. a few first generation lattice codes based of the four-factor formula are still in production use today. the second generation lattice codes features a consistent multi-group (between 50 and 400 groups) representation of the neutron energies. the main components of a typical second generation lattice code are the following:  library access and temperature interpolation.  resonance self-shielding calculation.  main flux calculation.  homogenization and condensation of the reaction rates  sph factor calculation.  isotopic depletion calculation; figure (1) illustrates the main components of a second generation lattice code [9] http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 216 resd © 2015 http://apc.aast.edu fig .1. the main components of a second generation lattice code for realistic systems with complex geometry and detailed energy dependency, transport equation can only be solved by using numerical methods implemented in the lattice codes. those calculations go through several levels before the final solution is obtained. each level of the calculation has its own characteristics, and any simplification at any step can lead to a poor final result. [2] in this paper, we focus on the self-shielding step as it is responsible of the biggest inaccuracy in any lattice code used to solve the multi-energy transport equation. a self-shielding model is required in any lattice code in order to take into account the resonant behavior of the cross sections. [3] selfshielding is an algorithm that produces an average cross-section defined over the complete energy domain of the neutrons in a nuclear reactor. the microscopic self-shielded cross section for any reaction ρ in group g ( σ_(ρ,g)^( ̃ )) which is defined in equation (1) as: 𝜎𝜌,𝑔 ˜ =µ𝑔 ∫ 𝑑𝑢 𝜎𝜌 𝛷(𝑢) 𝑈𝑔 𝑈𝑔−1 ∫ 𝑑𝑢 𝛷(𝑢) 𝑈𝑔 𝑈𝑔−1 (1) where u is the lethargy (= ln(e0/e)), ug is the upper lethargy limit of group g, µg is the sph factor obtained from the multi-group equivalence procedure, φ(u) is the neutron flux inside the resonances and σρ(u) is the microscopic cross section for nuclear reaction ρ. [3],[5] the development of methodologies used to treat resonance self-shielding with respect to energy was improved from assuming that the resonant material was purely absorbent to the improvement made by applying the approach used by michel livolant and his doctoral student françoise jeanpierre in the late 1960s. this improvement allowed for scattering and slowing down by the resonant material, which affected selfshielding factors, heterogeneous-homogeneous equivalence, dancoff effect and doppler effect. this theory was introduced at that time in the first version of apollo. with the new developments introduced in version 2 of this code, there was renewed interest in the theory of resonant absorption of neutrons, because the inadequacies of livolant and jeanpierre’s original theory had been clearly identified. [8] two resonance self-shielding shielding models are commonly applied [2]:  model based on equivalence and dilution: this approach is based on the rational expansion of fuel to fuel collision probabilities, either in closed or open cell (or assembly). for infinite and homogeneous problems, each self-shielded cross section of each resonant isotope is tabulated against the dilution parameter. for heterogeneous problems, a heterogeneous resonant situation is replaced with a linear combination of homogeneous resonant problems. in its simplest form, this technique reduced to the use of bell and dancoff factors. this kind of model is implemented in the deterministic code wims-d5. the extension of this model has been proposed by stamm’ler and abbate (phoenix code) and later by hébert and marleu (dragon code, shi module) [11]. it is known as a generalized stamm’ler model (gsm). to achieve better accuracy with the gsm model, two additional improvements are implemented in the dragon code: http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 217 resd © 2015 http://apc.aast.edu  use of the nordheim distributed self -shielding effects in a fuel rod (level=1 in dragon code)  the nordheim distributed self-shielding model and use of the riemann integration method (level=2). ii. materials and method a. physical model (case study) to perform cell calculations, we selected our physical to be the initial composition of the seed fuel pin used thorium/uranium fuel. this design uses whole assembly seed and blanket, where individual seed and blanket regions each occupy one full size pwr assembly. figure 2 illustrates sbu and wasb assembly configuration & pin cell models of seed and blanket. the initial composition and the design parameters are illustrated in tables 1, 2 respectively.[4] fig .2. sbu and wasb assembly configuration & pin cell models of seed and blanket table 1. initial isotopic composition table 2. pin cells design parameters b. self-shielding calculations the neutronic calculations were carried out using dragon code with dragon library (or wims-5d library) and two self-shielding modules (shi for equivalence and dilution method, uss for sub-group method) to calculate kinf. the results are then benchmarked using the well-known monte carlo mcnp5 code. hence, various self-shielding modules and data libraries are tested. also, the sensitivity to various self-shielding deterministic approximations are tested. c. nuclear codes used for analysis two different classes of codes are available in respect to solving transport equation: stochastic and deterministic models. in our study we used stochastic models in mcnp, which are the most accurate but http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 218 resd © 2015 http://apc.aast.edu also the most time consuming, as well as the deterministic code dragon version 4. the nuclear codes used for cell calculations are:  mcnp5 [6] it is a general-purpose monte carlo n–particle code that can be used for neutron, photon, electron, or coupled neutron/photon/electron transport, including the capability to calculate eigen values for critical systems. the code treats an arbitrary threedimensional configuration of materials in geometric cells bounded by firstand second-degree surfaces and fourth-degree elliptical tori. it was tested on several criticality benchmarks, so it is verified to be a reliable and accurate code. therefore, in this paper obtained value kinf of fresh seed fuel is set to be the reference value of all deterministic calculations, because it has point wise consentaneous energy data that eliminates selfshielding issue of multi-groups.  dragon [7], [2] the computer code dragon contains a collection of models, which can simulate the neutronic behavior of a unit cell or a fuel assembly in a nuclear reactor. it includes all of the functions that characterize a lattice cell code, namely: the interpolation of microscopic cross sections which are supplied by means of standard libraries; resonance self-shielding calculations in multidimensional geometries; multigroup and multidimensional neutron flux calculations which can take into account neutron leakage; transport or transport-diffusion equivalence calculations as well as editing of condensed and homogenized nuclear properties for reactor calculations, and finally isotopic depletion calculations. the code dragon contains a multi-group iterator conceived to control a number of different algorithms for the solution of the neutron transport equation. each of these algorithms is presented in the form of a one group solution procedure where the contributions from other energy groups are included in a source term. the current version of dragon contains many such algorithms. the sybil option which solves the integral transport equation using the collision probability method for simple one dimensional (1–d) geometries (either plane, cylindrical or spherical) and the interface current method for 2–d cartesian or hexagonal assemblies. the excell option solves the integral transport equation using the collision probability method for general 2–d geometries and for threedimensional (3–d) assemblies. the mccg option solves the integro-differential transport equation using the long characteristics method for general 2–d and 3–d geometries. the execution of dragon is controlled by the generalized gan driver. [2] version 4 is a new distribution of the reactor physics computer code sat gan .its components are: dragr module in njoy, gan lib tools, and modules (calculation operators) of the following codes:  dragon: lattice code  trivac: reactor (full core) code donjon: simulation of reactor operation  optex: reactor design optimization.[9] d. nuclear data libraries used in order to obtain the final solution, isotopic cross section libraries are required. we used the following libraries:  172 energy group wims-d5 library format based on endf/b-vii.0 evaluated nuclear data library (wims-d5)  172group dragon-lib library format based on endf/b-vii.0 evaluated nuclear data library (dragon 4)  a compact endf ace format in mcnp5 based on endf/b-vii.0 e. deterministic methods used in this paper, we study sixteen deterministic methods; each method is given an identification number from 1 to 16. all these methods are implemented using the same lattice code-dragon version4and calculated for the same number of energy groups (172), but they have different tracking modules and data libraries( dragon-lib/ wims-d5-lib). http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 219 resd © 2015 http://apc.aast.edu these sixteen deterministic methods are:  one dimensional self-shielding calculations are made using the equivalence and dilution method to obtain the microscopic cross-sections of isotopes with resonance present in the material without using neither norhdeim distribution nor rimman integration improvements on the equivalence and dilution method (shi level=0 in dragon code). also, livolant and jeanpierre normalization scheme (which modifies the selfshielded averaged neutron fluxes in heterogeneous geometries) is not used (nolj module in dragon code). the data library used is 172 energy groups wims-d5 library.  one dimensional self-shielding calculations are made using the equivalence and dilution method with norhdeim distribution improvement (shi level=1 module). but without livolant and jeanpierre normalization scheme (nolj). the data library used is 172 energy groupswims-d5 library.  one dimensional self-shielding calculations are made using the equivalence and dilution method using both norhdeim distribution and riemann integration improvements (shi level=2 module). but livolant and jeanpierre normalization scheme (nolj module) is not used. the data library used is 172 energy groups wims-d5 library.  one dimensional self-shielding calculations are made using the equivalence and dilution method with resonance present in the material without using any improvements on the equivalence and dilution method (shi level=0 module). livolant and jeanpierre normalization scheme (lj module) is used. the data library used is 172 energy groups wims-d5 library.  one dimensional self-shielding calculations are made using the equivalence and dilution method with using norhdeim distribution improvement (shi level =1 module). livolant and jeanpierre normalization scheme (lj module) is used. the data library used is 172 energy groups wims-d5 data library.  one dimensional self-shielding calculations are made using the equivalence and dilution method using norhdeim distribution and rimman integration improvements (shi level=2 module). livolant and jeanpierre normalization scheme (lj module) is used. the data library used is 172 energy groups-dragon library.  one dimensional self-shielding calculations are made using the equivalence and dilution method without any improvements on the equivalence and dilution method (shi level=0 module). livolant and jeanpierre normalization scheme is not used (nolj module). the data library used is 172 energy groupsdragon library.  one dimensional self-shielding calculations are made using the equivalence and dilution method norhdeim distribution improvement (shi level=1 module). livolant and jeanpierre normalization scheme is not used (nolj module). the data library used is 172 energy group dragon library.  one dimensional self-shielding calculations are made using the equivalence and dilution method with using norhdeim distribution and rimman integration improvements (shi level=2 module). livolant and jeanpierre normalization scheme is not used (nolj module). the data library used is 172 energy groups dragon library.  one dimensional self-shielding calculations are made using the equivalence and dilution method without using any improvements on the equivalence and dilution method (shi level=0 module) with the livolant and jeanpierre normalization scheme (lj module). the data library used is 172 energy groups dragon library.  one dimensional self-shielding calculations are made using the equivalence and dilution method using norhdeim distribution improvement (shi level=1 module). livolant and jeanpierre normalization scheme (lj) is used. the data library used is 172 energy groups dragon library.  one dimensional self-shielding calculations are made using the equivalence and dilution method using norhdeim distribution and rimman integration improvements livolant and jeanpierre normalization scheme (lj) is used. the data http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 220 resd © 2015 http://apc.aast.edu library used 172 energy groupsdragon library.  two dimensional self-shielding calculations are made using the subgroup with 172 energy groups wims-d lib calculations with subg method where the physical probability tables are computed using the rms approach (root-meansquare).  two dimensional self-shielding calculations are made using the subgroup with 172 energy groups wims-d lib calculations with ptsl method where mathematical probability tables and slowing down correlated weight matrices can be computed in selected energy groups using the ribbon extended approach.  two dimensional self-shielding calculations are made using the subgroup with 172 energy groups dragon calculations with subg method where the physical probability tables are computed using the rms approach (root-mean-square).  two dimensional self-shielding calculations are made using the subgroup with 172 energy groups dragon library calculations with ptsl method where mathematical probability tables and slowing down correlated weight matrices can be computed in selected energy groups using the ribbon extended approach. these sixteen deterministic methods are summarized in table 3 as follows: table 3. sixteen self-shielding methodologies which are applied and tested method number code used tracking module data library 1 dragon sybil+shi (l=0) nolj 172gwims-d 2 dragon sybil+shi (l=1) nolj 172g wims-d 3 dragon sybil+shi (l=2) nolj 172gwims-d 4 dragon sybil+shi (l=0) lj 172gwims-d 5 dragon sybil+shi (l=1) lj 172g wims-d 6 dragon sybil+shi (l=2) lj 172g wims-d 7 dragon sybil+shi (l=0)nolj 172g dragon 8 dragon sybil+shi (l=1) nolj 172g dragon 9 dragon sybil+shi (l=2) nolj 172g dra gon 10 dragon sybil+shi (l=0) lj 172g dragon 11 dragon sybil+shi (l=1) lj 172g dragon 12 dragon sybil+shi (l=2) lj 172g dra gon 13 dragon uss-subg 172gwims-d 14 dragon uss-ptsl 172gwims-d 15 dragon uss-subg 172g dragon 16 dragon uss-ptsl 172g dragon iii. results and discussion a. mcnp5 result of kinf for our physical model (fresh seed cell used in thorium/uranium pwr) using mncp 5 the resultant value of kinf is 1.66440 with an estimated standard deviation of 0.00061. figure (2) illustrates the mcnp5 simulation of fresh seed fuel cell drawn by vised program, the design parameters are as indicated in tables 1 and 2. fig .3. mcnp5 seed cell simulation http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 221 resd © 2015 http://apc.aast.edu in this paper, sixteen deterministic self-shielding methods are tested by comparing the resultant kinf with the reference value obtained by mcnp5 code. the resultant values of kinf for different modules in dragon code compared with the reference mcnp value of kinf illustrated in figure 3, show that of the sixteen tested deterministic methods the best are methods of numbers 11, 12, 15, and 16. in these methods, high accuracy was that found using the equivalence and dilution method with norhdeim distribution and rimman integration improvements and livolant and jeanpierre normalization scheme with 172 energy groups dragonlib. (method number 12)the absolute error in this case is 0.000662 which is approximately the standard deviation of the monte carlo result of kinf. also, using subgroup method with subg with 172 energy groups dragon-library is also a very sufficient selfshielding treatment as its absolute error is only 0.001039. b. sensitivity of kinf to various deterministic modules and data libraries using dragon code the sensitivity of the obtained value of kinf to the various modules and data libraries is studied to identify the impact of each of these modules on the efficiency of the self-shielding treatment used. fig .4. kinf as obtained by the different 16 self-shielding methodologies implemented in dragon code vs. the reference value obtained by mcnp5 code. c. effect of changing data libs. on shi module the resultant values of kinf in case of using equivalence and dilution method for various deterministic options are lj/nolj, l=0 / l=1 / l=2. these calculations are performed using dragonlib/ wims-lib is illustrated in fig 4. it shows that there is advantage of using dragon-lib with the equivalence and dilution method of self-shielding treatment. fig .5. kinf using shi module for wims-d5 lib implemented in dragon code vs. the reference value obtained by mcnp5 code the results show that a high accuracy is obtained using dragonlib especially with the lj module. fig .6. absolute error in kinf using shi module for different libraries 0 0.005 0.01 0.015 0.02 0.025 1 2 3 4 5 6 7 8 9 10 11 12 s.s method number absolute error shi+ (wims d5lib/dragon lib) wims-d5-lib. dragon-lib. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 222 resd © 2015 http://apc.aast.edu the absolute error in kinf for shi with dragon library and wims-d5 library (figure 5) may be divided into two periods:  period contains points (1, 2, 3, 4) for wims-d5 library and points (7, 8, 9, 10) for dragon library.  period contains points (5, 6) for wims-5d-library and points (7,8) in dragon library. it is observed in fig.5 that the effect of changing data-lib in the first period is trivial, but the effect of changing data-lib in the second period has a significant effect. hence, it can be concluded that for equivalence and dilution and without livolant and jeanpierre normalization scheme (shi + nolj), changing between wims-d5 and dragon libraries has a trivial effect. however, the results also show that dragon library is more suitable with livolant and jeanpierre normalization scheme (shi +lj) than wims-d5 library as higher accuracy is obtained. d. effect of changing data libraries on uss module the use of dragon-lib and wims-lib for selfshielding using sub-group method and subg / ptsl modules (fig. 6) illustrates that the result of kinf using dragon library results in higher accuracy than wims-sd library. fig .7. kinf results of using uss module for wimsd5/dragon data libraries compared with reference value obtained by mcnp5 e. effect of norhdeim distribution and rimman integration improvements in figure 7, the effect of norhdeim distribution alone (level=1), normalization distribution and riemann integration improvements (level=2) on improving the results of a deterministic module uses equivalence and dilution method with lj normalization scheme. the effect was tested by comparing the resultant value of kinf in each case with the reference value obtained using the monte carlo mcnp5 code. fig .8. kinf using shi module for different improvement levels compared with the reference value obtained by mcnp5 the results show that the improvements are sufficient to obtain higher accuracy. where level=0 stands for the case in which neither norhdeim distribution nor riemann integrations are used. iv. conclusion for our standard fresh seed fuel, the following items are concluded:  for equivalence and dilution self –shielding method without applying livolant and jeanpierre normalization scheme (shi + nolj), changing between wims-d5 and dragon data libraries has a trivial effect. however, the results also show that dragon library is more suitable if livolant and jeanpierre normalization scheme is used (shi +lj) than wims-d5 library, as higher accuracy is obtained.  using equivalence and dilution method with norhdeim distribution and rimman integration improvements and livolant and jeanpierre http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 223 resd © 2015 http://apc.aast.edu normalization scheme is a very sufficient deterministic method to deal with resonant selfshielding problem for fresh fuel – even with a relatively high u-235 concentration, as the absolute error is only 0.000662 .  using sub-group method with ptsl or subg with 172 energy groups dragon library method shows high accuracy for fresh fuel.  norhdeim distribution and rimman integration improvements are sufficient to improve the results id dragon library is used. references [1] m. shafii, z. s. (2012). “nuclear fuel cell calculation using collision probability with linear non flat flux approach”. world journal of nuclear science and technology, 2, 49-53. [2] dušanćalić, marjankromar, andrej trkov. (2011). “use of monte carlo and deterministic codes for calculation of plutonium radial distribution in a fuel cell. international conference of nuclear energy for europe. [3] h´ebert, a. ( april 6 – 11, 2003). development of a new resonance self-shielding methodology based on probability tables. proc. int. mtg. on nuclear mathematical and computational sciences . gatlinburg, tennessee. [4] wang, m. s., & driscolld, m. j. (june 2003). phd thesis : “optimization of a seed and blanket thorium-uranium fuel cycle for pressurized water reactors” . mit. retrieved from http://dspace.mit.edu/handle/1721.1/29956 [5] h´ebert, a. (april 25-29, 2004). “a mutual resonance shielding model consistent with ribon subgroup equations. physor the physics of fuel cycles and advanced nuclear systems: global developments”, (pp. on cdrom, american nuclear society, lagrange park, il. (2004)). chicago, illinois. [6] team, x.-5. m. (april, 2003). mcnp5 “user manual” (vol. volume i: overview and theory). lanl [7] g.marleau, a. h. (april 25, 2012). “user guide for dragon version4. institut de g´enie nucl´eaire d´epartement de g´enie m´ecanique ´ ecole polytechnique de montr´eal”. retrieved from www.polymtl.ca/merlin/downloads/ige294.pdf [8] reuss, p. (2008). neutron physics. france: edp sciences. [9] alainh´ebert. (2008). "neutronslowing-down and resonance self-shielding". in course ene6101. institut de g´enie nucl´eaire ecole polytechnique de montr´eal. [10] cullen, d. e. (n.d.). "nuclear data preperation" in d. g. cacui, handbook of nuclear engineering, volume 1 (p. 279). [11] marleau, a. h. (1991). "generalization of the stamm’ler method for the self-shielding of resonant isotopes in arbitrary geometries". nuclear science and engineering , 108, 230239. retrieved from http://www.ans.org/pubs/journals/nse/a_23821 http://apc.aast.edu/ http://www.polymtl.ca/merlin/downloads/ige294.pdf http://www.ans.org/pubs/journals/nse/a_23821 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.126 126 recent positioning techniques for efficient port operations and development of suez canal corridor ahmed i elhattab faculty of engineering-port said university, egypt dr.ahmed.elhattab@gmail.com abstract the majority of positioning systems for marine traffic are satellite based such as gps. the developments of real time kinematic networks and their applications such as virtual reference station are considered one of the recent high precision techniques for global navigation satellite systems (gnss). these techniques will have great impacts on construction and operation of smart and efficient ports. the advantages of using virtual reference station technique in different port operations and constructions have been discussed in this paper. to apply this technique in suez canal corridor zone, a design of gnss continuously operating reference station network has been proposed. this network could be used during different construction and operations phases of suez canal corridor project. the recommended system could reduce the time and cost of project constructions and improve navigation and safety through the suez canal. keywords suez canal corridor, rtk gps, vrs, smart ports, vertical datum, dredging, under-keel clearance i. introduction one of the main objectives of port authorities is maintaining safe movements of ships during entry, exit and inside the water area of the port. the efficient ports should perform continuous and economic services to ships without delay. the current development in satellite based positioning systems and their applications such as virtual reference station (vrs) provide three-dimensional high precise positions which are critical for efficient ports. the international maritime organization (imo) issued minimum maritime user requirements for positioning for marine navigation as in table (1). to meet these requirements, augmented gnss is required in ports and port operations [1]. table 1. minimum maritime user requirements for positioning. system level parameter absolute accuracy integrity horizontal/vertical (meters) alert limit (meters) time to alarm (seconds) integrity risk* (per 3 hours) ocean/ costal/ port approach / restricted waters 10 (h) 25 10 10-3 port 1 (h) 2.5 10 10-3 inland waterways 10 (h) 25 10 10-3 track control 10 (h) 25 10 10-3 automatic docking 0.1 (h) 0.25 10 10-3 ship-to-ship/-shore 10 (h) 25 10 10-3 search and rescue 10 (h) 25 10 10-3 hydrography 1-2 (h) 0.1(v) 2.5-5 10 10-3 oceanography 10 25 10 10-3 dredging 0.1 (h) 0.1(v) 0.25 10 10-3 construction works 0.1 (h) 0.1(v) 0.25 10 10-3 container/cargo management 1 (h) 1(v) 2.5 10 10-3 cargo handling 0.1 (h) 0.1(v) 0.25 1 10-3 *integrity risk is the probability of providing a signal that is out of tolerance without warning the user in a given period of time. http://dx.doi.org/10.21622/resd.2016.02.2.127 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 127 the high accuracy gnss techniques such as real time kinematic (rtk) and network-based applications such as vrs are considered very efficient tools for precise port operations such as dredging, real-time under-keel clearance monitoring, hydrographic survey, terminal asset management, and other applications. with the draft of ships increasing mega ships capable of carrying more than 20000 teu containers are now coming into service, it is now more crucial than ever that ports operate as efficiently as possible. the network-based rtk positioning is very effective for port construction and developments such as suez canal corridor development project. this mega project in egypt aims to increase the role of the suez canal region in international trading and to develop the three canal cities. in this paper a design of gnss continuously operating reference station (cors) network has been proposed. this network can be utilized during different construction and operations phases of the project. the efficient operations can be achieved in suez canal and all ports in the area by using the different applications of the proposed cors network such as vrs. ii. positioning systems in ports and waterways presently, the use of land based positioning systems for waterways such as loran-c is becoming uncommon due to its cost and low accuracy. the accuracy specification for loran-c is a 95 percent probability of a radial error within 400m over water. however, differential loran can achieve accuracies of order 10m at selected locations, such as airports and harbors [2]. the majority today use satellite based systems such as gps. the imo has recognized that global navigation satellite system (gnss) will improve, replace or supplement existing position fixing systems since some of which have shortcomings with regard to integrity, availability, control, and system life expectancy. a. differential gps positioning differential global positioning system (dgps) is an improvement to navigation solution of a standalone gps receiver. the position accuracy might improve from the 15-meter nominal gps accuracy to reach decimeter level in case of the best implementations [2]. dgps uses a network of fixed, ground-based reference stations to broadcast the difference between the positions determined by the gps and the known fixed positions of the stations. these differences are received by the users as corrections which can be applied to improve the accuracy of their gps positions as in figure 1. fig .1 concept of dgps the dgps network in egypt consists of six control stations, each has one reference station and radio beacon broadcast site with integrity monitoring and communications links. along the mediterranean, three sites (mersa matruh, alexandria, and port said) provide coverage for egypt's north coast. the three southern sites (ras umm sid, ras gharib, and quseir) provide coverage from the northern end of the gulf of suez south to egypt's border with sudan as shown in figure 2. port said and ras gharib together also provide full and overlapping coverage of the suez canal and the oil fields in the gulf of suez. fig .2. coverage of dgps service in egypt [3] journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.126 128 b. real time kinematic gps positioning real time kinematic gps allows the user to obtain centimeter-level positioning accuracy in real-time. the basic concept behind rtk is that a base station receiver is set over a known point and sends the observed gps data to other rover receiver [4]. the rover receiver is equipped by a controller which has software capable to process the double difference gps data of both receivers and resolve the integer phase ambiguities. once the integer ambiguities are correctly resolved, the position of the rover station can be determined with accuracy reach centimeter level in real time while the station is in motion [5]. the base station data is normally sent via uhf or spread spectrum radios that are built specifically for wireless data transfer as in figure 3. fig .3. real time kinematic gps technique c. network rtk and virtual reference stations the virtual reference station is a concept which helps to reach centimeter-level, or even better accuracy of positioning by using single receiver. it requires the use of dual-frequency carrier phase observations using a network of reference stations. these observations are usually processed using a differential gps algorithm, such as rtk. gps network configuration such as cors networks often makes use of multiple reference stations. this approach allows a more precise modeling of distance-dependent systematic such as ionospheric and tropospheric refractions, and satellite orbit errors [5]. the network of receivers is linked to a main control center, and each station contributes its raw data to create network-wide models of the distance-dependent errors. the computation of errors based on the full network’s carrier phase measurements involves the resolution of carrier phase ambiguities and requires knowledge of the reference station positions. at the same time, the rover calculates its approximate position and transmits this information to the computation server, via internet protocol. the computation center generates in real time a virtual reference station at or near the rover position as shown figure 4. this is done by geometrically translating the pseudorange and carrier phase data from the closest reference station to the virtual location and then adding the interpolated errors from the network error models. when vrs data received, the rover receiver uses standard singlebaseline algorithms to determine the coordinates of the user’s receiver, in rtk or post-processed modes [6]. in the vrs positioning, many techniques can be employed such as the virtual reference station method (vrs) and the area correction parameter technique. these methods have differences in the amount of data to be sent to the user, the processing strategy, amount of computations at the station, and the type of communications between the network and the rover receiver. the objective is to avoid the distance dependent decrease of accuracy and the equivalent increase of the required time to fix ambiguities. in order to dominate the distance dependent errors in real-time applications, it is necessary to perform a real-time data analysis using all data from the participating reference stations. in practice, this means that all reference stations need a data link to a computing server where the analysis is executed in quasi real-time, and the distance dependent errors coming from the orbit, the ionosphere, and the troposphere are estimated. this information is then used to correct the results at any given station within the working area. the technique could be named “interconnected reference network”, “linked network”, or “coupled network”. the main advantages of the network rtk can be summarized as follows [7]:  cost and labor reduction, as there is no need to set up a base reference station for each user. http://dx.doi.org/10.21622/resd.2016.02.2.127 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 129  accuracy of the computed rover positions is more homogeneous and consistent as error mitigation refers to one processing system.  accuracy is maintained over larger distances between the reference stations and the rover.  the same area can be covered with fewer reference stations compared to the number of permanent reference stations required using single reference rtk. the separation distances between networks stations are tens of kilometers, usually kept less than 100 km.  network rtk provides higher reliability and availability of rtk corrections with improved redundancy, such that if one station suffers from malfunctioning, a solution can still be obtained from the rest of the reference stations.  network rtk is capable of supporting multiple users and applications. fig .4. virtual reference station concept iii. rtk applications in port operations a rtk system is a precise and accurate system for both horizontal and vertical measurements and centimeter-level accuracy could be obtained over a large site. the rtk systems have many benefits and applications which can be used in numerous activities at ports such as:  hydrographic surveying of the ports water area and navigation channels.  precise and economic dredging and construction of quay walls and coastal protection.  ship under-keel clearance monitoring, berth docking and piloting systems.  precise tracking for position and speed to feed into the vessel tracking systems.  a positioning system infrastructure for terminal asset management. this paper focuses on the advantages of using rtk network and its application vrs in hydrographic surveying, dredging, and real time under-keel clearance monitoring. a. advantages of using rtk in hydrographic surveying the hydrographic survey mainly depends on measuring the horizontal and vertical position of the survey vessel. the accuracy of the vessel positioning journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.126 130 directly affects the accuracy of the seabed survey. conventional hydrography determines a chart depth by measuring the distance from the sounding transducer to the bottom and then applying corrections for draft and tide. rtk gps receivers can measure the latitude, longitude and height above the wgs-84 reference ellipsoid to within a few centimeters. using this vertical accuracy, water level corrections (tide corrections) can be determined. this eliminates the need to use conventional tide gauges or to assign personnel to monitor tide staffs. the separation between the wgs-84 reference ellipsoid and the appropriate chart datum of the survey as it has to be pre-determined area. figure 5 illustrates the relationship between different vertical datums in hydrography. fig .5 relationship between different vertical datums in hydrography. fig .6 tide values measure by the tide gauge and by rtk gps [3]. tide gauges can only report the tidal condition at the place where they are installed and they cannot measure other long waves at the vessel position. in case of projects located far from the tide gauge, significant differences may occur. to investigate these differences data obtained during a maintenance dredging project in port said east port were utilized [3]. figure 6 depicts the tide values measured by both the tide gauge and rtk gps for an area about 10 km away from the tide gauge. data obtained during a maintenance dredging project in port said east port were utilized. it becomes clear that there is nearly a 10 cm gap between the measured values in each case. tide measurements at the location of tide gauge diverge from the tide values at the project site due to the change in the sea state conditions and other factors. the limitation of using rtk gps for measuring tide is the assumption that the separation http://dx.doi.org/10.21622/resd.2016.02.2.127 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 131 between ellipsoid and cd for the project area is constant where the gradient of chart datum is considered zero. many errors associated with gnss positioning can be eliminated through careful calibration procedures prior to each survey. the remaining errors affect the measured coordinates depending on the type of equipment and measurements technique. figure 7 illustrates an example of effect of error in horizontal position of survey vessel on the measured depth and consequently on the calculated dredged volume. in areas with flat bottom, this effect may not be significant. fig .7 example of effect of errors in position on the measured depths b. precise and economic dredging and construction using the rtk network provides centimeter-level accuracy for both horizontal positioning and depth. therefore, possibilities of missing spot shoals are decreased. also, knowing accurate draft of the vessel enables increased accuracy for dredge cuts. in addition, the improved accuracy makes dredging around piers and pilings easier [8]. to inspect the effect of the used positioning equipment on the estimated dredged volume, an experiment has been carried out in arish port. hydrographic survey has been performed using two different positioning equipment rtk gps model leica 1230 and dgps model trimble dsm132. odom echotrack single frequency echo-sounder is used for depth measurements and haypack max hydrographic survey software v.6.2b is used for data collections and processing [3]. figure (8) shows spot height differences of areesh port obtained using rtk gps and dgps positioning systems. the spot height differences range from -2.56 m to 1.48m with -0.03 m mean and 0.32 m standard deviation. the estimated dredging volume to level (-13 m) is 977603 and 974474 cubic meters in case of using dgps and rtk gps, respectively. considering the average cost of dredging is 7$ per cubic meter, the direct difference in cost is 21903 $, which is nearly the difference between the purchasing cost of rtk gps and dgps. fig .8 differences in hydrographic survey results using dgps and rtk (all dimensions are in meters) journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.126 132 to investigate the effect of using rtk gps in tide measurements, the volume of the dredged materials of port said east port maintenance dredging project has been calculated. the volumes of the dredged materials were 1,874,363 and 1,610,095 cubic meters estimated by using rtk gps and tide gauge, respectively. the difference in volumes is a considerable amount and has a significant impact on the project cost. c. real-time ship under-keel clearance monitoring under-keel clearance (ukc) is the most important factor which determines the possibility of ship hull touching the bottom; therefore it is one of the basic elements which decide navigation safety in restricted waters. the basic navigator’s responsibility is to keep under-keel clearance safe in any conditions. typically, a channel is dredged to a defined depth and any deep draft vessel exercises a margin of safety such as entering port in high tide, or exiting with a lighter load. it is recommended to reduce ukc without compromising safety for less cost and reduce possible environmental impact of dredging [9]. the total allowance or gross ukc can be diagrammatically represented in figure (9). in addition to the conditional factor allowances identified in figure (9), most real-time ukc calculations include a “bottom clearance”, which refers to the remaining clearance allowance required after all other conditional factor allowances are removed. the bottom clearance allowance is based on internationally accepted guidelines, and is intended to be a representation of the gross ukc value. there are a few technologies available for ukc measurement using gps. dynamic ukc technique characterizes the performance of each class of ship in the port area. this is carried out by using precise gps while sailing in and out. for following up port entries, that data are used plus wave buoy information, nominal draft, vessel speed and wind data and report in real-time on the actual draft. another technique is to install rtk gps receivers on deep draft vessels so that the precise absolute depth of the keel is known independent of tide gauges and changing vessel draft. when combined with an accurate digital terrain model of the navigable depth of the port , the ukc can be determined. the ability of rtk gps receivers to determine the altitude of fixed points on the vessel relative to a known vertical datum means that the potential exists to bypass the measurement of tide heights, ship drafts and local sinkage in determining the elevation of a ship’s keel relative to chart datum. when combined with charted bathymetry, the under-keel clearance can then be obtained. the rtk gps concept for monitoring real-time ship under-keel clearance is shown in figure 10 and equation 1&2 [11]. fig .9 factor allowances associated with a gross ukc calculation [10] http://dx.doi.org/10.21622/resd.2016.02.2.127 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 133 fig .10 gps concept for monitoring ship ukc [7] real-time ukc at bow = h+hb-hbk (1) real-time ukc at stern = h+hs-hsk (2) where hs is stern gps altitude, hsk is stern gps altitude above keel, hb is bow gps altitude, hbk is bow gps altitude above keel, and h is water depth. similar relations are used at other points on the ship. overseas operational experience confirmed that applying a real-time ukc monitoring systems give greater understanding of the margin of navigational safety and increase the potential for economic benefit to the users by permitting increased cargo uplift [10]. iv. applications of cors networks in development of suez canal corridor the suez canal corridor area scca project is a mega project in egypt. the project's aim is to increase the role of the suez canal region in international trading and to develop the three canal cities: suez, ismailia, and port said. the project involves building new ismailia city, an industrial zone, fish farms, completing the technology valley, seven new tunnels between sinai and ismailia and port said, and improving five existing ports. such a mega and promising project could benefit from the advantages of gnss networks during the construction and operation phases. there is an endless number of potential applications that might benefit by vrs and gnss networks. figure (11) shows the proposed cors network for scca. fig .11 the proposed gnss network in suez canal corridor area journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.126 134 cors station location follows some requirements needed to provide a good network in terms of geometrical arrangement around the area of interest. this was done by carefully selecting locations which were strategically viable for installing this kind of technology. the proposed baseline lengths for the network range from 30 km to 70 km. some factors need to be considered before a base station can be installed in a particular location and these are following:  location where the instruments receiving antenna can clearly view the sky above and no obstruction hindering them from gathering satellite data. 360o view of the horizon and 5o elevation mask is recommended.  locations where one can get good geometrical network by positioning it to an evenly spaced network forming an interconnected triangular polygon in each and every location.  locations far away from the nearby transmitters, it is recommended to position it 300 meters or more away from these structures.  avoid locations where there are unstable environmental conditions such as: thermal expansion that can cause shifting of position, excessive wind forces that can bend materials that are supporting the receiving antenna and condition where there is an unstable ground that can generate structure settlement and shift the original position because of excessive tilt.  locations where security procedure is tight enough to guard this kind of installation.  accessibility of the installation must be in good condition as much as possible in order to get into this installation directly whenever there are troubleshooting issues that needs to be addressed immediately. a. benefits of cors in scca during construction stage the construction stage of scca project includes the building of roads, highways, tunnels, quay walls, terminals, factories and water and electricity infrastructure and many other constructions. there are numerous existing and potential applications of gnss technology in this area. the majority of major construction projects now utilize precision guidance in site surveying and earthmoving. with regard to earthmoving, adoption rates of machine control systems are steadily increasing and information obtained from suppliers of precision gnss equipment indicates very high degree of accuracy at the growth in sales of machine control systems in construction that are among the highest of any precision product line. vrs technology allows surveyors to determine critical coordinates instantly without the need for calculations with centimeter-level of accuracy. the high accuracy obtained from the use of vrs means fewer mistakes are made and checking processes can be performed quickly and easily. importantly, the accuracy and reliability obtained by gnss means that less site rework is required thus benefiting both surveyors and construction parties relying on the survey information. the application of machine guidance technology to earthmoving machinery has been one of the biggest growth areas for precision gnss equipment. precision gnss technology allows for site plans to be programmed into earthmoving equipment, such as bulldozers, excavators and graders. the earthmoving equipment can then be controlled to conform to the site plan via the use of continuously updated gnss positioning information. conventional earthmoving involves a significant amount of rework, or machine passes, to provide an accurate finish. in addition, conventional methods require surveyors to be continually on site to stake out routes. precision gnss technology, however, significantly reduces the amount of rework and in some cases completely negates the need for surveyors to stake out routes. cors network and its application vrs, as applied to construction earthmoving, results in significant benefits. these benefits are outlined in table 2 and table 3 [12]. http://dx.doi.org/10.21622/resd.2016.02.2.127 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 135 table 2. benefits of cors/vrs in land surveying [12]. time savings • negates the need to set up control points when starting a new project – 0.5-1 day saved per project • reduces time spent doing manual calculations • reduces time spent in the office – from 40% to around 10% per project • time savings of up to 75% for large projects and 60% for small projects are possible labour savings • reduces the number of surveyors required for a project from 50 to about 10 for large projects • allows for the use of non-survey staff to do simple mapping tasks that would otherwise require a qualified surveyor infrastructure savings • reduces the need for traffic disruptions, such as lane closures, and associated risk to survey and road workers safety improvements reduces the need for maintenance of ground marks table 3. benefits of cors/vrs in earthmoving in construction [12] earthmoving in construction time savings • reduces project time significantly – savings of between 30% and 80% are possible • negates the need for surveyors to physically stake out routes • negates the need to navigate machines around stakes and pegs • reduces the frequency with which dirt is moved around a site by up to 60% • reduces the time spent conducting as-built surveys capital savings • productivity of bulldozers, excavators and graders is significantly increased • reduces the amount of re-work up to 70% • reduced need for support machines • reduced downtime labour savings fewer workers are required for a project safety improvements • reduces the number of workers on a site and in close proximity to machines, particularly workers with grade stakes and string lines quality improvements • work is generally more accurate – e.g. grader trimming b. 2 benefits of cors in scca during operation stage cors applications and benefits during operation of scca projects are varied. there are many applications in ports operations as mentioned before. the proposed cors network could improve navigation through the suez canal and permit vessels to transit in all weather condition, which keeps the canal open all times for ship transits. using vrs technique through suez canal will provide real-time 3d monitoring of the vessel position and ukc improving navigational safety. the proposed network will keep controlled piloting and berthing, so minimal damage to infrastructure and ships occurs. cors may have relevant benefits and applications in operation of scca projects such as container terminals management, intelligent transport systems, assets management,etc. [13]. v. conclusion this paper shows the current development in gnss positioning techniques and its impact on both construction and operations of ports. the benefits of journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.126 136 rtk gps in hydrographic surveying, dredging and ukc monitoring are discussed and examined. the results agree with the previous studies and showed that using rtk gps networks and its application vrs could be more economic and accurate than other positioning system such as dgps. in this paper a design of gps continuously operating reference station network has been proposed. the benefits for this network have been discussed for different construction and operations phases of the project. the efficient operations could be achieved in suez canal and all ports in the area by using the different applications of the proposed cors network such as vrs. references [1] international maritime organization. "revised maritime policy and requirements for a future gnss", international maritime organization, london, england, 2001. [2] p. d. groves. "principles of gnss, inertial, and ultisensor integrated navigation systems.” artech house , 2008. [3] a. el-hattab. "investigating the effects of hydrographic survey uncertainty on dredge quantity estimation." journal of marine geodesy, vol. 37(4), pp. 389-403, 2014. [4] b. hofmann-wellenhof, h. lichtenegger and e. wasle. "gnss global navigation satellite systems: gps, glonass, galileo & more." newyork: springerwien, 2008 isbn 978-3-21173012. [5] j.v. sickle. "gps for land surveyor." taylor & francis group, 2008. [6] l. kislig "what is a virtual reference station and how does it work?" in gnss magazine, julyaugust 2011. pages 28-31 [7] a. el-mowafy. "precise real-time positioning using network rtk." in global navigation satellite systems : signal, theory and applications, s. jin, ed., 2012. [8] p. r. drummond. "satellite positioning and monitoring solutions for dam, levee and other water retention systems." proceedings of the 29th united states society on dams annual meeting and conference, april 20-24 2009, nashville tn usa. [9] l. gucma and m. schoeneich. "monte carlo method of ship's underkeel clearance evaluation for safety of ferry approaching to ystad port determination." journal of konbin. vol. 8, issue 1, pp: 35–44, , doi: 10.2478/v10040-008-0098-3, may 2009. [10] t. clarke. "assistance with the implementation of an under keel clearance system for torres strait." report prepared for: the australian maritime safety authority (amsa),client reference: amsa no. 790/36186, australia, 2007. [11] t. p. gourlay and w.g. cray. "ship under-keel clearance monitoring using rtkgps." proc. coasts and ports, wellington, september 2009. [12] acil allen consulting. "economic benefits of high resolution positioning services." report prepared for the victorian department of sustainability and environment and the cooperative research centre for spatial information, australia, 2008. [13] acil allen consulting. " precise positioning services in the maritime sector." report prepared for the department of industry, innovation, climate change, science, research and tertiary education, australia, 2013. http://dx.doi.org/10.21622/resd.2016.02.2.127 journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.284 284 resd © 2017 http://apc.aast.edu real options analysis of renewable energy investment scenarios in the philippines casper agaton institute of development research and development policy, ruhr university of bochum, germany casper.agaton@rub.de abstract with the continuously rising energy demand and much dependence on imported fossil fuels, the philippines is developing more sustainable sources of energy. renewable energy seems to be a better alternative solution to meet the country’s energy supply and security concerns. despite its huge potential, investment in renewable energy sources is challenged with competitive prices of fossil fuels, high start-up cost and lower feed-in tariff rates for renewables. to address these problems, this study aims to analyze energy investment scenarios in the philippines using real options approach. this compares the attractiveness of investing in renewable energy over continuing to use coal for electricity generation under uncertainties in coal prices, investments cost, electricity prices, growth of investment in renewables, and imposing carbon tax for using fossil fuels. keywords real options approach, investment under uncertainty, dynamic optimization, renewable energy. nomenclature adf augmented dickey-fuller bau business as usual dcf discounted cash flow fit feed-in tariff gbm geometric brownian motion irena international renewable energy agency npv net present value o&m operations and maintenance pv photovoltaic res renewable energy resources roa real options approach i. introduction increasing environmental concerns and depleting fossil fuels have caused many countries to find cleaner and more sustainable sources of energy. currently, renewable energy sources (res) supply 12.65% of the total world energy demand in 2016 which includes wind, solar, hydropower, biomass, geothermal, and ocean energies [1]. in the recent years, new investments in renewable energy have grown from us$1043.8b (2007-2011) to us$1321.9 (2012-2016) with a geographic shift from the asiapacific region [2], [3]. in the philippines, renewable energy accounts to 25% of the energy generation mix, mostly from geothermal (13%) and hydropower (10%) [4]. the country is aiming to increase this percent share to 60% in 2030 by investing and developing localized renewable sources at 4% annual growth rate [5]. according to international renewable energy agency (irena), the country’s topography and geographic location makes a good potential for renewable energy with 170gw from ocean, 76.6gw from wind, 4gw from geothermal, 500mw from biomass, and 5kwh/m2/day from solar energy [6]. despite its potential, the country’s 60% renewable energy goal seems unachievable as the growth in electricity demand increases faster than investment and generation from res. meanwhile, the country is burdened by heavy dependence on imported fossil fuels, particularly coal and oil. as more power plants are needed due to closing old coal plants and rising electricity demand, renewable energy seems to be the long-term solution to address the country’s problem on energy security and sustainability. however, investment in renewable energy sources is challenged by competitive prices of fossil fuels, high investment cost and lower feed-in tariff (fit) rates for renewables. these serve as an impetus to evaluate the comparative attractiveness of renewable energy over coal for electricity generation in the philippines. this study presents a general framework of investment decision-making for shifting technologies from coal to renewable sources that can be applied to developing countries. by taking the case of the philippines, this study applies the real options approach (roa) to analyze various investment scenarios. traditionally, the discounted cash flow (dcf) or net present value (npv) techniques are mostly used in evaluating investment projects. these http://dx.doi.org/10.21622/resd.2017.03.3.284 http://dx.doi.org/10.21622/resd.2017.03.3.284 http://dx.doi.org/10.21622/resd.2017.03.3.284 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.284 285 resd © 2017 http://apc.aast.edu methods, however, do not cover highly volatile and uncertain investments because they assume a definite cash flow. this assumption makes dcf and npv underestimate the investment opportunities leading to poor policy and decision-making process, particularly to energy generation projects. further, these approaches do not allow an investor to define the optimal time to invest or to estimate the true value of project uncertainties [7]. roa overcomes this limitation as it combines risk and uncertainty with flexibility of investment as a potential positive factor, which gives additional value to the project [8]. this approach evaluates investment projects by considering the investor’s flexibility to delay or postpone his/her decision to a more favorable situation [9]. these roa characteristics are highlighted in this paper as the decision-making process to invest in res is evaluated in every investment period (annually) using dynamic optimization under various uncertainties. recent studies employ roa to analyze investment decisions, specifically renewable energy, including: zhang et al. [10] on investment in solar photovoltaic (pv) power generation in china by considering uncertainties in unit generating capacity, market price of electricity, co2 price, and subsidy; kim et al. [11] on analyzing renewable energy investment in indonesia with uncertainties in tariff, energy production, certified emission reduction price, and operations and maintenance (o&m) cost; kitzing et al. [12] on analyzing offshore wind energy investments in the baltic under different support schemes as fit, feed-in premiums, and tradable green certificates; tian et al. [13] on evaluating pv power generation under carbon market linkage in carbon price, electricity price, and subsidy uncertainty; and ritzenhofen and spinler [14] on assessing the impact of fit on renewable energy investments under regulatory uncertainty. this research contributes to existing literatures by presenting a multi-period investment coupled with uncertainties in coal prices, cost of renewable technologies, growth of renewable energy investment, fit price of renewables, and externality for using coal. the main goal of this paper is to analyze investment scenarios that make renewable energy a better option than continuing to use coal for electricity generation. specifically, this study employs roa to evaluate the (1) maximized option value of either continuing to use coal or investing in renewables, (2) value of waiting or delaying to invest in renewables, and (3) optimal timing of investment characterized by the trigger price of coal for shifting technologies from coal to renewables. sensitivity analyses are done to investigate how the above-mentioned uncertainties affect the optimal investment strategies. ii. methodology the proposed real options methodology is divided into two subsections. the first subsection describes dynamic optimization to calculate the maximized value of investment and identify the optimal timing of investment. the second stage includes the sensitivity analyses with respect to growth rate of renewable energy investment, prices of renewable energy, investment costs, and co2 prices. • real options model consider a renewable energy project with lifetime tr, which can be irreversibly initiated in three installment periods 𝜏, 𝜏 + 5, and 𝜏 + 10 with investment costs 𝐼𝑅_0, 𝐼𝑅_5, and 𝐼𝑅_10. assume that the project construction can be finished instantaneously and operated in full load after project completion. if renewable energy project starts in period t, the total net present value of the project 𝑁𝑃𝑉𝑅 can be represented by equation 1. 𝑁𝑃𝑉𝑅 = 𝑁𝑃𝑉𝑅0 + 𝑁𝑃𝑉𝑅5 + 𝑁𝑃𝑉𝑅10 = ∑ [∑ 𝜌𝑡 𝑃𝑉𝑅,𝑡 − (1 + 𝜑𝑟 )𝐼𝑅,𝑟 𝑇𝑅+𝑟 𝑡=𝜏+𝑟 ]𝑟=0,5,10 (1) where 𝑟 is the installment periods of renewable energy investment, 𝜑𝑟 is the growth of renewable energy investment cost, and 𝜏 is the period where investor decides to invest in renewable. the yearly cash flow 𝑃𝑉𝑅,𝑡 of renewable energy project comprises of returns from selling electricity from re and o&m cost 𝐶𝑅 . 𝑃𝑉𝑅 = 𝜋𝑅 = 𝑃𝐸𝑅 𝑄𝑅 − 𝐶𝑅,𝑟 (2) on the other hand, there exists a power plant generated with coal. the net present value of yearly cash flow from coal depends on the returns from selling electricity from coal, o&m cost 𝐶𝐶 , stochastic http://dx.doi.org/10.21622/resd.2017.03.3.284 http://dx.doi.org/10.21622/resd.2017.03.3.284 http://dx.doi.org/10.21622/resd.2017.03.3.284 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.284 286 resd © 2017 http://apc.aast.edu cost of fuel 𝑃𝐶,𝑡, and 𝐶𝑂2 price 𝐶𝐶_𝐶𝑂2 as given in equation 3 𝑁𝑃𝑉𝐶 ,𝑡 = ∑ 𝑃𝑉𝐶 ,𝑡 𝜏 𝑡=0 = ∑ 𝜌𝑡 𝜋𝐶,𝑡 𝜏 𝑡=0 = ∑ 𝜌𝑡𝜏𝑡=0 {𝑃𝐸𝐶 𝑄𝑅 − 𝑃𝐶 ,𝑡 𝑄𝐶 − 𝐶𝐶 − 𝐶𝐶_𝐶𝑂2 } (3) where 𝜌 is the social discount factor, 𝑃𝐸𝐶 and 𝑃𝐸𝑅 are the prices of electricity from coal and renewable, 𝑄𝑅 is the quantity of electricity generated from coal/renewable, and 𝑄𝐶 is the quantity of coal needed to generate 𝑄𝑅. following previous literatures [15]-[19], this research assumes that the price of coal is stochastic and follows geometric brownian motion (gbm). the current price of 𝑃𝐶 depends on its previous price, and the drift and variance rates of time series of coal prices as shown in equation 4 𝑃𝐶 ,𝑡 = 𝑃𝐶 ,𝑡−1 + 𝛼𝑃𝐶 ,𝑡−1 + 𝜎𝑃𝐶,𝑡−1𝜀𝑡−1 (4) with 𝛼 and 𝜎 are the gbm rate of drift and variance of coal prices, and 𝜀 a random number. the parameters α and σ are approximated using augmented dickey-fuller (adf) test from time series of coal prices [20]. the estimates obtained in adf test are used to generate a matrix of random numbers that represent possible prices of coal from initial values of zero to us$200 at every investment period from zero to t. these values are then used to calculate the present values of electricity generation from coal for each period. using monte carlo simulation, the expected npv for generating electricity from coal is estimated by calculating the 𝑁𝑃𝑉𝐶,𝑡 in equation 3 and repeating the process for a sufficiently large number 𝐽 = 10000 times. expected net present value is calculated by taking the average of 𝑁𝑃𝑉𝐶 for every initial price of coal 𝑃𝐶,0 as shown in equation 5. 𝔼{𝑁𝑃𝑉𝐶 ,𝐽 |𝑃𝐶,0} ≈ 1 𝐽 ∑ 𝑁𝑃𝑉𝐶 ,𝐽 ≈ 𝐽 𝑗=1 𝔼{𝑁𝑃𝑉𝑐 |𝑃𝐶,0} (5) the next exercise in identifying the optimal timing and associated trigger price of coal for shifting technologies is done with dynamic optimization as shown in equation 6. 𝑚𝑎𝑥 0≤𝜏<𝑇+1 𝔼{∑ 𝜌𝑡 𝜋𝐶,𝑡 𝜏 𝑡=0 + ∑ 𝜌 𝑡𝜋𝐶,𝑡(1 − 𝕀{𝜏≤𝑇}) + 𝑇 𝑡=𝜏 [𝑁𝑃𝑉𝑅 + 𝑁𝑃𝑉𝐶 ](𝕀{𝜏≤𝑇})} (6) where 𝕚𝜏≤𝑇 is an indicator equal to 1 if switching to renewable energy, otherwise, equal to 0. this model describes an investor who is given a specific period 𝑇 to decide whether to continue generating electricity from coal or invest in renewable energy. in this model, ∑ 𝜌𝑡 𝜋𝐶,𝑡 𝜏 𝑡=0 accounts to the net present value of using coal from initial period t= 0 until τ when the investor makes the decision. if the investor chooses not to invest (𝕚𝜏≤𝑇 =0), he/she incurs a net present value of ∑ 𝜌𝑡 𝜋𝐶,𝑡 𝑇 𝑡=𝜏 from period τ until the end of the coal plant’s lifetime. if the investor chooses to invest (𝕚𝜏≤𝑇 =1), he/she incurs a net present value of 𝑁𝑃𝑉𝑅 from successive (three-period) investment in renewables plus 𝑁𝑃𝑉𝐶 , as generation from coal will continue at a lower quantity because other electricity will be generated from renewables. from equation 6, the investor’s problem is to choose the optimal timing of investment 𝜏, to maximize the expected net present value of investment. the problem is solved backwards using dynamic programming from the terminal period for each price of coal 𝑃𝑐,𝑡 as shown in equation 7 𝑉𝑡 (𝑃𝑐,𝑡 ) = 𝑚𝑎𝑥{𝜋𝐶,𝑡−1 + 𝑉𝑡 (𝑃𝑐,𝑡−1), 𝑁𝑃𝑉𝑅 + 𝑁𝑃𝑉𝐶 } (7) with 𝑉𝑡 as the option value of investment at coal price 𝑃𝑐,𝑡. the optimal timing of investment 𝑃�̃� is characterized by the minimum price of coal so that switching to renewable energy is optimal as shown in equation 8 [19], [21]. 𝑃�̃� = 𝑚𝑖𝑛{𝑃𝑐,𝑡 |𝑉0(𝑃𝑐,𝑡 ) = 𝑉t(𝑃𝑐,t)} (8) finally, investment strategy is described by a decision to invest when 𝑃�̃� ≤ 𝑃𝑐 , otherwise, investment can be delayed in later periods until 𝑃�̃� = 𝑃𝑐 . http://dx.doi.org/10.21622/resd.2017.03.3.284 http://dx.doi.org/10.21622/resd.2017.03.3.284 http://dx.doi.org/10.21622/resd.2017.03.3.284 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.284 287 resd © 2017 http://apc.aast.edu • parameter estimation and investment scenarios the following scenarios describe various environments that affect investment decisions in renewable energy in the philippines. sensitivity of investment values and optimal timing are analyzed with respect to growth rate of renewable energy investment, price of electricity from renewable energy, investment cost, and carbon prices. the first scenario is the bau case which describes the current renewable energy investment scenario in the country. to estimate a suitable set of parameters in this scenario, secondary data from the philippine’s department of energy and energy information administration are used [12], [ 22]. a 30-year period of average annual coal prices from 1987-2016 is used to run the adf test described in equation 4. the adf test result (see supplementary information table 2) implies that the null hypothesis that 𝑝𝑡 has a unit root cannot be rejected at all significant levels, hence, coal prices conform with gbm. from this test, the estimated gbm parameters are α=0.032027 and σ=0.249409, and are used to approximate stochastic prices of coal for each investment period. the social discount rate is set to 7.5%. from equation 3, 𝐶𝐶_𝐶𝑂2 is set to zero as there are no existing carbon prices in the philippines at present. the growth rate of renewable energy investment is set to 2% per annum. this is equivalent to 470gwh of electricity generation from renewables. from this value, the investment cost and operations and maintenance cost for renewables are estimated, as well as the costs and quantity of coal needed to generate this amount. the prices of electricity, 𝑃𝐸𝑅 = 𝑃𝐸𝐶 =us$182.2/mwh are set equal to the current domestic electricity price, constant during the entire investment period, and independent of the domestic demand. assumptions indicate that renewable energy sources can generate electricity at an annual average of 𝑄𝑅 all throughout its lifetime; there are no technological innovations that affect energy efficiency and overnight costs of renewables; and stochastic prices of coal are independent of the demand for renewable energy. the second scenario describes a situation of an accelerated growth rate of renewable energy investment from the current 2% to 4%, 6%, and 8%. meanwhile, the third scenario analyzes the effect of prices of electricity from renewable energy by increasing the current fit rates to proposed rates. three prices are set: us$182.2/mwh at the bau case, us$160/mwh which is 10% lower than the bau case, and us$200/mwh which is 10% higher. the third scenario describes a situation of a decline in investment costs for renewable energies by 5%, 10%, and 15%, respectively. the last scenario proposes a government policy of introducing carbon tax for electricity generation from coal. the carbon tax is set to us$ 0.504/mwh. iii. results and discussion • business as usual scenario the dynamic optimization process described in the previous section results in three significant values. first is the option value which is equal to the maximized value of either investing in renewables or continuing to use coal. second is the value of waiting as described by the vertical distance between option value curves: initial period (dotted) and terminal period (bold) of investment. this value approximates the gains of an investor if investment is delayed or postponed to some period. the last estimated value is the optimal timing of investment denoted by the trigger prices of coal for shifting electricity source from coal to renewables. this trigger price is illustrated as the intersection of the two option value curves, and indicates the threshold where the value of waiting is zero and that an investor has no benefit to delay the investment to renewables. figure 1 shows the dynamics of option values at different prices of coal in the business as usual scenario. the first point of interest is the positive option values. it indicates that investment in renewable energy incurs positive returns at the current energy situation in the philippines. this contradicts with the result of detert and kotani [19] where the optimization yields negative option values describing a government controlled, operated, and subsidized energy regime. the next point of interest is option value curves sloping downward. this indicates that option values decrease with increasing cost for input fuel. at certain point on the curves, the option values become constant. these are the prices of coal where investment in renewable is a better option than continuing to use coal for electricity generation. the positive values further indicate http://dx.doi.org/10.21622/resd.2017.03.3.284 http://dx.doi.org/10.21622/resd.2017.03.3.284 http://dx.doi.org/10.21622/resd.2017.03.3.284 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.284 288 resd © 2017 http://apc.aast.edu positive 𝑁𝑃𝑉𝑅 for investing in renewables. in this scenario, the result shows that the trigger price of coal for shifting technologies is us$ 129/short ton. this trigger price is higher than the current price of coal us$93.13/short ton (year 2016), and implies that delaying investment in renewables is a better option. however, at the current coal price, the value of waiting to invest is -us$105.4 million. this negative value indicates possible losses incurred from delaying investment in renewables. fig .1. option values at the business as usual scenario • growth rate of renewable energy investment scenario this scenario describes an accelerated growth of investment in renewable energy sources. while the country is aiming to increase the current share of energy generation from renewables from 25% to 60% by 2030 at 4% annual growth rate [5], this goal seems unattainable as the country’s electricity demand is increasing at a faster rate than renewable investments [4]. this scenario examines how changing the rate of growth in renewable energy investment affects the option values and trigger prices. the results of dynamic optimization at various growth rates are shown in figure 2. it can be observed that option value curves shift upwards. this implies that increasing investment in renewables incurs higher returns from economies of scale. doubling of wind farms could result in price reductions as the costs can be spread over large production of electricity [23] [25]. it can be noticed that the trigger prices of coal have also decreased from us$129/short ton in the bau scenario, to us$120, us$113, and us$105 at 4%, 6%, and 8% growth rates. finally, the value of waiting to invest varies from -us$105.4m at bau scenario, to -us$139.5m at 4% growth, -us$146m at 6%, and -us$153.7m at 8% growth rates. these results suggest that accelerating the current growth rate from business as usual prevents potential losses from waiting to invest in renewables. fig .2. option values at different rates of renewable energy investment • price of electricity from renewable energy in this scenario, the effect of changing electricity prices from renewables on option values and trigger prices is analyzed. currently, the philippines is one of the countries with the highest electricity rates in the asia-pacific region. compared with neighboring countries including thailand, malaysia, south korea, taiwan, and indonesia, the prices are lower as the government subsidized the cost through fuel subsidy, cash grants, additional debt, and deferred expenditures. in the philippines, electricity prices are higher due to no government subsidy, fully costreflective, imported fuel-dependent, and heavy taxes across the supply chain [26], [27]. by changing the value broadly, this scenario presents how potential government actions regarding electricity prices affect investment conditions in renewable energy. figure 3 illustrates the optimization outcomes with varying electricity prices. the result shows an upward shift of option values at higher electricity prices. this result is expected as higher price increases the revenues and the net present value of electricity generation from renewable energy. on the other hand, the result shows the inverse relationship of electricity prices and trigger prices from http://dx.doi.org/10.21622/resd.2017.03.3.284 http://dx.doi.org/10.21622/resd.2017.03.3.284 http://dx.doi.org/10.21622/resd.2017.03.3.284 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.284 289 resd © 2017 http://apc.aast.edu us$129/mwh in bau to us$100/mwh at 10% higher and us$159/mwh at 10% lower electricity price. the values of waiting to invest also show a similar trend from -us$105.4m at bau to -us$25.9m at higher and -us$241.6m at lower electricity price. this implies that setting the price of electricity generated from renewables higher than current tariff provides a better environment for renewable energy investments. nevertheless, this study also considers the possibility that extensive electricity generation from renewable energy sources has significant impact on the electricity prices as stated in previous literatures [28-30]. fig .3. option values at various electricity prices from renewable sources • investment cost scenario this scenario describes how decline in overnight cost affects investment in renewables. in the recent years, growth in renewable energy investments is driven by several factors including the improving costcompetitiveness of renewable technologies, policy initiatives, better access to financing, growing demand for energy, and energy security and environmental concerns [2], [31] this scenario focuses on the effect of renewable energy cost on investment option values and trigger prices of coal for shifting technologies. figure 4 shows the dynamics of option values at various investment cost scenarios. the result shows an upward shift in the option value curves. this outcome is evident as lower investment cost incurs higher net present value for renewable energy,leading to higher option values. the trigger prices decrease from us$129 in bau to us$124, us$119, and us$114 at 5%, 10%, and 10% cost reduction. the value of waiting also decreases from -us$105.4m in bau to -us$86.5m, -us$68.6m, and -us$52.2m, respectively. this result confirms the rapid growth in investment as caused by the sharp decline in renewable technology costs. fig .4. option values at different decline trends of renewable investment cost • externality scenario the last scenario discusses the effect of carbon prices for electricity generation from coal. currently, there are no carbon prices in the philippines. this study evaluates the effect of imposing carbon tax as proposed in previous literatures [32]-[34]. as shown in figure 5, the option values and trigger prices decrease with the addition of externality cost. this result is anticipated as additional cost decreases the value of electricity generation from coal. it can also be noted that the trigger price is lower than the current price of coal equal to us$93/short ton (year 2006). this implies that investing in renewables is a better option than continuing to use coal if carbon tax is imposed. furthermore, with carbon tax, the demand for carbon-intensive inputs, including coal and oil, will decrease, while less carbonand carbon free energy inputs eventually increase. this finally supports the research aim of analyzing renewables as a cleaner and more sustainable source of energy and a better alternative to coal. http://dx.doi.org/10.21622/resd.2017.03.3.284 http://dx.doi.org/10.21622/resd.2017.03.3.284 http://dx.doi.org/10.21622/resd.2017.03.3.284 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3, issue 3, december 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.3.284 290 resd © 2017 http://apc.aast.edu fig .5. option values with externality cost for using coal iv. conclusion this study presented various investment scenarios that represent energy switching decisions that apply to developing countries. by taking the case of the philippines, this study employed real options approach to evaluate the maximized option values of investing in renewables, value of delaying investment, and trigger prices of coal for shifting technologies from coal to renewable sources. while numerous studies applied this approach to analyze renewable energy investments, this study expanded the existing body of research by considering a multi-period investment and taking account of uncertainties in input fuel prices, renewable technology cost, growth of investment in renewables, and externality cost for using coal. the analyses conclude that renewable energy is a better option than continuing to use coal for electricity generation in the philippines. delaying the investment in renewables may lead to possible welfare losses. shifting from fossil-based to renewable sources is very timely as the costs of renewable technologies have decreased immensely throughout the years and expected to continuously fall. to support investments in renewable energy, the government must set higher fit rates than business as usual and impose carbon tax for using carbon-intensive fuels. further, the growth in investment in renewables should be increased to meet the country’s goal of 60% energy generation from renewable sources and decrease its dependence on imported fossil fuels. while this study compared coal and renewables, particularly wind energy, for electricity generation, future studies may also analyze other sustainable energy sources including hydropower, solar, geothermal, biomass, tidal/ocean, and other technologies designed to improve energy efficiency. further, environmental uncertainty, such as climate variability and weather disturbances, that affects energy generation may also be included to further capture investment scenarios relevant to climate change policy. references [1] eia. 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[34] h. cabalu, p. koshy, e. corong, u. e. rodriguez and b. a. endrigad.(2015). “modelling the impact of energy policies on the philippine economy: carbon tax, energy efficiency, and changes in the energy mix.” economic analysis and policy vol, 48, pp. 222-237. https://doi.org/10.1016/j.eap.2015.11.014 http://dx.doi.org/10.21622/resd.2017.03.3.284 http://dx.doi.org/10.21622/resd.2017.03.3.284 http://dx.doi.org/10.21622/resd.2017.03.3.284 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ https://doi.org/10.1016/j.eneco.2011.06.008 https://doi.org/10.1016/s0301-4215(03)00205-2 https://doi.org/10.1016/j.eneco.2014.04.003 https://doi.org/10.1016/j.eneco.2009.10.018 https://doi.org/10.1016/j.eneco.2011.07.027 https://doi.org/10.1016/j.eap.2015.11.014 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.001 small scale renewable generation unlocking an era of peer-to-peer energy trading and internet of energy dr. i a gowaid and dr. ahmed aboushady glasgow caledonian university, 70 cowcaddens road, glasgow, g4 0ba, united kingdom azmy.gowaid@gcu.ac.uk; ahmed.aboushady@gcu.ac.uk millions of people worldwide suffer from lack of reliable electric energy supply. energy justice scholarship has noted that small scale decentralized renewable energy offers a unique opportunity to democratize local energy provision, increasing the access to and affordability of electricity for those who are currently on the margins of centralized energy provision systems. this, in turn, is believed to result in critical human development benefits at the local level. there is a strong drive in the industrial and academic community toward the deregulation and decentralization of power systems to enable wider deployment of medium and small-scale renewable energy resources such as wind and solar systems. in a centralized power system, the flow of electric power is unidirectional from generators to consumers. in a decentralized system of distributed generators and consumers that are also able to produce energy (prosumers), power flow is no more unidirectional, and so are payments. to this end, peer-to-peer (p2p) energy trade concept aims to provide the business model and technical infrastructure enabling prosumers to trade their produced energy with one another in addition to (or instead of) trade with the utility. this eventually will realize a power grid structure based on the concept of internet of energy (ioe) where electric power becomes a commodity tradable in an open market. implementation of this concept is made possible by the ongoing migration of traditional power grids from centralized systems to more decentralized networks so as to accommodate renewable and distributed energy resources (ders) as well as smart grid infrastructure. the generic p2p energy trading system can be represented as a four-layer architecture. the basic (physical) layer is the power grid layer followed by communications layer, a control layer, and business layer at the highest level. these interoperable layers control the whole p2p trading process whereas peers can be prosumers, electric vehicle (battery) owners, microgrids, or regions of the power system. much of the attention in the literature has been dedicated to developing appropriate structures of the communications and business layers in a bid to realize p2p trading without expensive alterations to the existing ac grid physical infrastructure. therefore, researchers and innovators focus on developing platforms that run different forms of trading processes among peers taking in account grid security, economic incentives, and system operator requirements. various criteria for peers to select who to trade with are possible, including ‘least power loss’, ‘highest reliability’ or ‘most environmental’. as it is very hard to trace actual power flows in a power grid and reward prosumers for their energy production, energy market regulators normally issue renewable energy certificates (recs) as an incentive for system operators to purchase renewable energy from der owners. for instance, in the us each der owner is issued 1 rec, which is tradable with utilities, for each 1mwh of energy produced (rec is named differently in different countries). likewise, it is the common theme between the various p2p energy trade platforms whether in operation or under development to manage energy trade between peers and third parties by means of trading recs, or equivalent tokens, efficiently and securely. some of such platforms utilize third party for transactions auditing, while the more advanced platforms are built on blockchain technology to realize near-instant decentralized payment and auditing of transactions without the need for a third party. 1 resd © 2019 http://apc.aast.edu http://dx.doi.org/10.21622/r http://dx.doi.org/10.21622/r mailto:azmy.gowaid@gcu.ac.uk mailto:azmy.gowaid@gcu.ac.uk mailto:ahmed.aboushady@gcu.ac.uk mailto:ahmed.aboushady@gcu.ac.uk http://apc.aast.ed/ http://apc.aast.ed/ journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.001 about the authors: dr. i. a. gowaid received the b.sc. (first class hons.) and m.sc. degrees in electrical engineering from alexandria university, egypt, in 2007 and 2011, respectively. from 2013 to 2017 he was with the power electronics, drives, and energy conversion (pedec) research group, university of strathclyde as a phd candidate then as a postdoctoral research associate. he was a teaching assistant (currently on leave) at the department of electrical engineering, alexandria university as of 2008. he is currently with the department of electrical and electronic engineering, glasgow caledonian university as a lecturer of electrical power engineering. his current research interests include power electronics, solar and wind energy integration, high voltage dc transmission (hvdc), smart grids, and power system dynamics. over 8 years of active research, dr gowaid has co-authored a number of highly-cited publications in top-ranked journals and conferences in the field of electrical power engineering. dr. ahmed aboushady received his b.sc. (hons) and msc degrees in electrical and control engineering from the arab academy for science and technology, egypt in 2005 and 2008 respectively. following this, he obtained his phd degree in power electronics form the university of strathclyde, glasgow in 2013. he is currently a lecturer in power electronics at glasgow caledonian university, uk and the msc programme lead in electrical power engineering. dr. aboushady has over 10 years of lecturing and research experience in power electronics and its applications. as principal investigator, he has been awarded a number of projects totalling over £0.5m from scottish power energy networks, energy technology partnership and oil and gas technology center on new wireless charging technology applications and technology assessment of subsea dc power electronic systems for the offshore oil and gas sector. dr. aboushady had successful industrial collaborations in the past with aker solutions, technip umbilicals and alstom grid, and has published over 20 technical papers in refereed journals and conferences, a single-authored book, a book chapter contribution and a pct patent. to date, he supervised 4 phd students, a postdoctoral researcher and a number of master students. dr. aboushady is a senior member of ieee, and his main research interests are in medium and high voltage dc transmission systems, integration of renewable energy systems and wireless power transfer applications. 2 resd © 2019 http://apc.aast.edu http://dx.doi.org/10.21622/r http://dx.doi.org/10.21622/r http://apc.aast.ed/ http://apc.aast.ed/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-85 96 http://dx.doi.org/10.21622/resd.2017.03.2.209 209 resd © 2017 http://apc.aast.edu renewables within the german electricity system experiences and needs martin kaltschmitt hamburg university of technology (tuhh), germany kaltschmitt@tu-harburg.de abstract during the last two decades renewable sources of energy as an environmentally friendly alternative to fossil fuel energy have gained greater importance within the german electricity system. their share has increased from less than 4 % to roughly one third of the gross electricity production in the last 25 years. against this background, the goal of this paper is to present briefly the current status of the use of renewables within the german electricity system, to assess selected developments taking place during this development process and to identify given challenges and needs as well as the necessary actions to pave the road for a further use of renewable sources of energy. the political driver for the latter is the overarching goal to reduce greenhouse gas (ghg) emissions which have been confirmed within the paris agreement signed by the end of 2015. i. introduction as one consequence of the kyoto protocol, the european union (eu) has implemented binding greenhouse gas (ghg) reduction targets. following this overall goal also germany has to reduce energy related ghg emissions substantially. thus, a broad variety of policy measures have been implemented within the last decades among others to bring renewable sources of energy closer to the market and to exploit their possible contribution to this overarching political goal. within the electricity sector the most important policy instrument implemented by the government has been and still is an act on the use of renewable sources of energy for electricity generation, i.e. the erneuerbare-energien-gesetz (eeg; electricity-feed-in law). initially, within this act fixed reimbursement rates for different electricity generation options from renewable sources of energy have been defined. these fixed feed-in rates for "green" electricity are guaranteed by the government for 20 years and electricity from renewable sources is granted priority access to the public electricity grid independent from the actually given demand for electrical energy within the electrical distribution system. the remuneration of the fixed and guaranteed reimbursement for "green" electricity is financed by a surcharge to be paid by all electricity consumers except for an increasing number of large scale industrial consumers that face strong competition on international markets or whose expenditures amounts to a high share of their gross value added. based on such measures the share of renewables within the electricity supply system has increased significantly in germany (figure 1) from less than 4 % in 1990 to roughly on third in 2015; within the last year all over close to 200 twh (2015) of electricity has been produced from renewables and the overall german electricity consumption has been roughly 600 twh (2015). wind energy (i.e. onshore and offshore use) contributes with close to 45 %, biomass (i.e. solid biofuels, biogas) with 26 %, photovoltaics with ca. 20 % and hydropower with less than 10 %. the avoided ghg emissions due to this renewable electricity generation have been summed up to more than 167.5 mill t (2015). related to the overall energy related ghg emissions of close to 900 mill t (2015) and this represents a share between 18 and 19 %. http://dx.doi.org/10.21622/resd.2017.03.2.209 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ mailto:kaltschmitt@tu-harburg.de journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-85 96 http://dx.doi.org/10.21622/resd.2017.03.2.209 210 resd © 2017 http://apc.aast.edu fig .1. gross electricity generation in germany (lower chart: overall development, upper chart: electricity generation from renewables) (data according to [1, 2]) ii. experiences and lessons learned wind energy. as a consequence of the promising feed-in tariffs and the stable long term conditions guaranteed by the legal framework, electricity generation from wind energy has steadily expanded from basically zero around the year 1990 to 79.3 twh (only onshore installed wind mills) in 2015. this increase in power generation has taken place in parallel with a strong and impressive technological development of the wind mill technology. thus during the 25 years between 1990 and 2015 wind mill technology has been characterized by a strong increase in the installed electrical power per unit from roughly 100 to 250 kw in the late 1980s / early 1990s to more than 5 to 6 mw today. this power increase throughout these roughly 25 years has been accompanied by clear reductions in specific market prices as well as continuously increasing overall efficiencies and reliabilities. beside this, wind mills become more environmentally sound, their operation much more reliable, their safety features more advanced, and their interaction with the electricity grid more system compatible. in parallel, wind mill manufacturing in germany has been developed to a fast growing large scale innovative industry sector with high technological standards and a strong export orientation during this quarter of a century due to globally strongly growing markets. this impressive development has been supported and accompanied by the development and implementation of binding and non-binding guidelines and standards defining various side aspects for the increasingly larger wind mills (e.g. noise, safety and environmental standards); i.e. a process has been takening place to develop the wind mill industry to industry branch fully integrated within the german overall economy. the wind mills currently available on global markets from the german manufacturers present a fully marketable technology easily adaptable to locations with a different wind supply, which can even support grid stability. this development has been accompanied by considerable and controversial as well as very emotional discussions related to the visual impact of wind mills on the landscape due to their over time strongly increasing dimensions as well as the rotor rotation putting movements into a formerly more or less static landscape. thus, with an ongoing http://dx.doi.org/10.21622/resd.2017.03.2.209 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-85 96 http://dx.doi.org/10.21622/resd.2017.03.2.209 211 resd © 2017 http://apc.aast.edu expansion of the installed wind mills and thus an increased use of this technology the acceptance by the local population as well as promising wind mill sites with high average wind speeds continuously decreased. especially in areas where many wind mills have been installed due to favorable wind conditions (e.g. in areas close to the north sea coast) citizens’ initiatives became more active and hindered or even prohibited further installations. to alleviate this obstacle, the german government promoted the installation of offshore wind farms in the north sea as well as the baltic sea. advantages of this approach to go offshore are significantly higher electricity yields at a certain spot due to considerable higher wind speeds compared to most onshore locations and a much better acceptance by the public. severe technological challenges clearly higher specific electricity generation costs and still hard to fulfill legal conditions for the protection of the fragile offshore ecosystems present strong disadvantages of this approach. to overcome the challenging environmental, economic and site-specific conditions given at locations more than 50 km off the north sea coast in water depths of 30 m plus hindering an increased wind energy use, the existing political framework has been adjusted to set appropriate conditions to foster offshore wind energy utilization; i.e. the feed-in tariffs have been increased several time to compensate the given technical risks and the high costs necessary to master the challenging conditions regarding location as well as to fulfill the environmental protection requirements controlled by the local authorities. even due to these challenge in 2015 already 8.7 twh provided from offshore located wind mills have been feed into the german electricity grid in addition to several additional offshore wind parks which are under construction. in parallel great effort is put into the development of advanced wind mill technologies operating reliable even under the rough and challenging environmental conditions offshore as well as the necessary foundations to fix the mills securely on the sea ground; experiences available so far have shown that there is indeed a huge demand to adjust the wind mill technology to face successfully the significantly different environmental conditions given at a certain offshore location. the developments in the years to come will show if the cost reductions to be expected with an increasing installation of offshore wind parks combined with a much better wind supply within these locations will offset the additional investment and maintenance costs of offshore installations. if this turns out to be the case, this option offers huge electricity generation potentials as well as immense markets for equipment and services globally. besides, on the longer term a significant share of the electricity needed by the german population might come from offshore wind parks due to the huge potentials as well as the relatively high wind speed. photovoltaic (pv). the support scheme implemented by the german feed-in law has originally been designed to support electricity generation systems based on renewable sources of energy to become marginal profitable by the owner / operator. beside climate protection as the main driver the intention was to help these technologies to become market mature (i.e. to overcome the market entrance barriers) and in parallel to treat the electricity customer / the payer of this additional financial burden with care with respect to the resulting costs (i.e. to minimize the additional costs for the final user of the electricity). this has been especially true for pv systems, which were politically intended to be operated by individuals in the one digit kw-range and to be installed on dwelling houses without additional land use to increase acceptance; the original politically intended long term vision was to upgrade each dwelling house to a small power plant. these circumstances combined with the still relatively high costs and limited return on investment some 10 years ago, the share of pv within the german electricity system was almost negligible till 2006/07. in the following years, prices of pv modules dropped fast and significantly due to a strong development of the respective production capacities especially in china among others due to the incentives granted by the chinese government. these strong decreases in module prices in these days, combined with the now relatively high reimbursement rates guaranteed and continuously confirmed by law resulted in a rapid development of small and especially large scale pv systems operated by individuals as well as financially strong market participants (e.g. investment funds, utilities, pension funds). and this relative profitability during these days increased on a daily basis because the feed-in tariffs defined within the german feed-in law have not been adapted adequately in parallel; i.e. it has been very profitable to invest in pv systems for financially strong investors as well as private market participants. this development shows clearly the disadvantage of fixed reimbursement rates with an unlimited expansion option as it has been realized within the german feed-in law these days. if market http://dx.doi.org/10.21622/resd.2017.03.2.209 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-85 96 http://dx.doi.org/10.21622/resd.2017.03.2.209 212 resd © 2017 http://apc.aast.edu prices change rapidly due to new production facilities and/or a strong expansion of the market volumes the reimbursement rates could not be adjusted fast enough due to the time consuming administrative procedures necessary to amend an existing law. fig .2. yearly installed pv capacity in germany (data according to [7]). this development results in an installation of roughly 7 to 8 gw/a in pv systems in the years 2010, 2011 and 2012 (i.e. 22.5 gw within these three years, figure 2). during the beginning of this time period roughly half of the global pv module production has been installed only in germany, this share decreased then to about one third in 2012. thus, the (subsidized) german market helped significantly to pass through the learning curve, to overcome the market entrance barriers, and therefore to bring the prices for pv modules globally down. as a consequence the foundation of the worldwide market break-through of pv systems has been set these days based on the money of the german electricity consumer. as a result of this impressive development, the surcharge to be paid by electricity consumers in germany has reached roughly 10 bill €/a, which corresponds to 0.0263 €/kwh to be paid according to the legal frame work with the monthly electricity bill mainly by the household and other small customer of electrical energy (some large scale industrial consumers of electricity do not have to pay this fee due to the legal situation in germany). in total, the overall capacity of the installed pv modules reached 39.7 gw in 2015, providing 38.4 twh (2015) of electricity. to limit the significant cost increase and to meet the instructions from the european union (eu), the legal support scheme for renewables in general and pv in particular has been changed completely in recent years. a bidding system with a clearly defined cap (i.e. a maximum amount of electrical capacity to be installed each year) has been introduced. the very limited practice with this support scheme has shown so far that the aspired goal of 1.5 gw/a of pv capacity to be installed have not been reached due to numerous reasons related to the design of this support concept as well as a strongly changing environment within the electricity market. solid biofuels. the electricity-feed-in law has also triggered a significant and unexpected increase in electricity production based on solid biomass. in 2015, ca. 18.2 twh of electricity and 19.3 twh of heat have been produced by co-generation (chp) from solid organic matter. the technical maturity of an energy generation from solid biomass based on chpsystems under operation within the wood processing industry already since generations resulted in a rapid market increase in 2000 as soon as the feed-in law was opened up to electricity generation from such fuels (figure 1). these existing plants operated by industry are needed to produce electrical energy for the various wood processing facilities, to provide heat for drying the manufactured wood products, and to get rid-off the wood waste piled up during wood processing. after the implementation of this option within the feed-in law new plants have been erected by investment companies as well as various utilities using contaminated wood waste. thus, this legally pushed increase of energy generation from solid biomass has been taken off on decades of experiences available already within industry from the construction as well as the operation side. therefore an immediate roll-out of this technology has been possible and has been realized successfully. however in argumentum e contrario basically no major new technological advancements have taken place. thi has also been one of the main original goals of the feed-in law; i.e. only state-of-the-art technology has been installed within the growth process and thus for example no gasification facility promising higher electrical efficiencies has been realized due to potentially too high technological and thus economic risks. all over germany started to use on large scale demolition wood as a fuel for electricity generation and/or for combined heat and power (chp) starting roughly in the years around 2000. independently from this, since the 1990s this fuel has been used extensively for power and/or heat generation in such http://dx.doi.org/10.21622/resd.2017.03.2.209 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-85 96 http://dx.doi.org/10.21622/resd.2017.03.2.209 213 resd © 2017 http://apc.aast.edu european countries where a co2-tax has been implemented and/or low emission standards have been valid; i.e. during these days demolition wood incurred in germany have been exported e.g. to italy and to sweden. however, with the implementation of the feed-in law in germany this development has come to a stop. subsidizing electricity from (contaminated and non-contaminated) wood (waste) and thus developing own wood-fired power plants in germany has induced not foreseen market and thus price effects within the markets for such solid biofuels. prices for fuel wood / demolition wood / waste wood have increased significantly and waste wood has changed from being considered waste bringing money(i.e. the institution producing the waste wood has to pay deposing fee to the waste management company to get rid of this waste) to a valuable energy carrier with a market price defined by the average heating value; (i.e. power plant operators formerly received wood waste disposal fees and now they have to pay for the waste wood according to the average heating value). the increased demand for fuel wood due to an over-expansion of the amount of the respective power plants furthermore resulted in an overall price increase for all types of fuel wood / waste wood for industrial/ energetic purpose thus, potential economic profits to be exploited by the owner of a power plant using waste are not possible any more. but, still the producer of the waste wood has to pay to get rid of this material. the economic margin in between has been exploited by fuel wood / waste wood traders. due to these effects the profitability of power plants fueled by waste wood have been lowered considerably. this development has increased the economic pressure on power plant operators / owners dependent economically on disposal fees or very low fuel prices. resulting effects have been the shut-down of some of these newly build power plant facilities and/or the conversion of a wood fired power plant to a coal fired facility. besides, also the prices for virgin wood fuels have increased. this price increase have also had a strong influence on the market prices for wood as a raw material and thus on the feedstock used by the wood processing industry. this development has been very much appreciated by most of the producers (i.e. the forest owner) but not at all by the wood processing industry interested in low feedstock prices. this was the reason why the german wood processing industry has been strongly opposed to this part of the feed-in law and thus has campaigned heavily against an electricity generation from wood even due the fact that an electricity generation from wood waste piling up during wood processing has been and still is realized to a large extend within their own factories. the consequence of these political activities of the various responsible associations has been a strong cut of the reimbursement rates preventing economically the use of virgin wood within large scale power plants as well as large chp-plants. additionally, nowadays basically the overall available amount of demolition and other wood waste that is not useable as a raw material for producing recycled wood products (e.g. chip board, oriented structural board) is used energetically. thus the installation of new wood waste fired power or chp plants has come to an abrupt stop when the fuel wood demand of the existing plants exceeded available potentials of demolition wood / waste wood in germany. this development is supported by the fact that reimbursement rates are too low resp. the prices for fresh wood are too high to allow the use of significant amounts of virgin wood material within the large scale energy market. as a consequence, electricity generation from solid biofuels has been more or less stable in recent years because the yearly incurred demolition wood / waste wood is more or less constant in germany and an increased import is not possible due to economic constraints. biogas. also biogas production and a subsequent electricity provision have shown a remarkable development in recent years in germany. starting basically from a plant inventory of some 100 "homemade" biogas plants some 25 years ago the technology has become technically mature with highly efficient, easy to operate, reliable and environmental sound plants. in 2015, close to 9,000 biogas plants (figure 3) have been in operation primarily within the agricultural sector. these plants produced roughly 31.8 twh of electricity and in parallel 16.8 twh heat in 2015. http://dx.doi.org/10.21622/resd.2017.03.2.209 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-85 96 http://dx.doi.org/10.21622/resd.2017.03.2.209 214 resd © 2017 http://apc.aast.edu fig .3. development of the installed capacity in biogas plants in germany (2014 and 2015: preliminary data; data according to [7]). this biogas production is based on two different types of feedstock: organic residues and wastes as well as energy crops. both material streams are a priori limited. • organic residues and wastes suitable for biogas production, e.g. animal manure, organic urban waste fraction from household waste, organic waste from the food processing industry, need to be collected and transported. but, such organic material is characterized by high water content typically contained within such organic material streams and a low energy yield. thus, this material cannot be transported over long distances due to economic reasons (i.e. mainly water is transported). in contrast, due to "economy of scale"-effects, biogas plants become specifically clearly cheaper with increasing capacity and very small biogas plants are typically specifically extremely expensive. due to this dilemma only a (small) part of the overall available organic residues and wastes are used so far, even considering the fact that the subsidizing scheme supports the use of such organic matter in small scale biogas systems with a bonus, which is however too low to fully exploit the existing technical potentials. thus the debate on how the existing agricultural and non-agricultural waste and residue streams could be utilized in the most efficient manner related to technical, economic and environmental aspects taking also acceptance aspects into consideration is still ongoing. it is not expected that this discussion will come to an end in the months to come. • fertile agricultural land is limited and cannot be expanded at least in germany. however, in recent years, slightly increasing yields of roughly 1 to 2 %/altogether with a stable population with more or less a constant food pattern resulted in an ongoing reduction of the demanded agricultural land for food production. thus during the last decades an increasing amount of agricultural land has not been needed any more to produce food and feed for the domestic market. this development will most likely be ongoing and even accelerate in the years to come because the german population will probably decline in the future due to low birthrates; this is supported by an ongoing trend towards a higher share of vegetarian food. to keep this "surplus" land fertile energy crops can be produced on this agricultural land which is basically not needed for food and fodder production any more – if these land resources will not be used to produce food for an increasing export of food "made in germany" and/or set aside based on public money e.g. due to ecological considerations (e.g. increase in biodiversity). additionally, the availability of fertile agricultural land is also very much influenced by other regulations, e.g. the common agricultural policy (cap) of the ec, land requirements for other energy crops, e.g. rape for biodiesel production, the need for biomass as a raw material, e.g. for the chemical industry, as well as the agricultural production intensity in germany. taking these influencing parameters into account, the potential of producing energy crops is already used to a considerable extend (currently substrates for biogas plants are grown on ca. 1.4 mill ha and the overall agricultural land in germany is 11.8 mill ha). additionally public acceptance of growing energy crops is limited and some ngo's are working hard to reduce the amount of land used for this purpose due to ethical and/or environmental objections. beside this, agricultural feedstock production for biogas plants is expensive and thereby contributes to high electricity generation costs. thus, also discussions on the energy provision costs of biogas are on the political agenda. thus it is not expected that the amount of land used for the production of biogas feedstock will expanded significantly in the years to come. consequently, a further expansion of biogas production will reach sooner or later its limit in germany. this is independent from the fact that http://dx.doi.org/10.21622/resd.2017.03.2.209 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-85 96 http://dx.doi.org/10.21622/resd.2017.03.2.209 215 resd © 2017 http://apc.aast.edu biogas production is anyway controlled by the reimbursement rate granted by the feed-in law which has been step by step reduced in recent years. thus, after the end of the boom phase in recent years the industry producing and constructing biogas plants urgently need to find new and/or additional markets for their products nationally and in particular internationally if they want to survive and thus stay in business in the longer term. in this respect the food processing industry seems to be a promising commercial market for biogas plants. companies providing food products produce necessarily organic waste streams to be treated and/or utilized in one way or another in most countries globally due to environmental reasons. additionally these companies always need energy, i.e. heat and electricity, to process the food biomass to a marketable food product meeting the needs of the customer. the use of these organic waste streams – together with waste water polluted with organics typically provided necessarily in parallel – to provide biogas could contribute significantly to solving both challenges. this is a reason why some countries have already started to force the food processing industry to install biogas plants as an adequate measure for the management of the produced organic waste streams, for environmental protection, for "green" energy provision and for cost reasons as well as for a better acceptance within the local population. these arguments and developments are some reasons why in germany there is currently a tendency to reroute the developments within the biogas sector towards the use of organic waste streams from commerce and industry as well as from households instead of expanding the production of biogas from energy crops to be produced on fertile agricultural land. the fact that the increasingly more local waste management companies start to collect organic household waste separately adds up to this. geothermal energy. the feed-in law grants also feed-in revenues for electricity from geothermal energy. due to the less promising (i.e. average to below average) geological conditions in germany compared, for example, e.g. to new zealand, the philippines, and iceland, the reimbursement rate has been defined generous according to the status of knowledge more than 15 years ago when geothermal electricity generation has been included within the legal subsidizing scheme. based on this a gold rush mentality developed visible in popping up of lots of different companies with basically no relevant experience promising very high revenues to public and private investors. some of these companies have been successful in convincing communities to invest in geothermal chp plants. but none of these projects have been completed in time achieving the aspired performance figures. some of these projects have even been terminated in the design phase already. others have not been successful in finding enough hot water to meet the necessary design criteria (i.e. temperature level, specific production rate and water quality) within the unlocked reservoir. some projects even failed in unlocking the geothermal reservoir due to severe technical problems during the drilling process. this invidious situation has also been recognized by the german government. to give the emerging geothermal industry a chance to develop towards a reputable industry branch yearly several 10 mill. € of public money for research and demonstration activities have been provided to support at least two or three geothermal chp plants to go successfully into operation. besids, the reimbursement rate has been increased several times to improve the economic incentive to bring such geothermal plants closer to the market. in parallel, subsidies have been made available by the state-owned kfw-bank to develop also heat distribution infrastructure to allow the sale of "green" geothermal heat provided in parallel to geothermal electricity within the geothermal chp units. after the first geothermal energy systems have gone successfully into operation with some years of delay several new projects have been initiated. most of them failed; but roughly a handful has been realized. thus, due to these administrative measures so far 8 geothermal power resp. chp plants are under operation in germany with an overall installed electrical capacity of roughly 33 mw. these plants provide 0.13 twh of electricity and in parallel 1.2 pj of heat (2015). the experiences gathered during the operation of these plants have been very much mixed. one plant initiated a weak seismic incident. due to the resulting fear of additional earth shattering and the respective disapproval of the local people this plant is only allowed to operate in part load to avoid or at least to minimize further seismic effects. other plants do have significant economic problems among others due to expensive maintenance efforts especially with the submersible pump transporting the geothermal fluid http://dx.doi.org/10.21622/resd.2017.03.2.209 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-85 96 http://dx.doi.org/10.21622/resd.2017.03.2.209 216 resd © 2017 http://apc.aast.edu from the underground to the above ground. these are some of the reasons why there is basically no visible development in this field so far. the only exemption is the area around munich where the molasse basin shows relative stable geological conditions allowing for a reliable chp-operation. additionally in munich a big district heating system has been installed during recent decades which can distribute geothermal heat on a large scale to the final customer, but even there the available potential does not exceed a couple of plants. iii. final considerations renewable sources of energy have gained more importance within the german electricity system. important aspects can be summarized as follows (see also [3-11]). • the use of renewable sources of energy can be expanded significantly within the electricity system by administrative measures; the development in germany during the last 25 years has proven that such a political strategy can be successful (even to due the fact that not all implemented measures and each renewables source of energy getting financial support have proven to be a success story). with a share of roughly one third of the electricity generation coming from renewables in 2015 two main political goals of this legally controlled development has been achieved: the amount of greenhouse gas (ghg) emissions has been significantly reduced and the share of domestic energy carrier within the electricity system has been noticeable increased. • if the legal frame work is set adequately and the overall goal of such a politically intended development is clearly defined and widely accepted by the majority of the population (as it is still the case in germany) such a strategy can push the technological development and thus create additional benefits for the overall society, e.g. availability of new jobs, creation of value in rural areas, and set-up of export oriented industry branches. from a purely technological point of view the following experiences could be observed. a. if a conversion technology has already been available on the market and a significant growth potential is given the legal frame could trigger an impressive und unforeseeable technological development; in germany this has been especially true for wind mill technology and photovoltaic systems as well as for biogas plants. new and not market mature technologies as well as options with a limited expansion potential have not or to a very limited extent, been further developed (e.g. electricity generation from solid biofuels). other electricity provision options characterized by too much uncontrollable risks related to the potential return on investment together with insufficient and error-prone technological solutions failed respectively and showed only a very limited development (e.g. geothermal electricity generation). b. due to the market introduction of conversion technologies using renewable sources of energy based on administrative measures considerably more efficient – and thus theoretically cheaper – conversion plants have been developed throughout recent years; the development of completely new industry branches has been a consequence. this development has been supported by yearly decreasing reimbursement rates to force industry to come increasingly closer to electricity generation costs competitive on global energy markets. in parallel, technological, economic and environmental as well as societal and safety demands to be fulfilled by these plants have increased also due to local demands promoted especially by environmental ngo's. to fulfill these numerous and partly contradicting demands from various sides the respective costs have increased. hence, the achieved cost reduction due to improved technological solutions was compensated respectively. overcompensated by higher technological, safety and environmental as well as societal standards. thus as a consequence of this development, conversion systems based on renewables have become more efficient and technologically more mature over time but not necessarily specifically cheaper. • to initiate and control such a transformation process towards an increased use of renewables, public money as well as a reliable and stable long term strategy implemented by the government is absolutely needed; if such a strategy is designed well the benefit for the overall economy could (and should) overcompensate this necessary initial investment based on public money. for germany this has only been partly successful. within the wind http://dx.doi.org/10.21622/resd.2017.03.2.209 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-85 96 http://dx.doi.org/10.21622/resd.2017.03.2.209 217 resd © 2017 http://apc.aast.edu sector a strong industry for manufacturing wind mills has been developed creating value also in rural and economically less developed areas. this has not been the case for photovoltaic systems. here, other countries have been much more successful in building up a prospering industrial infrastructure and german companies producing pv modules have gone bankrupt to a large extent. • so far, the german legal framework has supported electricity generation from renewable sources of energy. this has been realized with a broad approach to give all options a realistic chance at the market. however, with an increasing use of these options within the overall electricity system cost aspects gain more importance. the consequence is that the public and political discussion moves more in the direction of recommending a further financial support only for the most cost efficient options characterized by huge unexploited potentials and a high public acceptance. according to current knowledge and based on today's technology, these are wind mills and photovoltaic systems. these electricity generation options show a strong fluctuating electricity production characteristic. thus the next move is to find concepts as well as technologies to integrate significantly higher shares of such generation plants within the electricity supply system by guaranteeing an ongoing high security of supply throughout the overall year. thus the current discussion focuses on the identification of technologically efficient, environmentally sound and economic viable as well as socially acceptable solutions. altogether, the german example has shown that a strategy to use renewables more intensively within the overall energy system is possible and could be successful in terms of an increased energy provision as well as a significant reduction in greenhouse gas emissions. references [1] energy statistics. available: http://bmwi.de/de/themen/energie /energiedaten-undanalysen/energiedaten.html.[may 10, 2016]. [2] energy statistics. available: http://www.agenergiebilanzen.de/6-0primaerenergieverbrauch.html. [may 10, 2016]. [3] m. kaltschmitt, h. hartmann and h. hofbauer (eds). energie aus biomasse: grundlagen, techniken und verfahren. 3rd edition. springer, berlin, heidelberg, 2016. [4] m. kaltschmitt, w. streicher and a. wiese, a. (eds). erneuerbare energien – systemtechnik, wirtschaftlichkeit, umweltaspekte. 5th edition. springer, berlin, heidelberg, 2013. [5] p. keineidam and m. kaltschmitt et al. renewable power generation 2013. renewable energy focus, issue 7/8 (2015), pp.16 – 37. [6] k. bloche-daub, j. witt, m. kaltschmitt and s. janczik. erneuerbare energien – globaler stand.“ bwk, vol. 67, 7/8, s, pp. 6 – 22, 2016. [7] lenz, k. naumann, m. kaltschmitt and s. janczik. erneuerbare energien – erkenntnisstand 2014 in deutschland bwk, vol. 68, 5, pp. 60 – 80, 2016. [8] s. janczik and m. kaltschmitt. statusreport tiefe geothermie 2015: nationale und internationale nutzung erdöl erdgas kohle, vol. 131, 7/8, pp. 301 – 307, 2015. [9] m. kaltschmitt d. thrän and j. ponitka. holz als energieträger – möglichkeiten und grenzen im kontext von globalen entwicklungen. forst und holz, vol. 65, 12, pp. 18 – 25, 2010. [10] s. janczik, m. kaltschmitt, h. rüter. anthropogen induzierte seismische aktivitäten bei nutzung des tiefen untergrunds energiewirtschaftliche tagesfragen, vol. 60, 8, pp. 34 – 39, 2010. [11] m. kaltschmitt and d. thrän. logistik bei der versorgung von anlagen zur energetischen nutzung biogener festbrennstoffe – anforderungen und randbedingungen.“ zeitschrift für energiewirtschaft, vol. 30, 4, pp. 247 – 256, 2006. http://dx.doi.org/10.21622/resd.2017.03.2.209 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://bmwi.de/de/themen/energie/energiedaten-und-analysen/energiedaten.html http://bmwi.de/de/themen/energie/energiedaten-und-analysen/energiedaten.html http://bmwi.de/de/themen/energie/energiedaten-und-analysen/energiedaten.html http://www.ag-energiebilanzen.de/6-0-primaerenergieverbrauch.html http://www.ag-energiebilanzen.de/6-0-primaerenergieverbrauch.html http://www.ag-energiebilanzen.de/6-0-primaerenergieverbrauch.html renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.024 this paper has been accepted and presented in the (first international conference on new trends for sustainable energy) 1-3 october, 2016 at pharos university, alexandria, egypt. 24 resd © 2017 http://apc.aast.edu reliability improvement of power distribution systems using advanced distribution automation m. r. elkadeem, m. a. alaam and ahmed m. azmy elec. power and machines eng. depart., faculty of eng., tanta university, tanta, egypt mohammad.elkadim@f-eng.tanta.edu.eg, mhmd.aboelazem@feng.tanta.edu.eg, azmy@f-eng.tanta.edu.eg abstract towards the complete vision of smarter distribution grid, advanced distribution automation system (adas) is one of the major players in this area. in this scope, this paper introduces a generic strategy for cost-effective implementation and evaluation of adas. along with the same line, fault location, isolation and service restoration (flisr) is one of the most beneficial and desirable applications of adas for selfhealing and reliability improvement. therefore, a localcentralized-based flisr (lc-flisr) architecture is implemented on a real, urban, underground medium voltage distribution network. for the investigated network, the complete procedure and structure of the lc-flisr are presented. finally, the level of reliability improvement and customers’ satisfaction enhancement are evaluated. the results are presented in the form of a comparative study between the proposed automated and non-automated distribution networks. the results show that the automated network with proposed adas has a considerable benefit through a significant reduction in reliability indices. in addition, it has remarkable benefits observed from increasing customers’ satisfaction and reducing penalties from industry regulators. keywords advanced distribution automation system, fault location, isolation and service restoration, selfhealing grid, relaibilty assessment study. i. introduction in the contemporary world, the electrical distribution system is the backbone of the smart grid environment. however, most of customer outages are a result of the distribution networks, where 80% of customer interruptions attribute to faults and component failure at the feeder level [1]. conventional distribution systems do not involve much automation i.e. rely mainly on manual operations, and do not have any communication or information exchange i.e. blind system. during system events, the absence of monitoring and lack of information with increasing failure rate would dramatically increase the duration and number of customers affected by specific outage. the technical impact will appear in decreasing the reliability level of the network and the quality of supply. the significant economic impact of this would be observed in increasing the outages cost of utility and their customers. for these reasons, improving system reliability and power quality becomes an important issue. keeping the above problems in mind, distribution automation (da) is the key answer to many challenges facing electrical distribution networks. referring to electrical power research institute (epri), advanced distribution automation system (adas) has been defined as “a fully controllable and flexible distribution system that will facilities the exchange of electrical energy and information between participants and system components” [2], [3]. the expected results of applying da on medium voltage (mv) distribution networks include, for example, reliable, resilience, selfhealing, fully controllable and efficient distribution system for energy delivery to end users in customers’ domain. much of efforts that depend upon modernizing the distribution network are accomplished and many utilities around the world started distribution automation projects [4]-[9]. adas combines different applications that have been discussed in [10] and summarized as follows:  fault location, isolation, and service restoration  volt/var control and optimization  distributed generation resources management  adaptive distribution feeder protection coordination  optimal feeder reconfiguration  automatic meter reading  demand side management http://dx.doi.org/10.21622/resd.2017.03.1.024 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.024 25 resd © 2017 http://apc.aast.edu fault location, isolation and service restoration (flisr) is defined as the most beneficial, attractive application among all applications of adas in order to getting self-healing grid, enhancing the reliability level of distribution networks, reducing operation and maintenance cost and increasing customers satisfaction. this is achieved by means of reducing the outage time from several hours to few minutes [11]. there are different architectures for flisr implementation based on where the decision is made: fully-centralized (fc-flisr) [6],[7], fully-decentralized (fd-flisr) [8],[9] and local-centralized (lc-flisr) architectures. in fully centralized architecture, the flisr algorithms are implemented in dms/scada system located at the control centre (cc) in so far area. in the decentralized architecture, the flisr uses an intelligent local controller, integrated with the multiple switches distributed along feeder nodes. the scope of this paper is to evaluate the effective utilization of adas within power distribution systems. in the context of adas implementation, to avoid the huge investment and maximize the benefits towards a complete vision for the smart distribution grid, a generic strategy for adas is developed in this paper. also, a local-centralized architecture is presented as the most appropriate architecture for flisr implementation within the investigated distribution network. the reasons and encouragements for this choice are discussed in the next sections. in addition, the structure and procedure of flisr system are presented. finally. the reliability assessment study is performed using analytical technique. the results are presented in the form of a comparative study between the proposed automated and non-automated distribution networks. the results show that the automated network with proposed adas is able to achieve a significant and considerable improvement in reliability level of the distribution network. ii. description and operation of the distribution network under study a. description of the investigated distribution network to prove the validity of the proposed study, it will be performed on a real distribution network as a case study. this distribution network is an actual, urban, underground, 11 kv rated distribution network with open-ring configuration. as demonstrated in fig. 1, the investigated network consists of an 11 kv distribution substation fed from a 22 kv distribution system, which has a 750 mva short circuit capacity. this distribution substation supplies four outgoing feeders. each is protected by and intelligent electronic devices (ied) at the beginning of the feeder. the lengths of these feeders are 5.485 km, 1.750 km, 3.725 km, and 6.725 km, respectively. the distribution network contains thirty-five 11 kv compact secondary substations (csss), which are installed over the four feeders. each css is a fully equipped package substation divided into three main compartments: incoming mv compartment, transformer (xfmr) compartment and low voltage feeder panel (lvfp) compartment as illustrated in fig. 2. cb 3cb 1 cb 4cb 2 5 mva xfmr 750 mva sc grid supply system 11 kv 22 kv s/s with nc sw s/s with no sw s/s 5-1 s/s 6-2 s/s 4-2 s/s 4-3 s/s 7-3 s/s 7-4 s/s 11-4 s/s 11-1 fig .1. 11 kv underground distribution network sf6 cb incoming cable outgoing cable 0.4 kv lvfp 11/0.4 kv ` xfmr mccb loads facilities 11 kv rmu lbs lbs mccb fig .2. compact secondary substation compartments http://dx.doi.org/10.21622/resd.2017.03.1.025 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.024 26 resd © 2017 http://apc.aast.edu b. operation mode of the investigated distribution network the existing mv distribution network is a conventional network and have not involved much automation i.e. rely mainly on manual operations. traditional flisr still exhibits long time and stressful efforts as follows:  the fault is detected via the outage reports received from the outage customers.  afterwards, investigation process for fault localization to determine the faulty section is started. this process necessitates the patrolling of the entire network.  for successful isolation of the faulty section, manual-switching actions are completely accomplished by human intervention.  finally, other manual switching actions are executed to restore the service to healthy customers. briefly, flisr is performed manually via human intervention and hence, the network operator is facing some of technical and financial issues that are defined and represented by increasing the outages time and outages costs, especially with the presence of the underground cables spread over long distances. consequently, it is suffered from low level of service reliability and low customers’ satisfaction. iii. the propsed advanced distribution automation system motivated by the earlier mentioned issues in the previous section, adas is an imperative solution in order to strengthen the operation of mv distribution networks. this following section attempt to discuss some issues related to adas implementation from different points of view, e.g. adas strategy of implementation, selection of the most appropriate architecture. finally, the structure and requirements of the proposed automation system is introduced. a. implemented strategy of adas although it may be not possible to describe a successful adas strategy, rapid deployments worldwide have thought some lessons [11], [12] that help to construct the proposed implemented strategy for the existing distribution network, as illustrated in fig. 3. the target of the proposed adas strategy is to determine the main requirements of adas including selection of the most appropriate architecture or approach for adas, defining of automation degree and complete structure of adas. the detailed explanation of the proposed adas strategy will be presented as follows: define the most appropriate adas scheme specify the automation degree determine the structure and requirements of adas technical and financials issues determine the optimal automation level $ monitoring control partially adas fully adas flisr operation fig .3. general strategy for distribution automation implementation the proposed strategy starts with selection of the most significant and beneficial application that is currently needed for the system. this application will be the first phase of the smart distribution network and will be defined according to the existing technical and financial issues facing the distribution network e.g. for the existing distribution network, which is presented as a case study, flisr is defined. the second step is to define the most appropriate architecture for adas. the adas scheme is refer to where the decision is made. three different scheme are introduced in section i. the selection criteria are based on the requirements of the defined application, the nature of the existing control strategy of the network, network size and configuration, as well as economic resources. the next step is the specification of the automation degree. the automation degree is categorized into three categories; monitoring, control, and operation or any combination of them. this is based on the network operator target and requirements. after that, utility have to determine the copmlete structure and requirements of the adas. in general, the main structure and requirements of adas include: flexible electrical hardware facilities, modern communication technologies and intelligent software applications [11]. finally, for for reasonable degree of improvement in system performance and economic justification and profitability, cost/benefit analysis is performed to determine the optimal automation level of the distribution network. the automation level of mv distribution network is considered to be percentage of http://dx.doi.org/10.21622/resd.2017.03.1.025 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.024 27 resd © 2017 http://apc.aast.edu automated points in the network. for underground networks, the automated points are the number of secondary substations (s/ss) retrofitted with smart devices such as feeder remote terminal units and fault indicators. b. proposed local-centralized flisr nowadays, the great evolution of smart sensors, advanced communication technologies and utilization growing of scada/dms, accelerates the transformation of the traditional distribution networks into automated systems. following the proposed strategy for adas, flisr application is defined as the most appropriate solution among all applications of adas to achieve self-healing grid and to improve the reliability level of distribution network. flisr is implemented on the existing mv distribution network based on local-centralized architecture, called (lcflisr). the information is acquired and analysed in primary substation. then, the control decision is executed automatically on real network or after confirmed by the operator using the scada interface. the idea behind flisr is to achieve the self-healing grid, where the service for all customers is restored automatically after few minutes (< 5 minutes) from fault from fault occurrence [11]. the main objectives of the lc-flisr are illustrated in fig. 4. so, as shown in fig. 5, the proposed structure of adas consists of: therefore, this paper aims to present a simple and more efficient cbpwm technique to control three to five-phase matrix converters, which can be used to supply a five-phase induction motor drive system that delivers some advantageous features for industrial applications. the basic concept of the proposed technique is already published in [27]. thanks to its simplicity, the proposed technique will be based on the indirect modulation of the 3×5 mc which control the converter as a double stage converter. therefore, the carrier based pwm methods are applied for each stage independently. the proposed modulation will maximize the converter vtr by operating the converter in the overmodulation mode as well as in the linear modulation mode. it also controls the input power factor by controlling the input current displacement angle. the proposed modulation technique is verified using simulation and experimental results based on a laboratory prototype and the dspace-ds1104 controller platform and the results are compared by the existing svm technique.  master unit controller (called mu) as the “decision support system” of the adas. the information is acquired and analysed by mu. then, the control decision is executed automatically on real network or after confirmed by the operator using the scada interface  intelligent software applications (flisr algorithms); as this paper focus on flisr application. thereby, there are two main intelligent algorithms are needed to be integrated with adas: “fault location” and “service restoration” algorithms.  modern communication technologies as the heart of adas. the core mission of the network communications is to provide information exchange facilities between field devices dispersed geographically along the distribution grid and master unit located at primary substation.  flexible electrical hardware facilities (field devices). detect the fault quickly locate the fault accurately isolate only the faulty section restore the service within < 5 min fig .4. flisr objectives wire/ wireless two-away communication network no ie d-1 scadaflisr algorithms ie d-2 frtu smart s/s frtu frtu frtu frtu frtu frtu master unit communication getaway fig .5. over view of local-centralized adas structure http://dx.doi.org/10.21622/resd.2017.03.1.025 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.024 28 resd © 2017 http://apc.aast.edu regardin to field devices, the secondary substations play a vital role in the evolution toward the self-healing grid. therefore, the retrofitting of the existing traditional s/ss with smart equipment suitable for adas. a typical configuratuon of smart s/s is presented in fig. 6, where the figure is taken from [13]. however, the smart devices that are suitable for the propsed adas are only highlighed. so, the smart s/s is consists of: smart rmu equipped with motorized lbss, motorized cb, fault indicators (fis), voltage indicators (vis), and uninterruptible power supply (ups). also, the smart s/s is supported with feeder remote terminal unit (frtu) acts as a local controller for field devices. in addition, frtu acts as a gateway between field devices and mu. from the literature [14], the communication between mu and frtus in this paper will take place through public gprs communication based on iec 60870-5-101 protocols as a cost-effective solution [5]. on the other hand, connection with field devices will be wired (serial rs232/rs-458) using conventional iec 60870-1-104 or modbus rtu protocols supported by field devices. on the way to realise a high level of reliability, reducing outage time and outage cost, increasing customer satisfaction, a fully automated system is implemented. so, all s/ss would be retrofitted with smart equipment that are suitable for das. fi fi m lbs lbs sf6 cb cable loads 11/0.4 kv mccb 0.4 kv lvfp vi vi frtu gprs iec 60870-5-101 ups 11 kv smart rmu xfmr kiosk rs 232/458 iec 60870-5-104 m m fig.6. typical configuration of smart s/s with adas equipment c. proposed adas architecture: in this paper lc-flisr architecture is selected as the most appropriate solution due to the following reasons: the choice of a lc-flisr architecture to be implemented in this paper is judged by the following reasons:  compared to fully centralized architecture, there is no need for huge investment that is required for fcflisr scheme including scada/dms hardware and software. the decision is taken from mu located at the primary substation within the same graphical area of the entire network. the results, the communication is over relatively short distances. hence, high-speed data transfer is achieved and the service restoration time is lower. the significant economic impact of would be observed in decreasing the customer outages cost of utility and their customers.  compared to distributed architecture that has limited functionality, in lc-flisr, the structure of constructed algorithm located in primary substation is easy to be modified and expanded to accommodate the upcoming extensions in the network. also, because of the communication network between mu and rftus are already used in the system e.g. gprs network, a few costs are required with adding more adas application such as volt/var control and distributed generation resources management d. lc-flisr procedur in this subsection, the steps of lc-flisr procedure are discussed as follows:  firstly, with permanent fault occurrence the ieds at the beginning of each feeder will detect and initiate the corrective action as quickly as possible for the corresponding feeder cb.  with the help of the fpis installed in each smart s/ss, the faulty section well-known between the last flashed fi and first unflashed fi.  the next is to isolate only the faulty section. so, a control commands are automatically issued by mu in order to open the proper lbss surrounding the fault.  after the faulty section is isolated successfully, the lcflisr algorithms are triggered swiftly through scada inputs such as lbss and fpis statuses. with fault location capability integrated with the proposed adas system. the probable location of the faulty point will be estimated, [15] rather than determining the faulty section. consequently, the fault damage inspection and repairing time and money can be saved. http://dx.doi.org/10.21622/resd.2017.03.1.025 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.024 29 resd © 2017 http://apc.aast.edu  finally, the service can be restored again for the customers of remaining healthy sections by the help of the service restoration algorithm implemented in mu. the service restoration algorithm is responsible for generating a suitable restoration-switching plane to the proper lbss in the system to achieve the goal [16]. as a result, it will improve the service reliability and increases the operational efficiency of the network. iv. reliability assessment study a. reliability indices and technique in order to quantify and evaluate the benefit of adas implementation, reliability assessment study is performed. system reliability refers to the capability of the system to perform its specified task correctly for certain duration of time. the system reliability is represented using two terms “system adequacy” and system security”. there are two categories of indices that used to define the reliability level of the distribution system; load point reliability indices and system reliability indices. the load point indices include; average failure rate, λi (f/yr), expected outage duration, ri (hr), and unavailability, ui (hr/yr) for load point “i” [17]. also, the expected energy not supplied index at each load point, eensi (mwhr/yr) can be used to assess the performance of the system. from theses load point indices, the system reliability indices such as saidi, saifi, caidi and eens can be then calculated for the whole system [17]. theses indices can be calculated according to references, [18], [19] as follows: λi = λ1 + λ2 + ⋯ λm = (f/yr) (1) ui = λ1r1 + λ2r2 + ⋯ λmrm = ∑ λx m x=1 rx (hr/yr) (2) ri = ui λi = ∑ λx m x=1 rx ∑ λx m x=1 (hr) (3) 𝐸𝐸𝑁𝑆𝑖 = 𝑃𝑖 𝑈𝑖 (mwhr/yr) (4) saidi = ∑ 𝑼𝒊𝑵𝒊 𝑵𝑻 𝒊=𝟏 𝑵𝑻 (hr/yr) (5) saifi == ∑ λini nt i=1 nt (int/yr) (6) caidi = saidi saifi (hr/int) (7) eens = ∑ piui nt i=1 (mwhr/yr) (8) where: λj is failure rate of component j (f/yr), m is the number of components that affect the load point “i”, rj "is" the restoration time of load point “i” after failure of component “x” (hr), pi is the total demand at load point “i” and nt is the total number of customers served (mw). the reliability level of the distribution system depends mainly on the overall time of the flisr procedure after fault event. this time is estimated according to the operating strategy non-automated and automated distribution network. in this paper, the reliability study is performed using analytical technique based on failure mode effect analysis (fmea) [20]. the basic procedure used in the analytical technique is shown in fig. 7. obtain network and customer data consider the failure for component x identify the affected area and load points start no calculate λix , rix and uix for an affected load point i is all components are considered yes accumulate load point indices to calculate the total load point indices λi , ri and ui calculate system indices saidi, saifi, ... report the results end x = x+1 x = 1 fig. 7. procedure of the analytical technique for reliability assessment http://dx.doi.org/10.21622/resd.2017.03.1.025 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.024 30 resd © 2017 http://apc.aast.edu b. simulation results the structure and configuration of the investigated 11 kv distribution network is presented in section ii-a. the reliability indices of the distribution network are evaluated with two operating philosophy: nonautomated distribution network strategy e and automated distribution network. then, the results are compared in order to ensure the achievement of improving the reliability indices using adas. the network reliability data are taken from ieee standard 493-2007 (golden book) [19], and given in table. 1. table 1. network reliability data equipment category failure rate (failure/year) repair time (h/failure) unavailability (h/year) comments lv cb 0.0027 4 0.0108 mv cb 0.0036 2.1 0.0076 lv cable 0.00141 10.5 0.0148 1000 circuit ft. mv cable 0.00613 26.5 0.1642 1000 circuit ft. disc. switch 0.0061 3.6 0.022 mv transf. 0.003 130 1.026 replace by spare lv swgr 0.0024 24 0.0576 mv swgr 0.0102 26.8 0.2733 the reliability study is performed under the following assumption: normally, the distribution network operates in open-ring configuration, but some of the network feeders can be connected to each other through the normally open tie switch and the average restoration time for the healthy customers defined to be under 5 minutes with automated network and two hours with non-automated one. also all the cbs and lbss are assumed to be 100% reliable and all failures are statistically independent. the load point reliability indices such as λ, r, u and eensi are calculated using fmea method with the help etap®12.60 software package and the results are presented in table 2 for comparative study purpose between non-automated and automated network. in addition, the system reliability indices such as saidi, saifi, and eens are also calculated for each of four feeders and whole system and given in table 3. the results indicate clearly that the load point indices are improved significantly for all load points in the investigated distribution network by implementing the proposed adas. in addition, there are a clear reduction in system indices, i.e. saidi and eens, for all system feeders and whole system. for the whole system, there is a reduction in both saidi and eens by 34 % and 32 % respectively by using adas as shown in fig. 8. this is observed through the reduction in reliability indices. so, this will directly lead to the improvement of the reliability level of the investigated distribution network, increase customer satisfaction, reducing system interruption cost for various load categories (residential, commercial, industrial and so on) by quick restoration of service and reducing penalties and achieve incentives offered by regulators. table 2. results summary of load point indices for non-automated and automated distribution network lp feeder non-automated automated r (hr) u (hr/yr) eensi (mwhr/yr) r (hr) u (hr/yr) eensi (mwhr/yr) 1 #1 4.744 1.108 0.148 3.029 0.707 0.094 2 #1 4.916 1.157 0.284 3.214 0.757 0.186 3 #1 4.826 1.131 0.303 3.117 0.731 0.196 4 #1 5.023 1.188 0.172 3.330 0.788 0.114 5 #1 4.934 1.162 0.081 3.234 0.762 0.053 6 #1 6.035 1.500 0.045 4.424 1.100 0.033 7 #1 4.726 1.131 0.056 3.009 0.702 0.035 8 #1 4.826 1.188 0.101 3.117 0.731 0.065 9 #1 5.023 1.167 0.083 3.330 0.788 0.055 10 #1 4.735 1.105 0.077 3.019 0.705 0.049 11 #1 5.049 1.196 0.153 3.359 0.796 0.102 12 #1 5.995 1.487 0.156 4.381 1.087 0.114 13 #1 4.853 1.139 0.186 3.146 0.738 0.121 14 #2 7.934 0.860 0.292 6.491 0.704 0.239 15 #2 8.213 0.904 0.360 6.792 0.748 0.298 16 #2 8.196 0.902 0.252 6.775 0.745 0.208 17 #2 8.309 0.920 0.047 6.896 0.763 0.039 18 #2 8.530 0.956 0.227 7.135 0.800 0.190 19 #2 8.180 0.899 0.355 6.757 0.743 0.293 20 #2 8.066 0.881 0.095 6.634 0.724 0.078 21 #2 8.196 0.902 0.230 6.775 0.745 0.190 22 #3 5.875 0.961 0.211 4.257 0.696 0.153 23 #3 5.998 0.987 0.073 4.389 0.722 0.053 24 #3 6.309 1.054 0.135 4.725 0.790 0.101 25 #3 6.438 1.083 0.048 4.864 0.818 0.036 26 #3 7.013 1.215 0.389 5.486 0.951 0.304 27 #3 7.013 1.215 0.112 5.486 0.951 0.087 28 #3 6.610 1.122 0.103 5.051 0.857 0.079 29 #3 5.924 0.971 0.618 4.310 0.706 0.449 30 #3 6.747 1.153 0.101 5.198 0.888 0.078 31 #3 6.022 0.992 0.045 4.415 0.727 0.033 32 #3 8.204 1.517 0.194 6.773 1.252 0.160 33 #3 10.35 2.177 0.279 9.09 1.913 0.245 34 #4 5.403 1.444 0.252 2.914 0.779 0.136 35 #4 5.169 1.366 0.190 2.652 0.701 0.098 36 #4 5.326 1.418 0.238 2.828 0.753 0.127 37 #4 5.224 1.384 0.145 2.714 0.719 0.075 38 #4 5.232 1.387 0.371 2.723 0.722 0.193 39 #4 5.380 1.436 0.460 2.888 0.771 0.247 40 #4 5.224 1.384 0.169 2.714 0.719 0.088 41 #4 5.411 1.447 0.296 2.923 0.782 0.160 42 #4 5.240 1.390 0.193 2.732 0.724 0.101 43 #4 4.405 1.165 0.149 2.661 0.704 0.090 44 #4 5.326 1.418 0.149 2.828 0.753 0.079 45 #4 5.341 1.423 0.198 2.845 0.758 0.106 46 #4 5.318 1.416 0.085 2.819 0.750 0.045 47 #4 5.310 1.413 0.091 2.810 0.748 0.048 48 #4 5.310 1.413 0.197 2.810 0.748 0.104 http://dx.doi.org/10.21622/resd.2017.03.1.025 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.024 31 resd © 2017 http://apc.aast.edu table 3. comparison between system reliability indices for nonautomated and automated distribution network operating philosophy feeder saidi (hr/yr) saifi (int/yr) caidi (hr/int) eens (mwh r/yr) nonautomated feeder 1 1.20 0.24 5.08 1.85 feeder 2 0.91 0.11 8.23 1.86 feeder 3 1.22 0.17 7.04 2.31 feeder 4 1.40 0.26 5.37 3.18 system 1.20 0.21 5.86 9.19 automated feeder 1 0.80 0.24 3.37 1.22 feeder 2 0.75 0.11 6.81 1.53 feeder 3 0.96 0.17 5.52 1.78 feeder 4 0.75 0.26 2.86 1.7 system 0.79 0.21 3.87 6.23 (a) effect of distribution automation on saidi (b) effect of distribution automation on eens fig. 8. reduction in saidi and eens with adas v. conclusions the growing importance of adas and its expected benefits on the operation of distribution systems encourage the investigation of this subject. the results show that the determination of the generic strategy for adas will avoid the huge investment toward a complete vision of smarter distribution systems. following the proposed implemented adas strategy, flisr application has been implemented on real, urban, underground 11 kv distribution network based on local-centralized architecture. from the investigation, the presented architecture is defined as a cost-effective solution with the existing network. the results of reliability analysis for both automated and non-automated distribution network are evaluated and compared. it is concluded that the automated network with the proposed adas has a tangible benefit through considerable reduction in load point indices. along with the same line, the system indices such as saidi and eens exhibit a significant reduction by 34 % and 32 %, respectively. in addition, the proposed adas provides an intangible benefits observed by grater customer satisfaction and reduced penalties by industry regulators through the reduction of the outage time and outage cost. references [1] shang-wen luan; jen-hao teng; shun-yu chan; lain-chyr hwang, “development of an automatic reliability calculation system for advanced metering infrastructure,” in industrial informatics (indin), 2010 8th ieee international conference on, pp. 342-347, 13-16 july 2010. [2] m. mcgranaghan and f. goodman, "technical and system requirements for advanced distribution automation," electricity distribution, 2005. cired 2005. 18th international conference and exhibition on, turin, italy, 2005, pp. 1-5. [3] r. w. uluski, "the role of advanced distribution automation in the smart grid," power and energy society general meeting, 2010 ieee, minneapolis, 2010, pp. 1-5. [4] shahin, m.a., “smart grid self-healing implementation for underground distribution networks,” in innovative smart grid technologies asia (isgt asia), 2013 ieee, pp.1-5, 10-13 nov. 2013. [5] siirto, o., kuru, j., and lehtonen, m., “fault location, isolation and restoration in a city distribution network,” in electric power quality and supply reliability conference (pq), 2014, pp. 367-370, 11-13 june 2014. [6] gomes, d.; colunga, r.; gupta, p.; balasubramanian, a., “distribution automation case study: rapid fault detection, isolation, and power restoration for a reliable underground distribution system,” in protective relay engineers, 2015 68th annual conference on, 0 0.1 0.2 0.3 0.4 0.5 feeder 1 feeder 2 feeder 3 feeder 4 system p u 0 0.1 0.2 0.3 0.4 0.5 feeder 1 feeder 2 feeder 3 feeder 4 system p u http://dx.doi.org/10.21622/resd.2017.03.1.025 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ renewable energy and sustainable development (resd) volume 3 issue 1, special issue, march 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.1.024 32 resd © 2017 http://apc.aast.edu pp.325-334, march 30 2015-april 2 2015. [7] kuru, j.; ihonen, t.; haikonen, j., “controlcenter-based automatic fault isolation and restoration system for rural medium voltage networks,” in electricity distribution (cired 2013), 22nd international conference and exhibition on , pp.1-4, 10-13 june 213. [8] chollot, y.; wild, j.; berry, t.; jourdan, a.; raison, b.; marguet, r.; houssin, j.; joubert, r., “decentralized self healing solution tested in the framework of greenlys smart grid project,” in powertech 2013 ieee, grenoble, pp. 1-7, 16-20 june 2013. [9] coster, edward; kerstens, wim; berry, tom, “self healing distribution networks using smart controllers,” in electricity distribution (cired 2013), 22nd international conference and exhibition on. stockholm, pp.1-4, 10-13 june 2013. [10] ieee distribution automation workig group, “smart grid for distribution systems: the benefits and challenges of distribution automation(da),” ieee white pap., 2007. [11] madani, v.; das, r.; aminifar, f.; mcdonald, j.; venkata, s.s.; novosel, d.; bose, a.; shahidehpour, m., “distribution automation strategies challenges and opportunities in a changing landscape,” in smart grid, ieee transactions on , vol.6, no.4, pp.2157-2165, july 2015. [12] r. das, v. madani, f. aminifar, j. mcdonald, s.s venkata. d., novosel, a.bose and m. shahidehpour, "distribution automation strategies: evolution of technologies and the business case," inieee transactions on smart grid, vol. 6, no. 4, pp. 2166-2175, july 2015. [13] späck h., schüpferling b., riemenschneider j. and schelte m., "intelligent transformer substations in modern medium voltage networks as part of “smart grid”," power generation transmission, distribution and energy conversion (medpower 2010), 7th mediterranean conference and exhibition on, agia napa, 2010, pp. 1-7. [14] v. gungor, d. sahin, and t. kocak, "smart grid technologies: communication technologies and standards," in ieee transactions on industrial informatics, vol. 7, no. 4, pp. 529-539, nov. 2011. [15] yanfeng gong; guzman, a., “integrated fault location system for power distribution feeders,” in industry applications, ieee transactions on , vol.49, no.3, pp.1071-1078, may-june 2013. [16] sudhakar, t. d., & srinivas, k. n. "restoration of power network–a bibliographic survey," european transactions on electrical power, vol. 21, no. 1, pp. 635-655, 2011. [17] subban, p.p., awodele, k.o., “reliability impact of different smart grid techniques on a power distribution system,” in innovative smart grid technologies latin america (isgt la), 2013 ieee pes conference on, pp.1-8, 15-17 april 2013. [18] ieee guide for electric power distribution reliability indices," in ieee std 1366-2003 (revision of ieee std 1366-1998), pp.1-50, may 14 2004. [19] ieee recommended practice for the design of reliable industrial and commercial power systems," in ieee std 493-2007 (revision of ieee std 493-1997), pp.1-689, june 25 2007. [20] ahmed r. abul'wafa, “reliability improvement of radial distribution system with different configurations of disconnecting switches,” the 16th international middle east power systems conference (mepcon'14). cairo, egypt, 3-25 december 2014. http://dx.doi.org/10.21622/resd.2017.03.1.025 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.137 137 importance of communication and information technology and its applications in the development and integration of performance in seaports tarek m. attia national telecom regulatory authority (ntra), b-4, km28, cairo alex. desert road, smart village, 6 october, giza, egypt. tattia@tra.gov.eg abstract the maritime industry is a global transporter of the goods of modern globalized economies. shipping plays a vital role in today’s economy, with over 90% of the world’s trade carried by sea. the efficient transportation of cargoes impact on both consumers and the global economy. in order to improve the safety and efficiency of maritime transport and the protection of the sea and marine environment, it is inevitable to use modern information and communication technologies when collecting, storing, processing, presenting and distributing relevant data and information to the participants in maritime transport. the smart port used information technology (it) extensively to create a high-tech port. the key factors contributing to the success of the it and communication infrastructure in the smart port are the ability to meet the changing demands of users and to keep up with the rapid developments in it and the ability to accommodate new technology developments without having to constantly restructure. this paper presented the key issues related to navigation systems, communication networks and information technology and its applications to secure the ships and the development of business performance for the transfer and circulation of goods within the seaports with high efficiency and the impact of this on the national economy. keywords communication networks and information technology; navigation systems; smart ports. i. introduction navigating the seas safely is not just important for the lives of the people on board; shipping plays a vital role in today’s economy, with over 90% of the world’s trade carried by sea[1]. the maritime industry is regulated by the international maritime organization (imo) which is responsible for the safety, security and efficiency of shipping and the prevention of maritime pollution. technology and innovation, such as the internet of things (iot), are said to be a driving force behind smart port productivity. this type of technology, in the form of physical and it infrastructure could be the best way to see benefits in a smart port environment. the ultimate smart port may be the fully automated port where all devices are connected via iot. in port operations, the integration of various infrastructures, both physical and it, includes different network technologies like radio, lan, wan and wlan, rfid and positioning technologies. the effectiveness of the smart port environment may lie in the technology and smart practices’ ability to be able to work together to effectively share information, both for the benefit of ports and for its customers. a key element to all this is some sort of internal cloud gathering information about all events related to the port. when analyzed and presented in a smart way, that data can help to achieve the goal of doing things smarter. the efficient transportation of cargoes impact on both consumers and the global economy. the correct planning and execution of operations on a containercarrier vessel is a decisive element in the strategy of a seaport. the operational process of a container terminal can be considered as a large productive process where the final element is not a physical product but rather a specified service. the handling and storage of the containerized goods of a particular customer need to be delivered as rapidly as possible to enable the vessel to spend the minimum time necessary in port and, consequently, to obtain maximum economic utilization and to be both energy and environmentally efficient. http://dx.doi.org/10.21622/resd.2016.02.2.137 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 138 communication networks and computers technologies and all their associated equipment present the technical foundation of smart ports. computer technology is experiencing a rapid development geared towards increasing processing speed, increasing capacity of the memory, mobility and the use of all media designed for receiving and storing data, greater compatibility and continuous price cuts, etc. in order to improve the safety and efficiency of maritime transport and the protection of the sea and marine environment, it is inevitable to use modern information and communication technologies when collecting, storing, processing, presenting and distributing relevant data and information to the participants in maritime transport. in order to meet rising customer expectations and stay ahead of the competition, the overall port operation services can be enhanced by moving to a paperless environment and providing a valuable and relevant solution that completely restructures the manual process of documents exchange among port community members. automation aimed at and achieved the optimization of the port management processes by decreasing the vessel and cargo turnaround time to making available the necessary real time data for yard operations and performing all statistical and data analysis for decision makers. this paper is organized as follows: section 2 outlines wireless and satellite communications networks for maritime sector; section 3 presents navigation and tracking systems and their applications; section 4 outlines sensing technologies and services provided for the maritime sector; section 5 presents a glance at some of the technological applications and services offered in smart ports; section 6 presents information technologies and integration between different maritime services; and section 7 concludes the paper. ii. wireless and satellite communications network the communication infrastructure currently available in the maritime sector has enabled shipping companies to integrate their ships within their own overall it networks. however, integration technology for the shipping industry must take into account the communication systems in use today and the ones which will be available in the foreseeable future. communication systems available to and used by the maritime and transport industries cover the terrestrial networks (hf/vhf/uhf radio, land lines, fiber optics) and satellite communication systems; the availability of these has enabled the use of the internet, webbased processes and the possibility of real time information flow. the choice and availability of the different types of communications depend on the geographic location. wireless and satellite communications are keys to the success of the maritime industry because they provide the medium by which maritime safety information, ship position reporting and weather forecasts, as well as other information, can be passed to ships at sea. for a vessel in trouble, the accuracy and update rate of the reporting of the ship’s position aids rescue, potentially avoiding the loss of the ship, saving the lives of the crew or preventing an environmental disaster. seaports are relying more and more on wireless technologies to enhance the flexibility of operations and improve efficiency. wireless network equipment is used for better handling of equipment, to improve cargo integrity, real time surveillance, effective administration through building connectivity etc. radio data communications are widely used within the port environment today. common use includes communication from a central computer to mobile computers, such as those that are hand held or fixed and used by personnel on site or drivers of trucks, cranes and straddle carriers. the significant benefit from using radio data communication is that it allows transfers within the container terminal to happen in real time, with the immediate updating of container movements. the central computer can assign a carrier to do a particular job based on what equipment is most suitable. the radio data communication link can also be used to transmit sensor data from the container moving equipment to the central computer, for example giving details about its location obtained using positioning techniques and satellite communications. in a world where most workers still record container numbers on clipboards, wireless solutions can drive significant cost savings and faster operations. smart port is set to strengthen significantly through a range of innovative communication technologies, which will increase interconnectivity and enhance the port’s overall competitiveness. smart port can harness the use of mobile technology and wireless connectivity to enhance journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.137 139 communications, productivity and crew welfare at the maritime center. these include providing 3g/4g broadband mobile telecommunications technology access for vessels operating within waters of the port and the immediate maritime community. the lowcost, secure wireless 3g/4g broadband service and wimax network will be available to users within 15 km of the coastline to further enhance network coverage across the port to benefit the maritime community[2]. wi-fi services at the port and launching new mobile application for the maritime community and members of the public to conveniently access maritime information and services on their mobile phones will further enhance passenger experience and business operations at ports. iii. navigation and tracking systems and their applications the global navigation satellite system (gnss) is a navigational system of satellites that provides autonomous geo-spatial positioning with global coverage. it allows small electronic receivers to determine their location (longitude, latitude, and altitude) within a few meters using time signals transmitted from navigational satellites. gnss technology is the backbone of traffic management and modernization at seaport container terminals. one of the most important properties of gnssenabled systems is the ability of tracking container arrivals and their docking at the port [3]. gnss improves navigation, transport economics and consumption at sea; on the other hand. it can avoid casualties like collisions helping to limit risk to safety and the environment and has an effect on transport quality, loading factor and service. the ability to accurately determine and communicate one’s position at any moment, thanks to gnss, is starting to have a major impact on the management of ship and lorry fleets, road and rail traffic monitoring, the mobilization of emergency services, the tracking of goods carried by multimodal transport and air traffic control. a smartphone application can use gnss to capture information about location, speed, acceleration and driving times. based on the specific freight, vehicle weight and predefined reference profiles, this data can then be used to calculate the exact fuel consumption, which can then be integrated with the specific route parameters. the logistics company and the driver will immediately receive these metrics via the specific server. this will help reduce emissions and save fuel, which in turn will help to reduce the overall costs for the providers of logistics services. an additional benefit will be that an efficient driving style also reduces the amount of maintenance required on vehicles and can thereby help to increase their periods of active usage. there are obvious examples used as application for tracking and monitoring vessels during sailing in the sea such as long range identification and tracking system (lrit) and automatic identification system (ais). a. automatic identification system (ais) the automatic identification system (ais) is a shipborne transponder system designed in the first instance for maritime safety and, in particular, for collision avoidance. it consists of a transponder unit including gps, vhf transmitter/receiver and display/terminal. the unit broadcasts a message at regular intervals containing its identification, position, speed, course plus a number of detailed items about the ship and its cargo. the broadcast carries vhf range which is basically line of sight[4]. it is used for identifying and locating vessels by electronically exchanging data with other nearby ships and vts stations. ais displays incoming vessel information on a suitable device, collects vessel movement information and assembles it into an ais compliant data sentence, and initiates and controls the flow of data sentences between participating units. figure.1 depicts ais tracking system for vessels. the ais sender and receiver are generally present on the big ship and the information is often available through dedicated internet sources. an ais system has limited coverage based on radars specifications but this problem will be overcome with the implementation of satellite ais. ais information supplements marine radar, which continues to be a vital method of collision avoidance for waterborne transport, hence it avoids marine casualties and environmental pollution. http://dx.doi.org/10.21622/resd.2016.02.2.137 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 140 fig .1. ais tracking system for vessels. b. the long range identification and tracking (lrit) system lrit system is a designated international maritime organization (imo) system designed to collect and disseminate vessel position information received from imo member states ships that are subject to the international convention for the safety of life at sea (solas). lrit consists of the ship borne lrit information transmitting equipment, the communication service provider(s), the application service provider(s), the lrit data centre(s), including any related vessel monitoring system(s), the lrit data distribution plan and the international lrit data exchange. certain aspects of the performance of the lrit system are reviewed or audited by an lrit coordinator acting on behalf of all contracting governments. lrit regulation requires operators of ships regulated by solas contracting governments and engaged on international voyages, including passenger ships, cargo ships of 300 gross tons and above, and mobile offshore drilling units, to provide compliant ship borne equipment for the transmission of lrit information. inmarsat-c equipment already installed on the majority of vessels is frequently used for lrit compliance[5]. figure.2 depicts lrit tracking system for vessels. lrit is available to all vessels having the appropriate equipment and comply with the imo regulation for the system. lrit information can be used for security, safety and environmental protection. the main distinctions between ais and lrit are first that ais is line of sight while lrit is global, and second that ais is broadcast whereas lrit is only sent to specific recipients for confidential treatment. furthermore, the ais message contains much more information than lrit systems. fig .2. long range identification and tracking (lrit) system for vessels. iv. sensing technologies and services provided for the maritime sector technological advances in telecommunications and information technology, coupled with ultramodern/state-of-the-art microchip, rfid (radio frequency identification) and inexpensive intelligent beacon sensing technologies, have enhanced the technical capabilities that will facilitate motorist safety benefits for intelligent transportation systems globally. sensing systems for its are vehicleand infrastructure-based networked systems, i.e., intelligent vehicle technologies. infrastructure sensors are indestructible devices that are installed or embedded in the road or surrounding the road (e.g., on buildings, posts, and signs), as required, or by sensor injection machinery for rapid deployment. vehicle-sensing systems include deployment of electronic beacons for identification communications journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.137 141 and may also employ video automatic number plate recognition or vehicle magnetic signature detection technologies at desired intervals to increase sustained monitoring of vehicles operating in critical zones. some examples for sensing technologies are rfid, ocr and cctv. a. radio frequency identification and tracking (rfid) technology rfid are deployed to support the identification and tracking of assets typically associated with operations within a facility, to automatize processes, to improve operational productivity and equipment utilization as well as for safety of people and assets and security of containers. rfid is a technology that uses radio waves to transfer data from an electronic tag, called rfid tag or label, attached to an object, through a reader for the purpose of identifying and tracking the object. rfid can be applied to all transport modes and to all transport and supply chains. with rfid transport, chains can significantly improve loading factors as well as increase cost efficiency. rfid technology can be used efficiently in container ports to improve container security and regulatory compliance, improved quality, container identification, location and tracking, and access control. human errors can be reduced by up to 70% and in-port transaction completion time can be reduced by up to 50% [6]. rfid real-time data allows for dynamic optimization yielding better planning, higher efficiency and overall performance as a whole. an important advantage is that it enables dynamic optimization in container ports, a much needed tool for solving increasingly complex problems. the high level of flexibility and dynamic optimization allow the achievement of real time solutions that could have neither been obtained nor reached otherwise. the following figure.3 is an example of used rfid with gps and mobile network technologies in order to track containers in chennai port of india. fig .3. rfid in container[3]. the container freight station operator based in chennai india, a.s. shipping agencies, is mixing both rfid with gps/ gprs technologies in order to track containers throughout its yard, situated 16 kilometers away from the port of chennai. rfid interrogators, antennas, and gps receivers are fixed on cranes. once a container arrives at the storage yard, it is weighed and by means of a small touch-screen device, the crane operator enters its information into the system. then, a passive rfid tag is linked with the container number and mounted on the top of the container. the tag data is updated with the gps latitude and longitude information, and then conveyed via gprs to a central server database. the container's location is then visualized on a web application. the container’s location is thus updated automatically as the container moves through the yard area [7]. the main advantages of this system are the clear reduction in the container’s location time in the yard, better yard capacity planning and accurate customer billing knowing the exact storage time. moreover, container information can be accessed, through a web application, by clients anywhere in the world. all these factors increase the service level provided by the company. however, this system still needs to be integrated with the company’s billing system [7]. a joint venture of ibm and maersk logistics resulted in a development of a system for tracking shipping containers around the world. this system goes beyond rfid technology and uses it just as a part of a collection of wireless technologies to transmit location and sensor data [8]. this system, called later the http://dx.doi.org/10.21622/resd.2016.02.2.137 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 142 secure trade lane (stl) solution, is using tracking devices called trecs (tamper-resistant embedded controllers), which are small intelligent wireless monitoring boxes mounted on containers [9] and making them smarter. trecs perform an automatic container events data collection including physical location based on gps and state of the container (temperature, humidity, acceleration, door status.., etc). trecs' communication can be achieved through communicating over a satellite, a cellular system (gprs/3g), or a wireless personal area network (wpan) based on zigbee3 /ieee 802.15.4 radio. a handheld device can also communicate with the trecs over a wpan for the automatic creation of the container manifest, invoices, bills of lading, etc. the shipment information system (sis) ensures that the information provided by the trec is available to the supply chain authorized actors with the appropriate information sharing among them [9]. this stl platform enables real-time access, tracking and monitoring of containers each participant with its authorized view, thus granting a full visibility of the supply chain from the manufacturer to the store. b. optical character recognitions (ocr) in addition to the rfid, optical character recognitions (ocr) is one of many technologies now available for asset identification and process automation in ports and terminals. the key advantage is that it enables not only the automated ‘hands free’ identification and locating of assets, but also the recording of an object’s visual condition at that time. it also provides a deviceless method of identification, without requiring the application of any tag or device to the asset. ocr scans the id numbers while the truck is in motion, based on a set of sensors. it automatically operates the illumination, takes pictures from a number of cameras, extracts the id numbers, classifies the type of containers, verifies the results, then outputs the results to the port automation and control system or a local terminal operating system. c. closed circuit tv(cctv) the port management entity can supplement both perimeter and access control systems with new arrays of high resolution, low-light and/or infrared closed circuit television (cctv) cameras to determine the nature of any alarm or intrusion and to guide response by law enforcement personnel. the cctv deployment can be extended to other perimetral sensitive locations in and around the ports and can be fully integrated with port operations and control centers advance perimeter security improvements. the port entities can deploy a combination of advanced security technologies to support surveillance of port perimeters and to improve detection of unauthorized intrusions. this package of technologies can include the innovative use of ground-based radar and state-of the-art motion sensors that can activate alarms at port security centers, indicating the specific location of a potential intrusion of persons or vehicles. v. a glance at some of the technological applications and services offered in smart ports port e-services can be categorized as based on the functionality offered, their integration/maturity level, and their business and organizational sophistication. regarding their integration and maturity level, port eservices can be divided to informational and transactional. informational are the services that only provide information regarding the port and the provided services. transactional are the services that enable the users to perform transactions, payments, bookings and to interact with the port authority or other port service providers. the services can be further “functionally” distinguished to navigation, ship, cargo, logistics, business intelligence, security and environmental safety related. navigational services are the services that assist the navigation of the ships to and from the port. ship services help the communication of the ship with the port authority and port service providers regarding ship and crew related documentation, supplies and parts. cargo related services concern cargo documentation and cargo handling/tracking. logistics e-services assist the connection with the logistics chain. e-services regarding business intelligence assist the shipping companies’ and industry actors’ decision making by providing information and management supporting tools. security and environmental safety related e-services provide information regarding security and environmental safety matters in port area.  vessel traffic management and information system (vtmis): addressing traffic congestion was one of the initial motivations to look at intelligent transport systems solutions for a better utilization of transport capacity through the exchange of real-time information on infrastructure journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.137 143 and traffic conditions. since then, new transport applications based on ict have emerged and continue to emerge, ranging from basic traffic management systems (e.g. navigation, traffic control) to management of containers; from monitoring applications such as closed-circuit television (cctv) security systems to more advanced applications integrating live data and feedback from a variety of information sources. a common structure of the vtmis system consists of the vtmis functions and vtmis subsystems. vtmis functions are grouped into operational and complementary roles, while vtmis subsystems include communication networks, sensors (the automatic identification subsystem and a marine radar subsystem), operator consoles, servers, databases, system software, application software and web services. the integration between various port entities is very important. fig .4. system architecture of vts service. this includes conducting all necessary studies to reorganization procedures among different parties in order to regulate the operational cycle for integration purposes. in general, the elements composing vts are shown in figure.4. vts is the system in which the followings are connected to one another: the vts center on the land, the base station site on which various sensors (sensing devices such as cctv, radar, df, met, etc.) and ais are installed, the control center that actually operates vts, and it is a complicated system consisting of various types of telecommunications networks that connect ships, satellites, and sensing devices [10]. technologies provide a broad range of sophisticated systems for wide area security, automated surveillance and instrument controls for the private sector and for governments. artificial intelligencedriven digital security systems integrated with actionable video-based surveillance intelligence are technical solutions with potential to be tailored for the maritime industry includes:  security corridor systems: this system could easily be adapted to isolated fence line perimeters as well as rail lines entering and exiting port facilities both overland and also across water. the virtual fence is based on digital video recorders driven by the innovative intelligent sensor detection suite which integrates fixed and high resolution, color, day/night cameras, rfid active scanners and other sensor types, positioned at strategic locations along the line of the asset. the system establishes virtual fence lines within the field of view of each of the cameras. live streaming video is interpreted to deliver low false alarm, real-time vigilance for common behaviors that can indicate a security breach. data is encrypted and transmitted using tcp/ip based communication either via a chain of wi-fi radio transmitters, satellite, and fiber optic or hard-wire connectivity to local and remotely located command and control centers. the virtual fence is fully integrated with all other system components to provide centralized command unity [11].  virtual gates: virtual gates are installed in conjunction with the virtual fence application. these are installed at a pre-determined distance from the actual port/marine facility entry point, thus creating a buffer zone. the virtual gate serves as a remote controlled advance checkpoint for inbound traffic. gates include vehicle presence http://dx.doi.org/10.21622/resd.2016.02.2.137 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 144 sensors, cameras, chemical detection sensors, radiation detection sensors, and i/o controllers. vehicles and personnel approaching the virtual gates are detected and the real time video together with potential rule breaches are presented and routed simultaneously to the command and control center and other locations where operators can view live, streaming video images and alarm events in real time.  smart yard digital management system: port facilities are typically large, asymmetrical activities dispersed over hundreds of acres of land and water so that they can simultaneously accommodate ship, truck and rail traffic, petroleum product/liquid offload, storage or piping, and container storage. like a rail yard, they are crowded, and with huge stacks of containers, warehouses and cranes, and often have limited visibility. installation of a smart yard digital management solution in the port area provides robust, fully scalable live video with real-time, intelligent video capability. this enables the central port authority to coordinate the activities of its personnel and assets day-to-day by monitoring critical road or rail transit areas, checkpoints, or container offload/stack locations. unprotected crossings can be monitored and critical navigational assets can be monitored for operation or critical change. smart yard employs a network of fixed and digital video cameras connected to digital video servers. each digital video recorder includes the rule-based intelligent vision suite to automatically deploy audio and visual alarms, process live video feed and create a video digital archive. the cameras also function as intrusion detectors providing live streaming video of vulnerable security areas and potential threats to vulnerable areas within the facility viewed on a customized graphical user interface (gui). the gui shows intrusion points and critical port locations so that port authority controllers can simultaneously view and control cameras positioned throughout the facility to analyze incoming video and sensor feeds, and thus maintain a real time situational awareness of container operations, truck transport on-load/off-load activity, crane operation, warehouse security, and shipping movement in and out of the port facility and adjacent areas[10]. in addition to remote real-time viewing of events, images are also automatically digitally recorded, time stamped, and stored for later retrieval. a powerful video search engine allows for easy retrieval of stored video files.  intermodal container exit system (ices): port security and operations are particularly vulnerable to theft, smuggling and vandalism. terrorism is also an increasingly significant concern, particularly with respect to the movement and identification of containers and contents. technologies have developed a system that can identify and track containers and link them to transport companies, drivers and specific vehicles. the system gives law enforcement a significant tool to track containers of concern, and at the same time allows port authorities to keep their operations running smoothly.  ices is a completely automated application for tracking and recording intermodal containers exiting, or entering, a container yard. the core technology of the system is the video optical character reader (vocr) which takes video imagery from moving containers, extracts relevant data (user defined) and populates a database with the extracted data. ices will capture and store the following information in a simple user interface: container numbers; trailer numbers; front and rear license plates; driver’s license data; video of vehicle and container; video and audio of driver and guard interaction at the port; biometric capture of fingerprints.  friend or foe detection system (ffds): this system component is achieved and can be incorporated into a port authority’s overall security plan by adding an rfid technology layer. it can be an especially important element of protection of critical infrastructure and hazardous material or loading points within the port. all personnel and visitors authorized to access the facility would receive an active rfid tag, which is constantly scanned by an array of scanners installed throughout the facility. tag geo-spatial information (achieved through scanner triangulation) is displayed on the gui, thus revealing the location of each person at any time. if the virtual fence is breached, ffds automatically validates approaching “authorized” personnel to prevent false alarms [11]. vi. information technologies and integration between different maritime services information systems are used to enhance the journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 http://dx.doi.org/10.21622/resd.2016.02.2.137 145 efficiency of terminal operations and improve turnover. the important competitive advantage of a port is to move cargo quickly and safely through the port. ports face increasingly complex range of operational challenges in management of highly complex, multitenant port environments. from the operational point of view, a consolidated, reliable, flexible and secure flow of information is vital in order to provide quick, reliable and cheap services at seaports. container and other marine terminals require increasingly versatile terminal operating and other it systems to plan, schedule and manage operations for efficient cargo handling. terminal operating system (tos) is key part of the supply chain and primarily aims at controlling the movement and storage of various types of cargo in and around a container terminal or port. ports are natural bottlenecks in the transport chain. port community systems have played a major role in facilitating the most efficient movement of goods, while allowing customs and other government departments to maintain effective controls. such systems reduce the overall amount of administrative work by providing some means of capturing information at once and allowing controlled access by all appropriate members of the port community. wasted effort is avoided because duplication of entry and storage of data is reduced to a minimum. the time required to release cargoes is reduced because the necessary information is instantly available to those who may need it. it is important to integrate the electronic business workflow in the port community via port single window including port authority, customs, shipping agents, transportation companies, etc.; the system simplifies and accelerates data exchange between different entities by providing the needed tools and procedures including message exchange system and portal that enable a single authorized entity to collect all business documents from customers and coordinate document processing with other entities until reaching custom declaration/cargo release or cargo shipping/vessel departure. integration between various port entities is very important. this includes conducting all necessary studies to re-engineer procedures among different parties in order to regulate the operational cycle for integration purposes. in order to meet rising customer expectations and stay ahead of the competition, the overall port operation services can be enriched by moving to a paperless environment and providing a valuable and relevant solution that completely restructures the manual process of documents exchange between port community members. automation aimed at and achieved the optimization of the port management processes from decreasing the vessel and cargo turn-around time to making available the necessary real time data for yard operations and performing all statistical and data analysis for decision makers. the agent of the shipping company access the webbased system to prepare and sent the necessary documentation to customs office and port authorities. the customs office receives through the web-based system the documentation and processes it to provide customs clearance. through the system the customs office sends the clearance to the agent and the port authority. the port authority enters the cargo data into the port management system which automatically assigns personnel and equipment to discharge the cargo according to port’s current condition and shipping company’s needs. the system auto arranges storage and sends data through the wireless system to stevedores and warehouse. the port authority also forwards information to the agent. through the web interface, the agent tracks the procedures and the cargo current position with the use of the port’s container tracking system. through the web interface it contacts the logistics provider and sends the information regarding the ships location as well as the necessary documentation. through the web interface the agent has access to a database of suppliers. during the procedures we can see the interaction between the various actors with the use of the two distinguished information systems. the web interface enables the shipping company agent to interact with the port authority, the customs office and the logistics provider, while the integrated management system supports the port authority’s decision making and communication with the stevedores and the warehouse. vii. conclusion the growth of e-business is having major effects on the maritime transportation industry including increasing pressures for advanced integrated, intermodal transportation and logistics systems and http://dx.doi.org/10.21622/resd.2016.02.2.137 journal of renewable energy and sustainable development (resd) volume 2, issue 2, december 2016 issn 2356-8569 146 technology applications. the growth of maritime transportations and port services requires highly flexible, information-intensive and efficiently integrated transport systems. key elements for developing such systems are the development of integrated applications of intelligent transportation systems and the creation of electronic business applications for intermodal transport, with port being a major node of the transport value chain. at the same time, ict technologies in ports and terminals are becoming a key to absorb the growth linked to world trade expansion to achieve the integration of ports in logistics and intermodal transport systems. with the advent of ict enabled network business models, port product and processes are considered as “augmented” products and processes, as their traditional, physical nature is overplayed with an informational and electronic transactions component. thus, inter-organizational network models provide a great opportunity towards the ‘smart networking’ of the plurality of port actors, including public port authorities, terminal service providers, shipping companies, customs, logistics and transportation companies and other third parties. overall, ‘networking’ as based on the advancement of a rational coordination, for operating and strategically developing a port can renovate port authorities in a new blended virtual agency role, that is a combined physical and electronic mode of operation. against this background, a classified port services for systematic identification, assessment and selection of individual port e-services is presented, as based on port e-service categorization by the level of integration, sophistication and functionality. deployment of consolidated technological solutions based on the it is considered as a crucial factor in sound and efficient operation of the ports that considerably contribute to the ports’ competitiveness and efficiency. the ongoing revolution in ict, smart devices and iot can interconnect port with high-speed internet, extensive use of data analytics and innovative mobile solutions to enhance services in the smart port and this will benefit all users at the smart port. references [1] d. steenken, s. voβ and r. stahlbock. “container terminal operations research-a classification and literature review.” or spectrum, vol. 26, pp. 3-49, 2004. [2] http://ec.europa.eu/research/transport/projects/in dex_water_en.htm. [3] l. jacobson. gnss markets and applications. norwood, ma: artech house, 2007. [4] http://www.imo.org/en/ourwork/safety/navigatio n/pages/ais.aspx. [5] http://www.imo.org/ourwork/safety/navigation/p ages/lrit.aspx. [6] j. banks, m. pachano, l. thompson and d. hanny, rfid applied, john wiley & sons, hoboken – new jersey, 2007. [7] d. friedlos. “chennai container yard finds rfid sharply boosts productivity.” rfid journal, oct. 2009, http://www.rfidjournal.com/articles/view. [8] j. collins. “ibm, maersk developing cargo tracker.” rfid journal, sept.22,2005, http://www.rfidjournal.com/article/articleview/1884 /1/1/. [9] f. dolivo. “the ibm secure trade lane solutiona new, open approach to optimizing the global supply chain.”, jan.2007, http://www.zurich.ibm.com/csc/process/ securetradelane.html. [10] b. lee and n. park. “performance improvement based authentication protocol for intervessel traffic service data exchange format protocol based on u-navigation system in wot environment.”, hindawi publishing corporation journal of applied mathematics, vol. 2014, article id 734768, 7 pages. [11] c. golsin, “maritime and port security white paper.” in duos technologies, inc., pp.1-16, 2008. http://www.imo.org/en/ourwork/safety/navigation/pages/ais.aspx http://www.imo.org/en/ourwork/safety/navigation/pages/ais.aspx http://www.imo.org/ourwork/safety/navigation/pages/lrit.aspx http://www.imo.org/ourwork/safety/navigation/pages/lrit.aspx http://www.rfidjournal.com/articles/view http://www.zurich.ibm.com/csc/process/ journal of renewable energy and sustainable development (resd) volume 4, issue 2, december 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.2.072 72 resd © 2018 http://apc.aast.edu improved theoretical conversion efficiency of a dual junction gainp/si mechanically stacked photovoltaic cell debashish pal m.tech., department of electronics and communication engineering, institute of engineering and management, kolkata, india pal.debashish@gmail.com abstract dual junction tandem solar cells can utilize the solar spectrum photons with a broader range of energies as compared to the conventional single junction solar cells; thereby demonstrating higher conversion efficiency. this paper deals with the numerical modeling of a dual junction gainp/si based multijunction tandem photovoltaic cell. the semi empirical modeling approach was used for simulation which produced a theoretical one sun conversion efficiency of over 30% for the proposed four terminal configuration. keywords arc, open circuit voltage, pc1d, short circuit current, tandem cell, tco i. introduction multijunction solar cells are more sensitive to solar spectrum than single junction solar cells [1-2]. single junction silicon based solar cells have reached their peak conversion efficiency limits in the field of photovoltaics [3]. however, stacking a silicon solar cell with a higher bandgap material solar cell enables theoretical one sun conversion efficiencies exceeding the 30% limit. a larger bandgap material on the top absorbs photons with higher frequencies ensuring reduction in the efficiency losses associated with the thermalisation process. the materials most suited for the development of high efficiency multijunction solar cells are the iii-v compound semiconductors, where the lattice matching condition can be managed. additionally, silicon as a substrate has the advantages of being relatively cheap and abundant as well as having good radiation resistance [4-5]. mostly tandem cells use series connection of subcells resulting in two terminal devices. boundary condition associated with two terminal configuration requires that the current in both the subcells remains equal. for the power output to reach the maximum under these conditions exact current matching is required. this can be achieved by adjusting the thickness and doping concentration of different layers. the power deliverable to an external load is strongly. limited by the efficiency of the top cell. in a four terminal configuration however, the operating points of the subcells can be controlled independently ensuring maximum transfer of power. in a four terminal configuration, the maximum power of each subcell is independent of one another, therefore, the electrical matching remains optimal. four terminal mechanically stacked gainp/si cells are connected by an adhesive which allows higher degree of flexibility in terms of circuit wiring [6-8]. ii. modeling in this paper, semi empirical modeling was used to demonstrate the performance of gainp/si dual junction solar cell. the gainp and silicon sub-cells were simulated independently each at its own maximum power point. unlike the monolithic multijunction devices there is no need for the current matching between the sub-cells here as it is a four terminal configuration. the integration of the gainp cell with the si cell reduces the intrinsic limitation associated with the standalone si cell. conversion of the short wavelength radiation associated with the solar spectrum can be achieved by the gainp cell while the conversion of the longer wavelength radiation is taken care of by the si cell. fig .1. schematic diagram of the four-terminal photovoltaic cell journal of renewable energy and sustainable development (resd) volume 4, issue 2, december 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.2.072 73 resd © 2018 http://apc.aast.edu fig. 1 shows the schematic diagram of the dual junction tandem solar cell which comprises a gainp based top cell of thickness 1.7 µm and a siliconbased bottom cell having thickness of 230 µm. the top cell has an algaas based wide bandgap (2.1ev) window material having variable thickness. each of the subcells has uniformly doped emitter and base layers of variable thickness and doping concentrations. to generate an electric field barrier for the minority carriers, the top and the bottom subcells have back surface field (bsf) layers of adjustable doping concentration and thickness. the electric field avoids the possibility of surface recombination. however, these adjustments are made keeping the total thickness of the top and the bottom cells constant at 1.7 µm and 230 µm, respectively [9]. in practice, to avoid the inherent optical losses associated with the mechanically stacked solar cells, electrically insulating and optically transparent adhesives are used to bond the cells. for the sake of simplicity, the structure used for electrical characterization does not incorporate any defects at the interface and the surface or losses related to the tunnel junction (for the two terminal configuration) and the insulation. the operating temperature was chosen to be 25ºc with a device area of 1cm2. the optimization of the sub-cells was performed under am1.5g one sun illumination condition having an intensity of 0.1w/cm2. the modeling and simulations were performed using pc1d simulation software [10], which is a computer program used for modeling crystalline semiconductor devices with emphasis on photovoltaic devices and is used as a simulation tool to understand the operation of solar cells yielding reliable results. the parameters used in the simulation are taken from reference [9]. the gainp top cell has a zns anti-reflection coating on the front side and the si bottom cell has a tco coating on the front face (not shown in fig. 1). the zns and the tco coatings on the front side of the cells have been optimised using simulations. the modelling considers a 1.7µm thick gainp cell and a 230µm thick si cell with constant light trapping. iii. results and discussion historically, algaas/si dual junction solar cell has achieved 1-sun efficiency exceeding 21% by the epitaxial growth technique [11]. iii-v/si multi-junction solar cells were also demonstrated to achieve efficiencies of over 25% and 30% under 1-sun and 112-suns by means of direct wafer bonding [12-13]. mechanically stacked gainp/ingaas/si based solar cell has been reported to achieve efficiency of over 27% under 1-sun [14]. unlike the alinp window layer, s. essig, m. a. steiner, c. allebé, j.f. geisz, b. paviet-salomon, s. ward, a. descoeudres, v. lasalvia, l. barraud, n. badel, a. faes, j. levrat, m. despeisse, c. ballif, p. stradins, d.l. young, “realization of gainp/si dualjunction solar cells with 29.8% one-sun efficiency”, an algaas window layer having a dielectric constant of 10.63 is chosen over the gainp top cell having a lattice mismatch of only 0.03%. the window layer has a uniform n-type doping concentration of 1x1017atoms/cm3. the thickness of the window layer is varied to find the optimum value of efficiency. fig .2. window layer thickness vs. efficiency the result of the simulation (fig. 2) indicates that the efficiency is at a maximum value of 18.17% when the thickness of the window layer is at 0.01µm. a study to determine the influence of the thickness of the zns anti-reflection coating on the fraction of photon current absorbed and reflected for the gainp cell was performed. the incident light passes through the zns anti-reflective coating (refractive index=3.805-2.252) and the algaas window layer (refractive index=1.368-3.124) before reaching the gainp substrate. this structure causes a refractive index mismatch which makes the zns arc layer less reflective. a similar examination was conducted for the bottom cell having a tco layer (refractive index=2.447-1.953) on top of the si substrate. for different values of the zns and tco layer thickness, the fractions of photon current absorbed and reflected are summarised in table i. journal of renewable energy and sustainable development (resd) volume 4, issue 2, december 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.2.072 74 resd © 2018 http://apc.aast.edu table i. influence of the zns and ito layers on the percentage of photons absorbed and reflected by the gainp cell and the si cell, respectively cell thickness (µm) fractional photon current absorbed (%) fractional photon current reflected (%) efficiency (%) gainp zns layer 10 68.7 28.6 13.7 50 87.5 9.4 18.2 100 70.8 25.8 14.3 150 76.8 19.5 16.1 si ito layer 10 72.9 0.5 13.3 50 69.7 10.6 12.0 100 62.3 15.9 11.1 150 65.6 12.5 11.5 fig .3. dependence of efficiency on the thickness of zns arc and ito layer fig .4. current-voltage characteristics of gainp cell for different thickness of zns anti-reflective coating fig .5. current-voltage characteristics of si cell for different thickness of ito layer fig. 3, 4 and 5 show that there is a strong dependence of the solar cell i-v characteristics on the thickness of the zns anti-reflection coating and the ito layer. it can be observed from the i-v characteristics that for the gainp cell the efficiency is maximum with a zns arc coating thickness of 50nm. also, the efficiency is maximum for an ito layer thickness of 10nm for the si cell. these results are in direct agreement with the data presented in table i, which establishes that the percentage of photons absorbed by the base layer is greatest for the stated thicknesses. fig .6. influence of thickness of the si bottom cell on (a) voc (b) isc (c) efficiency journal of renewable energy and sustainable development (resd) volume 4, issue 2, december 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.2.072 75 resd © 2018 http://apc.aast.edu fig. 6 shows the dependence of the open circuit voltage, short circuit current and the efficiency on the thickness of the si cell. as the thickness of the cell increases, the interaction of the incident photons with the cell improves. thus, for greater cell thickness the incident photons generate a bigger number of electron-hole pairs, which in turn increases the overall photocurrent in the cell improving the efficiency. table ii. optimised parameters of the top and the bottom cell used for the final design parameters si cell gainp cell thickness (µm) 230 1.7 dielectric constant 11.9 11.8 bandgap (ev) 1.12 1.86 emitter thickness (µm) 10 0.1 emitter doping concentration (/cm3) 1x1017 (p-type) 5x1017 (n-type) base thickness (µm) 215 1.49 base doping concentration (/cm3) 1x1016 (n-type) 1x1016 (p-type) bsf thickness (µm) 5 0.1 bsf doping concentration (/cm3) 1x1017 (n-type) 4x1018 (p-type) front surface recombination velocity (cm/s) 10000 10000 rear surface recombination velocity (cm/s) 10000 10000 fig .7. current-voltage characteristics of the optimised fourterminal photovoltaic cell the theoretical model of the solar cell described in this investigation exceeds the experimental efficiency value of 25.6% [15] of a single junction si solar cell. the efficiency of the tandem cell described in this paper is also close to the record one-sun efficiency of 31.1% [16] which was achieved with a monolithic gainp/gaas dual junction structure. the tandem cell theoretical efficiency of 31.5% for the structure under investigation in this paper is in close agreement with the practical efficiency of 29.8±0.6% obtained in s. essig, m. a. steiner, c. allebé, j.f. geisz, b. pavietsalomon, s. ward, a. descoeudres, v. lasalvia, l. barraud, n. badel, a. faes, j. levrat, m. despeisse, c. ballif, p. stradins, d.l. young, “realization of gainp/si dual-junction solar cells with 29.8% one-sun efficiency”. an in-house efficiency of 31.5% was reported for a mechanically stacked interdigitated back contact dual junction solar cell. the si bottom cell efficiency recorded therein was 12.5%, while the gainp top cell demonstrated single junction efficiency of 19.1% [17]. furthermore, it was shown that dual junction iii-v/si mechanically stacked and independently operated solar cell could reach cumulative one sun efficiencies of over 32% [18]. table iii: summary of the results cell voc (v) isc (ma) efficiency (%) si 0.6056 27.4 13.3 gainp 1.455 15.7 18.2 tandem 2.0606 15.7 31.5 iv. conclusion studies performed on the mechanically stacked gainp/si based dual-junction solar cell structure achieved an accumulative one-sun efficiency of 31.5%. it can be observed that the overall efficiency of the solar cell is largely dependent on the efficiency of the top cell. the overall efficiency of the tandem cell is highly dependent on the thickness of the window layer, anti-reflection coating, ito layer and the substrate thickness. greater efficiencies can be achieved by increasing the open circuit voltage of the si bottom cell and increasing the short circuit current of the gainp top cell. references [1] s.r. kurtz, j.m. olson and p. faine. “the difference between standard and average efficiencies of multijunction compared with single-junction concentrator cells,” sol. cells, vol. 30, no. 1–4, 1991, pp. 501–513,. [2] p. faine, s.r. kurtz, c. riordan and j.m. olson. “the influence of spectral solar irradiance variations on the performance of selected singlejournal of renewable energy and sustainable development (resd) volume 4, issue 2, december 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.2.072 76 resd © 2018 http://apc.aast.edu junction and multijunction solar cells,” sol. cells, vol. 31, no. 3, 1991, pp. 259–278. [3] d.d. smith, p. cousins, s. westerberg, r. de jesus-tabajonda, g. aniero and y.-c. shen. “toward the practical limits of silicon solar cells.” ieee journal of photovoltaics, vol. 4, no. 6, pp. 1465 –1469, 2014. [4] m. yang, t. soga, t. jimbo and m. umeno. “high efficiency monolithic gaas/si tandem solar cells grown by mocvd,” in proc of twenty fourth ieee photovoltaic specialists conference, vol. 2, 1994, pp. 1847-1850. [5] j.f. geisz, olson, d.j. friedman, k.m. jones, r.c. reedyand m.j. romero. “lattice-matched ganpas-on-silicon tandem solar cells,” in proc of thirty-first ieee photovoltaic specialists conference, 2005, pp. 695698. [6] s. essig, s. ward, m.a. steiner, d.j. friedman, j.f. geisz, p. stradinsand d.l. young. “progress towards a 30% efficient gainp/si tandem solar cell,” energy procedia vol. 77, 2015, pp. 464-469. [7] j. yang, z. peng, d. cheong and r.n. kleiman. “iii-v on silicon multi-junction solar cell with 25% 1-sun efficiency via direct metal interconnect and areal current matching,” in proc. of the 27th european photovoltaic solar energy conference and exhibition, frankfurt, germany, 2012, pp. 160 -163. [8] k.m. gee and g.f. virshup. “a 30%-efficient gaas/silicon mechanically stacked, multijunction concentrator solar cell,” conference records of the 20th ieee photovoltaic specialists conference, las vegas, usa, 1988, pp. 754758. [9] s. essig, m. a. steiner, c. allebé, j. f. geisz, b. paviet-salomon, s. ward, a. descoeudres, v. lasalvia, l. barraud, n. badel, a. faes, j. levrat, m. despeisse, c. ballif, p. stradinsand d. l. young, “realization of gainp/si dualjunction solar cells with 29.8% one-sun efficiency.” ieee journal of photovoltaics, vol. 6, issue: 4, pp. 1-8, july 2016. [10] pc1d, version 5.9, school of photovoltaic and renewable energy engineering at the university of new south wales, australia, 2008. [11] t. soga, k. baskar, t. kato, t. jimboand m. umeno. “mocvd growth of high efficiency current-matched a1gaas/si tandem solar cell.” journal of crystal growth, vol. 174, pp. 579-584, 1997. [12] s. essig, j. benick, m. schachtner, a. wekkeli, m. hermle and f. dimroth. “wafer-bonded gainp/gaas//si solar cells with 30% efficiency under concentrated sunlight.” ieee journal of photovoltaics, vol. 5, no. 3, pp. 977-981, 2015. [13] k. tanabe, k. watanabe and y. arakawa. “iiiv/si hybrid photonic devices by direct fusion bonding,” scientific reports, vol. 2, no. 349, pp. 1-6, 2012. [14] j. yang, z. peng, d. cheong and r. kleiman. “iii-v on silicon multi-junction solar cell with 25% 1-sun efficiency via direct metal interconnect and areal current matching,” proc of the 27th european photovoltaic solar energy conference and exhibition, frankfurt, germany, 2012, pp. 160-163. [15] k. masuko, m. shigematsu, t. hashiguchi, d. fujishima, m. kai, n. yoshimura, t. yamaguchi, y. ichihashi, t. yamanishi, t. takahama m. taguchi, e. maruyama and s. okamoto. “achievement of more than 25% conversion efficiency with crystalline silicon heterojunction solar cell,” ieee journal of photovoltaics, vol. 4, pp. 1433-1435, 2014. [16] m. steiner et al., “article title,” proc of 41st ieee pvsc (write full name), tampa, usa, 2013, pp. 1429. [17] m. riennacker, m. schnabel, e. warren, a. merkle, h.schulte-huxel, t.r. klein, m.f.a.m. van hest, m.a. steiner, j. geisz, s.k.-schroder, r. niepelt, j. schmidt, r. brendel, p. stradins, a. tamboli and r. peibst. “mechanically stacked dual-junction and triple-junction iii-v/si-ibc cells with efficiencies of 31.5% and 35.4%.” in proc of 33rd european pv solar energy conference and exhibition, 2017, pp1-4. journal of renewable energy and sustainable development (resd) volume 4, issue 2, december 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.2.072 77 resd © 2018 http://apc.aast.edu [18] s. essig, c. allebe, t. remo, j.f. geisz, m.a. steiner, k. horowitz, l. barraud, j.s. ward, m. schnabel, a. descoeudres, d.l. young, m. woodhouse, m. despeisse, c. ballif and a. tamboli. “raising the one-sun conversion efficiency of iii-v/si solar cells to 32.8% for two junctions and 35.9% for three junctions,” nature energy, vol. 2, 2017, pp. 17-44. journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.196 196 resd © 2017 http://apc.aast.edu three new dc-to-dc single-switch converters barry w williams1, mona fouad moussa2 1department of electrical and electronic engineering, the university of strathclyde 2electrical engineering department, arab academy for science and technology and maritime transport (aastmt) cairo, egypt barry.williams@strath.ac.uk, mona.moussa@aast.edu + 44 01415482386 abstract this paper presents a new family of three previously unidentified dc-to-dc converters, buck, boost, and buck-boost voltage-transfer-function topologies, which offer advantageous transformer coupling features and low capacitor dc voltage stressing. the three single-switch, single-diode, converters offer the same features as basic dc-to-dc converters, such as the buck function with continuous output current and the boost function with continuous input current. converter time-domain simulations and experimental results (including transformer coupling) support and extol the dc-to-dc converter concepts and analysis presented. keywords dc-to-dc converters, switch mode power supplies, dc-to-dc power conversion i. introduction applications for dc-to-dc converters include dc power supplies for electronic systems, hand-held electronics, portable electronics, electric vehicles, battery chargers [1], [2], systems for the utilization of fuel cell [3]-[5], solar [6]-[8], and wind energy [9], which incorporate super-capacitors [3], smart grids and distributed generation [10]-[13], electronic ballast [14], energy harvesting [15], power factor correction, and dc motor drives. additionally, these converters form the basic building blocks for other power converter types, plus interleaved or multiphase converters [16]-[19], bidirectional dc-to-dc converters [20]-[23] multiple input converters [24], cascaded output converters [25], [26] and high voltage supplies. similar to basic dc-to-dc converter analysis [27], with snubbers [28], converters can be controlled in a voltage mode or a current mode [29], [30]. additional to the basic three converters, viz., buck, boost, and buck-boost converters, there are 27 other (plus three new converters here within) identified single-switch, single-diode transformer-less dc-to-dc converters. in all cases, continuous conduction operation is possible at light loads with two switch/diode combinations, which allow bidirectional inductor current, [2], [20]-[23]. also, in addition to a switch and diode, the three new dc-to-dc converters incorporate two inductors and two capacitors (as with the cuk, zeta, -ve lou, and sepic converters) from which a voltage sourcing output is derived.operational concepts of three new dc-to-dc converter topologies (with buck, boost, and buckboost transfer functions) are presented, along with component ratings and specifications, circuit simulations, and practical results. for reference purposes, performance and features of the three new converters are compared with the three basic (buck, boost and buck-boost) converters. experimental results for a transformer coupled version of the new buck-boost topology culminate the paper. ii. three new dc-to-dc converter topologies the three new converter topologies, termed p#1, p#2, and p#5, are shown in figure 1 row cct p. the buck-boost topology p#5 is derived by an alternative alteration rearrangement of the elements common to the cuk, sepic, and zeta converters. the buck converter p#1 has a current source output, being sourced by two inductors li and lo, converted to a voltage source output by the addition of load ac current shunt capacitor co as shown in figure 1p(a). the boost converter p#2 in figure 1p(b) has continuous input current properties since the input paths comprises two inductors li and lo. the buckboost converter p#5 in figure 1p(c) has discontinuous input and output currents, since a series switching device switches between the input and output circuits. these properties are the same features possessed by the basic three dc-to-dc converters, termed a1 buck, a2 boost, and a5 – buck-boost converters in figure 1 row cct a [31], in which all have one inductor less (one rather than two inductors) and no energy transfer capacitor. all converters use shunt output filter capacitor co to create a voltage sourcing output. http://dx.doi.org/10.21622/resd.2017.03.2.196 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ mailto:barry.williams@strath.ac.uk mailto:mona.moussa@aast.edu journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.196 197 resd © 2017 http://apc.aast.edu figure 1 row cct p′ shows the two states created by operation of the switch t, namely the current loops when the switch t is on, ton and when t is off, toff, (such that ton+toff = τ = 1/fs where fs is the switching frequency). energy transfer (voltage and current transfer function) analysis is based on the capacitor c voltage ripple δvc, specifically c×δvc = ∫ic dt, (eqn 1 in figure 1), assuming continuous but not necessarily constant current in the two circuit inductors li and lo (continuous conduction mode, ccm). three basic converter transfer functions result, viz., buck, boost, and buck-boost, which are only switch on-state duty cycle ton /τ = δ dependent, as shown by eqn 2 in figure 1. all three new topologies are characterized by a central kirchhoff voltage loop involving only a capacitor c and two inductors li and lo. by kirchhoff’s voltage law, the average capacitor voltage is zero, since each of the two inductors has an average voltage of zero. this zero average capacitor voltage is fulfilled by alternating balanced positive and negative charging (positive and negative voltages). kirchhoff’s voltage and current laws can be used to derive the average voltage and current ratings of the various circuit elements, which are summarised in table i. in table i the steady-state characterization (for sake of consistency) process makes extensive use of the fact that, in steady state, average inductor voltage [il(0)=il(τ)] and average capacitor current [vc(0)=vc(τ)] are both zero. fig .1. dc-to-dc voltage-sourced topologies, operating stages, and transfer functions. b a s ic v o lt a g e s o u rc e d c o n v e rt e rs cct a a1 (a) voltage buck  current boost p#1 a2 (b) voltage boost  current buck p#2 a5 (c) voltage buck-boost  current boost-buck p#5 cct n e w v o lt a g e s o u rc e d c o n v e rt e rs cct p switch t state switch t switch t on off switch t switch t on off switch t switch t on off t w o o p e ra ti n g s ta g e s cct p′ loop equations c×δvc =∫ic dt = ton × (ioii) = toff × ii c×δvc =∫ic dt = ton × io= toff × (ii io) c×δvc =∫ic dt = ton × io= toff × ii eqn 1 current and voltage transfer functions, fi(δ), fv(δ) eqn 2 p#1 (a) p#2 (b) p#5 (c)     1 v i f f        11 oi o i i v ie v i f f           1 1oi o i i v ie v i f f            11 oi o i i v ie v i f f           ii+io io io c r ii co + li lo ei li lo ii ii+io io c r ii io co + ii io io c r ii-io iiio co + li ii io io c r io co + li lo ei ii io ii io r io ii io ii io c r io ii ei c li lo co r + tf ii io vo ei t t + r io c d li co lo ii io vo ei c li co r + d lo ii io vo ei t lo co r + d ii io vo t ei ii io t + r io d li co vo ei co r + d lo ii io vo ei t http://dx.doi.org/10.21622/resd.2017.03.2.196 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.196 198 resd © 2017 http://apc.aast.edu table 1. dc-to-dc converter normalized component ratings voltage buck boost buck-boost figure 1 / cct a (a) a (b) a (c) topology p#1 p#2 p#5 transfer function voltage tfv vo / ei δ 1 1  1     current tfi io / ii 1  1-δ 1     switch t t (ave) voltage vt / ei 1-δ 1 1 current it / io 2  2  1   t (max) voltage vt / ei 1 1 1  1 1  current it / io 1 1 1  1 1  diode d d (ave) voltage vd / ei δ 1   1   current id / io  1  1 1 d (max) voltage vd / ei 1 1 1  1 1  current id / io 1 1 1  1 1  capacitor c current ton ic / io 1-δ 1 1 τ ton ic /io δ δ 1   voltage average vc / ei 0 0 0 ripple cδvc /τio cδvc /τii  1 1       1    1   inductor current il average current li ili / io ili / ii 1     1 1 1   lo ilo / io ilo / ii      1 1  1 1    1 1 dc losses pli + plo li = lo  2 2 2 i li lo i i i      2 2 2 2 1    2 2 2 1      2 2 2 2 1 ripple current li li δili /τei  1  δ δ lo lo δilo /τei  1  δ ≈ δ input/output ripple current input ii li δii discontinuous 0, io continuous 2δτei discontinuous 0, io /(1-δ) output into co // r lo δio continuous 2(1-δ)τvo discontinuous 0, io /(1-δ) discontinuous 0, io /(1-δ) http://dx.doi.org/10.21622/resd.2017.03.2.196 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.196 199 resd © 2017 http://apc.aast.edu ac wise, c is a short circuit resulting in li and lo being parallel connected such that each topology in figure 1 cct p reverts (degenerates), for analysis purposes, to the corresponding basic dc-to-dc converter in figure 1 cct a. this paper specifically exploits the benefits gained from zero average capacitor voltage, which are not available with the degenerate basic converters circuits. from table i, the average inductor currents ili and ilo are related to the input and output currents ii and io, and the duty cycle δ. thus as the load current decreases, the input current decreases, whence the average current of both inductors decreases. as the transferred energy decreases (average input current decreases), the capacitor ripple voltage (eqn 1 in figure 1) which is proportional to output current (energy transfer) decreases. eventually, with decreasing load current, discontinuous conduction occurs in c, characterized by continuous zero capacitor voltage regions at the end of each switching period. iii. simulation and experimental results: three the functionality operation aspects can be initially established by time domain transient analysis. additionally, component voltage and current stresses can also be assessed, confirming the circuit analysis used to derive the component ratings given in table i. table iia shows the component values and ratings used for both the simulations and the experimentation, although some ideal components (losses capacitors and inductors, no switch and diode switching losses) are assumed in the simulations so as to confirm the theoretical circuit analysis performance values in table i. transient analysis simulations were performed using national instruments, multisim power pro 11.0.1, with user defined initial conditions as shown in table iib. table 2.a component values ei 20v t, mosfet 200v, 54mω lo 1.0mh, 74mω, 10a d, sic 600v, 10a li 1.0mh, 74mω, 10a ton , toff 15μs, 5μs c 10μf δ 75% co 1000μf f 50khz table 2.b circuit initial conditions simulation initial values and results converter buck boost buck-boost p#1 p#2 p#5 ro 2.8125 80 45 ω co 0.01 100 100 μf iei 0, 5.40, 5.26 4 ± 150m 0, 5.66, 5.06 a ili 4 ± 37.5m 3 ± 150m 4 ± 150m a ilo 1.33 ± 37.5m 1 ± 150m 1.33 ± 150m a vc 0 ± 1 0 ± ¾ 0 ± 1 v vo 14.99 ± 0.1 79.95 ± 75m 59.96 ± 0.1 v io 5.33 ± 36m 1 ± 1m 1.33 ± 2m a the six plots of figure 2 show the simulation and experimental time domain results for each of the three converters, operating under the same frequency (fs=50khz), duty cycle (δ = ¾), and input conditions (ei = 20v and ii = 4a average, sourcing 80w). the same electrical components, rearranged, are used in each case. basically, in simulation and experimentally, the currents in both inductors and the supply input agree, as does the capacitor voltage ripple, all of which are predicted by the appropriate equations in table i. figure 2 also shows that the corresponding simulation and experimental current values agree with awing accurately. that is, the current regulation is good, unlike the voltage regulation which is significantly poorer and deteriorates with increasing input current. these converter regulation features are considered further in the next section. iv. further experimental results: three new converter topologies figure 3 shows the open loop dependence of efficiency, voltage regulation (droop), inductor ripple currents, capacitor voltage and ripple, and output current regulation (droop), on input current average magnitude ii. the experimental circuit component values are as shown in table iia. generally, these graphs show that efficiency and voltage regulation deteriorate (near linearly) with increased load/input current. in confirming the inductor ripple current equations in table i, the ripple current of the inductors is independent of load current – figure 3b. the effects of inductor saturation are observed first in the buckhttp://dx.doi.org/10.21622/resd.2017.03.2.196 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.196 200 resd © 2017 http://apc.aast.edu boost and buck converters, before the boost converter, as input current increases, since the buck converter decreases the voltage and increases the output current (hence inductor current) for a given input voltage and current (cf. figure 4b). figure 3a shows that the boost converter p#2 is the most efficiency hence has the best output voltage regulation, whilst the buck-boost converter p#5 has the lowest efficiency, whence the poorest output voltage regulation. figure 3b shows that the buck converter p#1 has the lowest inductor ripple currents, which is due to the fact that buck circuit voltages are lower than the boost and buck-boost circuit voltages, for a given input voltage ei (cf v=ldi/dt). also in accordance with the theory and eqn 1 in figure 1 and table i, the capacitor ripple voltage δvc in figure 3c increases linearly with increased load current (for a given δ, etc.). due to lo li c circuit loop losses, specifically the unequal inductor resistive component voltages, thus not included in the theory, the capacitor has a dc bias, which is duty cycle dependant, and increases with load current, as shown in figure 3c. important to ccm operation, figure 3c also shows that the offset voltage tends to zero as the input current, hence output current, approaches zero (that is, no load). (this bias is not explicitly shown in the ii = 4a experimental time domain ac coupled waveforms in figure 2.) figure 3b shows that if the inductances are equal (li = lo), the ripple current magnitudes are equal, whence the two inductors can be wound on a common core (as with the cuk, sepic and zeta converters) but with ripple current addition (not cancellation), resulting in an accumulated dc flux biases. from table i, the relative current magnitudes in the two inductor windings, change-over at δ=½ (the buck to boost boundary). in contrast to the output voltage regulation, the three converters exhibit good output current regulation characteristics, as shown in figure 3d. the voltage regulation in figure 3a deteriorates because semiconductor voltages and ir drops detract from the effective input voltage. on the other hand, the current transfer ratio is largely unaffected by voltage components; it is purely a relation between the input and output currents, independent of the input voltage. hence at the modest input voltage of 20v, the current regulation is an order of magnitude better than the voltage regulation. such a regulation feature is common to all dc-to-dc converters. (a) experimental and simulation buck converter p#1 waveforms: inductor and input currents and capacitor voltage for vo = 13.8v, io = 5.36a, η = 92.5%. (b) experimental and simulation boost converter p#2 waveforms: inductor and input currents and capacitor voltage for vo = 76.4v, io = 0.99a, η = 94.5%. http://dx.doi.org/10.21622/resd.2017.03.2.196 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.196 201 resd © 2017 http://apc.aast.edu p2 p1 p5 p5 p1 p2 p5 lo p2 li p2 lo p1 li p1 lo p1 li p1 lo p2 p1 p5 p2 δvc dc offset p1 p5 p2 p2 p2 p5 p1 p1 p1/p2/p5, p1/p2/p5, p1/p2/p5, p1/p2/p5, (c) experimental and simulation buck-boost converter p#5 waveforms: inductor and input currents and capacitor voltage for vo = 55.1v, io = 1.32a, η = 90.9%. fig .2. experimental and simulation results at 50khz, δ = 75%, ei = 20v and ii = 4a (ave): 80w for: (a) buck-p#1, (b) boost-p#2, and (c) buck-boost-p#5 converters. p5 li p5 p1 p2 fig .3. experimental results at 50khz, δ=75%, ei = 20v and varied average input current, for the three new dc-to-dc converters (p#1≡buck, p#2≡boost, p#5≡buck-boost): (a) output voltage regulation (droop) and efficiency, (b) inductor ripple currents, (c) capacitor voltages, and (d) output current regulation (droop). http://dx.doi.org/10.21622/resd.2017.03.2.196 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.196 202 resd © 2017 http://apc.aast.edu a2 a1 a5 a5 a1 a2 a2 a5 a1 buck-boost a5 boost a2 buck a1 voltage regulation current regulation fig .4. experimental result for basic single-inductor dc-to-dc converters, a1, a2, and a5: (a) voltage and current regulation (droop) and efficiency and (b) inductor ripple current. in the three basic dc-to-dc converters, a1, a2, and a5, inductor ripple current is an indication of minimum load current before loss of ccm operation. in the buck converter p#1 waveforms (simulation and experimental) in figure 2a, the ripple current is a constant ±37½ma (which is the same as for p#1 in figure 3b and a1 in figure 4b), which for the basic buck converter a1 represents a minimum load current of 37½ma, for ccm. in a light-load case for the new buck converter p#1, at 100ma (0.01pu) input current, the efficiency is 96.9%, and importantly the output voltage is 14.9v, representing voltage and current regulation droops of 2.5% and 0.7% respectively. in the case of the buck-boost converter, rearrangement of the basic components, giving the cuk, sepic and zeta converters, results in similar performance characteristics of efficiency and regulation, as well as ac closed loop performance. the main component difference between the four buck-boost converters is the capacitor dc bias. v. experimental comparison with the three basic converter topologies the experimental performance characteristics of efficiency, voltage and current regulation and ripple current of the three basic (buck – a1, boost – a2 and buck-boost – a5) [31] converters are shown in figure 4. the three basic converters have a single energy transfer storage element, namely an inductor; regulation would be expected to be poorer than that for the new converters which (like the cuk, sepic and zeta converters) have more storage elements. figure 5 compares the characteristics of the basic converters a1, a2, and a5 with the three new converters, p#1, p#2, and p#5. the boost converter has the best output voltage regulation, whilst the buck-boost converter has the poorest output voltage regulation. the buck converter output current regulation is similar for both buck converters (a1 and p#1) since the basic buck converter also has inductance in the output, which maintains current regulation. the basic boost and buck-boost converters have poor current regulation because the only inductor is not solely in the output (that is, the inductor is switched between the input and output circuits). figure 4b shows that the inductor current ripple of the three basic converters is similar to the ripple in the new converters, shown in figure 3b. inductor saturation at just under 10a input is shown in figure 4b, for the three basic converters. in the boost converter a2, the inductor is in series with the input, hence its current is the input current. the buck and buck-boost converters saturate at less than 10a input current, because the inductor average current is not the average input current, but is dependent on duty cycle. specifically, the basic buck converter inductor current is the output current, which is given by ii /δ, which is always greater than the input current. the same expression applies to the buckboost converter, thus saturation is seen to occur at δxii (¾×10a=7½a) in figure 4b, for both a1 and a5. the three new converters are correspondingly more efficient, independent of ripple current. for example, the ripple current of the two buck versions (a1 and p#1) is 75ma in each case, yet for the same input http://dx.doi.org/10.21622/resd.2017.03.2.196 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.196 203 resd © 2017 http://apc.aast.edu power conditions, the new buck converter p#1 is more efficient. the improved efficiency is related to the fact that the effective inductor dc current component is split between two inductors, which significantly decreases the total i2r loss. specifically for the buck converter p#1 in figure 2a, at 4a average input current, which gives 5⅓a output current at δ=¾, inductor copper losses are 42×74mω + 1⅓2×74mω = 1.3w as opposed to 5⅓2x74mω = 2.1w with the single inductor buck converter a1. figure 5 shows that the new converters have better performance indicators (efficiency and open loop regulation) than the corresponding basic converters, but inductor ripple current is the same. this performance improvement with the new converters would be expected since the new converters (like the cuk, sepic and zeta converters) have more energy storage components. from figure 5c, when comparing the basic and new converters, generally voltage regulation becomes poorer with increasing current. the current regulation for the new converters is near independent of current magnitude, while the current regulation is poorer for the basic boost and buckboost converters a1 and a5 as the input current decreases. these comparative performance results, based on figures 3 and 4, and collated in figure 5, are summarized in table 3. the closed loop design criteria are the same as for the cuk, sepic and zeta converters, all of which employ two inductors and a capacitor, rearranged. this is because all these topologies have the same ac equivalent circuit. fig .5. experimental result comparing three basic (a1, a2, a5) and three new dc-to-dc converters (p#1, p#2, p#5): (a) efficiency, (b) output current regulation (droop), and (c) output voltage regulation (droop). http://dx.doi.org/10.21622/resd.2017.03.2.196 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.196 204 resd © 2017 http://apc.aast.edu table 3. comparison of operational properties and characteristics (at δ=¾). vi. transformer isolated buck-boost converter the basic buck-boost converter a3 output can be isolated via a coupled magnetic circuit. additional features to isolation are voltage matching and better semiconductor utilization, but the limitation is that energy is temporarily stored in the magnetic coupled circuit core. thus for a given magnetic material, maximum energy transfer is limited by core volume, viz. ½bh×volume. the core volume is utilized differently if magnetic energy transfer is through transformer action (as with the cuk converter variation) rather than intermediate energy storage (as for the basic buck-boost converter variation). if energy is transferred from the source to the load via ripple current through a series capacitor, then that capacitor can be split so as to facilitate an interposed high magnetizing inductance shunt transformer as shown in figure 6. if electrical equivalence is maintained, each capacitor has the same capacitance as the original capacitor, if the transformer turns ratio is 1:1. this is the process used for the transformer isolated cuk converter, with a buck-boost voltage transfer function, which fulfills the series energy transfer capacitor requirement. the transformer acts in a current controlled mode where the voltage adjusts to meet the corresponding voltage requirement associated with the transformer equation (iin / iout = vout / vin = nout / nin) together with the converter current/voltage transfer function (ii / io = vo / ei =-δ/ 1-δ), both enforced since both equations must comply with instantaneous energy conservation. this operation is not to be confused with the problematic so called ‘verge of coupled circuit and transformer operation’. in the cuk converter case the split capacitor pair must also fulfill the important function of blocking a dc voltage component (ei on the primary, vo on the secondary) from the magnetic coupling circuit, which is catered for, blocked, by using large capacitance. the new buck-boost converter p#5 theoretically develops no dc voltage component on the primary or the secondary, because each is in parallel with inductance, which has zero average converters basic converters (one inductor) new converters (two inductors and one capacitor) transfer function buck boost buck-boost buck boost buck-boost classification a1 a2 a5 p#1 p#2 p#5 efficiency less than p1 better than a5 less than p2 better than a5 less than p5 poorer than a1 and a5 better than a1 better than p5 better than a2 better than p1 and p5 better than a5 poorer than p1 and p5 output voltage regulation better than a5 poorer than p1, p2, and p5 better than a1 and a5 better than p1 and p5 worse than a1 and a2 poorer than p1, p2, and p5 better than p5 better than a1 and a5 better than p1 and p5 better than a1, a2 and a5 worse than p1 and p2 better than a1 and a5 output current regulation similar to p1 better than a1 and a2 poorer than p2 poorer than a1 and a5 poorer than p5 poorer than a1 similar to a1 similar to p2 and p5 better than a2 slightly better than p1 better than a5 slightly better than p1 ripple current same as p1 less than a2 and a5 similar to p2 similar to a2 and a5 similar to p5 similar to a2 and a5 same as a1 less than p2 and p5 similar to a2 similar to p5 similar to a5 similar to p2 http://dx.doi.org/10.21622/resd.2017.03.2.196 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.196 205 resd © 2017 http://apc.aast.edu voltage. in practice, any dc voltage bias is modified (increased) due to component voltage drops, including inductor and transformer winding resistance associated voltages. the energy transferred is the load power vo io over the switching cycle period τ, which is related to the change in energy in the primary and secondary capacitors cp and cs. from eqn 1 in figure 1, for the buck-boost converter, the capacitor ripple voltage is given by     1 on ion o c o i t it i v i i c c c c              therefore the capacitor dv/dt requirement is c o c i on off c v c i v i t t       energy is transferred in a single direction through the transformer: the voltage polarities change depending on whether the capacitors are charging or discharging, but with zero average current. since the capacitors in p#5 have a zero average-voltage requirement, that is, do not need significant dc blocking capability, the capacitance is dimensioned based on dv/dt restrictions (as opposed to average voltage values in addition to superimposed dv/dt limitations as with the cuk, sepic and zeta converters). capacitance transfers transformer sides in the turns ratio, inverse squared (xcα1/c). figure 7 shows time domain simulation and practical results, which confirm the mechanisms proposed, when the component values are as used for assessment of the three converters, in table iia. the series energy transfer capacitors are both 10μf and the transformer has a 1:1 turns ratio. the practical results yield 80.5% efficiency at 80w input, falling to 70% efficiency at rated (200w) 10a input, for the given duty cycle, δ=¾. the capacitor dc offset of 380mv at 4a and 1.2v at 10a, implies joule losses consistent with 110mω resistance in the transformer (primary and secondary) and inductor (74mω), plus switch (54mω) loops. an rcd snubber or a transient surge suppressor (<1w for 20v, 10a input) is essential to preventing excessive switch voltages at turn-off due to transformer leakage inductance (≈200nh) related trapped magnetic energy. differences between the experimental and simulation results are due to the simulation models not accounting for switching losses, capacitor tan δ, and transformer leakage inductance losses and effects. fig .6. new dc-to-dc buck-boost converter p#5 conversion to transformer coupled version. figure 7. simulation and experimental results for the transformer coupled buck-boost converter p#5, at 20vdc, 4a ave (80w) input, η=80.5% (output 51.9vdc, 1.24a). ii + + io t ei li lo co + r c ei li lo co r + ii + io cp cs co blocking capacitors vcp = 320mv±1v vcs = -73mv±1v input inductor ili = 4a±147ma output inductor ilo = 1.33a±145ma output voltage vo = 57.5v±0.1v blocking capacitor vcp = 380mv±1.04v input inductor ili = 4.0a±136ma outupt inductor ilo = 1.24a±250ma switch voltage voff = 21.6v 2.5μs/div http://dx.doi.org/10.21622/resd.2017.03.2.196 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.196 206 resd © 2017 http://apc.aast.edu vii. conclusions three new dc-to-dc converters (buck – p#1, boost – p#2, and buck-boost – p#5) have been presented. like the cuk, sepic, luo and zeta converters, the disadvantage of the three new converters is that an extra capacitor and inductor are needed, compared to the three basic dc-to-dc converters (a1, a2, and a5). the advantages gained by the extra passive energy storage components, as with the cuk, sepic and zeta converters, are better efficiency and output voltage and current regulation. analysis wise, the new circuit topologies degenerate to the equivalent basic converter with the same voltage transfer function (a1, a2, and a5). the interesting features of the new converters are associated with the fact that the three topologies have zero average capacitor voltage. unlike the cuk, sepic and zeta converters, capacitor stressing is solely limited to dv/dt stressing, without a dc component. this property is best exploited in a transformer isolated version with a buck-boost transfer function, p#5, where the split capacitors have zero average voltage, that is, zero dc blocking voltage requirements, unlike the split capacitor transformer isolated cuk converter. this new topology has been validated by simulation and 20v, 200w experimentation, and is suitable for fuel cell, battery, and pv module isolated interfacing. references [1] f. nejabatkhah , s. danyali , s.h. hosseini , m. sabahi and s.m. niapour . “modeling and control of a new three-input dc–dc boost converter for hybrid pv/fc/battery power system.”, ieee transactions on power electronics, vol. 27pp. 2309-2324, 2012.. doi: 10.1109/tpel.2011.2172465 [2] r.k. singh. and s.a. mishra. “magnetically coupled feedback-clamped optimal bidirectional battery charger.” , ieee transactions on industrial electronics, vol. 60, issue2 pp. 422432, 2013. doi: 10.1109/tie.2012.2186776 [3] h. tai-sik , m.j. tarca and p. sung-yeul. “dynamic response analysis of dc–dc converter with supercapacitor for direct borohydride fuel cell power conditioning system.” ieee transactions on power electronics, vol. 27, pp. 3605-3615,2012.doi: 10.1109/tpel.2012.2185711 [4] h. tai-sik and p. sung-yeul . “seamless boost converter control under the critical boundary condition for a fuel cell power conditioning system.” ieee transactions on power electronics, vol. 27, pp. 3616-3626., 2012. doi: 10.1109/tpel.2012.2185250 [5] h. tai-sik , m.j. tarca, and p. sung-yeul . “dynamic response analysis of dc–dc converter with supercapacitor for direct borohydride fuel cell power conditioning system.” ieee transactions on power electronics, vol. 27, pp. 3605-3615., 2012. doi: 10.1109/tpel.2012.2185711 [6] c.n. ho, h. breuninger , s. pettersson , g. escobar , l.a. serpa and a. coccia. “practical design and implementation procedure of an interleaved boost converter using sic diodes for pv applications.” ieee transactions on power electronics, vol. 27, pp. 2835-2845, 2012.doi: 10.1109/tpel.2011.2178269 [7] f. locment , m. sechilariu and i. houssamo . “dc load and batteries control limitations for photovoltaic systems. experimental validation.” ieee transactions on power electronics, vol. 27, pp. 4030-4038., 2012. doi: 10.1109/tpel.2012.2189134 [8] z. zheng , x. ming, c. qiaoliang, l. jih-sheng and c. younghoon. “derivation, analysis, and implementation of a boost–buck converter-based high-efficiency pv inverter.” ieee transactions on power electronics, vol. 27, pp. 1304-1313, 2012. doi: 10.1109/tpel.2011.2163805 [9] l. yu-huei , h. shao-chang, w. shih-wei, w. wei-chan, h. ping-ching, h. hsin-hsin, l. yuantai and c. ke-horng .“power-tracking embedded buck–boost converter with fast dynamic voltage scaling for the soc system.” ieee transactions on power electronics, vol. 27, pp. 1271-1282. 2012. doi: 10.1109/tpel.2010.2101085 [10] s. vighetti, j.p. ferrieux and y. lembeye . “optimization and design of a cascaded dc/dc converter devoted to grid-connected photovoltaic systems.” ieee transactions on power electronics, vol. 27, pp. 2018-2027, 2012. doi: 10.1109/tpel.2011.2167159 [11] w. li, and x. he. “review of non-isolated highstep-up dc/dc converters in photovoltaic gridconnected applications.” ieee transactions on industrial electronics, vol. 58, pp. 1239-1250. 2011, doi: 10.1109/tie.2010.2049715 http://dx.doi.org/10.21622/resd.2017.03.2.196 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.196 207 resd © 2017 http://apc.aast.edu [12] y.p. hsieh, j.f. chen, t.j. liang, and l.s. yang. “novel high step-up dc–dc converter for distributed generation system.” ieee transactions on industrial electronics, vol. 60, pp. 1473-1482, 2013, doi: 10.1109/tie.2011.2107721 [13] s. vighetti, j.p. ferrieux and y. lembeye .“optimization and design of a cascaded dc/dc converter devoted to grid-connected photovoltaic systems’.”ieee transactions on power electronics, vol. 27, pp. 2018-2027, 2012. doi: 10.1109/tpel.2011.2167159 [14] a.v. stankovic, l. nerone andp. kulkarni.“modified synchronous-buck converter for a dimmable hid electronic ballast.” ieee transactions on industrial electronics, vol. 59, pp. 1815-1824, 2012. doi: 10.1109/tie.2011.2141094 [15] a. richelli, s. comensoli and z.m. kovacsvajna. “a dc/dc boosting technique and power management for ultralow-voltage energy harvesting applications.” ieee transactions on industrial electronics, vol. 59, pp. 2701-2708, 2012. doi: 10.1109/tie.2011.2167890 [16] il-oun l, shin-young c, gun-woo m, ‘interleaved buck converter having low switching losses and improved step-down conversion ratio’, ieee transactions on power electronics, vol. 27, issue 8, 2012. pp. 36643675. doi: 10.1109/tpel.2012.2185515 [17] l. il-oun , c. shin-young and m. gun-woo. “interleaved buck converter having low switching losses and improved step-down conversion ratio.” ieee transactions on power electronics, vol. 27, pp. 3664-3675, 2012. doi: 10.1109/tpel.2012.2185515 [18] r.f. foley, r.c. kavanagh and m.g. egan. “sensorless current estimation and sharing in multiphase buck converters’, ieee transactions on power electronics, vol. 27, pp. 2936-2946, 2012. doi: 10.1109/tpel.2010.2042072 [19] a.j. forsyth and g. calderon-lopez. “sampleddata analysis of the dual-interleaved boost converter with interphase transformer.” ieee transactions on power electronics, vol. 27, pp. 1338-1346, 2012. doi: 10.1109/tpel.2011.2163645 [20] j.y. lee, y.s. jeong and b.m. han. “a twostage isolated/bidirectional dc/dc converter with current ripple reduction technique.” ieee transactions on industrial electronics, vol. 59, pp. 644-646, 2012. doi: 10.1109/tie.2011.2109343 [21] l.s. yang and t.j. liang. “analysis and implementation of a novel bidirectional dc–dc converter.”, ieee transactions on industrial electronics, vol. 59, pp. 422-434, 2012. doi: 10.1109/tie.2011.2134060 [22] w. hongfei, l. juejing, s. wei and x. yan x. “non-isolated bidirectional dc–dc converters with negative-coupled inductor.” ieee transactions on power electronics, vol. 27, pp, 2231-2235., 2012. doi: 10.1109/tpel.2011.2180540 [23] z. honglin, x. shuai, y. geng and g. hua. “modeling and control for a bidirectional buck– boost cascade inverter.” ieee transactions on power electronics, vol. 27, pp. 1401-1413, 2012. doi: 10.1109/tpel.2010.2103957 [24] p. patra, a. patra and n. misra. “a singleinductor multiple-output switcher with simultaneous buck, boost, and inverted outputs’, ieee transactions on power electronics, vol. 27, pp. 1936-1951, 2012. doi: 10.1109/tpel.2011.2169813 [25] y. dongsheng, y. min y and r. xinbo. “onecycle control for a double-input dc/dc converter.” ieee transactions on power electronics, vol. 27, pp. 4646-4655, 2012. doi: 10.1109/tpel.2011.2164582 [26] w. rong-jong, l. chung-you and c. bo-han c. “high-efficiency dc–dc converter with two input power sources.” ieee transactions on power electronics, vol. 27, pp. 1862-1875, 2012. doi: 10.1109/tpel.2011.2170222 [27] t.j. liang, j.h. lee, s.m. chen, j.f. chen and yang l-s. “novel isolated high-step-up dc–dc converter with voltage lift.” ieee transactions on industrial electronics, vol. 60, pp: 1483 – 1491, 2013. : 10.1109/tie.2011.2177789 [28] a. elasser and d.a. torrey. “soft switching active snubbers for dc/dc converters.” ieee transactions on power electronics, vol. 11, pp. 710-722, 1996. doi: 10.1109/63.535403 http://dx.doi.org/10.21622/resd.2017.03.2.196 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 3 issue 2, june 2017 issn 2356-8569 http://dx.doi.org/10.21622/resd.2017.03.2.196 208 resd © 2017 http://apc.aast.edu [29] n. kondrath, n and m.k. kazimierczuk. “comparison of wideand high-frequency dutyratio-to-inductor-current transfer functions of dc– dc pwm buck converter in ccm.” ieee transactions on industrial electronics, vol. 59, pp: 641-643., 2012, doi: 10.1109/tie.2011.2134053 [30] c. restrepo, j. calvente, a. romero, e. vidalidiarte and giral r.: current-mode control of a coupled-inductor buck–boost dc–dc switching converter.” ieee transactions on power electronics, vol. 27, pp. 2536-2549, 2012. doi: 10.1109/tpel.2011.2172226 [31] r. tymerski and v. vorperian. “generation and classification of pwm dc-to-dc converters.” ieee transactions on aerospace and electronic systems, vol. 24, no. 6, pp. 743-754, november 1988.doi: 10.1109/7.18641 http://dx.doi.org/10.21622/resd.2017.03.2.196 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.001 photovoltaic: perovskite fever: is perovskite the future of solar cells? professor aziz naamane lis umr cnrs 7020 aix marseille university, cnrs sasv and hyres lab marseille, france email: aziz.naamane@lis-lab.fr perovskites, this somewhat "barbaric" term derived from the name of a 19th century russian mineralogist, lev perovski, is not yet known to the public. but in labs around the world researchers are feverishly active around this family of crystals that promise to revolutionize the conversion of solar energy into electricity. originally the perovskite is a crystal composed of calcium, titanium and oxygen. however, the term is now used to refer to other chemical compounds with identical structures. about ten years ago these materials, then used to make certain electronic components, suddenly emerged as potential candidates for the replacement of expensive silicon cells in solar panels. the hope was mainly based on the cost of perovskite cells, which are significantly lower than those made with silicon crystals and which currently equip most photovoltaic installations perovskite at a glance  perovskite solar cells are cheap, easy to implement and efficient, but their operation still lacks stability.  the latest developments in research tend to move closer to the goal: solar cells with long-term high performance.  to be successful, the new technology must be compatible with existing industrial manufacturing processes.  a new technology is in the starting blocks: solar cells with perovskites. this generic term refers to new materials whose crystalline structure is similar to that of the natural material called perovskite.  the solar cells with perovskites have undergone a flash development. over the past decade, their output has literally exploded from just 3% to over 20%. perovskites have remarkable properties: they absorb light particularly efficiently and evacuate the current produced well. in addition, they are both cheap and easy to manufacture and process. however, perovskite-based solar cells also have a significant drawback: they do not yet function consistently enough and are not durable enough for large-scale use. researchers from the eth lausanne and the university of freiburg are working to improve the stability and performance of this promising technology. perovskite rock in the urals massif, russia. the discovery of the photovoltaic qualities of perovskites dates back only to 2012. 1 http://apc.aast.edu http://dx.doi.org/10.21622/r http://dx.doi.org/10.21622/r http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.001 conclusions: in short, it would be tedious to describe all the research currently underway, but be aware that the results are there: lately not several weeks go by without a team proudly announcing that they have made progress towards the development of a photovoltaic technology based on perovkites, much cheaper than the current silicon cells and whose lifespan and efficiency are equivalent. theoretically, the yield of perovskite-based panels could even be as high as 30%, but we are not there yet. another area of research concerns the manufacturing technologies of perovskite-based cells. scientists are working on the possibility of placing thin-film materials on a flexible pet medium [1] using a process similar to inkjet printers. the solar module that we get is almost transparent, very flexible and offers a wide range of possibilities. for example, it could be integrated into building glazing or in complex shapes such as vehicle bodies. some even plan to make clothes out of them. the final issue is cost and marketing. according to media estimates, the price of perovskite-based solar modules is 4 to 5 times lower than that of current photovoltaic panels. if all these hopes and promises come true, we may well be on the cusp of a solar revolution that would definitively sound the death knell for fossil fuels and nuclear power. shall we agree that perovskites: these crystals will revolutionize solar energy? this question remains open. [1] pet polyethylene terephthalate: it is the plastic used to make bottles containing soft drinks references [1] frohna, samuel d. stranks, in handbook of organic materials for electronic and photonic devices (second edition), 2019. [2] nrel’s ‘best research-cell efficiencies’. available at: https://www.nrel.gov/pv/assets/pdfs/pv-efficiencies07-17-2018.pdf. (accessed: 14th december 2018) about professor aziz naamane dr abdelaziz naamane obtained a m.sc. in electronics, power electronics, and automatic control from the université de provence and a ph.d. in electronics and physics from aix marseille university. he is currently a professor at aix marseille université and a senior researcher at laboratoire d’informatique & systèmes (lis umr 7020 cnrs) current interest: modelling, simulation and control of complex hybrid systems. control-oriented modelling of nonlinear dynamical systems. energy-based modelling (bond graphs, euler-lagrange, port-hamiltonian methods) and control of nonlinear physical systems. applications of nonlinear techniques to modelling, analysis and control of electrical machines, power electronics drives, and general mechatronic systems, including robotics. energy management and control in micro smart grids. 2 http://apc.aast.edu http://dx.doi.org/10.21622/r http://dx.doi.org/10.21622/r http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 17 resd© 2015 http://apc.aast.edu power quality improvements in wind diesel power generation system omar feddaoui 1 , riad toufouti 1 , salima meziane 1 department of electrical engineering university of mohammed chérifmessaadia souk ahras, algeria omarispower@hotmail.com, toufoutidz@yahoo.frmeziane_elc@yahoo.fr i. introduction global warming is one of the most serious environmental problems facing the world community today. scientistsare highly interested in solving it. it is characterized by the increase in the average temperature of the earth and extreme weather conditions 1 . on top of that, the rapid depletion of fossil fuels worldwide has necessitated an urgent search for another alternative energy sources to meet the current human requirements. wind power is one of the renewable energy sources that scientists have recently drawn attention to 2 . being an abundantly availableand non-pollutingenergy, it can make a wonderful alternative source of power. moreover, this clean alternative source of energycan fit attractively for many usesand applications. on the hand, only 6.4% of total renewable energy sources available in the world are in use today. to get more consistent flow of energy to the user request, there has been a growing trend to combine renewable energy sources with diesel generators, giving a hybrid power generation system 4 .they are activated to serve as an electrical energy source in telecommunication systems or clinics in border crossings,remote areas, desertsand isolated habitats. these locationsneed systems which are generally independent from large interconnected networks 5 . in literature thousands of researches have been doneto find a way that hybrid systems could becontinually utilized in an isolated area or be connected to a power grid. in 6 a study a hybrid autonomous system was introduced and presented as 7 a power system in an island in bangladesh. several parameters are entered in the study as well as in the system design, but in books it is difficult to find how to measure the various components of an autonomous system.most of the books focus on the basic technologicaltheory of the device, not the measurements of equipment. variable parameters of most of renewable energy sources often take a complex control system 8 . however,the design of the right voltage and frequency used tocontrol a wind-diesel system is shown in 9 . in 10 p. s. panickar et al study a strategy of adaptive control by a variable wind speed for an application for a wind-diesel hybrid system. modeling is also a major factor in studies developed to simulate a functioning system. much software allows us to do that. there is an example of modeling and simulating various hybrid systems presented with matlab-simulink software in 11 , 12 . in 13 a model of a hybrid power generation is made by the homer software.to improve the quality of the energy produced by a system of wind energy production, a wind-diesel hybrid system is proposed in this study. simulation results in matlab \ simulink are presented to confirm the proper functioning of the wind diesel hybrid system to reduce greenhouse gas emissions. ii. different structures of hybrid system the configuration of the hybrid system obviously depends on the availability and use constraints of energy resources. this requires a measurement and a preliminary analysis of site conditions. there are several structures of an autonomous wind-diesel hybrid system: wind-diesel system with short-term storage, wind-diesel system with longterm storage (batteries, compressed air, hydrogen, etc.) 14 and wind-diesel system without energy storage. the choice of a suitable structure of a hybrid system is connected to two parameters. the first is the satisfaction of the technical performance in meeting the requirements of power quality;whereas the second is theeconomicincrease of saving fuel. thus, the costs of electricity production in the autonomous systemswill beminimized 15 . iii. wind-diesel without storage in our study we chose to work on the third structure of wind-diesel system without energy storage (figure 1). abstract— generation of electricity using diesel is costly for small remote isolated communities. at remote location electricity generation from renewable energy such as wind can help reduce the overall operating costs by reducing the fuel costs. however, the penetration of wind power into small diesel-based grids is limited because of its effect on power quality and reliability. this paper focuses on the combination of wind turbine and diesel generator systems for sustained power generation to improve the power quality of wind generation system. the performance of the optimal control structure are assessed and discussed by means of a set of simulations. keywordstriple – renewable energy, wind diesel system, a synchronous generator, asynchronous generator, diesel generators, micro grid; mailto:omarispower@hotmail.com journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 18 resd© 2015 http://apc.aast.edu fig.1. simplified diagram of a wind diesel hybrid system it is able to meet the need for electricity for consumers in isolated zones.it consists of the following subsystems: a wind generator and some diesel both connected to a load. during the functionality of the system studied, if the electricity generated by the wind generator is sufficient for the load demand, the diesel generator is inactive to producereactive energy compensation. except in the case where wind energy is insufficient to load demand, the diesel generator goes on to provide additional energy. a. wind generator a wind turbine consists of four main components: a turbine which is the main tool for the conversion of wind energy into mechanical energy,an electromechanical system as a tool for transformation of mechanical energy into electrical energy.it includes the asynchronous generator and associated electrical components. an interconnect system and a control system [13]. the low cost and the standardization of the asynchronous machine that does not require a complex installation has led to a wide domination of this type of generators installed in a wind system. it is less demanding in terms of maintenance and has a failure rate which is very low. in the wind turbine consequent size, rotation speed is low. it is therefore necessary to inserta mechanical speed multiplier between the turbine and the induction motor. in this work we will focus to study on an asynchronous machine squirrel cage self-excited. (figure 2) psm requires reactive energy to start (generation of rotating magnetic field). in a general case a capacitor connected in parallel with the stator circuit provide this energy [16]. fig.2. wind system b. diesel generator the diesel generator (figure 3) is generally composed of a synchronous generator coupled to a diesel engine. the frequency of the alternating output current is maintained by a speed regulator. the regulator operates by adjusting the flow of fuel to keep the engine speed and the speed of the generator constant.in the case of high speed wind, the clutch decouples the synchronous generator from the diesel engine, and the machine functions as a synchronous generator and provides reactive energy [16, 23]. diesel engines are more efficient than internal combustion engines. the speed of rotation of such generator depends on the amount of injected fuel and the load applied to the engine crankshaft. the diesel engine is a nonlinear system. it presents delays, which makes it difficult to control. diesel engines are equipped with cruise control: mechanical, electromechanical or electronic. it carries out the automatic control of the speed of the diesel engine by adjusting the fuel injection depending on the load. it acts on the acceleration mechanism [16, 23]. fig.3. the diesel generator iv. modeling of wind diesel generator to optimize a hybrid power generation system, it is necessary to know the various elements of it. for this, we will begin modeling the wind turbine with the asynchronous generator and as in a second step we model the diesel generator. a. modeling the wind system generator in the literature, several studies have been devoted to the modeling of different components of a wind power system for a quality generated. a single autonomous wind-poweredturbine model was presented in 17 . the authors in 18 did an analysis of different modeling methods; the first deals with themodel theoretically;whereasthe second relied on the experimental data. we can say that wind system transforms wing energy of the air mass to a mechanical power, characterized by the speed of rotation and mechanical torque. (figure 4). voltage regulator clutch sg ref v s v  ref   diesel engine speed regulator speed multiplicator ig capacitor wind generator diesel generator load coupling journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 19 resd© 2015 http://apc.aast.edu fig.4. model of the wing in our case the turbine is formed with a horizontal axis, the principle of wind conversion was established by betz.it assumes that the blades are placed in lively air to infinity upstream speed and downstream of an infinite speed 2 v with an air mass moving through the density ρ with surface s of the blades [19]. 2 ).(. 21 vvs m    (1) the power ; extracted is expressed as half the product of the mass and the change in wind speed. 2 ).( 2 2 2 1 vvm p m   (2) by replacing the expression of m in the equation number (2) 2 ))(.(. 2 2 2 121 vvvvm p m    (3) fig.5. tube of the current around the wind system undisturbed wind theoretically pass through the same area s with no variation in speed 1 v , the total power mt p would be written: 2 .. 3 1 vs p mt   (4) the ratio of the power extracted from the wind and the total power available is: 2 1.1 2 2 1 2 1                                    v v v v p p c mt m p (5) where :pc the power coefficient if we represent the corresponding feature in the equation above, we see that the power coefficient p c has a maximum of 0.59, see figure 6. this theoretical limit called betz limit which determines the maximum extractable power for a given wind speed. the evolution of the power coefficient is a specific data for each wind [20]. fig.6. coefficient of power with the combination of the equations (1), (4) and (5),the mechanical power available on the shaft of a wind turbine is expressed by [19]: 3 2 2 ...).( 2 1 .. vrpcpcp p p p pmtpmt mt m m  (6) the specific rate  is written as follows: 1 1 . v r  (7) given the ratio of speed multiplier k, the mechanical power mgp available on the shaft of the electric generator is expressed by: 3 1 2 1 2 ..... 2 1 vr kv r cp pmg           (8) with: :r radius of the wind turbine : 1  rotational speed before the multiplier : 2  rotational speed after the multiplier b. modeling the wind system generator modeling of the diesel engine must consider the moving parts of the engine, the power output i p and the total power dissipated dissp . the motor runs at constant speed for a given order to maintain the voltage and frequency of the current supplied by the alternator constant load. the principle of energy conversion can be written as follows [21]: 0 dissi pp (9) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.5 0.52 0.54 0.56 0.58 0.6 the power coefficient v1/v2 c p wind wing )(tv v c mec (t) ω (t) journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 20 resd© 2015 http://apc.aast.edu the power delivered can be represented by the following expression: ficii mnpp .. (10) with : ci p the calorific value of the fuel : i n the indicated engine performance : f m the flow of fuel injected into the combustion chamber the total dissipated power includes the effect of friction of the moving parts as (rods, pistons, crankshaft), and that of the load applied on the engine, can be expressed by the following formula:   .. 4 . r y mfdiss c c pp  (11) : mf p the average pressure of the friction losses : y c the total displacement of the engine : r c the resistive torque to the applied load the modeling of friction at different parts of the engine was the subject of numerous studies that lead to a variety of forms. given the complexity to treat each element separately, it was preferred to use the comprehensive assessment of the losses formulas [22]. the most accurate formula which represents the variation of the power of friction depending on the speed and pressure of the intake air of the engine as follows:    . 4 .)....1( 2 321 y af a in ffengmf c pk p p kksp          (12) v. simulation of wind diesel system the general structure of the wind diesel system is illustrated by figure 7. fig.7. tube of the current around the wind system in our system the configuration of the electrical energy provided by means of a system consisting of a wind turbine connected to an asynchronous generator with an apparent power 250kva diesel and another system which comprises a diesel engine coupled to a permanent magnet synchronous generator with power of 300kva, which provides the necessary reagent to initiate the asynchronous generator. this hybrid power generation system feeds a load of 250kw and a secondary variable load associated with a frequency regulator. the system operates on a voltage of 380v and a frequency of 50hz. the simulation time is 20s with a sampling period of 1ms. the primary load is 120kw up to t=5s, at this time we add another charge to reach a total 250kw (figure 8). the simulation results are shown in the figures below. fig.8. primary and secondary load fig.9. speed of the asynchronous generator fig.10. power in the hybrid system 0 2 4 6 8 10 12 14 16 18 20 0 50 100 150 200 250 300 primary and secondary loads times[s] p l s l [ k w ] sl pl 0 2 4 6 8 10 12 14 16 18 20 1495 1500 1505 1510 1515 1520 1525 1530 speed of the induction generator times[s] w [ ra d /s e c ] 0 5 10 15 20 0 50 100 150 200 250 300 350 wind, diesel power and primary and secondary loads times[s] p w p d p l s l [ k w ] p wind p desel sec load pri load journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 21 resd© 2015 http://apc.aast.edu fig.11. reactive power of the diesel generator fig.12. zoom of load voltage fig.13 .zoom of the load currents fig.14. zoom of the wind currents fig.15. zoom of the diesel currents fig.16 .frequency system from the simulation results it is noted that the turbine connected to the induction generator operates at a speed which is slightly greater than the synchronous speed (figure 9). we note that at t=5s the total load power is 250kw and according to the characteristic of the turbine for a wind speed 8m/s, the power generated by the wind turbine is 120kw, the latter is less the total power of the load, and for that at this moment the power generated by the diesel generator increases (figure 10) to meet the demand. in the same figure at time t=10s, we note that if the wind speed increases (8 to 10m/ s), the power supplied by the wind system increases, the power supplied by diesel generator decreases, which leads to a decrease the fuel consumption which is accompanied by a proportional reduction in toxic emissions and greenhouse gas emissions. conversely, if the wind speed decreases again, the power of gas decreases power diesel generator (that of the gs) increases to ensure the power demanded by the load. figure 11 shows the required reactive power generated by the diesel system to initiate the asynchronous generator. the load voltage and load, wind diesel currents are in sinusoidal shapes, see figuress (12-15). the phase current has fewer ripples and a nearly sinusoidal 0 5 10 15 20 0 50 100 150 200 250 300 350 reactive power of the diesel generator times[s] q d ie s e l[ k v a r] 10 10.05 10.1 10.15 10.2 10.25 10.3 -1.5 -1 -0.5 0 0.5 1 1.5 load voltage times[s] v la b c [p u ] 9.9 9.95 10 10.05 10.1 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 load currents times[s] ila bc [p u] 9.9 9.92 9.94 9.96 9.98 10 10.02 10.04 10.06 10.08 10.1 -1.5 -1 -0.5 0 0.5 1 1.5 current of asynchrounous generator times[s] ia b c [p u ] 9.9 9.95 10 10.05 10.1 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 current of synchrounous generator times[s] ila bc [p u] 0 5 10 15 20 45 50 55 frequency system time [s] f [ h z ] journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 22 resd© 2015 http://apc.aast.edu wave form. figure 14 shows that the frequency regulator maintains the frequency of the load at 50hz, after some changes are made in the load. vi. conclusion in this paper we have discussed a modeling of a micro-grid with wind-diesel generator hybrid system and its operations. the simulations in matlabsimulink are presented. according to these simulation results we show the importance and flexibility of operation of a diesel generator and a wind generator to reduce fuel consumption which is associated with a proportional reduction in toxic emissions and greenhouse gas emissions. we also showed how to improve the power quality of wind generation system by means of a wind-diesel hybrid system. references [1] supriyadi a.n and hashiguchi t., control scheme of hybrid wind-diesel power generation system, japon indonisia. [2] sebastiin, r. ,castro, m. ,sancristobal, e., yeves, f. and peire j., approaching hybrid wind-diesel systems and controller area network. ciudad university. spain. [3] borowy, b.s. ziyad salameh m., (september 1994) optimum photovoltaic array size for a hybrid wind/pv system, ieee transactions on energy conversion, vol. 9, no. 3,. [4] trifkovic,m. ,sheikhzadeh,m., nigim k. and daoutidis,p. hybrid energy system modeling and control, university of minnesota, canada. [5] devine, m.m. (february 2005) analysis of electric loads and winddiesel energy options for remote power stations in alaska, university of massachusetts: amherst. master. [6] rekioua, d., z. roumila et rekioua t. (2008), etude d’une centrale hybride photovoltaïque éolien diesel, university a. mira, bejaia. bejaia, algeria [7] al-masood,n. mirza, r. and jubaer, a.(2011) design of a cost effective off-grid wind-diesel hybrid power system in an island of bangladesh, world academy of science, engineering and technology 60. [8] stott, p.a. and mueller, m.a. modelling fully variable speed hybrid wind diesel systems, edinburgh university, uk. [9] murthy,s.s. mishra,s. mallesham, g. and sekhar,p. c. (december 2010) voltage and frequency control of wind diesel hybrid system with variable speed wind turbine, ieee magazine 20-23. [10] panickar,p. s. s. ,rahman,s. islam, m. and pryor,t. l. adaptive control strategies in wind-diesel hybrid systems, curtin university, western australia. [11] taylor ,j.h. and kebede,d. (1995) modeling and simulation of hybrid systems, university of new brunswick. conference on decision & control. canada. [12] kasera,j., chaplot, a. and jai, k. (2012) maherchandani, modeling and simulation of wind-pv hybrid power system using matlab/simulink, ieee students’ conference on electrical, electronics and computer science. [13] kansara, b.u and . parekh, b.r (2011) modelling and simulation of distributed generation system using homer software, international conference on recent advancements in electrical. [14] ibrahima,h. ilincaa ,a. and younesc, r. (2007) study of a hybrid wind-diesel system with compressed air energy storage, ieee electrical power conference. canada. [15] ibrahim,h., lefebvre, j., methot, j. f. and deschenes, j. s. (2011) no-storage wind-diesel system: mechanical modeling based on power flow models, ieee electrical power conference. [16] vechiu, i. (2005) modelling and analysis of the renewable energy integration in an autonomous grid, phd thesis. university de havre.. [17] idjdarene1, k.( december 2008)contrôle d’une génératrice asynchrone à cage dédiée à la conversion de l’énergie éolienne, jcge'08 lyon.. [18] j. chen and d. jiang, study on modeling and simulation of non-grid connected wind turbine,tsinghua university. china. [19] poitiers, f. (2003)study and control of induction generators for wind energy conversion systems, phd thesis. university of nantes.. [20] heier,s. (1998) grid integration of wind energy conversion systems. publications john wiley & sons.. [21] ibrahim,h. r. ,younès, a., ilinca, m. dimitrova and perron, j. may (2010) study and design of a hybrid wind-diesel system with compressed air energy storage system for remote areas, applied energy, vol. 87, issue 5, pp 1749-1762,. [22] younes,r. (1993) elaboration d'un modèle de connaissance du moteur diesel avec turbocompresseur à géométrie variable en vue de l'optimisation de ses émissions, phd thesis. école centrale de lyon. france. [23] gagnon, r. saulnier,b. sybille, g. and giroux, p. (april 2002) modeling of a generic high-penetration no-storage wind-diesel system using matlab/power system blockse.global windpower conference, paris, france. journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.015 15 resd © 2019 http://apc.aast.edu modelling and energy analysis of solar charging facility for electric vehicles in chile scarlett allende los zarzales 1533, santiago 9270842. chile. ssallend@uc.cl abstract this paper presents simulation and energy evaluation of a photovoltaic charging centre intended to supply the demand of 244,000 electric vehicles in chile. according to the obtained results, the transportation system was feasible from the solar radiation, energy consumption, geographic zone, type of pv farm and other sources. notably, the studied region has a solar potential to supply 10% of the total domestic cars existing in santiago, providing a total energy of 253.723 gwh/yr. furthermore, based on the study factors, the design of the system consists of approximately 428,590 pv modules and an average power generation of 31.89 w/hour for one single module. finally, the configuration of a solar charging facility allows applying a new method of energy supply to electric cars that improves the environmental conditions of the city and encourages sustainable development in the transport sector. keywords electric cars, photovoltaic, energy demand, solar radiation, design system, power generation. i. introduction one of the crucial issues addressed in the big cities is the number of petrol vehicles and the pollution produced. there are several reasons to continue improving the transportation system through electric cars that are considered as an alternative solution friendly to the environment. at the same time, electric cars allow the analysis of the potential of the system based on the solar resource of a geographic zone. overall, chile has severe issues of air pollution, of which 30% is the result of the transport emissions [1]. therefore, the implementation of innovative technologies of transport and the clean energy generation are crucial to help supply the demand of energy and decrease the levels of pollution in the city. on the other hand, chile has enormous potentials in solar energy and consequently in the development of electric vehicles. currently, the chilean government has used its their solar potential to create sustainable initiatives, such as the "electrolinera" project that involves the construction of 14 charging pv centres designated to solar cars [2]. ii. methodology 1. estimating energy demand there are eight procedures to obtain the energy data, as shown in figure 1. firstly, the route is selected on the smartphone by a route application (such as "runtastic"), then it applied driving in a diesel car in the streets in santiago. after that, the application generated graphs of speed (km/hr) and altitude (m). fig .1 flow diagram to obtain the energy demanded by the battery. 𝐸 = [(𝜇 ∗ 𝑚 ∗ 𝑔 ∗ 𝑐𝑜𝑠𝜃) + (𝑚 ∗ 𝑔 ∗ 𝑠𝑖𝑛𝜃) + ( 1 4 𝐶𝑑 ∗ 𝐴 ∗ 𝜌 ∗ (𝑉𝑓2 + 𝑉𝑖2))] ∗ ∆𝑑 + 1 2 ∗ 𝑚 ∗ (𝑉𝑓2 − 𝑉𝑖2) eq .1: energy consumption by the car [3]. http://dx.doi.org/10.21622/resd.2019.05.1.015 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.015 16 resd © 2019 http://apc.aast.edu where, m: mass of the car; a: is the frontal area of the car (2.754 m2 [3]),; cd: is the drag coefficient of the car (with 0.272 [3]); µ: is the traction efficiency of the surface (0.8 factor [4]); ρ: is the density of air kg/m3 (1.225 kg/m3 [5]); θ: is the slope angle; 𝞓d: is the difference of distance; g: is a gravitational constant equal 9.81 m/s2; vf: final velocity; vi: initial velocity. at the same time, the angle of the slope is calculated with the altitude data by equation 2. 𝜃 = (tan−1∗ (∆𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒)[𝑚] ∆𝐴𝑙𝑡𝑖𝑡𝑢𝑑𝑒 [𝑚] eq .2: angle of the slope in radians at the same time, throughout the route, the energy consumption was variate by the regenerative and traction braking. therefore, it is necessary to calculate the energy consumption considering ranges of efficient of the vehicle. the function represented in equation 3. where, ηbc: is battery charging efficiency; ηd: discharging efficiency; ηc: charging efficiency, et: energy of traction and ereg: energy of regeneration. in this case, it was considered a discharging factor of 0.85 [3], charging factor of 0.7 [3] and a battery charging efficiency of 95% [3] 𝐸𝑛𝑒𝑟𝑔𝑦 = ( 1 ɳ𝑏𝑐 ) [( 1 ɳ𝑑 ) 𝐸𝑡 − ɳ𝑐 ∗ 𝐸_𝑟𝑒𝑔] eq .3: total trip energy calculation [3] once obtained the value of energy battery (considering regenerative and traction efficiencies), it is necessary continuing with the calculation of average distance and energy consumed, as shown in figure 2. at the same way, determining the number of electric vehicles is essential, which represents 10% of the domestic cars existing in the city. fig .2 flow diagram to calculate the total energy demanded. following, equation 4 is used for the calculation of total demand energy, which involves the following factors. d: is the average driving distance (2.964 km); n: represents the number of electric vehicles (150) and eavg: is the average energy consumption of an electric car (961.06 wh). in this case, the number of electric cars considered is represented by the project "electrolinera" in chile [2] 𝐸𝑡𝑜𝑡𝑎𝑙 = 𝐷 ∗ 𝑛 ∗ 𝐸𝑎𝑣𝑔 eq .4: total energy demand [6] 2. calculation of temperature and irradiation the calculation method performed for the output power of the pv module detailed in figure 3. those involve obtaining the data of temperature and solar source. furthermore, it is necessary to consider pv modelling aspects, such as cell temperature and its efficiency. fig .3 flow diagram to calculate the module power output. the first step is to obtain the latitude and longitude by "google map", in this case, it was -33.52° and 70.76°, respectively. then, the coordinates data entered in the solar explorer [7] provide the data of temperature and irradiation by day and hour, in a direct way. with the data of global and direct irradiation the diffuse radiation can be calculated by the following formula. 𝐺𝐻𝐼 = 𝐷𝑖𝑓𝐻𝐼 + 𝐷𝐻𝐼 eq .5: calculation of diffuse radiation [8] specifically, ghi is the global horizontal irradiation w/m2, and dhi is the direct horizontal irradiation [w/m2]. with the difference of both irradiations, the http://dx.doi.org/10.21622/resd.2019.05.1.015 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.015 17 resd © 2019 http://apc.aast.edu diffuse radiation w/m2 is obtained. once collecting all the radiations, it was possible to calculate the slope irradiation by excel program calc 04-08 (muneer). after this step, the cell temperature is measured, considering the ambient temperature hourly, slope irradiation and other factors shown in equation 6. tc = ta + ( gslope gnoct )(tc, noct − ta, noct)(1 − ( ɳstc τα )) eq .6: calculation of cell temperature [9] where, g slope: global slope irradiation; gnoct: 800 w/m2; tc, noct: cell temperature at noct; ta, noct: air temperatures noct; n stc: cell efficiency at sct; tα: absorptivity of the module and ta: ambient temperature. by equation 7 is possible to calculate the pv cell efficiency under determinants of temperature fluctuations, efficiency at standard test conditions (ɳstc), cell temperature (tc), cell temperature under standard test conditions (tc, stc) and temperature coefficient value (αp) [9]. ɳ𝑐𝑒𝑙𝑙 = ɳ𝑠𝑡𝑐 [1 + 𝛼𝑝(𝑇𝑐 − 𝑇𝑐, 𝑠𝑡𝑐)] eq .7: calculation of cell efficiency [9] the last estimation is the electrical output power represented in formula 8, whose factors are ɳ mod: electrical efficiency under standard test conditions, a: surface area of pv panel, gtilt: consists on slope irradiation, and finally, tc: cell temperature calculated in the step before. 𝑃 = ɳ𝑚𝑜𝑑 ∗ 𝐴 ∗ 𝐺𝑡𝑖𝑙𝑡 [1 − 0.0045 ∗ 𝑇𝑐 − 298.15] eq .8: calculation of output performance [10] iii. results 1. unit demand firstly, the data collected in the route chosen were a total of 5.7 km of distance and at a time of 13 minutes and 20 seconds. according to the results, the speed was relative during the driven route with ranges between 0.5 and 16 m/s, and the average velocity was of 7.62 m/s. figure 4 indicates the different road gradients which variation is between the values 0 to over 400m. seeing the definition of altitude in the graph, it can be assumed that the route was ascending most of the time. with this database, it was possible to calculate the angle of the gradient (rad) to obtain energy consumption finally. besides, the illustration shows the performance of energy consumed on the route. some of these values are negative due to the retrieved energy which was generated by regenerative braking, and the positive values represent the energy consumed, which involves traction efficiency. the average energy consumption of the trip was of 961.06 wh. fig .4 altitude of the route and energy consumed by the battery. 2. national demand the total energy consumed per year was 253.7 gwh, considering supplying 244,000 electric cars per year. the details of the performance result can be seen in table 1. -250 -200 -150 -100 -50 0 50 100 150 200 250 1 5 6 1 7 9 1 0 3 1 2 3 1 3 5 1 8 2 2 5 8 2 7 7 3 0 6 3 3 3 3 5 9 3 9 4 4 1 9 4 3 9 4 8 0 5 3 6 5 6 2 5 8 2 6 4 8 6 8 3 7 1 1 7 3 6 7 6 8 7 8 0 -50 0 50 100 150 200 250 300 350 400 450 e n e rg y c o n su m e d [ k w h ] time [s] a lt it u d e [ m ] altitud energy consumed http://dx.doi.org/10.21622/resd.2019.05.1.015 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.015 18 resd © 2019 http://apc.aast.edu table 1. summary of total energy demanded average distance km average e consumed wh e total demand gwh e total demanded gwh/yr. 2.964 961.06 0.6951 253.7 3. calculation of temperature and solar source the hourly temperature data were obtained by solar explorer [7] considering coordinate of latitude -33.5 and longitude -70.7. the days measured by solar explorer were between the dates 1st jan 2016 and 26th dec 2016. however, only the data that belong to the 12th day of each month will be considered. figure 5 shows the elevated difference between the maximum and minimum temperature during the year, which was around 18 °c in the spring season. a similar procedure was applied to get the hourly irradiations, obtained by the solar explorer [7]. as described in figure 5 the best radiation performance is in the summerseason (between november and february) with over 300 w/m2 of global irradiation. in the rest of the months, steady rises and drops exist. on the other hand, the hourly global irradiation result showed that the maximum average of radiation is between 12 and 16 hours with over 500 w/m2.figure 6 describes the minimum performance, which is during morning and evenings when the global radiation declines dramatically. additionally, it represents the output power of a single pv module, whose peak is at 17 hours with more than 80w. fig .5 average hourly corresponding to the global horizontal irradiation (w/m2) and the difference between the maximum and minimum ambient temperature (w/m2) for the entire year. fig .7 comparison between cell temperature and panel efficiency. fig .6 annual average of ghi per hour (w/m2) and average of pv output power (w). 0 2 4 6 8 10 12 14 16 18 20 0 50 100 150 200 250 300 350 1 2 3 4 5 6 7 8 9 10 11 12 t e m p e ra tu re [ °c ] g lo b a l ir ra d ia ti o n [ w /m 2 ] month ghi 𝞓t 14.8 15.0 15.2 15.4 15.6 15.8 16.0 16.2 ja n f e b m a r a p r m a y ju n ju l a u g s e p o c t n o v d e c 0 5 10 15 20 25 30 m o d u le e ff ic ie n c y [ % ] m o d u le c e ll t [ °c ] cell temperature effciency 0 10 20 30 40 50 60 70 80 90 100 0 100 200 300 400 500 600 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 p o w e r [w ] g lo b a l ir ra d ia ti o n [w /m 2 ] hour ghi power http://dx.doi.org/10.21622/resd.2019.05.1.015 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.015 19 resd © 2019 http://apc.aast.edu 4. calculation of cell temperature after obtaining the temperature and irradiation per hour, the cell temperature was calculated considering the values g slope calculated previously; gnoct: 800 w/m2 [9]; tc of 47 °c [11]; ta, noct of 25 °c [11]; n stc of 15.2% [11]; tα of 0.8 [11] and ta, calculated earlier. figure 8 describes the relationship between ambient temperature and cell temperature per hour. the following result was the calculation of cell efficiency of the pv panel, and it was reached by formula 7, which involved factors of n stc of 15.20%; tc, stc of 25 °c; αp of 0.40 %/°c and tc calculated in the step before. figure 7 demonstrates the relationship between cell temperature and panel efficiency. fig .8 comparison between cell temperature and ambient temperature. 5. determination of the pv system a. pv modules quantity firstly, it was necessary to estimate the energy produced by one pv module, through formula 9. the equation involves factors of pv surface area (2.6 m2 [11]), the efficiency of the system (15.20% [11]) and tilted global irradiance (7.92 kwh/m2). 𝐸𝑚𝑜𝑑𝑢𝑙𝑒 = 𝐴𝑚 ∗∩ 𝑠𝑦𝑠 ∗ 𝐼𝑡𝑖𝑙𝑡 eq .9 : energy of pv module [3]. where am represents the useful pv area; ∩sys is the efficiency of the system and itilt is the tilted global irradiance calculated previously. the next step is to calculate the number of pv modules necessary to supply the total consumption, which is obtained by equation 10. 𝑋𝑚𝑖𝑛 = 𝐸 𝑡𝑜𝑡𝑎𝑙 𝑐𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 𝐸 𝑚𝑜𝑑𝑢𝑙𝑒 eq .10: number of pv modules. as a result, table 2 shows a summary of the number of pv modules required. the function involves the total energy consumption per year whose value was 253,723,041.351 kwh/year and the energy produced by one pv module was 591.99 kwh/yr., obtaining 428,590.713 modules overall. table 2. summary of the number of pv modules. e module/year kwh total consumption kwh/year number pv module 591.99 253,723,041.351 428,590.713 b. calculation of array size besides, it was necessary to measure the maximum open circuit voltage of the module as shown in equation 11. the factors are the voc that is open circuit voltage; tdcu, mod that represents the temperature voltage coefficient (0.4 [11]) and ∆tlow (-13.1°c) which is the difference between the ambient temperature (7.5 °c) and tc, stc (25°c [11]). as a result, the maximum voltage in the open circuit is 55.45v. 𝑉𝑑𝑐 max 𝑚𝑜𝑑 = 𝑉𝑜𝑐 ∗ (1 + (𝑇𝑑𝑐𝑢 𝑚𝑜𝑑 ∗ ∆𝑇𝑙𝑜𝑤 100 %)) eq .11: maximum voltage in open circuit [12]. 0 5 10 15 20 25 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 t e m p e ra tu re [ °c ] hour cell temperature ambient temperature http://dx.doi.org/10.21622/resd.2019.05.1.015 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.015 20 resd © 2019 http://apc.aast.edu at the same way, the minimum voltage in an open circuit can be calculated by formula 12. where, vmpp is the maximum power of the pv module (49.25v); tdc mod is temperature voltage coefficient (0.4) and ∆tmax (3.5°c) represents the difference between the tmax, mod and t sct. the minimum voltage open circuit is 49.94v. 𝑉𝑑𝑐 min 𝑚𝑜𝑑 = 𝑉𝑚𝑝𝑝 ∗ (1 + (𝑇𝑑𝑐 𝑚𝑜𝑑 ∗ ∆𝑇𝑚𝑎𝑥 100 %)) eq .12: voltage minimum in open circuit [12]. analogously, the maximum current of pv module was calculated by equation 13, which involves the shortcircuit current (i sc of 7.92a [11];); current temperature (tdc, mod of 0.05 [11]) and the difference between the maximum module temperature and stc temperature, represented by ∆tmax (3.5°c). the imax open obtained was of 7.93a. idc max str = i sc ∗ (1 + (tdc mod ∗ ∆tmax 100 %)) eq .13: maximum current of pv module. [12]. then the minimum number of strings was calculated through equation 14, whose factors are: maximum power generated (p dcgen); the maximum power of the module (p max, mod) and the number of strings per module (∩mod str). the calculation considered a p max of 54400w; p max mod of 13. 9w and n mod of 18 modules, obtaining a minimum number of strings of 217. ∩ min 𝑠𝑡𝑟 = 𝑃 𝑑𝑐𝑔𝑒𝑛 𝑃 max 𝑚𝑜𝑑 ∗∩ 𝑚𝑜𝑑 𝑠𝑡𝑟 eq .14: minimum number of strings [12]. finally, the total number of inverters was obtained by equation 15, which includes the number of pv modules (∩mod of 3905.2) and the total number of strings (∩array of 428,591). in this case, the total of inventers was 110. ∩ 𝑖𝑛𝑣 = ∩ 𝑚𝑜𝑑 ∩ 𝑎𝑟𝑟𝑎𝑦 eq .15: total number of inverters [12]. c. designing the pv facilities the pv charging zone proposed in santiago was located mainly in the western region of the city. the solar facilities placed around 2km of distance from the route done. the place has plenty of areas available and no risk of obstruction of radiation. the availability of solar pv installation is 1,008,000m2. around 60% of the mentioned area belongs to the pv facilities (576998.7437m2 of a useful area), and another 20% of the surface is left unoccupied to allow the maintenance between pv panels, which is 201,600m2. furthermore, the pv modules installed will have a 45° inclination and orientated towards the north. according to the previous calculation, each charging station will have 18 rows and 57 columns. also, the arrangement of 217 strings connected in parallel with 18 modules connected in series is considered. at the same time, one inverter manages 57 pv panels of one total of 428,591 pv modules. iv. conclusion according to the transport and environmental plans of the chilean government, the pollution problem is expected to be resolved. one alternative is by the promotion of solar charging facilities of electric cars, providing electricity for 10% of the national car fleet in santiago. specifically, the study demonstrated the following findings. • the energy consumption has a direct relationship with the type route (altitude) and the speed. that is because in some parts of the road the cars needed acceleration and in other deacceleration, causing more demand for energy consumption in the point of high altitude than others. at the same time, this produced an effect of regenerative braking and traction efficiency, which means negative and positive values of energy consumption. • overall, the solar analysis demonstrated that temperature and irradiation have a direct relationship. the maximum level of radiations is the summer season with maximum average values of global radiation of 340 w/m2. showing enough potential to supply the pv system. • on the other hand, the results showed that throughout the day the solar module increases its temperature considerably, around 13% more than ambient temperature, between hours 15 and 16. • at the same time, the cell efficiency was decreased by approximately 4% when the cell module got the maximum value of temperature. this period was http://dx.doi.org/10.21622/resd.2019.05.1.015 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.015 21 resd © 2019 http://apc.aast.edu between october and november. however, global competence represents an excellent performance for the system. • the best power performance of the pv module was between hours 18 and 19 (over 80w), increasing the output power by 27%. • to supply the energy required is necessary to count for the excellent pv facilities. in this case, the installation of 428,590.713 photovoltaic modules and the integration of 20% of the area in the solar facilities, whose objective is maintenance of work and reduction the possibilities of obstruction in solar radiation are a must. references [1] g. aymeric and s. françois. “case study for chile: the electric vehicle penetration in chile,” in electric vehicles: prospects and challenges, 2017, pp. 245–285. [2] j. m. vilches. “emol,” 2017. [online]. available: http://www.emol.com/noticias/tecnologia/2017/0 7/13/866601/el-panorama-de-los-autoselectricos-en-chile-cuantos-son-y-donde-secargan.html. [accessed 1st oct 2018]. [3] t. muneer, r. milligan, i. smith, a. doyle, m. pozuelo and m. knez. «energetic, environmental and economic performance of electric,» transportation research part d: transport and environment, vol.35, pp 40-61, 2015. [4] causadirecta. (2013) “investigación y reconstrucción de accidentes de tráfico.” [online]. available: https://causadirecta.com/especial/calculo-develocidades/tablas/tabla-de-factores-derozamiento-del-pavimento-para-neumaticos-degoma. [accessed 8th oct 2018]. [5] windpower. (2003) “danish wind industry associacion” [online]. available: http://xn-drmstrre-64ad.dk/wpcontent/wind/miller/windpower%20web/es/tour/wr es/enerwind.htm. [accessed 8th oct 2018]. [6] d. goos. “feasibility study of a solar charging facility for electric vehicles in munich.” master thesis, school of engineering & the built environment edinburgh napier university, edinburgh, 2015. [7] facultad de ciencias físicas y matemáticas, universidad de chile, “explorador solar,” 2018. [online]. available: http://ernc.dgf.uchile.cl:48080/exploracion. [accessed 11 oct 2017]. [8] r. escobar, j. m. cardemil, c. cortés and a. pino, “atlas solar de chile,” pontificia universidad católica de chile, santiago, 2013. [9] m. jeffrey, i. kelly, t. muneer and i. smith, “evaluation of solar modelling techniques through experiment on a 627 kwp photovoltaic,” school of engineering and built environment, edinburgh napier university, edinburgh, 2015. [10] d. a. beckmann, solar engineering of thermal process, madison: university of wisconsin, 1991. [11] advanced solar photonics. “asp-400gsm smart moduletm series high efficiency frameless monocrystalline solar modules”. (2012). [online]. available: https://www.enfsolar.com/product/pdf/crystalline/ 50bd9203a2fc0.pdf. [accessed 1st oct 2018]. [12] s. allende. "energy analysis of a solid oxide fuel cell (sofc) operated by pv system in the residential sector, in highland." master thesis, school of engineering & the built environment, edinburgh napier university, munich: grin verlag, 2018. [13] s. henriquez, “red de electrolineras ya cubre en forma continua desde coquimbo a biobío”.(2019). [online]. available: http://www.economiaynegocios.cl/noticias/noticia s.asp?id=550309. [accessed 1st mar 2019]. [14] comisión nacional de energía. (2015), “informe costos de inversión por tecnologia de generación”. [online]. available: https://www.cne.cl/wpcontent/uploads/2015/11/informe-costos-deinversi%c3%b3n-tec-de-generaci%c3%b3nago-2015.pdf. [accessed 1st oct 2018]. [15] comité nacional, gobierno de chile (2017). “estudio benchmarking de plantas solares http://dx.doi.org/10.21622/resd.2019.05.1.015 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.015 22 resd © 2019 http://apc.aast.edu fotovoltaicas en chile." [online]. available: http://www.comitesolar.cl/wpcontent/uploads/2017/04/informe-benchmarkingplantas-solaresfotovoltaicas_actualizaci%c3%b3n.pdf. [accessed 16th oct 2018]. [16] asociación chilena de energias enovables. (2017) “energía solar: prometedor futuro para chile” [online]. available: http://www.acera.cl/energia-solar-prometedorfuturo-para-chile/. [accessed 1st oct 2018]. [17] m.gutierrez. (2017). “economía y negocios.” [online]. available: http://www.economiaynegocios.cl/noticias/noticia s.asp?id=341770. [accessed 8th oct 2018]. [18] j. v. f. serra. «electric vehicles: technology, policy and commercial development,» 1st ed. london: routledge, 2012.. [19] m. mruzek, igorgajdáč, ľ. kučera and d.barta. «analysis of parameters influencing electric vehicle range,» procedia engineering, vol. 134, pp.165-174, 2016. [20] e.s. rubin and c.i. davidson. introduction to engineering and the environment, 1st ed. boson: mcgraw-hill, 2001. [21] t. muneer, c. gueymard and h. kambezidis. solar radiation and daylight models, 2nd ed. amsterdam: elsevier, 2004. http://dx.doi.org/10.21622/resd.2019.05.1.015 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.024 http://apc.aast.edu energy consumption and transportation in developing countries: need for local scenariobased energy efficiency plans assoc. prof. dr. houshmand masoumi1 2 1 senior researcher, center for technology and society, technische universität berlin, germany. 2 visiting associate professor, department of transport and supply chain management, university of johannesburg, south africa. email : masoumi@ztg.tu-berlin.de like several other sub-topics of urban planning and mobility research, research on the impacts of (urban) transportation on energy consumption is mainly based on the outcomes of studies on high-income and often western countries. developing countries and emerging markets have a smaller share of the international research on the topic, while policymaking based on local empirical research, they could cut a percentage of unnecessary energy overuse. the benefits of policymaking based on empirical transportation / energy research do not remain limited to energy efficiency; it also has positive effects on environmental pollution control. moreover, transportation [1] and urban planning [2,3,4] policies can limit both energy use and air pollution, however such efficiency improvements may be most effective when they are derived from the vernacular conditions. this is important because the energy consumption of the transportation sector is rapidly increasing. in a country as populated and large as china, the oil consumed by transportation corresponded to 49.6% of oil use in the whole country in 2006 [5], while the results of a study undertaken only four years later shows that 60.1% of the chinese petroleum end-use is caused by transportation [6]. out of the large part of overall energy use share caused by transportation sector, private cars are important users. in mexico, private vehicles account for 31% of transport energy consumption [7]. the chinese energy consumption and co2 emission conditions need further improvements in the transportation sector [8]. the conditions are the same in several other comparable countries. even though studies on developing countries and emerging markets are not comparable to those of high-income countries, still a few studies have been conducted on the relations between urban transportation and energy consumption in these geographical contexts. for instance, it has been shown that renewable energy use granger-cause energy consumption in road transportation in malaysia [9]. there is a unidirectional causality from transport infrastructure to energy consumption in india [10]. furthermore, there is a bidirectional causality between transport energy consumption, fdi and co2 emissions in thailand and malaysia [11]. nevertheless, a causal relationship between transport energy use and all environmental emissions has not been found, e.g. in pakistan no evidence for the role of transport energy consumption on co2 emission has been recognized [12]. in many developing countries, fast urbanization is related to transportation energy use. the reason lies in the close relationship between urbanization and urban sprawl on the one hand and motorization rate and traffic generation on the other hand. although many years ago it has been observed in several international cities that urban densities are positively correlated with transport energy consumption [13,14], it has also been shown that this relation exists only on the urban level. on a regional level, this relation is weak, as it has been shown in certain regions of iran [15]. in tunisia, vehicle fuel intensity, vehicle intensity, gdp per capita, urbanized kilometers and national road network were the main causes of transport energy consumption between 1990 and 2006 [16]. in china, the road transportation energy 24 http://dx.doi.org/10.21622/r http://dx.doi.org/10.21622/r http://apc.aast.edu/ http://apc.aast.edu/ mailto:masoumi@ztg.tu-berlin.de journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.024 http://apc.aast.edu consumption rises by 1.26 percentage points for every percent increase in urbanization [17], hence changing urban morphology can theoretically result in different urban transport energy consumption [18]. the association of urbanization and energy consumption is unsurprising, as urban growth and development is an essential attribute of economic growth. a recent empirical study on the countries of the middle east and north africa (mena) countries confirms the existence of associations of transport energy consumption and transport infrastructure with economic growth [19]. the overall conclusion of this editorial note is that although the number of recent studies on the connections of transportation and energy use in developing countries and emerging markets may look considerable, it is still not consistent and comprehensive because the mentioned studies are only considerable in number when they are accounted as a whole, as well as being focused generally on a very large geographical and cultural context. however, when investigating the smaller-scale correlation between transportation and energy use, it becomes clear that the number of reliable empirical studies in each country do not provide consistent and usable results for policymaking. the example of such studies have been produced for example on india, the results of which shows that “if rail could capture 50% modal share in the years 2005–2006 and 2020–2021, it would save nearly 35% energy consumption and emissions compared to the situation when existing patterns of modal split are allowed to continue without policy intervention.” [20]. in the example above, policymakers have received recommendations for controlling energy use and emissions based on scenario planning using the data and conditions of the local context, but the number of such studies are not enough for a population of 1.35 billion inhabitants accommodated in a wide cultural and geographical diversity. another example of energy consumption reduction strategies based on urban transportation local scenario planning, which many developing countries need, has been done on beijing, the results of which necessitates development of public transport in order to gain energy savings and emission reductions [21]. finally, the third example is on greater cairo, where impact assessment was undertaken applying the energy efficiency and greenhouse gases reduction scenario with the assumption of “metro did not exist” for the time period of 1987-2001. in conclusion, still much more research is needed to facilitate policymaking in countries listed as developing countries and emerging markets based on local data, analyses, and scenario planning. references [1] p. poudenx. the effect of transportation policies on energy consumption and greenhouse gas emission from urban passenger transportation. transportation research part a: policy and practice, 2008, vol. 42, issue 6, pp. 901-9. https://doi.org/10.1016/j.tra.2008.01.013 [2] m. breheny. the compact city and transport energy consumption. transactions of the institute of british geographers, 1995, pp. 81-101. [3] o. mindali, a. raveh, and i. salomon. urban density and energy consumption: a new look at old statistics. transportation research part a: policy and practice, 2004, vol. 38, issue 2, pp. 143-62. https://doi.org/10.1016/j.tra.2003.10.004 [4] r. hickman and d. banister. transport and reduced energy consumption: what role can urban planning play?, transport studies unit, university of oxford, 2007. [5] m. zhang, h. li, m. zhou, and h. mu. decomposition analysis of energy consumption in chinese transportation sector. applied energy, 2011, vol. 88, issue 6, pp. 2279-85. https://doi.org/10.1016/j.apenergy.2010.12.077 [6] j. i. shunping, m. a. baohua, l. i. shuang, and s. u. qipeng. calculation and analysis of transportation energy consumption level in china. journal of transportation systems engineering and information technology, 2010, vol. 10, issue 1, pp. 22-7. https://doi.org/10.1016/s1570-6672(09)60020-9 [7] j. c. solís, c. sheinbaum. energy consumption and greenhouse gas emission trends in mexican road transport. energy for sustainable development, 2013, vol.17, issue 3, pp. 280-7. https://doi.org/10.1016/j.esd.2012.12.001 [8] x. yin, w. chen, j. eom, l. e. clarke, s. h. kim, p. l. patel, s. yu, g. and p. kyle. china's transportation energy consumption and co2 emissions from a global perspective, energy policy, vol. 82, pp. 233-48. https://doi.org/10.1016/j.enpol.2015.03.021 25 http://dx.doi.org/10.21622/r http://dx.doi.org/10.21622/r http://apc.aast.edu/ http://apc.aast.edu/ https://doi.org/10.1016/j.tra.2008.01.013 https://doi.org/10.1016/j.tra.2003.10.004 https://doi.org/10.1016/j.apenergy.2010.12.077 https://doi.org/10.1016/s1570-6672(09)60020-9 https://doi.org/10.1016/j.esd.2012.12.001 https://doi.org/10.1016/j.enpol.2015.03.021 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.024 http://apc.aast.edu [9] a. a. azlina, s. h. law, and n. h. mustapha. dynamic linkages among transport energy consumption, income and co2 emission in malaysia, energy policy 2014. vol. 73, pp. 598-606. https://doi.org/10.1016/j.enpol.2014.05.046 [10] r. p. pradhan. transport infrastructure, energy consumption and economic growth triangle in india: cointegration and causality analysis. journal of sustainable development, 2010, vol. 3, issue 2, pp. 167-173. [11] v. g. chandran, c. f. tang. the impacts of transport energy consumption, foreign direct investment and income on co2 emissions in asean-5 economies. renewable and sustainable energy reviews, 2013 vol. 24, pp. 44553. https://doi.org/10.1016/j.rser.2013.03.054 [12] m. a. baloch. dynamic linkages between road transport energy consumption, economic growth, and environmental quality: evidence from pakistan. environmental science and pollution research, 2018, vol. 25, issue 8, pp. 7541-52. https://doi.org/10.1007/s11356-017-1072-1 [13] p. w. g. newman, j. r. kenworthy. gasoline consumption and cities: a comparison of us cities with a global survey., journal of american planning association, 1989, vol. 55, pp. 24–37 [14] p. w. g. newman, j. r. kenworthy. sustainability and cities: overcoming automobile dependence. island, massachusetts, 1999. [15] h. e. masoumi, h. soltanzadeh. a regional analysis of urban population and transport energy consumption. international journal for traffic & transport engineering, 2014, vol. 4, issue 4, pp. 372-385. http://dx.doi.org/10.7708/ijtte.2014.4(4).02 [16] r. mraihi, k. ben abdallah, and m. abid. road transport-related energy consumption: analysis of driving factors in tunisia, energy policy, 2013, vol. 62, pp. 247-53. https://doi.org/10.1016/j.enpol.2013.07.007 [17] j. chai, q. y. lu, s. y. wang, k. k. lai. analysis of road transportation energy consumption demand in china. transportation research part d: transport and environment, 2016, vol. 48, pp. 112-24. https://doi.org/10.1016/j.trd.2016.08.009 [18] j. zhou, j. lin, s. cui, q. qiu, and q. zhao. exploring the relationship between urban transportation energy consumption and transition of settlement morphology: a case study on xiamen island, china. habitat international, 2013, vol. 37, pp. 70-9. https://doi.org/10.1016/j.habitatint.2011.12.008 [19] s. saidi, m. shahbaz, and p. akhtar. the long-run relationships between transport energy consumption, transport infrastructure, and economic growth in mena countries. transportation research part a: policy and practice, 2018, vol. 111, pp. 78-95. https://doi.org/10.1016/j.tra.2018.03.013 [20] r. ramanathan. estimating energy consumption of transport modes in india using dea and application to energy and environmental policy. journal of the operational research society, 2005, vol. 56, issue 6, pp. 732-7. https://doi.org/10.1057/palgrave.jors.2601866 [21] x. liu, s. ma, j. tian, n. jia, g. li. a system dynamics approach to scenario analysis for urban passenger transport energy consumption and co2 emissions: a case study of beijing. energy policy, 2015, vol. 85, pp. 253-70. https://doi.org/10.1016/j.enpol.2015.06.007 about assoc. prof. dr. houshmand masoumi assoc. prof. dr. houshmand masoumi is senior researcher at technische universität berlin, germany, and visiting associate professor at university of johannesburg, south africa. his research interest is urban transportation planning with a strong focus on statistical analysis of urban travel behavior including land use, socioeconomics, public health, and human perceptions. until mid-2020, he published about 70 scientific publications, most of which peer-reviewed journal papers. 26 http://dx.doi.org/10.21622/r http://dx.doi.org/10.21622/r http://apc.aast.edu/ http://apc.aast.edu/ https://doi.org/10.1016/j.enpol.2014.05.046 https://doi.org/10.1016/j.rser.2013.03.054 https://doi.org/10.1007/s11356-017-1072-1 http://dx.doi.org/10.7708/ijtte.2014.4(4).02 https://doi.org/10.1016/j.enpol.2013.07.007 https://doi.org/10.1016/j.trd.2016.08.009 https://doi.org/10.1016/j.habitatint.2011.12.008 https://doi.org/10.1016/j.tra.2018.03.013 https://doi.org/10.1057/palgrave.jors.2601866 https://doi.org/10.1016/j.enpol.2015.06.007 3paper1.pdf (p.11-13) journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 21 resd © 2018 http://apc.aast.edu a proposal for desert house design in egypt using passive ground cooling techniques prof. dr. mohamed medhat dorra1, assoc. prof. dr. hend el-sayed farouh2 and eng. lubna a. amer3 department of electrical power and machines engineering, tanta university, tanta, egypt 1professor of architecture, faculty of engineering, cairo university, giza, egypt. 2associate prof. of sustainable architecture & urban development, housing & building national research center, giza, egypt 3phd candidate, faculty of engineering, cairo university, giza, egypt hfarouh@imc-egypt.org, lamer@mdd-architects.com abstract an area less than 5.5% of egyptian territory is where most of egypt‘s population lives. a narrow strip of land forms the nile valley and delta sector. the national project for desert hinterlands is one of the urban projects targeting rehabilitation of the poor in alternative villages in the near desert to stop urban sprawl over agricultural land and decrease congestion in the old habitats. low cost energy efficient houses are the aim of the architect in similar projects taking in consideration the high electricity consumption of egypt’s residential sector. based on a literature review, this paper presents a proposal for designing desert dwellings that accommodate the hot dry climate by incorporating passive elements and using stabilized earth blocks as a local building material. furthermore, simulation is used to test alternative proposals. the results show that an underground constructed house with a sunken courtyard incorporating an earth to air heat exchanger system (eahe) can reduce between 4272% of energy consumption used to achieve thermal comfort compared to contemporary desert housing projects. keywords earth sheltered houses, earth to air heat exchangers, earth cooling tubes, low cost energy efficient desert house. i. introduction the need has arisen to undertake extensive projects for redistributing the population. the desert hinterlands villages is one of these projects to establish low cost desert housing. these projects should be low cost energy efficient to avoid the increasing energy demand due to cooling needs. farouh and amer [1] explored the main passive and hybrid design techniques for low cost energy efficient housing in hot arid climate. they highly recommended using the technique of “cooling by thermal earth inertia”. this was the starting point for this research in which an approach to implement these techniques was examined by computer modeling using design builder program experimenting a proposed earth sheltered building with a sunken courtyard and using underground earth tubes. 1. aim of the study the authors constructed this work on implementing passive ground cooling techniques as a proposal for enhancing thermal performance of desert houses in egypt. the aim is to examine the ability of this proposal in saving energy and achieving thermal comfort in low cost desert housing in egypt. 2. egypt’s background a quick look at egypt’s conditions related to our study. 3. egyptian electricity consumption the building sector consumes most of the electricity (see fig.1) due to the increased consumption of the air conditioning machines [2], [3]. http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ mailto:lamer@mdd-architects.com journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 22 resd © 2018 http://apc.aast.edu fig .1. egyptian electricity consumption the most consuming areas are the residential ones. the egyptian electricity holding company annual report 2009/2010. egyptian electricity holding company, cairo, egypt, 2010. fig .2. classification of aquifer depth in egypt. m. salim, selection of groundwater sites in egypt. journal of advanced research, 2012 fig .3. earth’s energy budget diagram showing the short-wave (a) and longwave (b) energy fluxes. banks, david. an introduction to thermogeology: ground source: heating and cooling. wileyblackwell, 2012. a. groundwater levels the ground water is found far below the ground surface in most egypt's desert area [4] (see fig. 2). therefore, excavations are implemented easily without the need for water proof materials. b. type of soil: most egypt's desert land is a sandy soil and easy to construct on. thermal characteristics of soil affect the underground temperatures, which is a major factor in energy saving by earth inertia as will be explained later. ii. literature review : passive ground cooling the concept of ground cooling is based on heat dissipation from a building to the ground which, during the cooling season, has a temperature lower than the outdoor air. this dissipation can be achieved either by direct contact of a significant areas of the building envelope with the ground (earth shelters), or by injecting air that has been previously circulated underground into the building by means of earth-toair heat exchangers (eahe). heat storage capacity of the earth subsurface the rocks at the subsurface have high value of volumetric heat capacity but low value of thermal conductivity. therefore, the heat is rather stored than diffuses through the soil in the upstream [5]. when averaged globally and annually, about 49% of the solar radiation striking the earth and its atmosphere is absorbed at the surface [6] (see fig. 3). 1. earth shelters researchers, including anselm [6], found that earth sheltered houses maintain heating energy consumption lesser by up to 75% compared to conventional above-ground house. a. definition earth shelters can be defined as structures built with the use of earth mass against building walls as external thermal mass [7]. b. potential energy savings: based on several physical characteristics: [9] • the reduction of heat loss due to conduction through the building envelope. • less heat conduction into the house due to reduced temperature differential. • building protection from the direct solar radiation. • the reduction of air infiltration within the dwelling. (a) one of the partially buried homes in siwa http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 23 resd © 2018 http://apc.aast.edu (b) aerial view of a typical matmata earth shelter dwelling. (c) a typical earth shelter home in north-western china (d) the goreme valley of cappadocia in central turkey fig .4. historical earth sheltered homes [8-10] c. historical background and examples earth sheltered homes were primarily developed for shelter, warmth and security for the earliest human dwellers. most of the recorded cases of these shelters are found extensively in areas like asia and northern africa. • in egypt: [8] such as: nazlet elsemman in giza (for historical conservation reasons), paris village in upper egypt & siwa oasis in western desert (for climatic protection reasons). • in tunisia: [dry desert climate]: residents of matmata and in bulla regia, use of the sunken courtyard concept [9]. • in china: [humid subtropical climate]: yaodongs cave houses carved out of a hillside or excavated horizontally from a central “sunken courtyard” an estimated 40 million people live in yaodongs [10]. • in turkey: the goreme valley of cappadocia [dry steppe climate]: 260km2 with 200+ underground villages complete with hidden passages, secret rooms and ancient temples (see fig. 4). d. typology • bermed earth shelter: earth is piled up against exterior walls and heaped to incline downwards away from the house. the roof may, or may not be, fully earth covered. other variations are the elevational and in-hill. as in turkey (see fig. 4). • envelope or true underground earth shelter: the house is built completely below ground on a flat site, with the major living spaces surrounding a central outdoor courtyard or atrium which provides light, solar heat, outside views, and access via a stairway from the ground level,as in tunisia and china (see fig. 4). about 50% of the elevational structures exterior façade is in direct contact with the earth mass, while the ratio is 80% of atrium design and hence becomes an underground building type which offers better indoor conditions for both summer and winter temperatures [8], [11]. e. worldwide earth sheltered houses: will be explored to explain the typology of earth sheltered houses and enrich the knowledge of key projects of these types. on the hillside bermed underground relation to surface openings chamber atrium elevational penetrational fig. 5. typology of earth sheltered buildings. source: hassan, h. analytical study of earth-sheltered construction and its suitability for housing projects in the egyptian deserts. thesis, egypt. 2009. http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 24 resd © 2018 http://apc.aast.edu table 1 . some worldwide earth sheltered housing units project ecology house marstons milss, massachusetts, usa,1972. architect john e. barnard jr. climate hemiboreal type notes one-fifth normal heating cost, 25% lower building cost, privacy from neighbors. project underground-house-welsh-coase druidston, pembrokeshire, uk, 1998. architect future systems climate maritime temperature type notes the basic design is: one room inside, divided by prefabricated colored pods. project a home built in a cave in missouri, usa. architect curt and deborah sleeper climate hot summer continental type notes this house was made in an existing cave in the small town of festus, missouri. project the earth house estate lättenstrasse dietikon, switzerland, 1993. architect peter vetsch climate tundra type notes the organic construction consists of shotcrete, with a 25 cm layer of polymer bitumen and recycled glass foam on top. http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://www.homedit.com/earth-house-by-peter-vetsch/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 25 resd © 2018 http://apc.aast.edu project underground-home. located in the swiss village of vals. architect search and christian muller architects climate tundra type notes the introduction of a central patio into the steep incline creates a large façade with considerable potential for window openings. project earthship prototypes architect michael reynolds climate implemented in many climates including hot desert and maritime temperature of london. type notes offgrid prototypes •constructed using cans, bottles and tires (reuse) with natural adobe materials. • heat and cool themselves naturally via solar/thermal dynamics • collect their own power from the sun and wind • harvest their own water from rain and snow melt • contain and treat their own sewage on site (water is used and reused at four cycles). project spiritual house| sevilla, spain, 1980. architect emilio ambasz climate dry-summer subtropical type notes an underground "canopy" of fiberglass panels extends horizontally as a ten-foot cornice from the wall's top to keep water from soaking the ground around the house. http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://earthship.com/blogs/author/biotecture/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 26 resd © 2018 http://apc.aast.edu project earth house republic of korea, 2009. architect byoungsoo cho, yangpyeong-gun, gyeonggi-do climate hot summer continental type notes used a geothermal cooling system with a radiant floor heating system under the rammed clay, concrete floor. project woodland home london, uk. architect reardon smith architects climate maritime temperature type notes skylight in roof lets in natural feeling light. project aloni house greece, 2008. architect decaarchitecture climate dry-summer subtropical type notes the house's sides disappear into the ground, blending the structure into the landscape. there are five internal courtyards, which flood the rooms with light and shield windows and doors from stormy rainwater. project bolton echo housenorth west england, uk, 2009. architect make architects climate maritime temperature type notes designed to consume less energy than it uses; a ground source heat pump, photovoltaic panels and a wind turbine will generate on-site renewable energy. http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 27 resd © 2018 http://apc.aast.edu project cooltek house in malacca, malaysia. climate hot humid type notes the original concept was to have the heat passively ventilated out by solar chimney and draw in the cooled air from ground cooled duct. project uk’s first earth-sheltered social housing scheme at honingham (harrall, j., 2007). climate maritime temperature type notes it comprises four two-bed, four-person, earth-sheltered, passive solar design (psd) bungalows. f. ventilation system and air infiltration: to avoid sick building syndrome and ensure a desirable and healthy environment, the underground building units are usually incorporated with various types of passive induced ventilation techniques [12]. g. advantages and disadvantagesadvantages: underground homes provide a safer living environment [13] [14], energy efficiency compared to aboveground homes [15] [16], reduced maintenance-operating costs, and construction efficiencies. in addition to minimal visual impact, dual land use, and lower noise [17]. disadvantages: social acceptance: golany stated that there are some social and psychological problems to overcome in earth-sheltering [18]. but al-mumin found that in kuwait the occupants agreed to live underground and sunken courtyards are preferred [19]. thus negative aspects could be avoided by a good efficient design and a sufficient exposure to sunlight through elevations or sunken courtyards. h. construction cost: al-mumin concluded that underground courtyard homes are almost the same if not less expensive than aboveground ones [19]. the reduction is due to savings in the exterior cladding, wall materials, and thermal insulation, we must consider the running costs and thus the sunken courtyard concept may win [20]. however, additional studies are needed to investigate and to prove this point. advantages disadvantages minimal visual impact lack of outside views * thermal efficiency public acceptance* increased open space & dual land use lack of thermal performance data lower noise higher excavation and structural costs reduced maintenance and operating costs water drainage safer living environment ventilation * construction efficiencies design constrains * reduced life cycle coasts (* ) means could be avoided by aspects of good design i. construction considerations • climate: in dry climates with high temperature extremes – as in egypt’s desert earth-sheltered houses can be more cost-effective [20]. • site’s topography and microclimate: flat sites – as in egypt’s desert is the most demanding for excavations [20]. • type of soil: sandy soils are the best for earthsheltered houses because they compact well for bearing the weight of the construction materials and allow water to drain quickly ,which protects the underground constructions [20]. • the groundwater level: underground water exerts pressure against underground bearing http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 28 resd © 2018 http://apc.aast.edu walls so it is important to build above the water table [20]. j. construction materials earth sheltered houses require heavy duty, more enduring construction materials that can resist the pressure and moisture of the surrounding ground [due to their good waterproofing and insulation properties]. concrete, reinforced masonry, steel, and wood can be suitable. in developing countries, local materials have been used widely for their advantages economically, ecologically, and good energy performance. examples are cob, adobe, straw bale, brick, wood, cordwood, and stone [21]. here’s some recently proposed materials for low cost housing in egypt: rice-straw based cement brick: the rice-straw has replaced part of the aggregates used in the normal cement brick to generate a stable blend after which mechanical and thermal experiments have been conducted [22]. it showed promising energy savings but this material is presented mainly as a solution for recycling rice wastes and has not been widely approached in egypt. “rammed earth” is constructed by using a pneumatic tamper to ram a mix of earth and cement, into wall forms to produce walls, foundations and floors. the soil should have some silt and clay to act as binders and allow soil compaction which are not available in desert soils as the case in this research. also, rammed earth cannot be used for constructing ceilings. actually there is a lack of knowledge and access to tools for using this material in egypt [23]. the compressed stabilized earth block using a steel press to compress the moisturized soil raw or stabilized-producing cseb blocks. sandy soil is more suitable than clayey one. cement is preferred as a stabilizer for sandy soils to accelerate the strength. the ratio of cement should be around 5%. a finished m3 of cseb masonry is always cheaper than fired bricks: 19.4% less than country fired bricks and 47.2 % less than wire cut bricks [24]. in addition to its advantages, stabilized earth blocks also introduce a solution for reusing the excavated soil from basement in underground courtyard homes so the research recommends stabilized earth blocks as a building material for earth sheltered houses in egypt’s desert. table 3. .advantages of “cseb”[24] a local material socially accepted flexible production scale a bio-degradable material an adapted material: produced locally cost efficiency a transferable technology energy efficiency and eco friendliness: the energy consumption in a m3 can be from 5 to 15 times less than a m3 of fired bricks. the pollution emission will also be 2.4 to 7.8 times less than fired bricks a job creation opportunity market opportunity: cheaper than fired bricks reducing imports k. underground courtyard houses [constructing case studies] the courtyard plan is best suited in flat terrain sites that have permeable, dry or welldrained soils which are far from a ground water source [27] with reference to the traditional underground building which is constructed in arid climatic regions. some do not even require any supporting walls because of the land conditions [12]. this is the case in egypt’s desert. underground courtyard type is represented in historic underground homes and there are fewer examples of contemporary ones. http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 29 resd © 2018 http://apc.aast.edu in the next table 4, some underground courtyard houses will be shown. they are classified according to the courtyard number in each house and its proportions. consequently, design guidelines will be deduced in order to help in constructing research case studies later. table 4. sunken courtyard house examples and types project plans and sections s h e lt e re d a re a m 2 c o u rt y a rd a re a m 2 c o u rt y a rd a re a / s h e lt e re d a re a % c o u rt y a rd w id th / l e n g th % courtyard typology underground house, southern tunisia 82 66 80% 1:1.25 underground house, source: [9] 56%* 1:3.25* sunken courtyard by: gestalten, melbourne, australia http://www.archdaily.co m/259160/sunkencourtyard-gestalten 73 30 240% 1:2.5 underground house, source: [9] 132.5 52 40% 1:1.2 a typical earth sheltered home , northern western china 170%* 1:1.25* earth house by bcho architects, seoul, korea. 32.5 69.5 210% 1:1.15 casa de retiro espiritual by emilio ambasz, spain 280 173 62% 1:1 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 30 resd © 2018 http://apc.aast.edu source: unknown 180 36 20% 1:1 clark house, oregon, usa. norman clark 1977 ( sterling, r.,et al.) 190.5 41 21% 1:1.1 an underground house, uk architect: journeyman draughting + design http://plans-designdraughting.co.uk/recentprojects/ 190 75 40% 1:1.6 the national project for desert hinterlands villages, egypt aswan prototype** 85 48 56% 1:1.5 1:1.15 the national project for desert hinterlands villages, egypt fayoum prototype** 105 55 52% 1:1 1:1.5 note: * concluded from the plans’ drawings ** above ground prototypes from the national project for desert hinterlands villages, egypt as guidelines for houses needs in egypt. source: researcher from the scanning of habitable underground houses the researchers concluded that there are three courtyard types: • one square courtyard type. (recommended a 40m2 court for 80-120 m2 earth sheltered area) • one rectangle courtyard type with aspect ratio 1:1.25. • multiple courtyards (two or three) with aspect ratio ranging from 1:1 to 1:1.6. from the previous literature eight residential building types were proposed taking into consideration the low cost egyptian rustic dwellings’ needs, with the following criteria: • low rise. (one or two floors). [in order to measure the influence of coupling the building with the ground on the thermal performance of the house] • have an internal court. (from literature: most appropriate for underground houses in desert climate). • low cost. (rural house). • (area from 70 to 150 m2 + using local materials and local building roofing techniques such as domes and volts). the researchers also authenticated the zero-level in all the eight cases due to building services issues. placing the building services at zero level to avoid using a sewage pump for sewage disposal, which represents a non-affordable cost for low cost houses. http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 31 resd © 2018 http://apc.aast.edu fig. 6. deduced eight types of courtyard houses which represent the case studies source: researchers. 2. the principle of ground cooling by indirect contact: a long buried pipe – at a calculated depth for best efficiency that have an end for fresh outside air intake and the other end for inside cooled air released in the building, this is the main idea of the earth pipe cooling system. this system uses the ground as a heat sink for cooling in warm countries where the intake air, in the buried pipe, loses excess heat to the earth by convection. adequate air flow into the buried pipe is a must to get cooled air for occupants’ thermal comfort. a fan blower is needed at air intake if there is deficiency in air flow a. factors that affect earth pipe cooling performance as a conclusion from various published literature, the performance of earth pipe cooling are affected by four main parameters and they are: • pipe length: a parametric study using different pipe lengths : 10m, 30m, 50m,70m, 90m concluded that the longer the pipe, the better the performance of the earth tube [28], [29]. • pipe radius or diameter: the smaller the radius of the pipe the more decreased inlet temperature. • depth of the pipe inserted into the ground: as the pipe depth increases, the inlet air temperature decreases in all climate conditions [28]. • air flow rate inside the pipe: as the air flow rate increases, the inlet air temperature increases [28], [31] and the coefficient of performance (cop) reduces [32] (see fig. 7). other factors that could affect the performance of earth pipe cooling system is • the surface condition of the ground: bare or shaded. • soil type: sandy soil is much preferable than other soil types [33]. • the choice of pipe materials: different pipe materials have minor effects on the earth pipe cooling system performance [34]. b. application of earth pipe cooling models of earth to air heat exchanger system (eahe) made of low cost material like pvc pipes and exhaust fans a duct system suitable for small houses have been examined. models show [35] temperature reduction of 10-15ºc than outside during summer. this system can effectively reduce the energy consumption between 50 % and 60 %, which is consumed by building cooling (air conditioning) and warming systems. cop is a term used in refrigeration and air conditioning to describe the performance of a system. normally, heating and air conditioning systems have average year-round cops of about 2.0. the cops of the systems utilizing underground air tunnels are much higher. for open and closed loop systems, the cop can be as high as 10 [33]. http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 32 resd © 2018 http://apc.aast.edu the higher the cop, the higher the efficiency of the equipment [29]. table 5. some applications of earth pipe cooling [29] researcher location buried pipe design ambient t, °c energy saving goswami and biseli (summer, 1993) florida, usa 0.305m dia, 30.5m long pipe. 2.7m deep. 0.184kw fan blower and 2 ½ ton heat pump summer:23.9°c to 33.1°c open loop cop= 12 cop (air-cond) = 1 to 4 with heat pump cop = 13 pfafferott (2003) db netz ag cop = 88 fraunhofer ise cop = 29 lamparter cop = 380 c. limitations the risk of condensation in the buried pipe: to avoid his problem the pipe may be tilted slightly to allow the water condensed to drain away through a tiny hole [30], [37]. this is a preference to the arid climate of egypt. d. hybrid design for enhancement of ground cooling system maerefat and poshtiri introduced and investigated integrated eahe-sc system. they showed that the solar chimney can be perfectly used to power the underground cooling system during the daytime, without any need for electricity [39]. the air is heated up in the sc by the solar energy, and by natural convection mechanism the outside air is sucked-in through the earth–air pipe. fig. 8: schematic diagram of integrated earth to air heat exchanger and solar chimney (maerefat, m., poshtiri, a., 2010) poshtiri, et al., [40] examined sc-eahe system. the results show that proper configurations could provide good indoor condition even at poor solar intensity of 100 w/m2 and high ambient air temperature of 50oc. comparative survey shows the sc-eahe system is the best choice for buildings with poor insulation at day time. hammadi and mohammed investigated the solar chimney (sc) together with earth to air heat exchanger (eahe) as a low-energy consuming technique. a numerical program "fluent 6.3 code" of an earth to air heat exchanger (eahe) was used for predicting the outlet air temperature and cooling in le t t e m p . pipe length pipe radius depth of the pipe air flow rate fig. 7. factors that affect earth pipe cooling performance [28] http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 33 resd © 2018 http://apc.aast.edu potential of these devices in basrah climate which is hot arid. theoretical analyses have been conducted to investigate the ventilation in a solar chimney [41]. the results have shown significant temperature reductions at the buried pipe outlets from their inlets. maximum temperature drop through the buried pipe was found to be 11ºc. in both seasons. the performance of the buried pipe increases with increasing pipe length only up to 70m and with small pipe diameters and the best velocity is 1 m/s. e. geothermal energy researches in egypt hassan and el-moghasy, carried their field experiments using air as the working fluid in a pipe-air cooler. the results showed a reduction of the air temperature of about 12°c when it flowed for 50m of the pipe-air cooler when the inlet air temperature and relative humidity of 35, and 30%, respectively [42]. ali, m. investigated experimentally the effect of the layout of the horizontal ground heat exchanger using water instead of air from being straight or spiral [43]. the results showed that the effect of depth of the amount of heat extracted by the straight heat exchanger is weak when compared with that of the entering water temperature; both of the previous works were laboratory based ones. the real systems did not exist and it is required to have further research in which the real circumstances and actual systems are utilized. 3. computer modelling a wide range of scientifically validated building performance simulation tools bps is available internationally. attia mentioned ten major bps tools: ecotect, heed, energy 10, design builder, equest, doe-2, green building studio, ies ve, energy plus and energy plus-sketch up plugin (open studio) [25]. energy plus which will be used as a simulation tool in this research was developed based on two existing programs: doe-2 and blast. it includes a number of innovative simulation features [26]. 4. soil temperatures it is essential when researching the earth sheltered buildings or the (eahe) system to calculate the ground temperature of the location because it strongly affects the performance of these systems. [38] heat transfer in soils is governed by a number of variables which tend to fluctuate according to the changes in moisture content and other soil texture, structure and composition parameters. several mathematical models were developed to evaluate the temperature of the ground, such as those of morland, kusuda, and labs [45]. their models present a solution of the equation of heat transfer of a semi-infinite solid whose variation in the external temperature is sinusoidal. moustafa et al, ben jmaa and kanoun, al-ajmi et al., sharan and jadhav, ogunlela, mihalakakou et al, altemeemi a.,and harris d.j., gouda, a., nofziger, d. all worked to develop an empirical model for the prediction of soil temperature as a function of soil depth and time of the year and generate a subsurface temperature profile for various locations around the world using labs equation [11], [32], [44-51]. to evaluate the temperature of the ground, the soil is regarded as a semi-infinite solid. it is expressed according to the depth and time. labs equation predicts the long-term annual pattern of soil temperature variations as a function of depth and time for various soil properties. table 6: lab’s equation variables: [11] t(x,t) temperature of soil at depth x and on day t of the year (oc) x depth below surface [m] t time of year in days (jan 1 = 1) tm mean annual ground surface temperature (oc) [adding 1.7 to the average annual air temperature]. t0 the phase constant, [corresponding to the day of minimum surface temperature (days) the phase of the solar radiation wave lags behind the cyclic wave of the surface temperature by 1/8 of a cycle or 46 days]. as amplitude of surface temperature wave (oc). [adding half of the difference between july and january average monthly air temperatures+ 1.1oc] e euler's number ( constant) = 2.71828 α the thermal diffusivity of the soil (m2/day) [by dividing k (conductivity w/mk) over [p (soil density kg/m3) multiplied by c (specific heat j/kgk)]. [α= k/pc] [11]. http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 34 resd © 2018 http://apc.aast.edu iii. methodology for the proposed eight residential types [r1-r2……r8] (see fig. 6), a one zone building [the house can be considered as one zone due to assumed sufficiently uniform thermal conditions, source: iso 52000-1:2017] will be simulated using energy plus/design building program to measure: yearly discomfort hours for unconditioned cases and energy consumption assumed condition cases, as follows: 1. design variables: • location template, two options of the cities’ weather files inputs (aswan and ismailia). • orientation: 0° – and 90°. • building level: with two options: above ground or underground. • earth air tubes: with two options: yes or no. for each specific building type and orientation there are four plans or (arrangements): 1(po): above ground. 2pa): aboveground + eahe. 3(pb): underground with 0.50 m earth layer above it 4(pc): underground + eahe. 2. building specifications: occupancy density (m2/pp.) 20m2/pp number of floors 1 height per floor 3.5 table 7: openings & r values: (according to the egyptian energy efficiency code for buildings) elevation wwr r value north ≤30% 1.00 east & west ≤20% 1.3 south 20-30% 1.00 table 8: building activity options, assumed activity domestic lounge density 0.08 p/m2 heating set point temp. 21 heating setback temp. 12 cooling set point temp. 25 cooling setback temp. 28 target illuminance (lux) 150 computer & cattering on table 9: building assemblies, assumed note: bottom and vertical boundary conditions were set at the edges of a domain 15 m under a slab and next to the walls. it follows the hints of the european standard en iso 13370 “thermal performance of buildings – heat transfer via the ground – calculation methods”. above ground walls cement plaster .025m brick burned 0.12m cement plaster .025m u value : 2.6 w/m2k underground walls compressed cement stabilized earth blocks (cseb).5% cement. 0.12m bitumen pure 0.025m compressed cement stabilized earth blocks (cseb).5% cement. 0.05m cement plaster 0.025m u value : 0.76 w/m2k above ground building floors concrete tiles 0.02m cement plaster 0.025m sand and gravel 0.05m reinforced concrete 0.12m gypsum plaster 0.025m u value : 3.13 w/m2k above ground building roofs plaster ceiling tiles 0.02m sand and gravel 0.05m cast concrete 0.075m bitumine 0.02m (cseb).5% cement. 0.14m gypsum plaster 0.025m u value : 1.38 w/m2k http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 35 resd © 2018 http://apc.aast.edu table 10. used building material used building material walls roofs λ(coefficient of conductivity) compression strength tensile strength compressed cement stabilized earth blocks (cseb).5% cement. 24*24*13 cm blocks 14*7*7cm blocks for domes and vaults. 0.65 w/m oc 6mpa 1.5mpa notes source: [52] 1mpa = 10 kg/cm2 table 11. glazing type, assumed window type blends wwr window height still height window spacing frame shgc and sgr single clear 0.006m glazing internal blends 30% 1.50m 0.80 5.00 painted wooden don’t count 3. eahe simulation inputs table 12. variables of eahe system, assumed. values schedule name fan blower 24 hours design flow rate 0.0334m3/s min. zone temp. when cooling 20oc max. zone temp. when heating 30oc earthtube type intake fan pressure rise 520 pascal fan efficiency 0.85 pipe radius 0.15 m pipe thickness 0.01 m pipe length 30m pipe thermal conductivity 0.19 w/mk (pvc), pipe depth under ground surface 4m soil condition light and dry average soil surface temp. 24.9oc (at 4m depth) amplitude of soil surface temp. iv. results 1. underground and air temperatures using labs’ equation underground temperatures were calculated for the whole year for depths (0.5m, 2m, and 4m) which is very important for subsurface buildings simulations. max av. air temp. in aswan reaches 42°c in june while min. av. descends to 10°c in january with 32°c range. while at depth 4m temp. ranges from 25°c and 29.8°c with only 4.8°c range. in ismailia this range is also only 4°c. table 13. variable used for aswan soil temp. calculation variables calculated values for aswan tm 27.45oc as 10.6oc. t0 day 36. α 0.064 table 14. variable used for ismailia soil temp. calculation variables calculated values for ismailia tm 23.18oc as 8.96oc. t0 day 65. α 0.064 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 36 resd © 2018 http://apc.aast.edu fig.10. average monthly temp. compared to calculated soil temp.in aswan source : researchers fig. 11: average monthly temp. compared to calculated soil temp.in ismailia source : researchers 2. thermal comfort analysis and comparisons thermal comfort was monitored in simulated eight types (r1….r8) two orientations each per each of the four plans or (arrangements): po, pa, pb, pc by calculating yearly discomfort hours as an indication for thermal comfort as there is counter relation between discomfort hours and thermal comfort. yearly discomfort hours reached 2193h in above building base case in aswan [plan (po) for type r6] and min. of 1291h in [plan (pc) for type 3] which is an underground building with a eahe. in ismailia yearly discomfort hours reached 2351h in plan (pb) (underground building for type r6) and min. of 850h in [plan (pc) for (type3)], which is an underground building with an eahe. in both aswan and ismailia: the average readings point out that above ground (po) are the highest discomfort hours, while underground with eahe are the least. meanwhile underground (pb) in ismailia showed rise in discomfort hours due the time lag which needs further research and simulation (see fig. 12). fig. 12. yearly discomfort hours [ measured for the four plans(arrangements): (o-a-b-c)] source: researchers http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 37 resd © 2018 http://apc.aast.edu 3. energy consumption was monitored in simulated eight types (r1….r8) two orientations each per two plans or (arrangements): plan po [aboveground building with common building specification in new urban settlements in egypt] and plan pb [underground building with proposed (cseb).5% cement construction], both plans were assumed to be full conditioned in order to be able to calculate energy consumption to reach comfort conditions. energy consumption reached 343 kwh/m2 in the above building base case (r6 type-d2) in aswan and min. of 104 kwh/m2 in plan (pb) (r3 type-d2). in ismailia yearly energy consumption 187.5 kwh/m2 in above building base case (r6 type-d2) and reached 42 kwh/m2 in plan (pb) (r3 type-d2). note: all calculations were made for both building directions 0 & 90 for each eight building types for each city climate with a total of 96 readings. fig. 13. energy consumption to reach thermal comfort [measured for the two plans: [p (ob)]. source: researchers v. discussion and conclusion as mentioned before, calculated underground temperatures for both aswan & ismailia showed a sinusoidal behavior and the cyclical temperature wave that becomes more flat with the increases in depth. ismailia has more time lag (65 days) than aswan (36 days). for all eight types r1-r8, and two building orientations d1& d2 the researchers can conclude that: • in aswan discomfort hours decrease between 28% and 34% in the above ground building plan (po) compared to the underground building with an eahe plan (pc), while energy consumption decreases between 42% and 53% for the previous comparison. • in ismailia discomfort hours decrease between 24% and 29% between the above ground building plan (po) and the underground building with a eahe plan (pc), while energy consumption decreases between 57% and 72% for the previous comparison. in plan [arrangement (pb) (underground without eahe)], it is noticed that discomfort hours are the highest although there is less energy needed to achieve thermal comfort (see. fig. 13). this may be due to long time lag, which indicates that the earth keeps and loses the heat delayed 65 days than aboveground ambient air, which causes more discomfort hours while the standard deviation in temperature differentiation between aboveground and underground is small so that energy needed to achieve comfort is still low. (so further investigations on other climate regions within egypt are needed to prove these assumptions). vi. conclusion • the research concludes that earth-sheltered courtyard house constructed using cseb and combined with an eahe system is one of the promising passive solutions for saving energy in desert houses in egypt. • energy consumption in ismailia is more than in aswan due to the higher time lag between ground temperature and air temperature. http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 38 resd © 2018 http://apc.aast.edu • best case for aswan with maximum decrease in both discomfort hours and energy consumption is r3/d2, which is the max in the compacted plan. • ismailia’s best case is r6/d1, which has the max. area contact with earth. fig. 14: % decrease in energy consumption (% difference between plan po& pb) for the two directions of the eight types. source: researchers vii. research recommendations taking into account the arid climate, the dry soil, the deep ground water levels of egypt’s desert and the need for low cost energy efficient housing; a design proposal is presented according to the research: • locating the building underground level with 0.50 m earth layer above it, (this protects the roof from direct solar radiation while decreasing the dead loads on the roof). • using sunken courtyard about 40 m2 with buried area 80-120 m2 to provide ventilation, light, solar heat, outside views, and access via a stairway from the ground level. • the research recommends stabilized earth blocks as a sustainable low cost material that also helps to reuse the excavated soil resulted from basements with dome and vaults for roofing. • locating the service area above ground level can avoid using pumps for sewage. • using an (eahe) system with cheap irrigation tubes placed in the building foundations or on the underground bearing walls will be cost effective because the digging cost will be avoided as the basement was already dug. • the soil surface to be shaded or vegetated to obtain cooler soil temperature for better energy performance. • calculating ground temperatures using labs' equationis essential when modeling the efficiency of the underground house. • compact underground building is more effective in aswan, while more building earth contacted areas is more efficient in ismailia. • future detailed studies for more cities with different weathers in egypt are recommended. • further structural, economical, architectural refinements and users’ acceptance studies for the suggested building types are recommended. • the researchers recommend further studies on integrating sc with eahe system in earth sheltered homes. references [1] h. farrouh, h. and a lubna. “passive and hybrid techniques for low cost energy efficient housing in hot dry climate,” azhar university magazine, egypt, vol. 11, no. 41, pp. 1265-1274, 2016. [2] the egyptian electricity holding company annual report 2009/2010, egyptian electricity holding company, cairo, egypt, 2010, pp. 1-48. [3] m. ali . “modelling the performance of horizontal heat exchanger of ground-coupled heat pump http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 39 resd © 2018 http://apc.aast.edu systems with egyptian conditions,” university of manchester, 2013. 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[25] s. attia, et al. “architect friendly: a comparison of ten different building performance simulation tools," 11th ibpsa building simulation conference. glasgow, scotland, 2009. http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 40 resd © 2018 http://apc.aast.edu [26] d.b. crawley, et al. “energy plus: creating a new-generation building energy simulation program,” energy and buildings, vol. 33, no. 4, pp. 319–331, 2001. [27] a.a. al-temeemi and d.j. harris. “the effect of earth-contact on heat transfer through a wall in kuwait,” energy and buildings, vol. 35, no. 4, pp. 399–404, 2003. [28] k.h. lee and r. strand. ”implementation of an earth tube system into energy plus program,” energy and buildings, vol. 40, 2006. [29] a. sansui. “low energy ground cooling system for buildings in hot and humid malaysia,” de montfort university, malaysia, 2012. [30] m. santamouris, et al. “use of buried pipes for energy conservation in cooling of agricultural greenhouses,” solar energy, vol. 55, no. 2, pp. 111–124, 1995. [31] v. bansal and j. mathur “performance enhancement of earth air tunnel heat exchanger using evaporative cooling,” international journal of low-carbon technologies, vol. 4, pp 150158, 2009. [32] g. mihalakakou, et al. “parametric prediction of the buried pipes cooling potential for passive cooling applications,” solar energy, vol. 55, pp. 151-234, 1995. [33] a.k. misra, et al. “design and performance evaluation of low cost earth to air heat exchanger model suitable for small buildings in arid and semi-arid regions,” ksce journal of civil engineering, vol. 19, no. 4, pp. 853–856, 2014. [34] d.y. goswami and k.m. biseli. use of underground air tunnels for heating and cooling agricultural and residential buildings. fact sheet ees 78, pp. 1-4., florida energy extension service, university of florida, 1993. infohouse.p2ric.org/ref/08/07683.pdf&p=devex, 5066.1. [35] t. choudhury and a.k. misra. “minimizing changing climate impact on buildings using easily and economically feasible earth to air heat exchanger technique,” mitigation and adaptation strategies for global change, vol. 19, no. 7, pp. 947–954, 2013. [36] j. pfafferott. “evaluation of earth-to-air heat exchangers with a standardised method to calculate energy efficiency,” energy and buildings, vol. 35, no. 10, pp. 971–983, 2003. 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[45] m. derradji and m. aiche. “modeling the soil surface temperature for natural cooling of buildings in hot climates,” procedia computer science, vol. 32, pp. 615-621, 2014. http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.021 41 resd © 2018 http://apc.aast.edu [46] h.b.j. derbel and o. kanoun. “investigation of the ground thermal potential in tunisia focused towards heating and cooling applications,” applied thermal engineering, vol. 30, no. 10, pp. 1091–1100, 2010. [47] f. al-ajmi, et al. “the cooling potential of earth†air heat exchangers for domestic buildings in a desert climate,” building and environment, vol. 41, no. 3, pp. 235–244, 2006. [48] sharan, et al. “soil temperatures regime at ahmedabad.” econpapers, 2 nov. 2002, econpapers.repec.org/repec:iim:iimawp:wp000 50. [49] a.o. ogunlela. “modeling soil temperature variations,” journal of agricultural research and development, vol. 2, no. 1, pp. 100-109, 2009. [50] a. gouda. “using of geothermal energy in heating and cooling of agricultural structures,” benha university, 2010. [51] d.l. nofzigerd. “soil temperature changes with time and depth theory.” http://soilphysics.okstate.edu/software/soiltem perature/document.pdf, 2003. [52] editor in chief: a.m. bauchard. “compressed stabilized earth blocks,” auroville earth institute, india, 2012. • list of figures fig.1: egyptian electricity consumption (most consuming) is the residential. the egyptian electricity holding company annual report 2009/2010. egyptian electricity holding company, cairo, egypt, 2010. fig.2: classification of aquifer depth in egypt. source: m. salim, selection of groundwater sites in egypt. journal of advanced research, 2012. fig.3: earth’s energy budget diagram showing the short-wave (a) and long-wave (b) energy fluxes. source: banks, david. an introduction to thermogeology: ground source heating and cooling. wiley-blackwell, 2012. fig.4: historical earth sheltered homes. source: b. rudofsky. architecture without architects. doubleday & company, 1964. a. jideofor. “earth shelters; a review of energy conservation properties in earth sheltered housing,” energy conservation, pp.127, 2012. c. von dronkelaar. underground buildings. thesis / university of technology eindhoven, 2013. fig.5: typology of earth sheltered buildings. source: h. hassan. analytical study of earth-sheltered construction and its suitability for housing projects in the egyptian deserts. thesis, egypt. 2009. fig.6: deduced eight types of courtyard houses which represent the case studies source: reasearchers. fig.7: factors that affect earth pipe cooling performance. source: k.h. lee and r. strand. ”implementation of an earth tube system into energy plus program,” energy and buildings, vol.40, 2006. fig.8: schematic diagram of integrated earth to air heat exchanger and solar chimney. source: m. maerefat and a. poshtiri, 2010. fig.9: a.r1 model in energy plus program, b. r1-r8 house types source: researchers. fig.10: average monthly temp. compared to calculated soil temp. in aswan. source: researchers. fig.11. average monthly temperatures compared to calculated soil temp.in ismailia. source: researchers. fig.12: yearly discomfort hours [measured for the four plans (o-a-b-c)] source: researchers. fig.13. energy consumption to reach thermal comfort [measured for the two plans, p (ob)]. source: researchers. fig.14: % decrease in energy consumption (% difference between plan po& pb) for the two directions of the eight types. source: researchers. http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://dx.doi.org/10.21622/resd.2018.04.1.021 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 2, december 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.2.065 65 resd © 2018 http://apc.aast.edu detectable system of resistance of vertimec (abamectin) within the two-spotted spider mite, tetranychus urticae koch rania ahmed abd el-wahab plant protection research institute, agricultural research center, egypt rania-proline@hotmail.com abstract augmented resistance of pesticides remains a principal issue for unsatisfactory impacts on the environment. so, there is a need to distinguish it faster by innovated devices and then find effective tools to reduce it as soon as possible, especially for mites such as tetranychus urticae. detectable tools, which are powered with solar energy, were used to discover vertimec resistance depending on the assurance of the changes of electromagnetic field forces in comparison with sensitive mites. acquired results with certain differences of electromagnetic forces were affirmed by evaluation of resistance proportions (rrs) which recorded 8.52and 4.53 folds for resistant strains of vertimec (abamectin) on cotton and soybean, respectively, upon vertimec lc50s. furthermore, they were 5.97and 4.29folds for field vertimec strains on cotton and soybean, respectively. however, there were no significant differences between resistan and field strains; they appeared in comparing the mentioned strains with susceptible mites. it may be well concluded that pesticides’ resistance is now available to be detected by utilizing a simple and quick framework in the field. keywords detector, electromagnetic, tetranychus urticae, resistance and vertimec. i. introduction resistance of pesticides is an essential subject particularly when it is related to the two spotted spider mite, tetranychus urticae. it is vital to take the most important components of climate changes as top priority when resistance is the issue which agriculturists should give a hand to. in egypt, with elevated ratios of co2 and uv pro rata with pesticides’ resistance specifically of spider mites, it is difficult to control them with pesticides (nahar et al. 2005) due to their short life cycle, reproduction high capacity, and ability to create protection from miticides (georghiou 1990). even with the broad utilization of chemical pesticides, pests existed a noteworthy explanation behind crop production calamity worldwide. common used pesticides caused numerous ecological, agricultural, medical, and financial problems. imperatively, development of resistance occurred as a result of the overwhelming utilization of synthetic insecticides and the selection pressure on insects and mites. particular metabolic pathways utilized by insects to change over hindrances into less poisonous structures or their expulsion from the framework are featured. utilizing the proteomics approach, responsible proteins affected by pesticides in insects and then their alterations by pesticides’ resistance could be distinguished (dawkar et al., 2013). the available tool to assay pesticides’ resistance is depending on immunochromatographic dip-stickformat kits. they were created to distinguish resistance to carbamates and organophosphates and others. strips were upon polyclonal antisera versus resistance of pesticides which are related to esterase isozymes isolated from insects. they were simply used by farmers anywhere (kranthi, 2005), but the problem which is related to cost and accuracy still exists. using electromagnetic fields as traps or even to attract or eject pests, is an ordinary known process. it was started by gerharz (1991) who situated the electromagnetic field nearby or in a pest control. a gadget was chosen from the gathering comprising insect traps, insect teasing stations containing a pest poison, and pointer stations. for instance, a wide assortment of regular pest traps for slithering insects could be retrofitted with an electromagnetic field generator. devices could have the generator to a focal area of a trap with an electromagnetic field generator, contained or not, a chemical or biological attractant. http://dx.doi.org/10.21622/resd.2018.04.2.065 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 2, december 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.2.065 66 resd © 2018 http://apc.aast.edu so, there is a need to get a priceless device that would be able to get fast and accurate results to help farmers to discover the problem in the beginning before its development. in the same time, there will be a new use of electromagnetic fields to detect pesticides’ resistance in order to protect the environment of more quantities of acaricides. mites with certain changes in their bodies provided electric changes and then with the present magnetism in the instrument, electromagnetics field are available to react effectively with exposed mites. nevertheless, resulted electromagnetic fields’ forces and their axis graph magnetic meter were assessed by the innovated instrument in order to detect pesticides’ resistance easily and vastly as presented in this paper. ii. materials and methods • innovated instrument components: the prototype of the instrument is shown in image (1) with all of its components: a solar panel with its attachments and a dc-motor. electromagnetic field resulted from two magnets and with the passage of electric current, the required field was gained. whenever the current is gone through mites, the electrophysiological differences appeared in changes of voltages at lcd monitor. microcontroller system (pic16f627a) was used to detect the resistance through electrochemical changes in the resistant strain in comparison with the other sensitive one. the sensor, ugn3503u was used to determine the magnetic field strength and varying voltage provided at output proportions which are picked up to the fielstrength. also, electromagnetic interference (emi) detector was attached to the present circuit to provide and confirm accurate readings of the final electromagnetic field strength. comparison appeared in the magnetic field force and the current conductance with attention to any differences in food resource, weather conditions, etc. • maintenance of tetranychus urticae strains: 1. susceptible strain colonies of the spider mite, t.urticae were raised under lab conditions (25±20c, 60±5%rh and 12 hours light/12 hours dark) at plant protection research institute for several years without exposure to any contaminations or pesticides. image (1) instrument prototype parts: 1-solar panel 2-container of battery, microcontroller system (pic16f627a), ugn3503u, emi and others 3-power 4blue light emitting diodes (leds) 5red light emitting diodes (leds) 2. resistant strain original colony of the spider mite, t.urticae was set up from mites gathered from castor oil plants without exposing to pesticides. it was raised under laboratory conditions (25±20c, 60±5%rh and 12 hours light/12 hours dark) to assess the action of vertimec (abamectin 18 g lˉ¹ ec) against t.urticae grown-up females. the leaf-dip technique presented by dittrich (1962) was utilized. all treatments were done under laboratory conditions and each was replicated thrice . likewise, control discs were dipped in water only. mortality percentages were determined and corrected by using abbott's formula (1925). pooled data were subjected to probit analysis (polo pc) (leora software, 1994). the original strain females were selected for vertimec for 20 generations according to yang et al. (2002) with some modifications. 1000 adult females of this colony started this selection. every two generations, lc50s and lc90s were evaluated. new lc50 was applied as subsequent selection pressure. the next selection transferred to untreated leaves. lc50 estimations of the selected strain were compared to those of the susceptible strain. lc50 of field colony was got after exposure to the recommended concentrations of vertimec under certain values of uv and co2 which interacted with sprayed pesticide on infested cotton and soybean with t.urticae. then, the resistance ratio (rr) was computed. field colony was got after exposure to the recommended concentrations of vertimec under certain values of uv and co2 which interacted with sprayed pesticide on infested cotton and soybean with t.urticae. http://dx.doi.org/10.21622/resd.2018.04.2.065 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 2, december 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.2.065 67 resd © 2018 http://apc.aast.edu • determination of electromagnetic fields: samples of t.urticae, about 100 adult females, were placed inside the instrument. resistan and field strains were compared with the control which was reared on cotton and soybean leaves. differences of electromagnetic fields’ forces and axis graphs appeared and were recorded by the microcontroller system. • data analysis spss (v.16) was used to show differences among resistant, field and susceptible strains under electromagnetic’ forces instrument. jonckheereterpstra test, friedman test, kendall’s w and others were used to test significance between resistance and susceptible cases at probability with 5% and 1%. iii. results and discussion data revealed that strength of electromagnetic fields was changed particularly with significant differences between resistant and susceptible mites as appeared in figure (1). direct determination recorded high strength of electromagnetic fields in case of resistant mites to vertimec on cotton followed by resistant strain on soybean with 45.37 and 28.14 g, respectively.0020 therefore, there were specific differences in axis graph magnetic meter resulted of electromagnetic fields through both resistant and susceptible of adult females of t.urticae on certain crops as appeared in figure (2). jonckheere-terpstra test showed that std. deviation of j-t statistic=.957* among grouping variables of mites. therefore, both chi-square and median were =3.000a and 28.140 a. while, kruskal-wallis test showed that chi-square=2.000 b at 5%. proximity matrix proved that a dissimilarity matrix with 51.587 as euclidean distance among variables while a similarity matrix was determined by the correlation between vectors of values was -.997. fig .1. force of resulted electromagnetic fields through both resistant and susceptible of adult females of t.urticae on certain crops fig .2. axis graph magnetic meter resulted of electromagnetic fields through both resistant and susceptible of adult females of t.urticae on certain crops subsequently, toxicity of vertimec was compared both of field and resistant strains with the susceptible strain of t.urticae on cotton. whereas, lc50 values were 1542.91, 1915.47and 258.45µll¯¹, respectively, which showed that lc50 of cotton field strain exposed to moderately levels of co2 and uv recorded so close value to that of 20th generation of the laboratory resistant strain. the same situation was in the case of lc90's which recorded 14207.39, 16328.37and 1420.74µll¯¹, respectively. relative to the laboratory strain (s), the resistant ratios (rr) to vertimec for t.urticae laboratory resistant strain and field strain, shown at table (1). rr's at vertimec lc50's were 5.97folds and 8.52folds, respectively. the same trend occurred in case of assessment of vertimec resistance in t.urticae strain on soybean. data showed that lc50 values were 4013.25, 4220.17 and 198.82 µll¯¹, respectively, which showed that lc50 of cotton field strain exposed to moderately levels of co2 and uv recorded a so close value to that of 20th generation of the laboratory resistant strain. the same situation was in the case of lc90's which recorded 17210.74, 19102.35 and 780.34 µll¯¹, respectively. relative to the laboratory strain (s), the resistant ratios (rr) to vertimec for t.urticae laboratory resistant strain and field strain are shown at table (1). http://dx.doi.org/10.21622/resd.2018.04.2.065 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 2, december 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.2.065 68 resd © 2018 http://apc.aast.edu rr's at vertimec lc50's were 5.97folds and 8.52 folds, respectively. the same trend occurred in case of assessment of vertimec resistance in t.urticae strain on soybean. data showed that lc50 values were 4013.25, 4220.17 and 198.82 µll¯¹, respectively, which showed that lc50 of cotton field strain exposed to moderately levels of co2 and uv recorded a so close value to that of 20th generation of the laboratory resistant strain. the same situation was in the case of lc90's which recorded 17210.74, 19102.35 and 780.34 µll¯¹, respectively. relative to the laboratory strain (s), the resistant ratios (rr) to vertimec for t.urticae laboratory resistant strain and field strain are shown at table (2). rr's at vertimec lc50's were 4.29folds and 4.53folds, respectively. according to hayashi scale (1983), rrs of both strains resistant to vertimec lc50, infested cotton and soybean, could be ranked as low resistance. friedman test proved the highest significant effect of certain crops on lc50s values at 1% (chi-square =12.684**). kendall's coefficient of concordance (kendall's wa) = .705** with highly significant chisquare =12.684 at 1%. table 1. assessment of vertimec toxicity against certain strains of adult females of t.urticae t.urticae strains crops vertimec lethal concentrations lc90/lc50 ratio lc50 lc90 main µll¯¹ *rr50 main µll¯¹ *rr90 field cotton a1542.91 5.97 a14207.39 9.99 9.21 resistant a1915.47 8.52 a16328.37 11.49 8.52 susceptible 258.45ᵇ 1420.74ᵇ 5.50 field soybean a4013.25 4.29 a17210.74 22.10 4.29 resistant a4220.17 4.53 a19102.35 24.48 4.53 susceptible 198.82ᵇ 780.34ᵇ 3.92 *resistance ratio (rr) =lc50 or lc90 of resistant strain/ lc50 or lc90 of susceptible strain. pesticides resistance in tetranychus urticae is a portent which caused by many reasons. one of their causes is the introduction of exceeding levels of uv and co2, which could assume a critical part to get a resistant field strain. vertimec, an articulated miticide, lc50 of the research center safe strain which is kept up under selection pressure till f40 and the resistant field strain in comparison with susceptible strain were 2099.38, 200.01 and 50.822 µll¯¹, respectively. additionally, the raised esterases and mixed function oxidases (mfo) in both the laboratory and the field resistant strains had basically characterized the impact of extensive radiation of uv on the surpassed resistance levels recorded for the two strains (abd elwahab and taha, 2014). consequently, expanded co2 and global warming can be relied upon to positively influence the concoction barrier flagging framework in plants. those factors will render them more vulnerable pest assault. the expanded number of produced generations every year and incessant populace flareups of potential pests require ceaseless uses of high measure of pesticides. it will boost exposed mites and insects to create pesticides’ resistance vastly (petzoldt and seaman, 2007). further, prolongation of insects’ lifespan is prolonged under high co2 and temperature. besides, such climate variations will stabilize such insecticide resistant in assortments of pests in their populations. therefore, all mentioned will make more prominent harm plants even under broad pesticides measures. also, a few classes of http://dx.doi.org/10.21622/resd.2018.04.2.065 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 2, december 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.2.065 69 resd © 2018 http://apc.aast.edu pesticides have been appeared to be less powerful in controlling pests at higher temperatures (musser and shelton, 2005). vertimec (abamectin) resistance in t. urticae was also reported by several authors (beers et al., 1998). stumpf and nauen (2002) found that mfo (cytochrome p450-dependent monooxygenase) activity was higher in many strains of t.urticae than the susceptible strain. consequently, abamectin resistance was strongly synergized by pbo (piperonyl butoxide) and dem (diethyl maleate), suggesting that mfo and gst (glutathione stransferases) might be involved in abamectin resistance. astonishingly, levels of cytochrome p450 monooxygenases, specifically, cyp6cm1 in mix with a simple to utilize counter acting agent identification framework permit a quick, dependable, and extremely touchy detection of pesticides’ resistance to insects, and certainly to bemisia tabaci, to neonicotinoid and pymetrozine (nauen et al., 2013). nevertheless, li et al. (2016) demonstrated that rrs were ranged between 6.51 and 6.03 for myzus persicae (sulzer) infested tobacco, to certain pesticides in china. results demonstrated that resistance ratios were rr = 6.51 and 6.03which meant populaces have created minor imperviousness to imidacloprid. one populace (nc) has achieved a high resistance level to cyhalothrin (rr = 41.28), five populaces indicated medium level (10.36 ≤ rr ≤ 20.45), and the other six stayed powerless (0.39 ≤ rr ≤ 3.53). as respects carbosulfan, three populaces have created medium resistance, four populaces indicated just minor resistance, and the other five (0.81 ≤ rr ≤ 3.97) were as yet vulnerable. populace sz built up a medium level (rr = 14.83) to phoxim, the other 11 were vulnerable (0.29 ≤ rr ≤ 2.41). to examine the potential resistance system, restraint impacts of synergists and detoxifying compound exercises were identified. the outcomes showed that the mfo was the most vital detoxifying catalyst presenting imidacloprid resistance, and care was most imperative to cyhalothrin, carbosulfan and phoxim. our examination gave an exhaustive overview of insecticide resistance of m. persicae in chongqing, and proposed that distinctive districts should take comparing administration to postpone the insecticide resistance advancement and draw out the convenience of insecticides. furthermore, magnetic fields were tested on mites, tetranychus urticae and polyphagotarsonemuslatus latus which infested tomato leaves and some leaves were passed through 500 gauss magnetic field and others were sprayed with magnetic water (al-ani, 2010). results showed the significant decrease of mites’ individuals and raised numbers of mites’ eggs. that was explained upon hyperactivation of some enzymes in exposed mites to lay down more eggs. even though, magnetic water showed its effect on the preparation of spray liquids against on the viability of plant protection agents as shown by wachowiak and kierzek (2002). they reported raised effectiveness in the control of phytophthora sp. infested potato, after the use of these fungicides diluted in magnetic water. likewise, magnetic water incremented the efficacy of acaricides against tetranychus urticae. they were talstar, omite, magus and omite by the use of one and three magnetizers, one magnetizer and two semi-rings (górski et al., 2009). in addition, development of exposure methods to certain magnetic field is developed at this paper. electromagnetic field as shown could play an important role to detect resistance of pesticides in mites through an electromagnetic interference (emi) detector by translating electrophysiological changes that occurred mainly at glutamate-gated chloride channels (glucls) and γ-aminobutyric acid-gated rdl and glutamate-gated gluclα chloride channels (gabacl) and resulted to vertimec’ resistance in mites (riga et al.,2017). even though and according to other studies which suggested detoxification enzymes with no effective target site were able to cause abamectin resistance in field t. urticae populations (çağatay et al.,2018). near future, all recorded readings would be collected and stored at the cloud to be available whenever needed through internet of things system (iot). besides, data base was connected and joined with resistance ratios (rrs) which were gained from both fields and laboratory’ data. such system will be easier to be used by farmers wherever they are being. but utilizing the electromagnetic fields depending on physiological differences in resistant mites is appeared to be newly emergence trial through this paper. besides, the solution of metabolic resistance in mites is already done by exposure to specific colors of light emitting diodes (leds). each color could be linked to reduce metabolic pesticides resistance in specific pest on certain plant (abd elwahab,2015; abd el-wahab and abouhatab,2014; abd el-wahab and bursic,2014; abd el-wahab et http://dx.doi.org/10.21622/resd.2018.04.2.065 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 2, december 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.2.065 70 resd © 2018 http://apc.aast.edu al.2014). hence, leds with different colors are able to be connected with the full innovated system to do the two required steps: firstly, to detect the pesticides’ resistance and secondly to stop or reduce it effectively. iv. conclusion to conclude, as the pesticides’ resistance is a big problem that leads to disasters affecting the environment, there is a new innovated instrument to detect and then reduce it. the solution is depending on differences in electromagnetic forces in resistant strains of t.urticae in comparison with susceptible strain. then, resistance ratios have confirmed the presence of formed resistance. as a consequence, such device is capable to detect resistance to pesticides and farmers can count on it efficiently. references [1] r.a. abd el-wahab. “direct effects of light emitting diodes (leds) on the two-spotted spider mite, tetranychus urticae.” int. j. sci. res. agricul. sci., vol. 2, pp.79-85, 2015. [2] r.a. abd el-wahab. and e.e. abouhatab. “effects of light emitting diodes (leds) on the insect predators behavior against the two forms of tetranychus urticae.” int. j. chem. biol. sci. (ijcbs), vol. 1, no. 4, pp. 36-45, 2014. [3] r.a. abd el-wahab and v. bursic. “light emitting diodes (leds) reduce vertimec, resistance in tetranychus urticae (koch).” int. j. chem. biol. sci. (ijcbs), vol. 1, no. 3, pp. 28-40, 2014. [4] r.a. abd el-wahab and t.m. taha. “the relation between vertimec resistance in the two-spotted spider mite, tetarnychus urticae and climate changes in egypt.” int. j. chem. biol. sci., vol. 1, no. 3pp. 1-10, 2014. [5] r.a. abd el-wahab, s. lazic and v. bursic. “compatibility among insect predators and light emitting diodes (leds) against the two forms of tetranychus urticae in greenhouses.” int. j. chem. biol. sci. (ijcbs), vol. 1, no. 5, pp. 20-27, 2014. [6] w.s. abbott. “a method of computing effectiveness of an insecticides.” j. econ. entomol., vol 18, pp.265-267, 1925. [7] n. al-ani, “effect of magnetic field on mites.” j al-nahrain univ., vol.13, no.3), pp.104-109, 2010. [8] e.h.beers, h. riedl and j.e.dunley. “resistance to abamectin and reversion to susceptibility to fenbutatin oxide in spider mite (acari: tetranychidae) populations in the pacific northwest.” j. econ. entomol., vol. 91, pp. 352360, 1998. [9] n.s. çağatay, p. menault, m. riga, j. vontasd and a. recep. “identification and characterization of abamectin resistance,” in tetranychus urticae, koch populations from greenhouses in turkey, crop protection, vol. 112, pp.112–117, 2018. [10] v.v. dawkar, y.r. chikate, p.r. lomate, b.b. dholakia, v.s. gupta and a.p. giri. “molecular insights into resistance mechanisms of lepidoptera insect pests against toxins.” j. proteome res., vol. 12, no. 11, pp. 4727-4737, 2013. [11] v. dittrich. “a comparative study of toxicological test methods on a population of the two-spotted spider mite, t.urticae.” j. econ. entomol., vol 55, pp. 633-648, 1962. [12] g.p. georgiou “overview of insecticide resistance,” in managing resistance to agrochemicals eds. mb green, hm lebaron, wk moberg. pp. 18-41, american chemical society, 1990. [13] r. gerharz. “pest dislodgement by electromagnetic fields”. http://www. freepatentsonl ine.com/h000998.pdf ,1991. [14] r. górski , m. wachowiakm and m. tomczak. “the effect of water magnetized with negative magnetic field on effectiveness of selected zoocides in the control of two-spotted spider mite (tetranychus urticae koch).” j. plant prot. res., vol. 49, no. 1, pp. 87-91,2009. [15] a. hayashi. “history, present status and management of insecticide resistance” in pest resistance to pesticides. eds j fukami, y uesugi, k ishizuka. pp. 31-53. tokyo, japan, soft science (wash. d.c.), 1983. http://dx.doi.org/10.21622/resd.2018.04.2.065 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 2, december 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.2.065 71 resd © 2018 http://apc.aast.edu [16] k.r. kranthi, insecticide resistance -monitoring, mechanisms and management manual, nagpur, india: cicr and icac, washington. 2005, pp.153. [17] leora software. polo-pc. a user’s guide to probit or logit analysis leora software, pp. 28, berkeley, ca., 1994. [18] y. li, , z. xu, l. shi, l. he and g. shen. . “insecticide resistance monitoring and metabolic mechanism study of the green peach aphid, myzus persicae (sulzer) (hemiptera: aphididae),in chongqing, china.” pesticide biochem.physiol, vol.132, pp.21-28, 2016. [19] f.p. musser and a.m. shelton. “the influence of post-exposure temperature on the toxicity of insecticides to ostrinia nubilalis (lepidoptera:crambidae).” pest manag sci. vol. 61, pp. 508-510, 2005. [20] n.nahar, w. islam and m.m. hague.”predation of three predators on two-spotted spider mite, tetranychus urticae koch (acari: tetranychidae).” j life earth sci. vol. 1, pp. 14,2005. [21] r. nauen, k. raming and k.wölfel. online: 2013. available: http://www. google.com/patents/wo20131826 13a1?cl=en. [22] c. petzoldt and a. seaman. “climate change effects on insects and pathogens. fact sheet.” online: 2007. available: http://www.climateandfarming.org/clrcc.php. [23] m. riga, s. bajda, c. themistokleous, s. papadaki, m. palzewicz, w. dermauw, j. vontas and t. van leeuwen. “the relative contribution of target-site mutations in complex acaricide resistant phenotypes as assessed by marker assisted backcrossing in tetranychus urticae.” scientific reportss, vol. 7, pp. 9202-9214, 2017, doi:10.1038/s41598-017-09054-y [24] n.stumpf and r. nauen. “biochemical markers linked to abamectin resistance in tetranychus urticae (acari-tetranychidae).” pestic. biochem. physiol., vol. 72, pp. 111-121, 2002. [25] m.wachowiak and r. kierzek. “wpływ dawki środka ochrony roślin, dodatku adiuwanta i wielkości kropel na efektywność zwalczania agrofagów.” prog. plant protection/post. ochr.roślin, vol. 43, no. 2, pp. 994–997, 2003. [26] x. yang, l.l.k. buschmann, y. zhu and d.c. margolies”susceptibility and detoxifying enzyme activity in two spider mite species (acari : tetranychidae) after selection with three secticides.” j. econ. entomol., vol. 95, pp.399406, 2002. http://dx.doi.org/10.21622/resd.2018.04.2.065 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 51 resd © 2015 http://apc.aast.edu location and parameters of power system stabilizer for small perturbation of tunisian network ben salah rim 1, djebali meriam 1, kahouli omar 1, bouchoucha chokri 2, hadj abdallah hsan 1 1 control & energies management (cem-lab) national engineering school of sfax, enis 2 tunisian company for electricity and gas (steg) abstract this paper proposes the static stability of tunisian electrical network while facing small perturbation to maintain the security of the entire power system. in this context, after linearizing the power system, the concept of determining the placement of power system stabilizer is based on participation factor to find where it is going to be the most effective on a particular mode. then, the power system stabilizer tuning is calculated by using the method of residue. our objective is to improve the dynamic behavior of the electricity grid while facing various small disturbances. keywords the static stability of tunisian electrical network; power system stabilizer; automatic voltage regulator; method residue. i. introduction the purpose of a grid is to generate electrical power, and transport it to the load. a balance between the energy generated and the energy consumed must be maintained at all times. besides, for a safe and reliable operation, the grid must be able to maintain stability while encountering several types of disturbances. the electromechanical phenomena of small disturbances often occur with little damped oscillations of the system whose frequency range is between 0 to 2 hz [1]. these oscillations can lead to destabilize an alternator, a part of the network or the whole network causing a loss of the synchronism and consequently the entire system would collapse. the objective is to ensure a maximum damping of the inter-area modes as well as of the local modes, using power system stabilizers (pss) which are habitually used for the damping of electromechanical local modes. the additional signal is injected into the input of the avr [2]. conventionally, to adjust pss tuning, the equations of nonlinear system model are linearized around the operating point. furthermore, the problem of the psss adjustment is that the location must be optimal. the problem of ensuring better locations for psss can be determined by the participation factors and their parameters can be calculated by the method of residues [1]. then, the final decision for pss placement was made by looking at the changes of the eigenvalues after installation of a pss at the machine closely related to this mode. this work presents the application of our approach in a multi-machine power system as the tunisian grid [2]. the simulation is done by psat / matlab. ii. power system dynamic model a. machine models the synchronous machine is the main source of electrical energy in power system. the multi-machine modeling adopted in this paper uses as dynamical variables for each generator the angular velocity (ω), the rotor angle (δ), the internal voltage of quadrature axis q e_q^' and the internal voltage of quadrature axis d e_d^'[1, 3, 4]. nonlinear dynamic equations of the each machine can be summarized as follows [5]: (1) (2) (3) (4) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 52 resd © 2015 http://apc.aast.edu where ω is electric speed [rd/s], te is electrical torque [p.u], tm is mechanical torque [p.u], m is mechanical starting time [p.u/s], d is damping coefficient [p.u/p.u], se is equation of the magnetic circuit saturation, id is d-axis current [p.u], iq is q-axis current [p.u], xd is d-axis synchronous reactance [p.u], xd’ is d-axis transient reactance [p.u], td0’ is d– axis open circuit transient time constant [p.u], tq0’ is q–axis open circuit transient time constant [p.u], xq is qaxis synchronous reactance [p.u], xq’ is qaxis transient reactance [p.u] and vf is field voltage [p.u]. iii. power system controller there are many types of power system regulators in order to enhance the stability, the margin of safety or the power transmitted by lines. 1. turbine governor and frequency controller the frequency controller acts on the servomotor to open and to close the control valves, also to change the speed of the generator. thus, the role of the turbine is to drive the rotor of the synchronous generator speed. the tg is the variable of the speed control. in our case the speed controller tg is type ii, it is described by the following equation [5]: (5) where ωref is reference speed [p.u], t1 is transient time constant of turbine governor [s], t2 is time constant of turbine governor [s]. 2. voltage regulator automatic voltage regulator (avr) is used to regulate the output voltage through controlling the excitation field. this regulator is used to vary the external voltage of the filter vm, the voltage of regulator vr1, vr2 and the field voltage efd. the avr is type ii. it can be described as [5]: (6) (7) (8) (9) where vref is reference voltage [p.u], vg is terminal voltage of the generator [p.u], ka, ta are amplifier gain and amplifier time constant respectively [p.u/p.u] and [s], kf, tf are stabilizer gain and stabilizer time constant [p.u/p.u] and [s], ke, te are parameter stabilizer respectively [p.u/p.u] and[s]. 3. voltage regulator power system stabilizers (psss) are typically used for damping power system oscillations. the pss output signal is the state variable vs, which modifies the reference voltage vref of the avr. they usually consist of four blocks: an amplifier block, "filter washout" block, a phase compensation block and a limiter block. in our study, we used type ii. psss are defined by this equation, as follows: (10) (11) (12) (13) where vpss is voltage (pss) [p.u], tw is time constant filter [s], kw is stabilizer gain [p.u], t1 is first stabilizer time constant [s], t2 is second stabilizer time constant [s], t3 is third stabilizer time constant http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 53 resd © 2015 http://apc.aast.edu [s], t4 is fourth stabilizer time constant [s]. “fig. 1” presents the avr and the pss fig .1. combinaison of avr and pss iv. power system controller the general dynamic equations of the relevant system can be expressed by a set of nonlinear differential equations in the following form: (14) let x0 be the initial state vector, and u0 the input vector corresponding to the equilibrium point. the linearized system of the equation(14), which includes a synchronous generator connected over transmission lines to an ac network, is represented as the following state-space model [6, 7]: (15) where a is the power system state matrix of size (n * n), b is the input matrix of size (n * r), c is the output matrix of size (m * n), d is the feed forward matrix of size (m * r). the variables described above and the linearized equations define the linear system are: (16) where ∆x is the state vector of dimension n, ∆y is the output vector of dimension m and ∆u is the input vector of dimension r. a. eigenvalues the analysis of eigenvalues is a very effective tool to study the properties of the dynamic systems. the eigenvalues (λ) of the state matrix are given by the solutions of the characteristic equation of the state matrix a. it is defined by [1, 9, 10, 11]: (17) each eigenvalues has a real part of complex eigenvalues which provides the damping coefficient, and an imaginary part which gives the oscillation frequency. these are defined by the following expression. (18) the system will be stable if all the eigenvalues have a negative real part in the complex plane. the following relations give the frequency of oscillation: (19) the damping factor sets the decreasing of the oscillation amplitude. it is given by : (20) b. eigenvectors the linear model of the power system can be represented and described by equation (14). the eigenvectors is calculated. the right and left eigenvector related to the state matrix of the system by the following equations [12, 13]: (21) (22) λ_i : the ith eigenvalues ; φ_i: the right eigenvector http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 54 resd © 2015 http://apc.aast.edu for a state matrix of dimension n × n, the specific vector is a right column vector of dimension n x 1, while the left eigenvector is a row vector of dimension n × 1. the two vectors are defined as follows: the set of right eigenvectors of the system to form the right modal matrix is given as follows: (23) the left modal matrix is formed by the left vectors: (24) the right vector φi shows the relative influence of each variable in an excited state. the eigenvector left ψi mode, it determines the set of state variables involved regarding the composition of ith mode. c. participation factor the participation factor, which combines both the right and left eigenvectors, is defined by a matrix of participation in the following form [14]: (25) which (26) during the study of the stability at small disturbances, the participation factors allow the influence of a source of damping applied to a generator. in the participation matrix p, as shown in equation (25), the jth column shows how the user participates with respect to the evolution of the state variables of the system while the line ith shows how the different modes involved relatively the evolution of the ith state variable [15]. (27) the participation factors allow to us the identification of variables participants at specific oscillatory mode. d. residue the residues give an idea about the influence of the input stabilization or its optimal location in a multimachine power system. the transfer function affects only the behavior of inputs-outputs [1, 3]. considering the following system : (28) the transfer function is as follows: (29) s: laplace operator. the function g (s) can be composed by simple elements as follows: (30) where ri is the residues of g(s) given by: (31) v. control power system a. optimal placement of power system controller when installing such as a controller in multi-machine networks, the first conventional step is to find its optimum location within the network. to damp the local modes, the choice of location is still easy because the number of generators implicated mostly in local oscillations is very small. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 55 resd © 2015 http://apc.aast.edu on the other hand, for global modes, a great number of generators are generally associated with oscillations. that complicates the choice of the location of the pss. in addition, a bad location of pss can result in amplification of the oscillations, or contribute to the loss of stability of the system. when a pss is added in the system, it will affect all the electromechanical oscillation modes. thus, the interactions between pss must be considered when several psss are used [1]. all pss should be adjusted to provide sufficient damping of all electromechanical modes because the damping of each mode has a cumulative effect on the contribution of each pss. moreover, adjustment of pss must be robust: pss must be efficient not only during the change of the operating conditions but also when changing the network topology. b. design of pss to improve the stability of the system, the power system stabilizers that are simple and easy to install, practical, effective and cheap are often the most common stabilizers that are used to damp these oscillations as much as possible and also to increase the damping of oscillatory modes. these parameters of pss are adjusted sequentially and separately by method of residues [16]. the latter method of sequential setting usually gives satisfactory results for the damping of the oscillations. in this method, pss are resolved in a phased manner [16]:  first, the residual of transfer function at open loop system is calculated. then a pss is added and used the information of these residues.  next, a second pss is introduced and set based on information of the residues with the first pss.  this process continues until the system reaches satisfactory stability characteristics. the most method used for the selection of machines, which must be equipped with pss, is the method of participation factors [1, 10, 14, 17, 18, 19]. the transfer function of the pss for a system with an input / output is: (32) where t_w: the constant of the high pass filter, t_1,t_2 : the time constants of the controller, p: number of blocks lead / lag phase, k_p:gain “fig. 2” presents the moving of eigenvalue to another value. fig. 2. moving of eigenvalue moving these eigenvalues may be calculated by the following equation [20]: (33) where are calculated in equation (31) the methodology of sizing residue is divided into three stages  sizing the filter "washout" we usually take tw = 5s [1].  sizing block lead / lag phase: the total phase shift required φ_com is calculated from the residue of the critical mode. the phase angle required to direct the direction of the residue r_i so that the eigenvalue λ_(i )moves parallel to the real axis can be calculated by the following equation: (34) the time constants t1 and t2 can be determined by: (35) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 56 resd © 2015 http://apc.aast.edu (36) with :ω_i : est la fréquence du mode λ_i en rad/sec (37)  with a good lead-lag compensation, controller efficiency is related to the gain〖 k〗_p [16]. consequently, when we have a change of k_p, all modes of oscillation will be influenced. to calculate the gain〖 k〗_p, here is the transfer function following pss: (38) based on the equations (33) and (38), the gain value k_p is given by the following expression: (39) the output signal y(s) may be selected based on the maximum value of the residue data selected by the outputs [19]. in fact, not all the generators associated with electrical networks need to be equipped with pss since they do not participate in all of the most dominant electromechanical modes. therefore, the first step is to find the optimal locations of pss needed and determine their number using important information provided by the factor of interests whose goal is to achieve better damping compared to given criteria. vi. results and simulations the local modes are the most recurrent modes encountered in power systems. they are associated with oscillations between a generator (and a group of generators) of a power plant and the rest of the system. the local modes and inter modes, with frequencies of these oscillations are typically in the range of 0.2 to 2 hz, are studied. this application was processed on the tunisian network system generation and transmission of electric power steg. it consists of a network for transferring electrical energy production centers to consumption centers which are geographically often far away from each other. tunisian network (2012 version) consists of 3 wind farms, 172 lines, 83 transformers, 33 generators, 75 knots consumers. a. application on the tunisian network initially, before the use of pss, yet we had to ensure adequate damping of the oscillations, the method of residues will allow us to provide better localization of pss and better coordination of their parameters [2]. 1. location of pss the electromechanical generator participation factor is the first method used in this study; it allows us to determine the participation of a machine in each mode. thus, for a desired mode to be damped, the machine that participates the most is the machine where the pss should be installed. in our case, 14 generators mainly participate in 11 modes.next the frequency of each mode and the associated generator, the type of each mode is determined. then 11 modes are selected:  3 modes of interregional –type.  8 modes of local type. the results are given in “tab.1”: table 1. participants generators n° mode eigenvalue fre quency generators participants the mode type 1 -0,99146± 10,3388i 1.653 g1 local 2 -0,66359± 11,8818 i 1.894 g3, g4 local 3 -0.92013± 7.1822 i 1.1524 g10, g18 local 4 -0.43648± 8.1696 i 1.3021 g11 local 5 -0.77795± 11.3363 i 1.8085 g13 local 6 -0.51007± 5.6611 i 0.90463 g15, g23 interrégional 7 -0.49009± 5.8498 i 0.93429 g16 interrégional 8 -0.44439± 11.2483 i 1.7916 g19 local 9 -0.89544± 7.2212 i 1.1581 g22 local 10 -0.73736± 11.9208 i 1.9009 g27 local 11 -0.33778± 5.2691 i 0.84032 g33 interrégional http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 57 resd © 2015 http://apc.aast.edu factor analysis of participation shows the influence of each generator in that mode. if the participation of a generator is relatively small, the placement of a pss on this generator provides little improvement. “fig.3” and “fig.4” show the participation factors (pf) associated to the angle and the speed variations of each generator for the 11 electromechanical modes. fig. 3.the participation factors (pf) of local modes fig. 4. the participation factors (pf) interregional modes 2. setting the parameters of the pss to restore system stability and improve its overall damping, the pss is added to the desired generators. in the remainder of this section, the residue method is used to determine the parameters of the psss. these are summarized in “tab.2”: table 2. parameters of pss by the residue method pss n° g kpss t1=𝐓𝟑 t2=𝐓𝟒 1 1 0.0099 0.7970 0.0117 2 3 0.0538 0.3196 0.0222 3 4 0.6756 0.1053 0.0673 4 10 0.0147 2.9297 0.0066 5 11 1.4230 0.1922 0.0780 6 13 0.0022 0.9039 0.0086 7 15 3.3088 0.1889 0.1652 8 16 0.5092 0.4494 0.0650 9 18 0.0147 2.9324 0.0066 10 19 0.0396 0.5533 0.0143 11 22 8.2752 0.1618 0.1185 12 23 3.3062 0.1888 0.1653 13 27 0.4044 0.1744 0.0403 14 33 0.3312 0.9549 0.0377 1. analysis of the eigenvalues to demonstrate the effectiveness of the proposed approach, two cases are considered:  without pss  with pss http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 58 resd © 2015 http://apc.aast.edu the eigenvalues electromechanical modes for the both cases, their improvement and the improvements of the damping are given in “tab.3”: table 3. improving eigenvalue and damping n° g eigenvalue without pss eigenvalue with pss improvement of eigenvalue imrovement of damping 1 -0,99146±10,3388i -1,0142±10,3394 2% 17% 3 -0,66359±11,8818i -0,74261±11,9396i 8% 2% 4 -0,66359±11,8818i -0.71031±11.8841i 5% 2% 10 -0.92013±7.1822i -0.92906±7.2014i 1% 1% 11 -0.43648±8.1696i -0.44521±8.0851i 1% 1% 13 -0.77795±11.3363i -0.8044±11.4987i 3% 2% 15 -0.51007±5.6611i -0.5361±5.6987i 3% 3% 16 -0.49009± 5.8498i -0.49903±5.85i 1% 1% 18 -0.92013±7.1822i -0.92906±7.2014i 1% 1% 19 -0.44439±11.2483i -0.55527±11.2923i 11% 2% 22 -0.89544±7.2212i -0.90357±7.228i 1% 1% 23 -0.51007±5.6611i -0.53523±5.8241i 3% 3% 27 -0.73736±11.9208i -0.74291±11.9542i 1% 1% 33 -0.33778±5.2691i -0.48524±5.1309i 15% 1% based on the analysis of the eigenvalues of the system, the electromechanical modes (local and inter) are improved. to see this improvement, here is the breakdown of some eigenvalues in the complex plane which are given respectively in” fig.5”. fig. 5. distribution of some eigenvalues in the complex space as a second step, the performance and robustness of the setting of these regulators are evaluated. to do this, time domain simulations of the system in the presence of severe disturbance is done: load variation for both cases “fig.6” and “fig.7”:  before location of pss.  after location of pss. fig. 6. variation of the rotor angle for the machine 11 fig. 7. variation of the transient voltage 〖e'1〗_q for the machine 11 the amplitude of oscillations is reduced in the presence of pss and the system becomes more stable in less time if compared to the network without pss.finally and after a simulation of the selected tunisian improved network software. “fig.8” showing the location of the eigenvalues of the system in the complex plane. fig. 8. position of the eigenvalues of the tunisian system the most of the eigenvalues has a negative real part. the system is then stable. v. conclusion power systems continue to grow. the extension of networks interconnected makes them highly sensitive to interregional oscillations. these oscillations can severely restrict the transport of electrical energy. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 59 resd © 2015 http://apc.aast.edu under these new conditions, operators of electrical networks are often required to operate the systems to the limits of stability. therefore, improving the stability to small perturbations represents an objective.in this work, the problem of the dynamics of a network of multi machine stability distribution was handled. the nonlinear model of a network of electric power multi machine was developed. the nonlinear model was linearized to derive the model philips-heffron.using the method of residues based on the eigenvalues of the system; providing, passing by the conventional method of participation factors, not just a calculation of parameters stabilizers psss, but also a better location and an interesting reduction in their number. in this study, the psss satisfy both the damping of inter modes also the damping of local modes as perspective, the utility of using the method of residues on another network that combines two different regions of the world such as interconnection tunisia-libya will be validated. references [1] alkhatib, h. (2008) etude de la stabilité aux petites perturbations dans les grands réseaux électriques : optimisation de la régulation par une méthode méta heuristique. thèse de doctorat, université paul cézanne d’aixmarseille, [2] rim, b. s. mariam, d. (2014) etude de la stabilité statique du réseau tunisien et de l’interconnexion tunisie-lybie. projet de fin d’étude, enis, [3] kalifullah a. palanis., h. (2014) optimal tuning of pi power system stabilizer for multi machine power system using harmony search algorithm. jatit, [4] asrar ur rahman, m. sabah ul islam m, and abdul hafeez ansari m. (2014) enhancing power system oscillation damping using coordinated pss and svc controller. ijesi, [5] milano, f. (2006) power system analysis toolbox documentation for psat» version 2.0.0 [6] wang,sh. k, ji-pyng chiou,ch. w. l. (2008) parameters tuning of power system stabilizers using improved ant direction hybrid differential evolution . elsevier, [7] ali, e. s., abd-elazim, s. m. (2013) optimal power system stabilizers design for multimachine power system using hybrid bfoa-pso approach . dep of wseas transactions on power systems, [8] usman, j. mustafa,m. w.and aliyu,g. (2012) design of avr and pss for power system stability based on iteration particle swarm optimization. [9] zitouni m. f. (2010) amélioration de la stabilité transitoire des réseaux electriques par l’utilisation des systèmes facts. [10] febres c.a.t., araujo p.b. damping of lowfrequency oscillations by supplementary control of power system stabilizers . [11] sumina .d, bulic, miskovic, n.m. (2011) parameter tuning of power system stabilizer using eigenvalue sensitivity », elsevier, [12] kartubi, l. (2006) optimisation de la synthèse des facts par les algorithmes génétiques et les essaims particulaires pour le contrôle des réseaux electriques., p43 [13] bragason r. f. (2008) damping in the icelandic power system small signal stability analysis and solutions. dept. of industrial electrical engineering and automation lund university, [14] duc, h.n.( 2011) amélioration de l’amortissement des oscillations de puissance du réseau electrique les dispositifs facts et les mesures a distance . [15] custem t.v., (2002) systèmes electriques de puissance ii. cours elec 047, département d’electricité, electronique et informatique : institut montefiore, université de liège,. [16] yee s.k. and milanovic j.v (june. 2004) comparison of the optimization and linear sequential method for tuning of multiple psss. ieee power engineering society, general meeting denver, co,. [17] mekki k. (2002) mesures synchronisées par gps pour une meilleure stabilité des réseaux. [18] zea a. a. (2013) power system stabilizers for the synchronous: generator tuning and performance evaluation. [19] sebaa m. k. (2008) commande intelligente pour l'amélioration de la stabilité dynamique des réseaux d'énergie électrique . [20] ammari s. (2000) interaction des dispositifs facts avec les charges dynamiques dans les réseaux de transport et d'interconnexion http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 205 resd © 2015 http://apc.aast.edu rule-based control of off-grid desalination powered by renewable energies a. serna1, f. tadeo1, d. torrijos2 1 university of valladolid, 47005 valladolid, spain e-mail: fernando@autom.uva.es, 2 seta s.l., rivas-vaciamadrid, madrid, spain abstract a rule-based control is presented for desalination plants operating under variable, renewable power availability. this control algorithm is based on two sets of rules: first, a list that prioritizes the reverse osmosis (ro) units of the plant, based on the current state and the expected water demand; secondly, the available energy is then dispatched to these units following this prioritized list. the selected strategy is tested on a specific case study: a reverse osmosis plant designed for the production of desalinated water powered by wind and wave energy. simulation results illustrate the correct performance of the plant under this control strategy. keywords renewable energies, off-grid, desalination, rule-based control, reverse osmosis. i. introduction desalination is becoming increasingly used in many areas of the world to satisfy the demand of water. this process produces water (for human or industrial use) by removing most of the salts, generally from sea or brackish waters. desalination systems are ubiquitous. the capacity estimation for 2015 goes beyond 120 mm3/day and the cost of drinkable water obtained from desalination is steadily decreasing. although currently most large-scale desalination plants are connected to the grid, renewable energies are being introduced especially in small desalination plants located in areas without a reliable electricity grid. australia is an important exception, where the biggest seawater desalination plants are powered by renewable energies: see [1] and [2] for a detailed description of desalination plants powered by renewable energy sources. this paper concentrates on reverse osmosis (ro) plants, as this is the most frequently used process for small and medium sized plants. ro uses high pressures to force water molecules through a semi permeable membrane, retaining salt particles on the high pressure side (see, for example [3], and [4] for some general references of ro desalination). the pressure required goes from 40 to 80 bars, depending on the salt concentrations (see for example [5]). this pressure is supplied by highpressure pumps (positive-displacement, centrifugal, etc) that consume a significant amount of electric power. when renewable energy sources are the main source of energy, a central problem is balancing the power consumption with the power production; this is solved here using the active load concept used in micro grids (see [6], [7] and references therein). more precisely, small desalination plants are considered here, as they are frequently installed in remote areas powered by renewable energies (see [8] and [9]), and a proposal for its control, that has been developed in the context of the h2 ocean project*, is presented and evaluated here. in fact, many different ideas have been proposed in the literature for the control of these systems, as control significantly improves the performance (see for example [10], [11], [12] and [13] for some previous control proposals). in this case, following the proposal studied by some of the authors in [14], the desalination plant is considered to be partitioned in several stages, consisting of parallel lines connected through buffer tanks. each of them operates at a constant working point and can be connected or disconnected depending on the available energy and the amount of water stored in each tank. thus, the control proposal discussed here is based on deciding which sections would be switched on or shut down. so, only the energy available at each time is used; while unused energy would be temporarily stored in batteries for later use. in order to minimize the use of batteries, most of the power should be immediately consumed by the desalination system; yet at the same time the water in all the sections of the process should be secured (by ensuring that the water is properly stored in the buffer tanks), and thus no production is lost. the rest of the paper is organized as follows. in http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 206 resd © 2015 http://apc.aast.edu section ii the problem statement is presented. section iii discusses the control system. section iv presents the case study. section v evaluates the results and a discussion is given. finally the paper ends with a conclusion section. ii. problem statement figure 1 presents the main components of the desalination plants studied here. if the power supply changes by time, the production of water is also going to change by time in order to adapt to the available power. changing the working point of the plant by selecting a different flow/pressure set point is not adequate for most reverse osmosis systems, as they are designed to correctly operate at a given set point, although connection and disconnection of the devices of the desalination plant may have constraint in practice. thus, in a previous paper by the authors [14], it was proposed to partition the high pressure part of the ro plant in fig .1. renewable-energy powered desalination system under study the devices of the desalination plant may have constraint in practice. thus, in a previous paper by the authors [14], it was proposed to partition the high pressure part of the ro plant in different parallel sections. each section is operating as a standard ro plant (producing water at a fixed working point), regardless of being connected or disconnected when needed, as it follows a pre-programmed sequential functional chart. this proposal was selected as it is simple to implement in the existing control systems of desalination plants, making it possible to operate the whole plant as an active load by temporally disconnecting components until the predicted electrical consumption is fully used. unfortunately, the approach previously presented is not suitable enough in case there is a significant number of units of consumption being used, as it would conflict with the control objectives. particularly speaking, it is not quite adequate for multi-stage desalination plants operated by lines, as the number of components with high electrical consumption (high pressure pumps) is too big to make a functional block diagram that accurately represents the control objectives. thus, an alternative procedure is presented in the next section, which combines the possibility of implementation of existing control hardware (plcs) with the fulfillment of conflicting control objectives. iii. control system this section studies the control system to be developed for that class of desalination plants. there are some previous works that use rule-based control strategies in the case of energy management [15, 16]. in [15] a rule-based control for a case of a series of a hybrid vehicle is designed; whereas in [16] a type of control strategy in case of ice storage systems is developed. in our proposal, we have selected a ruledbased control strategy for a reverse osmosis plant powered by renewable energy as it is simple enough to be implemented and give good results out of its operation. a. control structure for simplicity, the controller is presented for a single first stage of desali a ion batteries second stage of desalination seawater pump renewable energy seawater desalinated water (1st stage) desalinated water (2nd stage) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 207 resd © 2015 http://apc.aast.edu seawater pump plant with two high pressure pumps for the first stage and two high pressure pumps for the second stage of the reverse osmosis. parallel approaches can be developed for other configurations, maybe by adding more components and supplying different rated powers. the main aim is to ensure a smooth operation of the facility by means of the control system. we need to balance power consumption with the available power, by deciding which components of the plant are connected or disconnected. these components are:  the seawater pump (swp).  each of the lines and stages of the desalination system: in the simplified structure presented in figure 2, they would be denoted ro1a, ro1b, ro2a and ro2b. the control variables are then the connection of the swp and the different sections of the reverse osmosis (see figure 2). b. control objectives the main objectives can be written in a prioritized way as follows:  keep all the buffer tanks over a minimum level, so the next section can operate properly.  once a unit of consumption is connected, it should be kept operating at its nominal value as long as there is enough energy. fig .2. proposed structure of the control system c. control algorithm the control strategy is based on two consecutive steps that are defined by different rules: 1. at each sampling time create a prioritized list of units of the water plant based on the current state of the plant (i.e., the tank levels and the units that are currently operating) and the expected water demand. this list of prioritized units is denoted {𝑈𝑖 }𝑖=1 𝑁 . another list of predicted energy demands should be associated, denoted {𝐸𝑖 }𝑖=1 𝑁 . these lists are generated based on the knowledge of the process, in order to fulfill the requirements given in section iii.b. for example, the following algorithm is used for the structure in figure figure 3 to generate  initialize: {𝑈𝑖 }{𝑆𝑊𝑃, 𝑅𝑂1𝐴, 𝑅𝑂1𝐵, 𝑅𝑂2𝐴, 𝑅𝑂2𝐵}  at each sample time: if the level of swt is low then increase the priority of swp decrease the priority of ro1a and ro1b if the level of bt1 is low then increase the priority of ro1a and ro1b decrease the priority of ro2a and ro2b if the level of bt2 is low then increase the priority of ro2a and ro2b if the level of swt is high then decrease the priority of swp increase the priority of ro1a and ro1b if the level of bt1 is high then decrease the priority of ro1a and ro1b increase the priority of ro2a and ro2b if the level of bt2 is high then decrease the priority of ro2a and ro2b estimation s of available energy r o 2 a o n /o ff r o 2 b o n /o ff desalination first stage desalination second stage seawater pump ruled-based controller plant measurements: tanks levels, pressures, flows, etc. r o 1 a o n /o ff r o 1 b o n /o ff s w p o n /o ff http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 208 resd © 2015 http://apc.aast.edu 2. distribute the available energy from among the units, following the prioritized list {𝑈𝑖 }𝑖=1 𝑁 ;; when possible, energy is assigned to those units with a higher priority. that is, a list of units that would be operating during the next sample, denoted {𝑂𝑗 }𝑗=1 𝑚 , is generated together with the corresponding list of predicted energy demands{𝐸𝑂𝑗 }𝑗=1 𝑚 . the disconnected elements would be {𝐷𝑗 }𝑗=1 𝑁−𝑚 ,, with the corresponding unsatisfied energy demands{𝐸𝐷𝑗 }𝑗=1 𝑁−𝑚 .the energy consumed by the connected units fulfill ∑ 𝐸𝑂𝑗 𝑚 𝑗=1 ≤ 𝐸, while all the units in the set of disconnected units fulfill 𝐸 − ∑ 𝐸𝑂𝑗 𝑚 𝑗=1 ≤ 𝐸𝐷𝑘 ∀𝑘 these lists can be generated by examining the list of predicted energy demands, {𝐸𝑖 }𝑖=1 𝑁 ,, generated in parallel with {𝑈𝑖 }𝑖=1 𝑁 ,, as given by the following algorithm: 1. at each sampling time  initialize {𝐸𝑂} = { }; {𝐸𝐷} = { }; m=0;  for 𝑖 = 1: 𝑁 if 𝐸𝑖 ≤ 𝐸 − ∑ 𝐸𝑂𝑗 𝑚 𝑗=1 then m=m+1 𝑂𝑚 = 𝑈𝑖 𝐸𝑂𝑚 = 𝐸𝑖 otherwise 𝐷𝑖−𝑚 = 𝑈𝑖 𝐸𝐷𝑖−𝑚 = 𝐸𝑖 iv. case study as a practical case study, the proposed control strategy was applied to a desalination plant for an industrial process designed to produce up to 68 m3/h of demineralized (demi) water and up to 20 m3/h of drinkable and service water. it consumes renewable electricity with variable production. a schematic diagram is presented in figure 4. the characteristics of each of its units of consumption are as follows:  a 51 kw (pswp) seawater pump that provides a nominal flow rate of 256 m3/h (qsw). qde qde high pressure pump hp2a hp1b hp2b demi water tank bt2 ro1a ro1b ro2a ro2b seawater intake pretreatment tank swt osmotised tank bt1 seawater pump (swp) high pressure pump hp1a osmotised water (1st stage) demi water (2nd stage) brine recirculation figure 3: structure of the desalination plants under study qos qos http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 209 resd © 2015 http://apc.aast.edu  the first stage of the reverse osmosis plant ro1 consists of two similar lines, each designed to produce 57 m3/h (qos) of water when connected (with a recovery ratio of around 45%), consuming 155 kw (php1) per line (corresponding to approximately 2.7 kwh/m3) when they are operating.  the second stage, ro2, also consists of two similar lines, which, when connected, produces 34 m3/h (qde) of demineralized water (recovery ratio of 75%), in each line, consuming around 38 kw (php2) per line (approximately 1 kwh/m3 of demineralized water produced). to validate the proposed control system, meteorological data at the target location was used, and previously derived production models for power and water were used [7, 13, 14]. v. results and discussion some preliminary results for 20 days of operation are shown in figures 5 to 13. the evaluation over 20 days confirms the correct operation of the control system for the parameters considered in the previous sections. as can be seen in figure 5, the value of the power consumed by the system is lower than the available power. figure 6 depicts the amount of demi water that is consumed in the electrolysis process. figure 7 shows the pretreatment level tank. figure 8 shows the osmotized level tank. figure 9 shows the demi water tank. in all cases, the levels are between the minimum and maximum defined to maintain them within a safety range. figure 10 depicts the operation of the swp. swp is not switched on/off very frequently (the exact value can be seen in table 1). figures 11 and 12 show the operation of the first and second reverse osmosis stages, respectively. as in the previous figure, the performance of both stages of the reverse osmosis process can be considered correct. figure 13 gives a zoom of the simulation results during 3 days of operation of all the figures explained above. finally, table 1 summarizes the total parameters and consumption for the summer results. this corresponds to a mean production of 32.39 m3/h of water for the electrolysis, consuming a mean power of 219.79 kw. hp2b 38kw demi water tank bt2 (58 m3) ro1a ro1b ro2a ro2b seawater intake pretreatment tank swt (58m3) osmotised water tank bt1 (58 m3) 256 m3/h 54000 tds hp1a 155kw hp1b 155kw 34 m3/h 3 tds 34 m3/h 3 tds hp2a 38kw 94 m3/h 57 m3/h 368 tds 57 m3/h 368 tds osmotized water (1st stage) demi water (2nd stage) 20 m3/h 368 tds 68 m3/h 3 tds brine 141 m3/h 91000 tds brin e 26 m3/h 570 tds figure 4: case study swp 51kw http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 210 resd © 2015 http://apc.aast.edu table 1. parameters and consumptions mean power available (kw) mean power consumed (kw) demi water (m3/h) osmotised water (m3/h) 271.66 219.79 32.39 55.71 sea water pump on/off (times/day) 1st reverse osmosis stage on/off (times/day) 2nd reverse osmosis stage on/off (times/day) 5.8 6.2 14.6 figure 5 power available and consumed by the desalination unit figure 6 demineralized (demi) water figure 7 pretreatment tank level (winter) figure 8 osmotized tank level (winter) 0 2 4 6 8 10 12 14 16 18 20 0 100 200 300 400 500 600 time (days) power (kw) consumed available 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 0 10 20 30 40 50 60 70 time (days) demi water (m3/h) tank level (m) 0 2 4 6 8 10 12 14 16 18 20 0 0.2 0.4 0.6 0.8 1 time (days) 0 2 4 6 8 10 12 14 16 18 20 0 0.2 0.4 0.6 0.8 1 time (days) tank level (m) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 211 resd © 2015 http://apc.aast.edu figure 9 demi tank level (winter) figure 10 operation of the seawater pump (swp) figure 11 operation of the first stage of the desalination unit (ro1a + ro1b) figure 12 operation of the second stage of the desalination unit (ro2a + ro2b) 0 2 4 6 8 10 12 14 16 18 20 0 0.2 0.4 0.6 0.8 1 time (days) 500 tank level (m) 0 2 4 6 8 10 12 14 16 18 20 off on time (days) 0 2 4 6 8 10 12 14 16 18 20 off 1 on 2 on time (days) 0 2 4 6 8 10 12 14 16 18 20 off 1 on 2 on time (days) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 212 resd © 2015 http://apc.aast.edu figure 13 zoom. from up to down and left to right: power available and consumed by the desalination unit, water flow to electrolyzers, pretreatment, osmotized and demi tank level, operation of the swp, first and second stage of the desalination unit. vi. conclusion this work has discussed the problem of operating reverse osmosis (ro) plants under variable power availability conditions, which is a problem encountered when local green energy sources are used in off-grid locations. a rule-based control strategy has been designed based on giving preference, at each sample time, to the operation of the high pressure (hp) pumps of the ro plant that require action to avoid the occurrence of not fulfilling the water demand. the tanks make it possible to dampen variations in production as long as they have enough water stored; so a central aspect of the control system is the use of the information from the measured tank levels. the proposed controller was evaluated for a specific ro plant, powered by wind and wave energies that produce demineralized water. simulation results are provided to depict the correct operation of the plant with the designed controller. it must be pointed out that the proposed estimation is based on lines that operate at a fixed working point. however, current technical advances in the integration of frequency variators in hp pumps would enable some more adequate applications to operate the lines at variable set points: the adaptation of the proposed rule-based control strategy to these alternative installations would be the aim of future work. finally, it is planned to include information on predicted energy availability and water demand. references [1] rodriguez, l.g. (2002) seawater desalination driven by renewable energies: a review desalination, 143:pp.103–113. [2] mathioulakis, e., belessiotis, v. and delyannis, e. (2007) desalination by using alternative energy: review and state-of-the-art, desalination. 203:pp.346–365. 5 6 7 8 off 1 on 2 on time (days) 5 6 7 8 off 1 on 2 on time (days) 5 6 7 8 off on time (days) 5 6 7 8 0 0.2 0.4 0.6 0.8 1 time (days) 5 6 7 8 0 0.2 0.4 0.6 0.8 1 time (days) 5 6 7 8 0 0.2 0.4 0.6 0.8 1 time (days) 5 6 7 8 0 10 20 30 40 50 60 70 time (days) 5 6 7 8 0 100 200 300 400 500 600 time (days) demi water (m3/h) power (kw) tank level (m) tank level (m) tank level (m) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 213 resd © 2015 http://apc.aast.edu [3] fritzmann, c. lowenberg, j. wintgens, t. and melin, t. (2007) state-of-the-art of reverse osmosis desalination, desalination, 216:pp.1– 76. [4] penate, b. and rodriguez, l. g, (2012) current trends and future prospects in the design of seawater reverse osmosis desalination technology, desalination, 284:pp.1–8. [5] wong, m. c., martinez, k. g., ramon, z. and hoek, e. m. v. (2012) impacts of operating conditions and solution chemistry on osmotic membrane structure and performance. desalination, 287:pp. 340–349. [6] lopes, j.a., moreira c. l. and madureira, a. g. (2006) defining control strategies for microgrids islanded operation. ieee transactions on power systems, 21(2), pp.916-924. [7] vandoorn, t. l., renders b., degroote, l., meersman, b. and vandevelde, l. (2011) active load control in islanded microgrids based on the grid voltage. ieee transactions on smart grid, 2(1), pp.139-151. [8] seibert, u., vogt, g., brenning, c., gebhard, r. and holz, f. (2004) autonomous, desalination system concepts for seawater and brackish water in rural areas with renewable energies. desalination, vol. 168, pp. 29-37. [9] tadeo, f., palacin, l. g., salazar j. and de prada c., (2011) desalination in remote areas: a prediction-based approach, in proc. ida world congress, perth, australia. [10] robertson, m. w., watters, j. c., desphande p. b., assef, j. z , alatiqi, i. m. (1996) model based control for reverse osmosis desalination processes. desalination, 104:pp.59–68. [11] gambier, a. and badreddin, e. (2003) application of hybrid modeling and control techniques to desalination plants. desalination, 152:pp.175–184. [12] mcfall, c., bartman, a., christofides, p. and cohen, y. (2008) control and monitoring of a high-recovery reverse-osmosis desalination process. industrial & engineering chemistry research, 47:pp.6698–6710. [13] palacin, l., tadeo, f., de prada, c., elfil, h. and salazar, j. (2011) operation of desalination plants using hybrid control, desalination and water treatment. vol. 25, pp. 119-126. [14] serna, a. and tadeo, f. (2013) offshore desalination using wave energy, advances in mechanical engineering vol., article id 539857, 8 pages. [15] jalil, n., kheir, n.a. and salman, m. (1997) a rule-based energy management strategy for a series hybrid vehicle, american control conference, 1997. proceedings of the 1997 (vol. 1, pp. 689-693). ieee. [16] drees, k.h, and braun. j.e. (1996) development and evaluation of a rule-based control strategy for ice storage systems. hvac&r research, 2(4), pp.312-334. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 7, issue 1, june 2021 issn 2356-8569 1 http://apc.aast.edu the role of a “civic university” in the frame of quadruple helix approach to development the paradigm of med-quad project anna tozzi professor in geometry, university of l’aquila anna.tozzi@univaq.it 1. the “civic university” originally universities were embedded in the cultural and economic life of the cities everywhere in the world. in the 19th century they were required to support industrialisation by providing scientific advice and skilled labour, but, through the organisation of medical schools and hospitals, they contributed also to improve the health and well-being of the population. gradually, during the 20th century, a changed policy concerning the higher education systems with an increasing central governmental support, produced a disconnection of universities from the places in which they were located. in the last 20 years, crisis and challenges of any kind, are forcing universities to revise their role and to reconnect with their cities, namely, to “re-invent the civic university” [3]. this means delivering benefits to society as a whole: local, regional, national, global by rediscovering the role of “anchor institution” in place making, innovation, economic and social development. but realizing the potential of a civic university does not depend only on what the university does, but also on the capacity of its city partners in the public and private sector. for a university, being anchored in a specific territory, requires, in one side, the identification of the academic practices that are relevant to the place where academics live and work as citizens, and on the other side, the solutions of the problems faced by the communities where they belong, by playing their role of repository and producers of that multidisciplinary knowledge necessary for coping with the increasingly complex challenges faced by the global society. on the other hand, cities are increasingly becoming direct responsible for the local economy, for the well-being and education of their citizens, for the environmental and cultural heritage preservation and enhancement. cities and universities should set priorities jointly and work together to achieve them with the awareness that this new approach benefits both sides. thus, the city engagement, for the civic university, represents also an opportunity for exploring new research methods and fields and stimulating the creative potential of its academic community [6]. a civic university is characterized by its ability to integrate its teaching, research and engagement missions with the outside world without reducing their quality. in this renovated scenario, universities and city partners must work in new ways: higher education http://dx.doi.org/10.21622/resd.2021.07.1.001 societ ies are wit nessing profound changes and coping with a g reat variet y of challenges, both foreseen and unexpected, for which are not fully prepared. the transformat ions at environmental, scient ific, technological, cult ural and social level force ever yone to rethink the meaning and even the value of the human experience and urge the academic communit y, polic y makers and decision-makers within higher educat ion and wider societ y to find proper solut ions. universit ies are at the center of this transformat ion process with their dual responsibilit ies at local and global scale, coping with the intrinsic difficult ies in addressing local and global demands to contribute to a more equitable and sustainable societ y. more and more, higher educat ion sector is required to play as a social agent by exploit ing the mult iplicit y of its knowledges as well as exploring teaching methodologies, curricula and the concept of lifelong learning. universit ies must analyse and interpret the current concept of universit y social engagement and social responsibilit y and reflect on how “glocal” engagement should be included in teaching, learning, research and inst it ut ional act ivit ies, governance and leadership. they should ident ify how the different social actors are involved in glocal engagement pract ices, and how they can interact with them. med-quad project provides an example of universit y civic engagement in the mediterranean region, including e u (i t and gr) and non-e u inst it ut ions (eg, tn, jo, pa). http://apc.aast.edu mailto:anna.tozzi@univaq.it http://dx.doi.org/10.21622/resd.2021.07.1.001 journal of renewable energy and sustainable development (resd) volume 7, issue 1, june 2021 issn 2356-8569 2 http://apc.aast.edu provides intellectual and human capital for the city, public sector develops coherent policies linking territorial development to innovation and higher education, private sector invests in people and ideas for creating growth. for achieving these goals new methods are needed. concepts such as “quadruple helix”, social innovation and living laboratories are some new tools for a multi-inter-disciplinary and trans-partner working, fundamental for addressing the new societal challenges. 2. the new paradigm the quadruple helix (qh) model of development integrates to the three pillars: research, industry, government, the “civil society” so as to provide additional perspectives to the (territorial) innovation ecosystem, where all stakeholders are active players in jointly experimenting new ways of doing things and creating new services and products. thus, the qh approach integrates the social component to the previous triple helix (th) model where the three components, universities, enterprises and governments, cooperate on the base of the existing university/enterprise, university/governments, enterprise/government relations, focusing on one or another of the bilateral cooperation. indeed, th model is based on the “knowledge triangle”: educationresearch-innovation that, focused on the concept of knowledge economy, proved to be not sufficient to support development and innovation. qh model moves towards the concept of knowledge society/democracy with the addition of a fourth sphere. this swift reinforces the role of universities as civic universities in the implementation of their third/ fourth mission. indeed, including “civil society” means considering (among others): citizens, as users requiring new services and products: user-driven innovation culture-based and media-based public, providing multiculturalism and creativity in hard and soft sciences: multi xxxx(local/national/ global)-level innovation external scientific experts, as advisors for governments: research/industry-driven innovation non-profit organisations, as patterns for combination of public/private funding arts and artistic research, as a new form of knowledge creation. thus, a quadruple helix approach to science, research and innovation that embraces university, business, government and civil society within the city, requires a changing process in the functions of the four components, with the awareness that these “four helices”, by joining forces, will be able to align goals, amplify resources, mitigate risk and accelerate progress. however, in order to cooperate, the four components, need to find or better, to build up, a place (living labs, co-working places) where they can discuss the problems and propose the possible solutions as well as a methodology for implementing the activities identified as those capable to stimulate and exploit the innovation potential. there is not a unique recipe to establish a qh development model. the methods and tools must be carefully chosen according to the several variables that characterize the territory and its university. the qh model proposed by med-quad project, offers a huge opportunity, but the 4 components need to acquire competences for exploiting the capacity of ict to stimulate long-run endogenous economic growth. the concrete activities outlined in the project, will adopt the twelve principles of open innovation 2.0 that clearly highlight how smes, in order to survive, need to establish trusted relations to the other components, by means arrangements that may be implicit (trust culture) or explicit (formal contracts), but in any case resulting from a people-to-people cooperation [1]. concerned territory – as well as the digital economy is characterized by small and very small sized companies, so open innovation 2.0, mainly discussed in large-scale companies, is not fully suitable. thus, in order to create the right environment for a balanced and equally committed cooperation among the 4 helices, the project will adopt the “embedded innovation 3.0” paradigm, where the notion of “embeddedness” is introduced to mark the increasing challenge of integrating firms into their surrounding communities to assure the absorption of their exploitable knowledge [7,8]. the main actors are the universities which will improve their capacity to be and act as “civic universities” in strict cooperation with the cities of which they are part as “anchor” institutions [5,6] together with the socio-economic stakeholders and the citizens, who all will learn how to contribute in local planning processes and in shaping the local economies. the project entails organisational innovation, not only as supporting factor for product and process, but also as tool for improvement of firms’ ability to learn and utilize new knowledge and technologies through a wise management of external relations, according to oslo manual (2005). the first innovative approach proposed by medquad is the use of new organizational methods in the firm’s relations with research institutions, (local) government and society. the aim is to create an environment where the key actors cooperate for coping with the limitations of the “technological paradigm” designed by ranga and 10.21622/resd.yyyy.vv.i.ppp where 10.21622 = journal identifier resd = journal name yyyy = four digits for the year vv = two digits for the volume number http://dx.doi.org/10.21622/resd.2021.07.1.001 http://apc.aast.edu http://resd.yyyy.vv http://dx.doi.org/10.21622/resd.2021.07.1.001 journal of renewable energy and sustainable development (resd) volume 7, issue 1, june 2021 issn 2356-8569 3 http://apc.aast.edu etzkowitz (2013) for the triple helix model [2], since in the region the knowledge space scarsely takes advantage of universities focused on applied sciences, and the consensus space suffers from a sound institutional support. the project intends to add a societal perspective in such a manner that the systematic way of pursuing research/technology-driven innovations (th), will be shifted to a systematic way of pursuing demandor user-oriented innovation (qh). the med-quad project expected results can be classified in three main categories: 1. innovative approaches, strategies and tools for the creation of a proper innovation ecosystem that, tailored on the specific characteristics of each territory, is able to boost innovation, 2. methodologies and means for enhancing competencies, capacities and skills of decision and policy makers in the local and national governmental departments in charge of territorial and economic development, 3. concrete examples of methodologies and tools application. in the first category there is the proposed qh model that integrates different approaches: user-centered (th+users), firm/university-centered and public/firm-centered, aimed at enhancing in an interconnected way social inclusion, user centrality, creativity and public services. this integration makes the model interdisciplinary and trans-disciplinary encompassing the whole disciplinary spectrum, thus going beyond the quintuple helix model where the inclusion of the environment as fifth helix is not sufficient to ensure the achievement of the un sustainable development goals. in the second category there are the training activities and the thematic seminars aiming to provide new indicators for measuring innovation. in the third category there are the two cross-border living labs and the city co-working spaces where real life problems are analysed and solved. all of them are sustainable and replicable and provide suitable and efficient tools for addressing the development priorities of universities, governments, enterprises and citizens. references [1] curley m., salmelin b., open innovation 2.0. the new mode of digital innovation for prosperity and sustainability,isbn: 978-3-319-62878-3, springer, 2018 [2] etzkowitz h. and leyesdorff l., the dynamic of innovation: from national systems and “mode 2” to a triple helix of university-industrygovernment relations, research policy, (2000) 29: 109-23 [3] goddard j., re-inventing the civic university, london: nesta, 2009 [4] goddard j.and vallance p., the university and the city, abingdon: routledge, 2013 [5] goddard j., kempton l. and vallance p., universities as anchor institutions in cities in a turbulent environment: vulnerable institutions in vulnerable places, cambridge journal of regions economy and society, 2014, 7(2),307312 [6] goddard j., the strategic positioning of cities in 21st century challenges: the civic university and the city, guni report 2017, 115 127 [7] hafkesbrink j., and evers j., innovation 3.0: embedding into community knowledge the relevance of trust as enabling factor for collaborative organizational learning, xxi ispim conference “the dynamics of innovation”, bilbao, 6 to 9 june 2010 [8] hafkesbrink j., and schroll m., innovation 3.0: embedding into community knowledge collaborative organizational learning beyond open innovation, journal of innovation economics & management, (2011)-1 (n°7), 55-92 about prof. anna tozzi education and training: 1970: master degree in mathematics relevant professional experience: 1970--1973: research fellow cnr (national research council) 1974--1983: assistant professor, university of l’aquila tasks: research and teaching courses of topology, and general mathematics since 1984: professor in geometry, university of l’aquila teaching activities: topology, algebraic topology, mathematical logic, geometry and linear algebra http://dx.doi.org/10.21622/resd.2021.07.1.001 http://apc.aast.edu http://dx.doi.org/10.21622/resd.2021.07.1.001 journal of renewable energy and sustainable development (resd) volume 7, issue 1, june 2021 issn 2356-8569 4 http://apc.aast.edu coordinator of local unit of the national research project-prin “constructive methods in topology,algebra and programme analysis” coordinator of local unit of the national research project-prin “constructive methods in topology, algebra and information technology” member of the research unit of padua university for the national research project-prin “constructive methods in topology, algebra and information technology” member of the research unit of padua university for the national research project-prin “logical methods of information management” organiser and scientific responsible of several scientific seminars and 5 international conferences on “categorical topology” author of 32 scientific papers and 5 didactic publications erasmus coordinator faculty of sciences, university of l’aquila vice-rector for the international relations and projects, university of l’aquila consultant for european policies and programmes, region abruzzo rector’s consultant for the internationalisation policies and rankings research activities: 1998-2000&2000-2002: 2002-2004 & 2004-2006: 2008 2010: 2012 2014: 1994 2010: 1996 2003: 2004 2018: 2002 2010: 2019 today http://dx.doi.org/10.21622/resd.2021.07.1.001 http://apc.aast.edu http://dx.doi.org/10.21622/resd.2021.07.1.001 journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.042 42 resd © 2018 http://apc.aast.edu generating electricity using geothermal energy in iran farhadtabarsa75@gmail.com abstract given that fossil fuels will end one day and that these types of fuels produce a lot of pollution, each country should look for new ways to generate energy that is needed for its people in proportion to its energy resources. given that iran is geographically located in an appropriate region of the earth, it has a great potential for using renewable energy. in this study, sources and uses of iranians’ geothermal energy have been studied, all of which indicate that iran has a very good potential for electricity production using geothermal energy. according to the information gathered, iran has one geothermal energy plant in meshkin shahr city and this plant power with a capacity of 100 megawatts is an active power plant in iran. also, the potential of geothermal power generation was verified in khoy located in azarbaijan gharbi province, sabalan ardebil province, sahand in azarbaijan sharghi and damavand in tehran province examination verified that around 8.8% of total land in iran is capable of geothermal energy production. keywords iran, geothermal energy, fossil fuels, renewable energy. i. introduction iran (islamic republic of iran) is located in the west asia, surrounded by caspian sea, azerbaijan, turkmenistan, armenia, pakistan, afghanistan, iraq, persian gulf, oman gulf and turkey [1]. total area of this country is 1.65 million km2, and its population is about 80 million people including 49.6% females and 50.6% males. iran has a warm and dry climate by long summers and short, cold winters[2] [3]. the same climate and the four seasons have led to a special look at using renewable energy in sustainable development in different fields. statistics showed that iran has the fourth largest crude oil reserves, the second largest natural gas reserves in the world [4], and a very high potential in renewable energy sectors, such as solar, wind, geothermal, etc. which can be used exclusively in any of the cities in iran [5]. on the one hand, energy plays a significant role in the economic and social activities of the humans and the country and the growth of energy and its use and productivity will also lead to the welfare of people. hence, over the past years, great attention has been paid to energy production in a variety of ways [6]. on the other hand, fossil fuels have been used extensively in the past two decades and fossil resources are limited and one day they will end. so any country should know the energy available in it and also lookto create new ways to produce energy[7]. also iran has a lot of fossil resources, which could be easily used for many years, but the point to consider is, how long can these fuels be used? figure 1 shows the use of renewable energy in seven countries, which is the largest amount of wind power use for china and the largest use of solar energy in germany [8]. armin ramezani, mohammad vahedi torshizi, arash attari and farhad tabarsa department of bio-system mechanical engineering, gorgan university of agricultural sciences and natural resources, gorgan, iran. mohammadvahedi4130@gmail.com, armin.ramzani@yahoo.com, arashattari1995@gmail.com, http://dx.doi.org/10.21622/resd.2018.04.1.042 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ mailto:mohammadvahedi4130@gmail.com mailto:armin.ramzani@yahoo.com mailto:arashattari1995@gmail.com journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.042 43 resd © 2018 http://apc.aast.edu fig.1. renewable power capacities in the word, eu-28, brics, and top seven countries in recent years, the consumption of fossil fuels in iran and the world has multiplied [9]. in addition, the rising cost of fossil fuels and their damaging environmental impacts, such as pollution, rising ground temperatures, and ozone depletion, have increased the desire to use renewable energies [10][11]. the large oil and gas producers iran is the world´s 7th largest emitters of co2 from fossil fuels. the diagrams below show the per capita co2 emissions from fossil fuels (without bunkers) and cement, annually since 2000. the green bars show the free emission level – the exceedance is the basis for calculating the national climate debt. iran was responsible for 1.9% of global emissions in 2015. also iran has the highest share of 36.15 % of greenhouse gas emissions in the middle east, and next to iran are saudi arabia and united arab emirates which are also ranked 24.29% and 14.9%, respectively. the use of energy carriers, with the production of pollutant and greenhouse gases in the conversion process and causing more warming of ground and climates in the destruction of the ozone layer, put the environment seriously in the face of the threat [12] [13]. figure 2 shows the contribution of different sectors to greenhouse gas emissions [14]. fig. 2. green house gas emissions by sector http://dx.doi.org/10.21622/resd.2018.04.1.042 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.042 44 resd © 2018 http://apc.aast.edu today, the challenge of energy policies is to reduce fossil fuel production and environmental costs. since the expansion of access to energy (heat, light, etc.) is very important in developing countries [15] and various political and other measures have been taken to reduce energy consumption, renewable energy is introduced to solve this problem and high productivity of renewable energy and the transfer of clean technologies are considered in different countries,. given the fact that in the last century there has been a significant growth of energy consumption in the world, meeting the energy needs of humans has been considered as well as the major role fossil fuels play in supplying this energy [16] [17]. also iran has abundant resources in fossil fuels. proven oil reserves include gas liquids of more than 137 billion barrels, accounting for 11 percent of the world's resources while natural gas resources are more than 26.7 trillion cubic meters or 15% of the world's total resources [18]. figure 3 shows the production of fossil fuels for iran [19] . fig. 3. production of fossil fuels in iran it is a well-known fact that iran's economy is a mixed economy where the government companies own oil and the other large companies agriculture and investment services. given the diversity of the iranian economy, iran's economy is still heavily dependent on oil exports. at present, oil exports account for 80% of total exports which accounts for nearly 50 percent of the government's budget and is 23 percent of the gross domestic product. with growing demand for energy, increased environmental pollution, and depleting energy sources, human society today faces multiple challenges of transition towards sustainable development and poverty eradication [20] .in 2005, 2713.4 million tons of carbon dioxide emissions from burning of combustible fuels have been released in the world. the 1671.7 million tons equivalent to greenhouse gas (co2) emissions in the middle east region have been released and 1,238.1 million tons of this gas were due to the burning of combustible fuels [21]. the total new global investments in renewable energy increased from $40 billion in 2004 to $244 billion in 2012 [22]. according to the international energy agency, utilization of renewable energy will triple between 2008 and 2035. also, it is anticipated that the share in renewable electricity production in the middle eastern regions, the heart of the world's fossil fuel reserve, will amount to 16% in 2035 [6]. http://dx.doi.org/10.21622/resd.2018.04.1.042 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.042 45 resd © 2018 http://apc.aast.edu table 1. lists of power plants with fossil fuels in different parts of the country rating province name power plants with a capacity of more than 1 mw power plants with capacity of 1 mw and less number capacity (mw) number capacity (mw) 1 khorasan razavi 8 43.1 110 662.2 2 kohkeloye va boyer ahmad 5 16.85 -------- 3 esfehan 4 14.46 21 317 4 zanjan 4 102.52 -------- 5 tehran 6 9.843 5 32.84 6 markazi 5 19.61 1 100 7 kerman 3 11.2 -------- 8 fars 4 13.975 2 66 9 khuzestan 3 18.66 -------- 10 gilan 2 53.78 -------- 11 kerman --------18 169 12 yazd 1 4 4 160 13 azarbayjan sharghi 4 3.96 -------- 14 khorasan jonobi --------12 155 15 mazandaran 1 1 1 1.2 16 kermanshah 1 10 -------- 17 azarbayjan gharbi 1 6 -------- 18 kordestan 1 10 -------- 19 chaharmah bakhtiyari 1 5 -------- 20 hamedan 1 2.8 -------- 21 ghazvin --------7 50 22 semnan --------3 15 23 lorestan 2 1.6 -------- 24 sistan va balochestan 1 0.66 -------- 25 boohsher --------1 2.5 26 hormozgan --------1 5 geothermal energy is one of the renewable energy resources witnessing increasing interest. it can supply energy demand in two different forms. it could be used indirectly for geothermal power generation or be utilized directly for heating purposes such as greenhouses, district heating, fish farming and others [23]. 82 countries around the world have reported installing direct use of geothermal applications. some of these countries have a long history in the research and development of direct geothermal energy use. amongst these countries are: the us, iceland, and new zealand. in the case of the us, the direct utilization of geothermal energy includes heating of swimming pools and spas, aquaculture and greenhouses, district heating, industrial applications and ground-source heat pumps. the largest application is ground-source heat pumps accounting for 88% of the annual energy use. in summary, when considering direct-use without geothermal heat pumps, the distribution of annual energy use is as follows: 34% for fish farming, 28% for bathing and swimming, 15% of individual space heating, 9% for greenhouse heating, 9% for district heating, and the rest is for agricultural drying, industrial process heating, cooling, and snow melting. the current installed capacity and annual energy use for district heating is 81.55 mw/th and 839.6 tj/yr [23] [24]. iran has a high geothermal energy potential. the country geothermal gradient range varies from 2°c/100m in the zagros belt to 13°c/100m around the damavand volcano in the north. most geothermal energy studies in iran have focused on electricity production, while, research on the direct use of geothermal energy have received less attention [25] [26]. http://dx.doi.org/10.21622/resd.2018.04.1.042 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.042 46 resd © 2018 http://apc.aast.edu the result indicated that 8.8% of land area in iran has geothermal potential with 18 promising hightemperature geothermal fields. these eighteen prospected areas have been recommended for detailed geological, geochemical and geophysical investigations. the most investigated field in iran is the sabalan geothermal prospect. sabalan lies in the moeil valley on the western slopes of mt. sabalan, approximately 16 km southeast of the meshkin-shahr city. eleven wells including 7 productions, 1 reinjection, and 3 monitoring wells have been drilled in sabalan, which is recognized as a potential for geothermal power generation [27]. ii. geothermal energy 1. what is geothermal energy? geothermal energy is one of renewable energy sources. geothermal is a greek term and is composed of two words; geo which means earth and thermal which means heating. geothermal energy is the energy available in the depths of the earth. it is created from solar energy that has been stored inside the earth for thousands of years [7]. also, the collapse or decay of radioactive uranium, thorium and potassium in earth originated in a long depth mainly in areas prone to earthquakes, volcanic young and tectonic plates of earth focused. the earth's heat is driven from parts of the earth in a variety of ways, including volcanic eruptions water springs, ocean springs and golfers, due to the reduced density of the earth and the conductivity [28] .geothermal energy, unlike other renewable energies, is not limited to season, time, and conditions and cannot be exploited without interruption. also, the cost of electricity in geothermal power plants is compatible with other conventional fossil fuels and it is even cheaper than other types of renewable energy [29]. figure 4 shows a schematic of a geothermal power plant [30]. fig. 4. schematic of a geothermal power plant figure 5 shows the geothermal energy dispersion in the world indicating that the united states, mexico and north america have more energy production [30]. http://dx.doi.org/10.21622/resd.2018.04.1.042 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.042 47 resd © 2018 http://apc.aast.edu fig. 5. worldwide geothermal based electric power generation 2. environmental benefits one of the most important advantages of using geothermal heat pumps is the reduction of environmental degradation effects given that heating systems work with fossil fuels and this kind of fuel is one of the main factors in the production of environmental pollutants. replacing a variety of new energies instead of fossil fuel systems can significantly reduce greenhouse gas emissions and pollutants [31] [32]. figure 6 shows the amount of co2 production for thermal power plants with fossil fuels and renewable fuels [30]. it can be seen that geothermal power plants have a very low co2 production rate compared to that of fossil fuels power plants, and the binary cycle produces very little co2 [33] . fig. 6. co2 emissions from various power plants also figure 7 shows the geothermal energy use in different sectors from 1995 to 2015. http://dx.doi.org/10.21622/resd.2018.04.1.042 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.042 48 resd © 2018 http://apc.aast.edu fig. 7. amount of geothermal energy used in different sectors from 1995 to 2015 in figure 8, the amount of electricity generated by geothermal energy in the ten countries has been investigated and it has been proved that united states is the highest in using this energy [34] fig. 8. geothermal energy capacity in ten countries 3. geothermal energy capacities and history in iran in iran, since 1975, extensive studies have been initiated in order to identify the geothermal energy source potential of the ministry of energy in cooperation with enel consulting engineers in the north and northwest regions of iran in an area of 260,000 square kilometers. the result of this research revealed that sabalan, damavand, khoy, mako and sahand areas, with an area of more than 31,000 square kilometers, are suitable for further studies and geothermal energy utilization. in this regard, the exploration program, including geological, geophysical and geochemical studies, was planned. in the year 1982, with the completion of preliminary exploratory studies in each of the areas mentioned, the areas susceptible are more precisely identified and as a result, in the sabalan area: meshkin shahr, sarein and busheli areas, in the damavand area of the district: neunal, in the makukhoy regions: black and dasht and in the sahand area, five smaller regions were selected to focus on the activities of the exploratory phase. after http://dx.doi.org/10.21622/resd.2018.04.1.042 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.042 49 resd © 2018 http://apc.aast.edu a relatively long interruption and with the aim of reactivating the plan, existing reports were revisited by undp experts in 1991 and the meshkin shahr geothermal region was introduced as the first priority for further exploratory studies [35]. following the mentioned studies, exploration, injection and descriptive drilling projects were defined in order to identify more potential in the sarein area of meshkin shahr in 2002 that drilling operations are the first geothermal wells in the same year began. the first phase of this project was completed in 2004. in total, three exploratory wells and two injection well bars were drilled at this stage and two-loop test of three exploratory wells was successfully carried out, which was the most important achievement of this phase of the project to acquire the know-how in geothermal wells. the second phase of the project began in 2005. in figure 9, areas with geothermal energy are shown. fig. 9. geothermal potential areas in iran in the project for the development of the geothermal field and the construction of meshkin shahr power plant, the drilling of wells, the operation of wells during the test period and the manufacture of test equipment in the country have been completely indigenous and were done by local experts. also, in the field of using geothermal heat pumps, t so far, the technology of installing earth coils has been completely and 100% native in iran n. [36] figure 10 shows the distribution of geothermal energy in iran, according to the figure, it can be stated that geothermal energy can be used in three parts of the northwest, center of iran and south of iran. of course, in the northwest of iran due to the presence of volcanoes and in the center of iran due to the presence of the desert, and in southern iran, the use of this energy can be very useful due to the persian gulf sea. http://dx.doi.org/10.21622/resd.2018.04.1.042 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.042 50 resd © 2018 http://apc.aast.edu fig. 10. distribution of geothermal potential in different regions of iran for review 4. iran geothermal power plant a. meshkin shahr brief history the meshkin shahr geothermal prospect lies in the moil valley on the western slopes of mt. sabalan, approximately 16 km se of meshkin shahr city. mt. sabalan was previously explored for geothermal resources in 1974, with geological, geochemical, and geophysical surveys being undertaken. renewed interest in the area resulted in further geophysical, geochemical and geological surveys being carried out in 1998. these studies have resulted in the identification of a number of prospects associated with mt. sabalan. the present study has been undertaken to find out what information is needed to establish baseline environmental conditions involving surveys of geology and land, weather conditions, noise conditions, ecology and socio-economic conditions [36]. b. meshkin shahr power plant meshkin shahr power plant (ardabil province, near meshkin shahr city) is one of iran's geothermal plants with a production capacity of 55 mw. in this power plant, the water is injected through the pipe and by 250 to 500 degrees celsius, the water is turned into steam, then the steam comes to the surface and the steam turbine circulates [37]. based on studies by the office of the new energy organization of iran, the meshkin shahr area is the best point for using the geothermal energy capacity in the country. so that the main purpose of this office is to build and operate a 100 mw nominal power plant in the area. according to studies, sabalan's domains in meshkin shahr have the capacity to build up to 400 megawatts of power plants [38]. according to the studies of the power plant of the energy office, the first exploration well of meshkin shahr was erected vertically in 2002 with a depth of 3,200 meters and a temperature of 250 degrees celsius. the second exploratory well was drilled in 2004 to a depth of 3,177 meters with a 140degree cavity at the end of the well, and then the third exploratory well at a depth of 2,695 meters and a temperature of 211 degrees celsius was drilled. the 17 wells forecast for this plant, so far, 11 wells have been drilled and three wells have successfully passed the steam outlet test stage [39]. table 2 shows the characteristics of this power plant. table 2. geothermal power station at meshkin shahr power plant specifications founding date 1377 type of power plant geothermal the number of geothermal wells 17 deep geothermal wells more than 2, 000 meters condition active the owner new energy organization of iran (sana) maximum power 400 mw power 100 mw c. sabalan geothermal power plant northern slopes of sabalan hosts many hot springs (seven in the mouil valle near meshkin shahr, one further west at yel sou, and three aligned along majo ne trending structure near ghotur-suii). the temperatures of these thermal springs range from 21°c to 82°c. chemically they fall into different types including neutral, cl-so4 and acid so4. giggenbach [40] (1992) analyzed the hot springs waters and found relatively low na-k-mg temperatures of about 150°c. mt. sabalan lies on the south caspian plate, which underthrusts the eurasian plate to the north. it is in turn under thrust by iranian plate, which produces compression in a northwest direction. this is complicated by a dextral rotational movement caused by northward under thrusting of the nearby arabian plate beneath the iranian plate. there is no benioffwadati zone to indicate any present day subduction. http://dx.doi.org/10.21622/resd.2018.04.1.042 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.042 51 resd © 2018 http://apc.aast.edu mt. sabalan is a quaternary volcanic complex that rises to a height of 4811 m, some 3800 m above the ahar chai valley to the north. volcanism within the sabalan caldera has formed three major volcanic peaks which rise to elevations of around 4700 m[41] . analysis of the single–flash geothermal power plant was conducted using energy and exergy concepts for sabalan, iran. reservoir fluid enthalpy and mass flow rate are 1000 kj/kg and 500 kg/s respectively. ees software was used to model the plant. optimization was done to maximize the net power output of the plant. optimum pressure value for separation is 5.5 bar. with these optimum pressure values the net power output of the plant is calculated to be 36594 kwe. pumps and compressor will use 843 kw e and 3350 kwe, respectively. table 2 illustrates important parameters at major stages of power plant at optimal pressure. the overall first and second law efficiencies of the power plant are 7.32% and 32.73%, respectively. the reference conditions for exergy analysis are 15ºc and atmospheric pressure. figure 11 shows exergy destruction at different stages of the plant. 1.38% of the total exergy destruction is due to transmission from the reservoir to wellhead. 1.09% of the exergy is destroyed at the separation step. 4.91% is lost at the steam expansion unit. 23.35% are destroyed in the condenser. 13.19% and 41.44% are the waste brine from condensing steam and separator, respectively. finally, the remainder is 32.73%, which is the fraction of the initial exergy that the plant turns to power [42] . fig. 11. grassman presentation of the overall exergy flow 5. resources and geothermal maps in iran the position of iran in the tectonic boundaries shows the enormous power of the country's framework [43]. the continental plate of saudi arabia and the indian ocean plate have, on the other hand, caused major deformations in iran and zagros region wrinkle is the evidence of the huge surface of these forces. being placed in a volcanic belt has made iran's geopolitical area very active and high potential of geothermal energy and the presence of volcanic activity and abundant hot water sources are evidence of this claim. there is eothermal energy potential in the country, according to studies conducted in more than 10 areas that have been identified based on tectonic activity, hot springs, surface emergencies and other geological evidence. according to studies conducted in 1377, these areas are as follows: district of sabalan, meshkin shahr, sarein and busheli damavand region, nandul area maku region, black area of fountain khoy region, dorsal region sahand region taftan district, bessman nayband region birjand area, ferdos takab region, hashtrood region khor, bayabanak isfahan district, localities ramsar district bandar abbas region, minab boushehr district, kazeroon and lar bastak area. according to the world classifications, iran is in the group of countries with potential reserves for the production of heat from geothermal energy using cyclic evaporation and binaries (for a period of 30 years) and the ability to generate electricity from geothermal energy with a capacity of more than 200 megawatts. http://dx.doi.org/10.21622/resd.2018.04.1.042 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.042 52 resd © 2018 http://apc.aast.edu table 3. geothermal energy potentiometric estimation (kj) in iranian provinces iii. summary and conclusions iran has more than 200 fossil fuel power plants which produce about 26,000 megawatts of electricity. according to the results, geothermal energy can generate about 100 megawatts of electricity. also, with the introduction of different regions of iran and using these energies, electricity production can be increased. given that fossil fuel consumption in iran is very high, pollution in iran is higher than the global level. however, with the use of geothermal energy, these contaminations can be reduced. also, surveys on geothermal energy in 18 regions of iran have suggested the largest areas of tabas, mahallat and sabalan for the use of geothermal energy. r province name the approximate number of hot springs number of possible geothermal areas thermal energy(kj) 1 azarbayjan sharghi 15 7 58×1016 2 azarbayjan gharbi 41 10 74×1016 3 ardebil 50 6 44.4×1016 4 esfehan 6 4 29.6×1016 5 ilam 2 1 7.4×1016 6 bosher 3 3 22.2×1016 7 tehran ------- ------- ------- 8 chaharmahl va bakhtiyari 1 1 7.4×1016 9 khorasan jonobi 1 1 7.4×1016 10 khorasan razavi 3 3 22.2×1016 11 khorasan shomali 3 3 22.2×1016 12 khuzestan ------- ------- ------- 13 zanjan 3 3 22.2×1016 14 semnan 1 1 7.4×1016 15 sistan va balochestan 10 5 37×1016 16 fars 3 3 22.2×1016 17 ghazvin 4 4 29.6×1016 18 ghom ------- ------- ------- 19 kordestan ------- ------- ------- 20 kerman 9 8 59.2×1016 21 kermanshah 2 2 14.8×1016 22 kohkeloye va boyer ahmad 1 1 7.4×1016 23 golestan 1 1 7.4×1016 24 gilan 2 2 14.8×1016 25 lorestan 2 2 14.8×1016 26 mazandaran 5 5 37×1016 27 markazi 6 1 7.4×1016 28 hormozgan 16 14 103.6×1016 29 hamedan ------- ------- ------- 30 yazd 1 1 7.4×1016 31 alborz ------- ------- ------- total 191 147 1.087×1019 table 3 shows the geothermal energy potential (kj) in the iranian provinces, which is the highest value for west azarbaijan. http://dx.doi.org/10.21622/resd.2018.04.1.042 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 4, issue 1, june 2018 issn 2356-8569 http://dx.doi.org/10.21622/resd.2018.04.1.042 53 resd © 2018 http://apc.aast.edu references [1] m. abedi , a. afshar , v. ardestani , g. norouzi and c. lucas ."application of various methods for 2d inverse modeling of residual gravity anomalies." acta geophysica, vol. 58, pp. 317336 2010, doi:10.2478/s11600-009-0053-2. 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"energy and exergy analysis of sabalan geothermal power plant, iran," in proceedings, world geothermal congress, 2010, pp. 25–9. [43] m. mohammadzadeh-moghaddam, b. oskooi, m. mirzaei and s.j. jouneghani. "magnetic studies for geothermal exploration in mahallat, iran," istanbul 2012 international geophysical conference and oil &amp; gas exhibition, society of exploration geophysicists and the chamber of geophysical engineers of turkey, 2012, pp. 1–4, doi:10.1190/ist092012-001.62. http://dx.doi.org/10.21622/resd.2018.04.1.042 http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.046 46 resd © 2019 http://apc.aast.edu probabilistic analysis of the reliability performance for power transformers in egypt 1 ahmed el-bassiouny, 2 mohamed el-shimy, 3 rizk hamouda 1 salah shaaban consulting office, cairo, egypt, 2 electrical power and machines department, faulty of engineering, ain shams university, cairo, egypt, 3 energy engineering, faulty of engineering, heliopolis university, cairo, egypt, 1mohamed_bekhet@eng.asu.edu.eg abstract from reliability, maintainability, and availability (ram) points of view, the performance of power transformers has significant impacts on the performance of the entire power network. their performance has also significant impacts on the power interruptions at various voltage levels and the consequent customer interruption costs. this paper l discusses the estimated remaining lifetime of power transformers in 500 kv, 220 kv, 132 kv and 66-33 kv subpopulations of the egyptian grid in which the best fit probability distribution is used through matlab program as the input data is time between failures (tbfs). the best fit probability distribution is used in this case study which is weibull distribution. finally, availability of the transformers per different voltage populations is calculated. different subassemblies (failures) are also subjected to the same process of determining tbfs and estimating remaining lifetime. the results are helpful in the manufacturing process of the transformers and enhancing the maintenance schedule. keywords transformers, weibull distribution, remaining lifetime, availability. i. introduction this paper discusses the probabilistic analysis of the reliability performance for the transformers of different voltage populations of the egyptian power grid so that failure rates are calculated. based on this, the overall performance of the transformer shall be observed. all the analyses are performed under probabilistic approach. the probabilistic analysis accounts for the uncertainties in the input data. the best fits of statistical probability distributions are determined for each transformer and for each of its subassemblies in various voltages subpopulations. main data, collected of the egyptian power grid from [1]-[3], are the number of transformers, number of failures, and repair time for every voltage subpopulation which are 500 kv, 220 kv, 132 kv and 66-33 kv of the egyptian power grid from the year 2002 till 2009. the statistical approach is performed by using matlab program. different continuous probability distributions were compared in order to obtain the best fit distribution for this case study. the input data is time between failures (tbfs) and weibull distribution is used as a main distribution in this paper because it is widely and commonly used in reliability and lifetime analysis [4, 5, 6]. remaining life time of the transformers in different voltage subpopulations are estimated by using the probability distributions and the results from the distributions will also be compared. using weibull distribution usually requires a defined failure time which is the time from the start of operation till failure occurred. since the study period is only 8 years from year 2002 till year 2009, therefore time between failures (tbfs) is used in this paper since the tbfs units are years. ii. probability distributions probability distributions are a mathematical method used to measure and analyze random variables [7]. reliability engineering provides the methods and tools used to estimate the life time of equipment or components without failure for a specific period of time [8]. probability distributions are categorized into continuous probability distributions and discrete probability distributions [9]. the selection of the most suitable probability distribution depends on every case. in this paper, since data are positive numbers and continuous, the selected distributions are weibull distribution, normal distribution, rayleigh distribution, logistic distribution and lognormal distribution. table (1) gives a summary regarding the five selected distributions. http://dx.doi.org/10.21622/resd.2019.05.2.046 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.046 47 resd © 2019 http://apc.aast.edu table 1 summary of five different probability distributions. probability distribution type characteristics 1 normal (gaussian) continuous it is used in reliability 𝑓(𝑡) = 1 √2𝜋𝜎 ℮ −1 2 ( 𝑡−𝜇 𝜎 )2 where 𝜇 is the mean 𝜎 is the standard deviation 2 logistic continuous it is used to describe growth, that is, the size of a population expressed as a function of a time variable 𝑓(𝑡) = ℮ 𝜇−𝑥 𝛼 𝛼[1 + ℮ 𝜇−𝑥 𝛼 ] 𝜇 is the mean or location parameter 𝛼 is scale parameter 3 weibull continuous used in reliability 𝑓(𝑡) = 𝛽 𝜂 ∗ ( 𝑡 𝜂 ) 𝛽−1 ∗ 𝑒 −( 𝑡 𝜂 )𝛽 𝛽 is shape parameter η is scale parameter 4 lognormal continuous it is used in life time modelling and very helpful in reliability engineering 𝑓(𝑡) = 1 √2𝜋 ∗ 𝜎′ ℮ −1 2 ( 𝑡′−𝜇′ 𝜎′ )2 t’ = ln(t) 𝜇′is the mean of log time to fail 𝜎′ is the standard deviation of log time to fail 5 rayleigh continuous 𝑓(𝑡) = 2 ∗ 𝛼 ∗ 𝜆2 ∗ 𝑡 ∗ 𝑒 −(𝜆∗𝑡) 2 ∗ (1 − 𝑒 −(𝜆∗𝑡) 2 )𝛼−1 𝛼 shape parameter 𝜆 scale parameter 2. a. data analysis and remaining lifetime estimate of the transformer a. tbfs calculations tbfs calculations for different voltage subpopulations are performed. all calculations are per transformer per year per failure. figure (1) shows the different tbfs values for every voltage subpopulation where tbfs decrease as time increases indicating an increase in the failure rate. in comparison between different voltage subpopulations, 132 kv population has the highest tbf among the different voltage populations followed by 500 kv then 66-33 kv and finally 220 kv. these differences in tbfs between different voltages populations due to the fact that every sub voltage population has its own collected data. b. best fit distribution tbfs after calculating tbfs, the second step is to determine the best suitable distribution by making a comparison between 5 different continuous distributions which are: weibull distribution, normal distribution, rayleigh distribution, logistic distribution, and lognormal distribution. after getting statistical mean and standard deviation results from matlab program, a percentage (%) difference of the mean and standard deviation (std) is made between arithmetic and statistical values. normal distribution is a flexible distribution that fits parameters according to given values where the distribution is always symmetrical around the mean and mean, median and mode are always the same results [4, 10]. accordingly, the normal distribution is used in comparison and in obtaining the deterministic values only not in the ranking of the best fit distribution. table 2 summarizes the findings and indicates the best fit probability distribution in this case study. from the comparison between the distributions, weibull distribution is common for all voltages subpopulations. this concludes that weibull distribution is suitable for http://dx.doi.org/10.21622/resd.2019.05.2.046 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.046 48 resd © 2019 http://apc.aast.edu this case study. the second common distribution used is lognormal distribution followed by logistic distribution. as per [5], the years with zero values shall be omitted from the population regarding weibull distribution and as for rayleigh distribution, it is a special deviation of weibull distribution [11, 12] thus population with zero values are omitted, too. therefore, for fair comparison, the study period is shortened and the results were obtained on this fact. weibull distribution acts as the main probability distribution in this paper in estimating the remaining life time of transformer. however, the weibull distribution is under the investigation as like the other 4 probability distributions. this does not mean that weibull distribution is not used in lifetime calculation, but it could not be suitable for this case only, also weibull distribution has proven a high efficiency in lifetime analysis [13, 14]. fig .1 tbfs for different voltage populations table 2 summary table indicating best fit distributions for every voltage subpopulation voltage probability distribution used subpopulation tbfs 500 kv lognormal & weibull 220 kv weibull & lognormal 132 kv weibull & lognormal 66-33 kv weibull & logistic iii. estimating the remaining lifetime of the transformers the study period is 8 years from the year 2002 to year 2009 and by using probability distributions as in table 2, tbfs will be the main input to the distributions in order to predict the remaining lifetime of the transformers. matlab program is used in the analysis where distribution fitter application in matlab is a very useful tool for the analysis. as for weibull distribution, parameters estimation in matlab coding is by the method of maximum likelihood estimation [15, 16] where this method is the most advanced and accurate method to determine the parameters. a. 500 kv subpopulation transformers from table 2, lognormal distribution and weibull distribution are used in determining the remaining lifetime of this voltage subpopulation where tbf is the input data to the two distributions and the output will be failure rate and reliability, respectively. figure 2, represents the failure rate where it is clear that failure rate increases by time, this concurs with ß is greater than 1 and failure rate increases by time, while, on the other hand, the failure rate of the lognormal distribution increases till it reaches the peak values and then decreases by time [6, 10, 17]. figure 3, represents the reliability of the transformers and remaining life time can be obtained at certain reliability rates. reliability rates depend on the geographical factor; for example, area with industrial complexes may require a high-level reliability other than different areas. http://dx.doi.org/10.21622/resd.2019.05.2.046 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.046 49 resd © 2019 http://apc.aast.edu fig .2 failure rates of different probability distributions for 500 kv subpopulation fig .3 reliability of different probability distributions for 500 kv subpopulation b. 220 kv subpopulation transformers this section focuses on 220 kv population transformers reliability and remaining life time through the same steps that were used in the 500-kv population. figure 4 indicates that failure rate regarding weibull distribution increases rapidly by time while failure rate of lognormal distribution reaches its peak at 4 years thus leads to the conclusion that the transformers must be replaced. figure 5 illustrates the reliability through 4 years in which the remaining life time of the transformers is exploited. fig .4 failure rates of different probability distributions for 220 kv subpopulation fig .5 reliability of different probability distributions for 220 kv subpopulation c. 132 kv subpopulation transformers this section focuses on 132 kv population transformers reliability and remaining life time through the same steps that were previously used in the 500 kv and 220 kv populations. figure 6 shows that the failure rate increases by time regarding weibull distribution, but it increases at slow rate while. on the other hand, the curve of the failure rate resulting from lognormal distribution started from peak and then decreases by time. figure7 shows that the reliability of both distributions in 50 years life span and reliability decreases gradually. however, reliability of lognormal distribution decreases faster than that of weibull distribution. http://dx.doi.org/10.21622/resd.2019.05.2.046 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.046 50 resd © 2019 http://apc.aast.edu fig .6 failure rates of different probability distributions for 132 kv subpopulation. fig .7 reliability of different probability distributions for 132 kv subpopulation. d. 66-33 kv subpopulation transformers this section focuses on 66-33 kv population transformers reliability and remaining life time where the same steps that were used in the 500 kv, 220 kv and 132 kv populations are reused again. however, this is the only population that has used logistic distribution instead of lognormal distribution along with weibull distribution based on the comparison of best fit distributions. figure 8 shows that failure rates of both distributions increase by time, this indicates that the transformers are in the wear out phase where failure rate increases rapidly regarding weibull distribution and increases in a slow rate regarding logistic distribution. figure 9 shows that it is clear that reliability was decreasing slowly in the first 2 years then falls back till it reaches zero nearly at 8 years period of time and the transformers remaining life time can be obtained at certain reliability rates. fig .8 failure rates of different probability distributions for 66-33 kv subpopulation. fig .9 reliability of different probability distributions for 66-33 kv subpopulation. e. transformers availability evaluation this section discusses the availability (a) of the transformers of different voltage populations as availability can be calculated from (1) after determining tbfs and ttr as listed in appendix c [18]-[20]. 𝑨 = 𝑻𝑩𝑭𝒔 𝑻𝑩𝑭𝒔+𝑻𝑻𝑹 (1) since (1) is per year, therefore for the whole 8 years study period, the mean time between failures (mtbf) and mean time to repair (mttr) is used as in (2) . 𝑨 = 𝑴𝑻𝑩𝑭𝒔 𝑴𝑻𝑩𝑭𝒔+𝑴𝑻𝑻𝑹 (2) figure 10 illustrates the different availability per year and for the overall study period for different voltage populations. in general, availability is high despite the increased failure rates and limited expected lifetime of transformers per voltage populations. from (2), the http://dx.doi.org/10.21622/resd.2019.05.2.046 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.046 51 resd © 2019 http://apc.aast.edu calculation for different voltage populations determined that 500 kv population has the lowest availability followed by 220 kv then 132 kv and finally 66-33 kv. fig .10 different availability of different voltages population. f. results discussion. the results were based on 8 years study period and of course the longer the years the better the results will be, as transformers life span cab be of average 40-60 years [21, 22]. the results indicate that the transformers are in the wear-out phase of the bathtub curve for all voltage populations. bathtub curve is a curve that describes 3 stages of any equipment. the first stage is the infant phase where the equipment starts operation for the first time with a low failure rate and high reliability. the second stage is the useful life phase where the failure rate is constant. the final phase is the wear-out phase in which the equipment operates for a long time, starts to fail at a certain point and needs replacing. in this phase, the failure rate increases and reliability decreases [4]. the remaining lifetime of the transformers for every voltage subpopulation is summarized in table 3 where the transformers in all voltages subpopulation must be replaced within few years with new transformers in order to deliver a higher reliability to the egyptian power grid. since weibull distribution is common between all populations and is based on percentage difference of mean and std, it is chosen to observe the remaining life time, where it is found that the remaining life span of the transformers in all populations is nearly alike and that the transformers will be expired with this range of years as shown in table (3). choosing different reliability levels depends on the operator, while these voltage populations must have a high reliability level as these voltage populations exist in the transmission power system that delivers the generated electrical power to the distribution systems (low voltage system), thus these voltages are the only link between generation and distribution. from the results, instructions can be delivered to the maintenance department in order to perform a proper maintenance schedule and to the operation department in order to operate and handle the transformers carefully. in addition, the results shall be sent to the manufacturer so that transformers with better components and with higher quality and technology are manufactured. this will lead to lowering the interruption power and lower repair time and customer interruption costs in which the costs were highly based on an earlier study of the same period of time to the transformers. table 3 remaining lifetime in comparison between different voltage populations. voltage population remaining lifetime in years 500 kv 220 kv 132 kv 66-33 kv weibull distribution at 90 % reliability level 1.6 years 1.3 years 2 years 2.4 years weibull distribution at 80 % reliability level 2.7 years 1.6 years 3.75 years 3 years weibull distribution at 70 % reliability level 3.7 years 1.8 years 5.75 years 3.45 years 3. g. subassemblies data analysis. as transformers are the most important equipment in the power system, analysis of their function, maintenance and observation reports are taken into consideration by the manufactures in order to deliver a much higher quality next generation transformers. [23, 24] mentioned the basis of the transformers design, protection, operation and maintenance. there are 16 subassemblies of failures in which the analysis is applied [1]-[3]. these failures are sometimes referred to as outage causes and categorized into five categories which are transformer related outages, power system related outages, environment related outages, human factor related outages (hm), and unclassified/no flag (nf) and other http://dx.doi.org/10.21622/resd.2019.05.2.046 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.046 52 resd © 2019 http://apc.aast.edu outage causes. the transformer related outages are buchholz and pressure relief (b&p), over current protection (oc), earth fault protection (efp), differential protection (dp), breakdown and damage (b&d), firefighting system (ffs), hotspots (hs), leakage of sf6 or oil (leakage), and flash over (fo). the power system related outage category includes the outage of incomers (oi), and bus bar protection (bbp) actions. the environment related outage category includes bad weather (bw), and animal and birds (a&b) caused outages a. estimation of remaining lifetime for each of the subassemblies similar to the steps taken in order to estimate the remaining lifetime of the transformers, tbfs of different subassemblies are calculated and listed in table 4. then the mean time between failures for every subassembly will be determined and compared to the mean time between failures for the whole transformer for different voltage populations. finally, the remaining lifetime for every subassembly is estimated using weibull distribution. table 4 and figure 11 compare between mtbfs for every subassembly and for different voltage populations. it is clear that there is no direct relation between the overall mtbfs of the transformers as a complete set and the different subassemblies. a comparison is made to determine the maximum and minimum mtbfs for every subassembly for different voltage populations as shown in table 5. this comparison is made by excluding nf and other failures as they are not physical but undetermined failures. table 5 also shows that that every voltage population has a different maximum and minimum values regarding mtbfs depending on number of failures and repair time. table 4 tbfs for every subassemblies regarding 500 kv population. voltage populations 500 kv 220 kv 132 kv 66-33 kv mean values mean values mean values mean values tbf for whole transformer 6.60 2.17 13.67 4.22 tbf for b&p 1.33 71.99 9.88 86.42 tbf for oc 9.38 11.50 22.93 19.28 tbf for efp 13.25 54.13 36.13 45.49 tbf for dp 13.25 21.21 34.42 37.19 tbf for b&d 15.00 39.31 28.69 62.72 tbf for ffs 15.25 106.5 10.63 340.2 tbf for hs 0.00 95.07 0.00 0.00 tbf for leakage 7.63 22.14 8.27 0.00 tbf for fo 0.00 77.00 0.00 0.00 tbf for oi 0.00 73.46 18.71 15.01 tbf for bbp 3.75 86.59 3.33 438.5 tbf for bw 7.50 92.46 3.54 580.4 tbf for a&b 0.00 106.7 34.50 582.9 tbf for hm 0.00 34.09 5.19 735.3 tbf for nf 5.63 76.81 10.00 134.4 tbf for others 15.75 15.63 13.16 197.6 http://dx.doi.org/10.21622/resd.2019.05.2.046 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.046 53 resd © 2019 http://apc.aast.edu fig . 11a. mtbfs for every subassembly regarding 500 kv population. fig . 11b. mtbfs for every subassembly regarding 220 kv population. fig . 11c. mtbfs for every subassembly regarding 132 kv population. fig . 11d. mtbfs for every subassembly regarding 66-33 kv population. table 5 maximum and minimum mtbfs for different voltage population. 500 kv 220 kv 132 kv 66-33 kv maximum mtbfs b&d ffs efp hm minimum mtbfs b&p oc bbp oi b. results discussion the overall tbf of the whole transformer does not depend on the tbf of every subassembly. in fact, every subassembly has its own tbf that depends on different variables. for every subassembly, the components can be used for other purposes after the shutdown of the transformer such as bus bars, as bars can be recycled into new ones, or in case the failure did not affect their functionality. as shown in figure 11, a comparison between different voltage populations is performed in order to check the mtbf among different subassemblies where mtbf differs from voltage population to another as it depends on the number of failures and the number of transformers. mtbfs indicates that the failure rate decreases as mtbf increases and vice versa as the tbfs decreases the failure rate increases. number of failures, repair time and cic per transformer analysis can provide solid data in order to improve maintenance schedules, inform the transformers’ manufactures to enhance the quality of materials by performing more tests and offering training courses to the employees to reduce human error. iv. conclusions this paper handled ram analysis for the transformers of different voltage populations in the egyptian power grid and the results showed that the transformers are http://dx.doi.org/10.21622/resd.2019.05.2.046 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.046 54 resd © 2019 http://apc.aast.edu in the wear out phase but the availability of the transformers is high. this leads to enhancing maintenance schedules, improve the manufacturing process and train more personals. table 6 remaining lifetime for every subassembly in different voltage populations. 500 kv 220 kv 132 kv 66-33 kv subassembly remaining lifetime at 90 % reliability (years) subassembly remaining lifetime at 90 % reliability (years) subassembly remaining lifetime at 90 % reliability (years) subassembly remaining lifetime at 90 % reliability (years) b&p occurred once b&p 12.5 b&p occurred once b&p 53.5 oc 3 years study period 16.5 oc 8 oc 6 years study period 6.5 oc 8.25 efp 4 years study period 20.25 efp 5.5 efp 4 years study period 52.5 efp 26.5 dp 4 years study period 20.25 dp 15.5 dp 6 years study period 23.5 dp 23.25 b&d 4 years study period this failure is constant at 30 years tbf b&d 10 b&d 4 years study period 28.5 b&d 30.5 ffs 6 years study period 10.5 ffs 26.5 ffs occurred once ffs 96.5 hs no failures occurred hs 18 hs no failures hs no failures leakage 3 years study period 11.25 leakage 13.75 leakage 2 years study period 24.75 leakage no failures fo no failures occurred fo 38 fo no failures fo no failures oi no failures occurred oi 15 oi 5 years study period 12.75 oi 5.75 bbp occurred once bbp 10 bbp occurred once bbp – 7 years study period 84.5 bw 2 years study period this failure is constant at 30 years tbf bw 29.5 bw occurred once bw 7 years study period 134 a&b no failures occurred a&b 75 a&b 4 years study period 40.5 a&b 7 years study period 184 hm no failures occurred hm 26 hm occurred once hm 188 nf 2 years study period 13 nf 17 nf occurred once nf 72.5 others 6 years study period 9.25 others 10.25 others 2 years study period 15.5 others 85.5 http://dx.doi.org/10.21622/resd.2019.05.2.046 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.046 55 resd © 2019 http://apc.aast.edu references [1] m. abdelfatah , m. el-shimy , and h.m. ismail. “outage data analysis of utility power transformers based on outage reports during 2002–2009,” international journal of electrical power & energy systems, vol. 47, pp. 41-51, may, 2013. [2] m. abdelfatah , m. el-shimy, and h.m. ismail. “reliability and maintainability analysis of medium voltage transformers in egypt,” in the 8th international conference on electrical engineering (iceeng-8) of the egyptian military technical college, cairo, egypt, 2012, pp. 1-17. [3] m. el-shimy , m. abdelfatah , and h.m. ismail. “reliability, availability, and maintainability (ram) analysis of utility power transformers in egypt,” elektrika-utm journal of electrical engineering, vol. 14, no. 1, pp. 1-5, jan. 2012. [4] life data analysis erence, reliasoft corporation [on-line] available: http://www.reliasoft.com [jan. 5, 2018]. [5] r.b. abernethy, j.e. breneman, c.h. medlin, g.l. reinman. weibull analysis handbook. pratt and whitney west palm beach fl government products, div, 1983. [6] w.b. nelson. applied life data analysis. place of publication: john wiley & sons, 2005. [7] c. forbes, m. evans, n. hastings, and b. peacock. statistical distributions. place of publication: john wiley & sons, 2011. [8] life data analysis erence, reliasoft corporation [on-line] available: http://www.reliasoft.com [ jan 5, 2018]. [9] oracle help center [online] available: https://docs.oracle.com/cd/e12825_01/epm.111/ cb_user/frameset.htm?apas04.html [jan 5, 2018]. [10] w.g. ireson, c.f. coombs, r.y. moss. handbook of reliability engineering and management. place of publication: mcgraw-hill professional, 1996. [11] j. mun. advanced analytical models: over 800 models and 300 applications from the basel ii accord to wall street and beyond. place of publication: john wiley & sons, 2008,, appendix c. [12] online help manual, matlab cooperation [online] available: https://www.mathworks.com/help/stats/rayleighdistribution.html [mar. 3, 2018]. [13] r.b. abernethy. the new weibull handbook: reliability and statistical analysis for predicting life, safety, supportability, risk, cost and warranty claims. north palm beach, fl: dr. robert b. abernethy, 2004. [14] d. martin, j. marks, t.k. saha, o. krause, and n. mahmoudi. “investigation into modeling australian power transformer failure and retirement statistics,” ieee transactions on power delivery, vol, 33, no. 4, pp. 2011-9, aug. 2018. [15] online help manual, matlab cooperation [online] available: https://www.mathworks.com/help/stats/wblfit.html [mar. 3, 2018]. [16] online help manual, matlab cooperation [online] available: https://www.mathworks.com/help/stats/weibulldistribution.html [mar. 3, 2018]. [17] a.d. telang, v. mariappan. “hazard rate of lognormal distribution: an investigation,” international journal of performability engineering, vol. 4, no. 2, pp. 103, apr. 2008. [18] m.f. aly, i.h. afefy, r.k. abdel-magied, and e.k. elhalim, “a comprehensive model of reliability, availability, and maintainability (ram) for industrial systems evaluations,” jjmie, vol. 12, no. 1, pp. 59-67, jun. 2018. [19] s. verbrugge, d. colle, p. demeester, r. huelsermann, and m. jaeger. “general availability model for multilayer transport networks,” in drcn 2005. proceedings. 5th international workshop on design of reliable communication networks, ieee, oct. 2005, pp. 85-92. http://dx.doi.org/10.21622/resd.2019.05.2.046 https://www.mathworks.com/help/stats/rayleigh-distribution.html https://www.mathworks.com/help/stats/rayleigh-distribution.html https://www.mathworks.com/help/stats/weibull-distribution.html https://www.mathworks.com/help/stats/weibull-distribution.html journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.046 56 resd © 2019 http://apc.aast.edu [20] e. vargas. “high availability fundamentals.”, sun blueprints series. 2000 nov: 1-7. california, usa nov.2000, pp. 1-17. [21] p. jarman, r. hooton, l. walker, q. zhong, t. ishak, and z. wang. “transformer life prediction using data from units removed from service and thermal modelling,” in proc. cigre session, 2010, pp. 1-7. [22] p. jarman, z. wang, q. zhong, and t. ishak, “end-of-life modelling for power transformers in aged power system networks,” in cigre 2009 6th southern africa regional conference, cape town, southern africa, 2009 aug 17, pp.1-7. [23] bureau of reclamation “transformers: basics, maintenance and diagnostics,”, us department of the interior bureau of reclamation. denver, colorado, usa. apr. 2005. [24] j.h. harlow. “electric power transformer engineering,”, crc press; new york, usa, dec. 2011 http://dx.doi.org/10.21622/resd.2019.05.2.046 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.033 33 resd © 2019 http://apc.aast.edu study of site location and pipeline routing for future natural gas importing terminal project in morocco 1mahmoud akdi, 2firdaous el ghazi, 3moulay brahim sedra 1simolab, ibn tofail university, kenitra, morocco, 2simolab, ibn tofail university, kenitra, morocco, 3fste, umi moulay ismail university of meknes, morocco, 1makerase@gmail.com, 2elghazi.firdaous@gmail.com, 3mysedra@yahoo.fr abstract in order to achieve sustainable supply combustible development, morocco is projecting to invest in its first natural gas importing and storage capacity by 2030. this future project should be designed for electric power plants and other sectors using energy. it is not worthy that up today most of the existing power plants in morocco are depending on coal in their electricity production, this is in contrast with the recent government environmental commitments. therefore, the aim of this article is to develop a research analysis related to the natural gas future project by introducing the main key aspects of choosing a site location and proposing an optimum routing for pipelines based on mathematic algorithms. it is proved that the port of jorf lasfar is a suitable importing terminal choice for morocco. afterwards, a pipeline routing will be proposed given the natural gas potential consumers. thereby, the optimum pipeline routing starting from the importing terminal and linking the furthest consuming point is estimated at 490 km. keywords dijkstra algorithm, financial preview, natural gas, nigeria morocco pipeline project, operational research, pipeline optimum routing. i. introduction facing major energy challenges, morocco is increasingly orienting its strategic decisions towards reducing the use of polluting energy based on fossil sources. the global economic context presents significant development opportunities of liquid natural gas (lng) becoming an accessible energy source that is environment friendly and less expensive than other fuel-based or coal-based energies with a more important calorific value [1]. this global context presents a long-term opportunity for morocco to develop electricity production and heavy industry plants that currently run on other polluting fuels. therefore, morocco has set itself the goal of achieving the first lng import and storage terminal in the kingdom. the ministry of energy, mines and sustainable development has confirmed the future investment, the import terminal should be designed to equip morocco with the capacity to import, store and supply natural gas to the gas to power (gtp) and gas to industry (gti) [2] sectors covered by this program. therefore, this article aims to develop a scientific approach for: • identification and choice of the importing site through a scoring system based on factual criteria; • as part of the future nigeria morocco pipeline project, proposal of the optimal routing based on the dijkstra algorithm; • tentative of a financial preview analysis. this article deals with a current topic of natural gas development opportunities in morocco, the analysis conclusion can significantly contribute to a decision making regarding the choice of the new lng importing terminal location and the pipeline routing. the introduction of natural gas can definitely reduce the use of other polluting energy sources in the kingdom. ii. choice of lng importing site location for any investment project, the selection of the site location weighs heavily in the investment decision in the importing terminal. choosing the best site location can significantly impact the profitability of a project and its future development. at the present time, there are three potential site locations choices that can host the lng import terminal project, these sites are: • jorf lasfar port site • kenitra port site « as is » • kenitra new port « to be » http://dx.doi.org/10.21622/resd.2019.05.1.033 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.033 34 resd © 2019 http://apc.aast.edu a benchmark of the three sites is achieved below based on factual criteria. afterwards, a comparison of the three sites is summarized through a scoring system considering the features of each site location [4]. 1. benchmark of the potential site locations a. jorf lasfar (location: 33°7’n-8°38’o) the port of jorf lasfar was built in 1975 to basically export raw phosphate produced by the cherifian office of phosphate (ocp) industrial group. the development of the industrial area has contributed to the development of the port and gradually supply the petrochemical companies as well. in 2011, an extension of the port was carried out to ensure the reception of oil tankers and phosphatic products. the port of jorf lasfar is served via the a1 highway and the regional road r306, as well as the national road n1 from el jadida and from safi via r316. a freight railroad line is also connected to the port. jorf lasfar is considered one of the most important ports in morocco, its capacity is expending to handle more traffic in the future. the evolution of the ports traffic is represented in figure 1. fig .1 jorf lasfar port traffic evolution [3]. figure 1 shows that the port ensures the reception of oil tankers and phosphatic products up to 30 000 000 tonnes in 2017. as for the jorf lasfar port connectivity, the researchers present in figure 2 a full description of the existing facilities. the design of jorf lasfar port and the diversity of products crossing through have enhanced this port expertise in the reception of large cargoes. this site has several more advantages, including: fig .2 jorf lasfar port caracteristics and connectivity. • access to the sea with a minimum water depth of 12 m at low tide for large transport vessels; • appropriate surface conditions for the development and extension installation that can accommodate other products; • proximity from power plants jorf lasfar energy company (jlec) unit 1-2, unit 3-4 and unit 5-6 and ocp power plants; • possibility of installing the required lng landing dock near the actual terminal site; • reasonable distance to install the lng transfer lines from the unloading dock to the lng storage tanks. 0 5,000,000 10,000,000 15,000,000 20,000,000 25,000,000 30,000,000 2011 2012 2013 2014 2015 2016 2017 jorf lasfar annual traffic in tonnes 1 dock at -15,6 m for phosphates. 2 dock at -12,50 m for fertilizers. 3 dock at -12,5 m for coal. 4 & 5 dock at -12,5 m for sulfur. 6 & 7 dock at -11,5 m for ammoniac. 8 dock at -15,6 m for petroleum products. 9 dock at -12,5 m for oil and gas. 10 dock at -12,50 m for various products. 11 dock at -9,5 m for various products. 12 dock at -5 m for various products. 13 dock at -5,25 m for various products. 14 dock at -4 m for various products. 15 dock at -2,5 à -3,5 m. 16 dock at -12,5 m. http://dx.doi.org/10.21622/resd.2019.05.1.033 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.033 35 resd © 2019 http://apc.aast.edu b. kenitra “as is” (location: 34°16’n-006°41’o) the port of kenitra was built in 1912 for political and commercial reasons by the french protectorate in order to neutralize the competitive attraction of the port of tangier. in 1996, the national ports agency (npa) carried out development works to increase the river's hydraulic power and allow larger ships to access the wharves. fig .3 kenitra port traffic evolution [3]. the evolution of traffic is represented in figure 3. as for the kenitra port connectivity, the researchers present in figure 4 a full description from the npa official newsletter. the current port has several limitations due to the crossing of oued sebbou river, the removal of the port of kenitra to a new site nearby is being considered by the government. the new location will be the region of oulad bel assal, at 24 km from oued sebou. c. kenitra “as is” (location: 34°16’n-006°41’o) this new location of the port should bring the answers to the current limits of the kenitra port by moving it to another location that remains nearby at 24 km at the north, and is even more accessible. this new port has the following advantages: • availability of land required for the construction of the new port (approximately 2000 ha). • being located far away from the urban areas, this new location guarantees therefore the possibility of future extension. figure 5 shows the preliminary shaping of this port. fig .4 kenitra port caracteristics and connectivity. fig .5 evaluation study of the new kenitra atlantic port by catram consulting [5]. the vocation of this new port is currently commercial as it will support the development of kenitra city in terms of automotive industry for export as well as the reduction of traffic at casablanca port that is already saturated. the disadvantage remains relative to the investment required for this new port, estimated at 5 billion mad [6]. this investment will be added to the investment required for the construction of the lng import terminal and pipeline routing estimated at 45 billion mad [7]. 0 50,000 100,000 150,000 200,000 250,000 300,000 350,000 2001 2002 2003 2004 2005 2006 2007 2008 2009 kenitra annual traffic in tonnes 1 dock at -5.00 m / zh with a length of 224 ml. 2 dock at -5.00 m / zh; with a length of 246 ml. 3 dock at -5.00 m / zh with a length of 300 m. 4 dock at -5.00 m / zh with a length of 100 ml. 5 dock at -5.00 m / zh with a length of 60 ml. http://dx.doi.org/10.21622/resd.2019.05.1.033 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.033 36 resd © 2019 http://apc.aast.edu 2. site selection criteria referring to feedback from other similar lng logistics platform projects [8], below are the main factors determining the choice of the appropriate import terminal location: • proximity of end use points and lng future consumption sites; • proximity of the new pipeline project coming from nigeria; • easy access and departure for lng cargos, • distance from population areas; • conformity and extent of the land (available area, soil quality, geographical and topographical features, existence of groundwater tables); • ability to accommodate a future extension; • weather conditions; • exposure to natural hazards (earthquakes, plate tectonics, high tidal risk or potential tsunami hazards); • sensitivity of the surrounding environment (to be confirmed via environmental impact studies); by using a scoring system from 1 to 5 for each criterion, the table below shows the comparison analysis between kenitra port “as is”, north atlantic kenitra port (nakp) “to be” and jorf lasfar location. the ratings being: 1not filled 2partially filled 3half filled 4satisfactory table 1. comparison analysis between site locations. j o rf l a s fa r k e n itra "a s is " n a k p "t o b e " comments proximity of end use points and lng consumption sites 3 4 4 the main consumption points are located in north west morocco the significant industrial areas remain half path between different ports. proximity of the new pipeline project coming from nigeria 5 4 4 the situation of the port of jorf lasfar further south allows more proximity of connection with the future pipeline connecting nigeria to morocco. easy access and departure for lng cargos 5 1 4 the present port "as is" of kenitra has a difficult access for large boats, because of the passage by a parcel of sebou river, additional investments are needed for site redevelopment. the ease of access to the nakp port is to be confirmed security distance available away from population areas 5 1 5 the jorf lasfar area is classified an industrial area to be and located outside the urban perimeter. same as for the nakp port “to be” conformity and extent of the land 5 2 5 only the port of kenitra "as is" is limited in terms of possibility of extension. ability to accommodate a future extension 2 1 5 availability of land in nakp port “to be” is estimated at 2000 ha. weather conditions 5 5 5 the weather is favorable in all locations. exposure to natural hazards 4 5 4 unlikely risk, close exposure level for all location. new investments necessary to accomodate the port site 5 4 1 the new nakp port “to be” is in its study phase, the planned investment is 5 billion mad. kenitra port "as is" requires investment to allow lng cargoes to pass through. only the port of jorf lasfar is currently adapted and ready to receive an import terminal. final scoring 39 27 37 jorf lasfar port and nakp “to be” locations have the best yet close final scoring. figure 6 represents the comparison result between the three possible locations. http://dx.doi.org/10.21622/resd.2019.05.1.033 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.033 37 resd © 2019 http://apc.aast.edu fig .6 final scoring of each potential site choice. in general, since it is difficult to meet all the optimal conditions on a single location, some requirements can be reached by making changes on site at a relatively acceptable cost, the feedback from several similar projects indicates that the key variable that is likely to be discriminatory is the depth of the maritime jetty: if the depth of the water is not sufficient, the cost of carrying out development work increases and several technical constraints of reception process will be considered. after careful considerations, the jorf lasfar location and the nkap “to be” seem both to be suitable locations for the future lng terminal. these two locations have more many advantages when compared to kenitra “as is” location. however, jorf lasfar location, being already an existing operating port, and the npka” to be” being a future port requiring an important construction budget, it is more cautious to select the jorf lasfar location if no further new data are revealed in the future. the jorf lasfar site presents the favorable geographic location and it the best location that meets the selection criteria. it represents the least expensive site in terms of new redevelopment investments and represents fewer uncertainties in terms of costs and deadlines. this port will have the capacity to meet the national lng import need for seizing future development opportunities. iii. pipeline optimum routing 1. lng future consumers the import terminal project is intended to meet the needs of the country regarding lng energy needed for the gtp and gti programs. the investment in pipeline routing is equally important as the investment in the terminal construction itself. it’s clear that finding the optimum pipeline routing shall improve the profitability of this investment project. the first step is to find out the different consuming points and their locations, then classify the planned connection points for the pipeline as follows. a. electricity power plants the power plants concerned, also called combined cycle gas turbine (ccgt), will have a percentage of electricity to be produced from natural gas. in order to do so, investments are planned to adapt the existing production facilities. the power plants concerned are listed below [9]. table 2. power plants locations. power plant name city/region capacity in mw ccgt kenitra kenitra 450 mw ccgt mohammedia mohammedia 450 mw al wahda sidi kacem city 2 × 600 mw dhar doum 120 km south to tangier 2 x 600 mw oued al makhazine 100 km south to tangier 2 x 600 mw tahhadart tahhadart region mw b. industrial areas and natural gas discovered basins the pipeline routing should be able to cross a large industrial area, known to be host to many energy consuming industries, such as the ceramics industry and other heavy industries located in casablanca – settat industrial area. on the other hand, there are two natural gas discovered basins: the underground basin of sidi yahya lgharb and the underground basin of tendrara. it’s preferable that the natural gas pipeline shall be able to cross the discovered natural gas basins. c. existing and future lng pipelines the pipeline routing should be able to cross a large industrial area, known to be host to many energy consuming industries, such as the ceramics industry and other heavy industries located in casablanca – settat industrial area. 0 2 4 6 proximity of end use points and… proximity of the new pipeline… easy access and departure… distance from population… conformity and extent of the land ability to accommoda te a future… weather conditions exposure to natural hazards new investments necessary… jorf lasfar kenitra "as is" nakp " to be" http://dx.doi.org/10.21622/resd.2019.05.1.033 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.033 38 resd © 2019 http://apc.aast.edu • existing gazoduc maghreb europe (gme) pipeline: it is the maghreb europe pipeline, which starts from algeria, goes through northern morocco, crosses the gibraltar and joins spain. its diameter is 48 inches, its total length is 1300 km, including 45 km offshore and 540 km onshore on moroccan soil. • future nigeria morocco pipeline: this megaproject is part of a development policy in africa, a cooperation agreement was signed between nigeria and morocco in december 2016. currently, the study of this project is in feed (frond end and engineering design) phase [10]. for several economic and political reasons, the routing of the pipeline will be operated on a combined onshore / offshore routing, the estimated length of the pipeline will be about 5.700 km. it should be noted that investment estimates are still being revised by engineering studies. the pipeline routing can be settled after signing and negotiating access rights. currently, this pipeline will serve many countries such as benin, togo, ghana, liberia, sierra leone, guinea, guinea bissau, gambia, senegal and mauritania before arriving to morocco. fig .7 planned pipeline routing, from the official website lesinfos.ma. in summary, the optimal pipeline routing shall be carefully designed to best meet consumption expectations, this pipeline must meet the following requirements: • being carried out in the continuity of the pipeline from nigeria, this pipeline will arrive to morocco through several countries in northwestern africa and passing through senegal. • powering the combined cycle power plants concerned by the gtp investment plan. • meeting the gti need via a passage through the most important industrial area. • the pipeline routing should take the shortest possible distance. • the optimum routing shall confirm the best choice of the new importing terminal. this is an optimization problematic of the pipeline routing. the researchers present their input data and working assumptions in the form of a short-run operational search problem, dijkstra algorithm is suitable to solve it. 2. dijkstra algorithm dijkstra algorithm [11] is known to be one of the most effective operational search algorithms for tracing the shortest path between multiple two distant starting and arriving points, including many intermediary possible stops and constraints. also called graph theory, this algorithm was invented by the dutch researcher edsger dijkstra in 1959. among the most common applications of this algorithm are the telecommunications networks and the supply chain traffic. the principle is to express the problem in the form of a graph with nodes that symbolize the intermediate stopping points, the edges symbolize the path in km between two successive nodes. we note the graph 𝐺 = { 𝑁 ; uij } we classify the nodes into 5 categories as follows: table 3. nodes classification. departure node α nigeria intermediary node β senegal possible locations for lng terminal x jorf lasfar y nakp “to be” power stations crossing points a mohammedia power station b kenitra power station c al wahda power station d dhar doum power station e oued al makhazine power station f tahhadart power station http://dx.doi.org/10.21622/resd.2019.05.1.033 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.033 39 resd © 2019 http://apc.aast.edu other crossing points a casablanca – settat industrial zone b underground basin of sidi yahya lgharb c gazoduc maghreb europe d underground basin of tendrara therefore, our dijkstra graph is composed of 14 nodes: 𝑵 = {𝜶 ; 𝜷 ; 𝑿 ; 𝒀 ; 𝑨 ; 𝑩 ; 𝑪 ; 𝑫 ; 𝑬 ; 𝑭 ; 𝒂 ; 𝒃 ; 𝒄 ; 𝒅 } the researchers consider the following assumptions: • the pipeline routing from the import terminal should be linked with the pipeline coming from nigeria. • the graph will contain two possible nodes for the import terminal, the algorithm will define the most ideal location to respect the shortest pipeline path. • in terms of lng consumption points, only ccgt power plants included in the gtp investment program are considered the most important crossing points. • the underground natural gas basins are optional crossing points since the main natural gas resource will be imported by the future lng terminal. u(i;j) represents the set of distances between two nodes i and j; therefore: { u(α; β) = 4000 km u(β; x) = 2400 km u(β; y) = 2700 km { u(x; a) = 114 km u(y; a) = 120 km u(y; b) = 15 km { u(a; b) = 115 km u(b; b) = 30 km u(a; b) = 140 km { u(x; a) = 130 km u(a; c) = 265 km u(b; c) = 60 km { u(b; d) = 90 km u(c; d) = 70 km u(d; c) = 5 km { u(c; d) = 110 km u(d; e) = 70 km { u(e; f) = 30 km u(c; d) = 70 km the distances are calculated between the nodes based on the global positioning system (gps) geolocation on the map. the indicated distances do not consider some potential disturbance factors such as soil surveys, driving constraints or natural obstacles that may arise to deflect the proposed routing. the problematic is represented in a graphic form in figure 8, the nodes represent the potential crossing points of passage of lng consumption, they are connected by arcs with the distance in km between the nodes. fig .8 dijkstra graphic representation. u(i,j) is the distance of the arc from i to j. starting from the top node α, d [i] the distance of the shortest path found at a given step. e is the set of nodes of passage composing the shortest definitive path. at first, e contains only the first node α, in each step, the next node is added to e and the distance d [i] is updated. therefore, our dijkstra algorithm can be expressed by the following function: 𝐸 = {𝛼} for each node ≠ 𝛼 , the researchers consider the following: 𝐷[𝑖] = 𝑈 [𝛼; 𝑖] http://dx.doi.org/10.21622/resd.2019.05.1.033 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.033 40 resd © 2019 http://apc.aast.edu the researchers consider 𝑡 є 𝐸 if d[t] the minimum possible distance, then et = e u {t}; for each: 𝑖 = [𝛽; 𝑋; 𝑌; 𝐴; 𝐵; 𝐶; 𝐷; 𝐸; 𝐹; 𝑎; 𝑏; 𝑐; 𝑑] i is successor passage node to t if: [ 𝐷(𝑡) + 𝑈 (𝑡 ; 𝑖)] < 𝐷 (𝑖) then, (3) d (i) = d (t) + u (t ; i ) and i ϵ e if not i ∉ e therefore, the representation of the dijkstra algorithm is as follows:                                                               1 3 1 2 1 1 1 0 9 8 7 6 5 4 3 /6 7 0 0/4 6 0 02 /4 0 0 001 6700/β 4600/β 4000/α yxs tep                                                   6890/e 6860/d 6790/c 6720/b 6630/a 6530/x         1 3 /6 8 9 01 2 1 1 1 0 /6 8 6 09 /6 7 9 08 /6 7 5 0/6 7 2 07 6 /6 7 0 05 /6 7 8 0/6 6 3 04 /6 5 3 03 2 1 e d c bb a aa x fedcbas tep                                                          1 3 1 2 1 1 /6 9 0 51 0 /6 7 9 59 8 7 /6 6 6 06 5 /6 6 5 54 /6 5 1 53 2 1 6905/c 6795/d 6660/b 6515/x c d b a x dcbas tep the interpretation of the result is done by following the step numbers and the nodes in bold and corresponding distances indicate the optimum routing. table 4. optimum routing steps. step t d (t) e 1 α 0 {α} 2 β 4000 {α; β} 3 x 6400 {α; β; x} 4 a 6515 {α; β; x; a} 5 b 6630 {α; β; x; a; b} 6 b 6660 {α; β; x; a; b; b} 7 c 6720 {α; β; x; a; b;b;c} 8 d 6790 {α;β;x;a;b;b;c;d} 9 e 6860 {α;β;x;a;b;b;c;d;e} 10 f 6890 {α;β;x;a;b;b;c;d;e;f} the optimum distance from point α (nigeria) to point f (tahhadart power station) is 6 890 km. given the 6400 km between nigeria and jorf lasfar, the shortest distance from jorf lasfar to power station tahhadart is 6 890 km – 6 400 km = 490 km. fig .9 dijkstra graphic solution. http://dx.doi.org/10.21622/resd.2019.05.1.033 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.033 41 resd © 2019 http://apc.aast.edu the optimal routing given by dijkstra algorithm goes through the following nodes marked in orange in figure 9. 3. results interpretation the optimum routing can be described as follows: table 5. optimum routing description part 1. departure α nigeria 4000 km β senegal 2400 km lng terminal x jorf lasfar location 115 km industrial area a settat casablanca 115 km power station 1 b kenitra power station 30 km undergroud basin 1 b sidi yahya lgharb basin 60 km power station 2 c al wahda power station 70 km power station 3 d dhar doum power station 70 km power station 4 e oued al makhazine power station 30 km power station 5 f tahhadart power station a complementary routing can also be proposed to link the pipeline project with the existent gme pipeline, and then arrive to tendrara underground basin. therefore, this complementary routing will be as follows: table 6. optimum routing description part 2. power station 3 d dhar doum 5 km gme gazoduc c gazoduc maghreb europe 110 km undergroud basin 2 d tendrara basin this study aims to achieve two main objectives; the first is to confirm the ideal location for lng importation terminal and the second is to propose the shortest pipeline routing between the departure point α representing nigeria and the arrival point f representing the tahhadart power station. the optimal routing is shown on the following map: using dijkstra algorithm, the jorf lasfar site is also suggested to be a suitable choice location for the future import terminal port. starting the jorf lasfar port, the crossing points are: 5 power stations, 2 underground basins and 1 industrial area. fig .10 optimum routing solution. iv. financial evaluation preview after defining the pipeline shortest routing, the cost for the future pipeline is hard to evaluate given the available data at this moment. the cost of the pipeline can weigh heavily in the amount of the project investment, its cost depends on several unknown parameters such as the type and the diameter of the pipeline, the cost of the steel, the width of the pipeline, the nature of the environment and the depth of its passage. the investment reference announced for 5660 km of the nigeria morocco pipeline project is estimated at 20 to 50 billion dollars [11]. therefore, considering the same pipeline characteristics for 490 km portion of pipeline proposed routing, the investment can be estimated at 1,8 to 4,5 billion dollars. this investment shall cover all the performances bellow: • engineering studies • execution study (works, cathodic protection ...) • civil engineering work • pipeline works • installation work of compression stations • piping and connection work http://dx.doi.org/10.21622/resd.2019.05.1.033 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.033 42 resd © 2019 http://apc.aast.edu • cathodic protection installation work • leak detection system installation work • pre-commissioning • commissioning it’s difficult to go any further in the rentabilitystudy since the international natural gas market is made up of different regional markets, making it difficult to talk about regular prices. figure 11 can demonstrate the extreme volatility in natural gas prices. fig .11 gas prices volatility from the international monetary fund official newsletter. the correlation between the price of oil and lng is difficult to establish as these two markets are distinct. all lng supply contracts are governed by a start date and an expiration date. during this period, the contract specifies the quantities supplied as well as the upper and lower tolerated variation limits. in general, the main components of the price of natural gas are: • the gas wellhead price • the sea freight, and • the cost of transportation along a distance price is governed by the strength of supply and demand, which can lead to price fluctuations as the market loses or regains its balance. to reduce its exposure to price volatility, significant storage capacity would be required to import and store the gas when prices are low often in summer when demand is lower. many buyers also use financial assurance systems, such as hedging. the rentability study of this project can be another interesting aspect to develop when more financial and contractual data about the project are revealed. v. conclusion the kingdom of morocco has shown a growing preference for lng to assure energy efficiency. given the significant international changes in energy supply and environmental protection, the new national energy strategy is progressively ensuring its procurement of natural gas while driving the energy transition with pragmatism and anticipation. in this context, this article developed two aspects of this program: • the choice of site location for the lng import, storage and regasification terminal • the shortest path for distribution and connection pipeline using the dijkstra algorithm the pipeline routing is an important part of the lng project in terms of necessary investment. this routing should adapt to many constraints of passage and come in continuity of the pipeline connecting nigeria to morocco. the port of jorf lasfar is a suitable importing terminal choice. the pipeline perimeter supported by the national lng project is identified between the import terminal and the furthest point of consumption, the pipeline routing starting from jorf lasfar terminal and linking the consumption points is estimated at 490 km. the environmental qualities of natural gas largely justify the conduction of this project. with its high hydrogen content, gas combustion is considered perfect and does not produce heavy unburnt harmful particles for environment or health. given the tax incentives and government conventions planned in morocco to encourage the use of natural gas, the profitability of this investment is guaranteed on a long term. references [1] r. laplante, f. l’italien, n. mousseau, and s. labranche, 2nd international summit of research cooperatives in community development, energy transition, how to get out from fossil fuel university of quebec, available on: http://normandmousseau.com/publications/159.p df [2015] http://dx.doi.org/10.21622/resd.2019.05.1.033 journal of renewable energy and sustainable development (resd) volume 5, issue 1, june 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.1.033 43 resd © 2019 http://apc.aast.edu [2] amara, ministry of energy, mines, water and environment, roadmap of the national development plan forliquefied natural gas. p. 11, available on: https://fr.scribd.com/doc/250255788/plannational-marocain-de-developpement-du-gaznaturel-liquefie-gnl [2014]. [3] the national ports agency. available on : http://www.equipement.gov.ma/carteregion/regionsafi/patrimoine-desinfrastructures-regionales/portsmaritimes/pages/fiche-synthetique-port-jorflasfar.aspx [2019] [4] the national ports agency. available on: https://www.anp.org.ma/services/portkenitra/pag es/presentation.aspx [2019] [5] catram consulting, evaluation study of the new kenitra atlantic. available on: https://www.catram consultants.com/kenitraatlantique/ 2017 [6] official announcement from the management of the national ports agency. available on: http://fr.le360.ma/economie/anp-5-milliards-dedirhams-dinvestissements-au-programme111725 [2017] [7] ministry of energy, mines, water and environment (2017). draft law relating to the downstream sector of natural gas in morocco. n° 9417, page 2. [8] r. tarakad, lng receiving and regasification terminals, an overview of design, operation and project development consideration, pp. 31--34, [2003]. [9] amara , ministry of energy, mines, water and environment, roadmap of the national development plan for liquefied natural gas. p. 7, available on: https://fr.scribd.com/doc/250255788/plannational-marocain-de-developpement-du-gaznaturel-liquefie-gnl [2014] [10] benchmark of the royal institute of strategic studies , available on: https://www.medias24.com/maroc/economie /economie/188546-gazoduc-maroc-nigeriavoici-un-benchmark-de-l-institut-royal-desetudes-strategiques.html [2018] [11] n.jasika, and n.alispaic . “dijkstra's shortest path algorithm serial and parallel execution performance analysis,” inspec accession number: 12865637. available on: https://ieeexplore.ieee.org/abstract/document/62 40942/figures#figures [2012] http://dx.doi.org/10.21622/resd.2019.05.1.033 27 journal of renewable energy and sustainable development (resd) http://dx.doi.org/10.21622/resd.2020.06.2.027 submitted on | 19 may 2020 accepted on | 12 june 2020 published on | 18 august 2020 volume 6, issue 2, december 2020 issn 2356-8569 ___________________________________ _____________________________________________________________________________________________________________________________ biokerosene analysis from the latex distillation as an alternative solution to national energy crisis 1 tungki pratama umar, muhammad galang samudra, kemas muhammad naufal nashor, machlery agung pangestu, 2 theodorus parulian 1 medical profession program, faculty of medicine, sriwijaya university, palembang, indonesia, 2 department of pharmacology, faculty of medicine, sriwijaya university, palembang, indonesia, tungkipratama@gmail.com abstract the energy crisis is ready to whack, according to the fact that about 66% of the earth's fuel comes from fossils. the urgency for alternative fuels discovery is increasing, one of such these fuels is being natural rubber latex. this material has a potential as an alternative fuel because of its high hydrocarbon content. this study was to determine rubber latex activity as biokerosene. in this study, the distillation of fresh natural rubber latex was performed and the process produces an average of 0.196 l of distillate per 0.5 kg of latex. the distillate was separated to obtain pure biokerosene. latex biokerosene analysis shows yellow color, strong odor, nonpolar properties, flammability, yellow flame color and black smoke, 873.9 kg/m3 density, rf=0.641 (4% methanol as mobile phase) and rf=0.883 (n-hexane and acetone as mobile phase) of the thin layer chromatography. it can be concluded that latex has the potential as a biokerosene and can be an alternative solution against the national energy crisis. keywords latex, biokerosene, energy crisis. i. introduction every aspect of life requires the energy provided by fuel. unfortunately, in many parts of the world, including indonesia, the condition of the energy crisis is becoming a protracted issue. based on the calculation from indonesian energy outlook, indonesia's oil reserves in 2014 is about 3.6 billion barrels and it is expected to be exhausted by 2026 [1]. that phenomenon is based on many factors such as population and economic growth [2]. the energy crisis is also related to the fact that around 66% of the world’s energy consumption in 2014 comes from nonrenewable fossil fuels [3]. attempts to overcome this energy crisis are crucial to preventing future downturns. one of the efforts exerted is to use material from nature such as latex as one kind of alternative energy that can be used as fuel to provide better productivity and decrease pollutants. latex potential as an alternative fuel is based on high rubber hydrocarbon content that reaches 30-40% [4], which has not been harnessed optimally. the hydrocarbon potential of rubber latex can be an alternative solution to help prevent the energy crisis. the potential of this renewable energy is based on a relatively short harvesting preparation period compared with its quite long harvesting period (five years of preparation and up to 35 years of harvesting period, though food and agriculture organization recommended that the harvesting period be up to 28 years) [5], [6]. in addition to its long harvesting period, rubber latex tapping can be done very frequently, ranging from twice a day to every four days depending on the season, soil (geographic area), and tree age [7]. south sumatera province, especially banyuasin regency, is one of the largest rubber-producing areas in indonesia, evidenced by the statistics in 2015 from the south sumatra forestry department that shows the rubber (hevea braziliensis) farms in banyuasin regency covering 248,501.86 hectares (ha) with rubber production reaching 239,707.79 tons [8]. based on these data, every hectare of rubber farms can produce about 1 ton/ha latex. in indonesia, this number is ranging from 892 kg/ha to 1.542 kg/ha annually [9]. this ratio shows a relatively high prospect in rubber production. in the meantime, the use of rubber is limited to tire production. it is a very huge problem especially with the phenomenon of scrap rubber tire generation which is exceeding 800 million pieces annually [10]. the recycling process is not going as expected and we http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.027 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.027 28 must search for a new way of utilizing rubber latex to optimize community activities. one of the ways that can be adopted is to develop latex biokerosene as a renewable fuel. the researchers in this study are analyzing latex biokerosene and its value as an alternative energy source. ii. methods and materials the research method is based on laboratory experiments. the study took four months and was carried out at the biomolecular laboratory of the faculty of medicine, sriwijaya university, and the sriwijaya state polytechnic chemical laboratory. 1. chemicals and materials in the process of making the biokerosene, the researchers used 2.5 kg of latex (rubber sap) from rubber farm in banyuasin, south sumatera as the main component, standard kerosene (pertamina®) as comparison substance, 6 liters of paraffin (sigmaaldrich®) and distilled water (sigma-aldrich®) in the distillation process, methanol (99.8%, sigmaaldrich®), n-hexane (98.5%, sigma-aldrich®), acetone (99.8%, merck®), silica gel thin-layer plate (tlc silica gel 60g f254, merck®) for the thin layer chromatography, cut into 5 cm (height)×2 cm (width) [11], and aluminum foil (sigma-aldrich®). 2. tools there are some tools used in this research including distillation apparatus, oil bath, temperature regulator, thermometer, stative and clamps, erlenmeyer flask 250 ml (pyrex ®), separator funnel, measuring cylinder in the distillation procedure, pycnometer for the density analysis, glass beaker (pyrex ®), dropping pipette (pyrex ®), capillary pipette (pyrex®) for thin-layer chromatography(tlc), ruler and ultraviolet (uv) reader (eppendorf ® ) for the determination of retardation factor (rf). iii. research procedure 1. biokerosene production the procedure of biokerosene production from latex is as follows: (1) put 0.5 kg of latex into the distillation flask, make five experimental samples, (2) set the distillation apparatus and the temperature regulator, (3) put the distillation flask on the oil bath and fill the oil bath with 3l paraffin, (4) put erlenmeyer flask (250 ml) at the end of the distillation apparatus, (5) heat the distillation flask containing the latex to 130oc, (6) dispose of the initial distillation product (water), increase the temperature to 150-165oc[12] and the later distillation product as the result of the distilled latex is stored in the form of kerosene (but is still mixed with water), (7) finally, separate the oil and water with separator funnel [13]. the distillation process was done for three hours for 500 grams of raw material and stopped when there is no distillate produced in the distillation apparatus. 2. analysis analysis for the biokerosene was done using physical examination (volume, color, smell, combustion capability, the color of the flame and smoke color), relative density measurement using a pycnometer at a temperature of 18oc and 28.8oc and thin layer chromatography test for the determination of retardation factor (rf). the retardation factor in planar chromatography which is used in this research is defined as the ratio of the distance traveled from the center of the spot to the distance simultaneously traveled by the mobile phase as compared with the solvent [14]. thin-layer chromatography was analyzed by using ultraviolet (uv) reader at 254 nm wavelength [15]. research procedures are simplified in figure 1. iv. results 1. distillation products volume from five distillation experiments, the average results were 0.196 liters per 0.5 kg of latex or about 2.55 kg of latex to obtain 1 liter of distillate. it is comparable with 39.2% of oil-yield (ratio of distillate per raw material dry weight). the results of distillation products can be seen in table 1. table 1. data of latex distillation product. distillation process latex mass distillates 1 0.5 kg 0.190 l 2 0.5 kg 0.180 l 3 0.5 kg 0.195 l 4 0.5 kg 0.205 l 5 0.5 kg 0.210 l average 0.5 kg 0.196 l 2. macroscopic examination the distillate is observed macroscopically and then http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.027 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.027 29 compared with pertamina (perusahaan pertambangan minyak dan gas bumi negara) kerosene. the researchers examined the oil color, smell, insolubility in water, combustion capability, the color of the flame, and its smoke. the macroscopic analysis showed that the produced biokerosene has relatively the same physical characteristics except for its smell and smoke color. the complete results are depicted in table 2. (a) (b) (c) (d) (e) (f) (g) (h) fig. 1. research procedure. (a) rubber sap gathering, (b) latex dried for one week to reduce its water content, (c) distillation procedure, (d) water and oil separation using separatory funnel, (e) latex biokerosene, then followed with outcome measurement (f) tlc analysis using uv reader, (g) density measurement, (h) combustion capability measurement. table 2. macroscopic properties comparison between latex biokerosene and pertamina. parameter latex biokerosene pertamina kerosene oil color yellow yellow smell stinky (++) stinky (+) insolubility in water negative negative combustion capability flammable flammable the color of the flame yellow yellow smoke color black (++) black (+) 3. density measurement the experimental procedure was examining biokerosene density at two different temperatures, 18oc and 28.8oc as the room temperature. there was no density difference between the two temperatures with 873,9 g/cm3 value. 4. thin layer chromatography the distillate was then analyzed using thin-layer chromatography. thin-layer chromatography is performed by using two solvent (mobile phase/eluent), 4% methanol, and the mixture of nhexane and acetone at 8:2 ratio. the average rf value for the produced biokerosene was slightly different with a smaller number for methanol solvent (0.641 vs. 0.696) and higher for n-hexane and acetone (0.883 vs. 0.815). the full result of the retardation factor calculation is shown in table 3. the thin layer chromatography result is shown in figure 2. http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.027 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.027 30 (1.a) (1.b) (2.a) (2.b) fig .2 results of thin layer chromatography. (1.a) latex biokerosene-methanol, (1.b) kerosene-methanol; (2.a) latex biokerosene-hexane & acetone (2.b) kerosene-hexane & acetone. table 2. retardation factor (rf) for latex biokerosene and pertamina kerosene. no rf sample 1 rf standard 1 rf sample 2 rf standard 2 1 0.600 0.700 0.900 0.800 2 0.580 0.750 0.890 0.850 3 0.625 0.680 0.843 0.833 4 0.650 0.675 0.910 0.790 5 0.750 0.675 0.870 0.800 average 0.641 0.696 0.883 0.815 note: 1 = using methanol 4% as mobile phase, 2 = using nhexane + acetone (8:2) as mobile phase 5. utilization testing a biokerosene utilization test was done by boiling 100 ml of water. then it was compared to pertamina® kerosene. boiling time using biokerosene is five minutes with 2,5 ml of biokerosene as fuel. it is 25% slower than boiling time using pertamina kerosene (four minutes) with the same amount of fuel. this was examined by using a standard oil stove. v. discussion based on the measurement of pure rubber latex distillation results, no significant difference is found in every distillation process. the maximum difference per experiment is 0.03 liters. the result of distillation ranged from 0.18 liters to 0.21 liters. as stated above, the produced biokerosene return oil yields about 39.2%. biokerosene from waste cooking oil distillate has a 20% oil yield [16]. meanwhile, the analysis of rubber seed showed the highest yield of 32,4% [17]. on the macroscopic examination, it is found that distillate color is clear yellow and visually similar to kerosene. the combustion capability shown by the lamplight test is also quite good as compared to kerosene. this is due to the considerably high hydrocarbon content, which is about 30-40% [4]. the combustion process results in sufficient black smoke due to its main hydrocarbon content which is in the form of cis-1.4-polyisoprene [18]. meanwhile, the color of the yellow flame that appears is similar to kerosene. the distillates show practically insoluble properties in the water, like nonpolar compounds, such as kerosene. latex biokerosene odor is quite foulsmelling because of the existence of several compounds, like low molecular weight fatty acids such as acetic acid, butyric and isovaleric acids; long-chain fatty acids such as stearic acid and aromatic compounds such as p-xylene and phenol as well as unexpected compounds such as isoamyl alcohol, benzyl alcohol, benzaldehyde, benzoic acid and phenolic acids [19]. from density measurement, the kerosene density obtained is about 873,9 kg/m3, slightly higher than pertamina kerosene density which has a maximum value of 835 kg/m3 [20]. this density value is still in the range of kerosene density reference value according to the u.s. department of health and human services, where kerosene is known as number 1 fuel with density between 810-936 g/cm3 [21]. past research on jatropha curcas biokerosene in nigeria showed a very small difference in density with the product (ρ= 874.7 kg/m3) [22] of this research. the higher density values are due to the existence of contaminants that need to be separated furtherly. researchers also compared the density of latex biokerosene with other fluid as shown in graph 1 [9],[10]. graph 1. latex biokerosene and other fuel density comparison (in kg/m3). k = kerosene, lb = latex iokerosene, pk = pertamina® kerosene, g = pertamina® gasoline, pd = pertamina® diesel. data comparison [9],[10]. the analysis of thin-layer chromatography was done by using a uv reader at 254 nm wavelength to read and calculate the retardation factor (rf). the first experiment is done by using 4% methanol as the 936 770 860 810 873.9 835 715 815 0 250 500 750 1000 k lb pk g pd http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.027 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.027 31 mobile phase and shows an average value of 0.641, on the other hand, pertamina kerosene control has an average rf of 0.696. based on the data from ko et. al., the biokerosene reaches a value of 0.641 by using 4% methanol as a mobile phase is included in the kerosene rf range, i.e. 0.6-0.7 [11]. in this experiment, there are two readings, which can be concluded as the result of impure latex biokerosene. the second experiment was done by using a mixture of n-hexane: acetone (8:2) as a mobile phase and resulting in an average rf value of 0.883 for latex biokerosene, besides pertamina kerosene control has a mean rf value of 0.815. the results of the sample test showed that there are movements of fluid on the silica paper due to the mobile phase and the stationary phase interaction. however, based on ramteke et. al., biokerosene rf value of 0.883 is more than expected, which is 0.8 [23] because the distillate is not pure and still has some contaminants. the semi-quantitative method above shows that the distillate may contain biokerosene, although it needs to be purified further. future research also must assess the functionality of this biokerosene product. latex biokerosene utilization was assessed by boiling water in the standard oil stove. it was proved that latex biokerosene has a 25% slower time to boil the water as compared with standard kerosene (pertamina®) and can, therefore be used for household activity although it needs more improvement. the researchers did not find a suitable comparison for the utilization test. on the other hand, we found a burning test for efficiency testing of biokerosene from used frying palm oil as compared with standard kerosene (110 ml/minute vs. 92 ml/minute). it is concluded that standard kerosene is still better in efficiency considering the potential of biokerosene from used frying oil [24]. in the future, biokerosene implementation should be on a larger scale to fulfill national needs or even worldwide use. when we are talking about latex production especially in indonesia, it is estimated that 3.229.861 tons of rubber latex generated yearly [25]. based on these data, latex biokerosene, if effectively produced, can reach more than 1.2 billion liters or about 7.8 million barrels annually. it is exceeding kerosene demand in indonesia by 2014 which is 4.620.000 barrel [1] and it can be concluded that latex biokerosene can be used as an alternative for facing a national energy crisis. the produced biokerosene is still far from large scale production due to its basic method and high cost related to its production process. we need to implement some strategies before such biokerosene can be produced on a large (mass) scale. it includes enlarging biomass resource basis, providing better agricultural technology and biomass production, a greater combination of biomass production and its marketing, in addition to maximizing assessment of sustainability criteria throughout the overall provision chain [26]. vi. conclusion biokerosene from latex distillation has relatively similar characteristics as standard kerosene and therefore has the potential to be used as an alternative source of energy. according to scarcity of pertamina kerosene in indonesia, biokerosene production can be optimized as a newer option although in the meantime calculation of its production cost is still high due to the small scale production. vii. acknowledgement the researcher would like to thank the ministry of research, technology and higher education of the republic of indonesia for the funding of this study as well as silvalena and fikram ahmad fauzan as language reviewers. we are also grateful for yuni paradita djunaidi’s advice for this research references [1] badan pengkajian dan penerapan teknologi. “outlook energi indonesia 2016: pengembangan energi untuk mendukung industri hijau,” pusat teknologi sumberdaya energi dan industri kimia badan pengkajian dan penerapan teknologi, jakarta, 2016. [2] j. meliala. “upaya optimalisasi penghematan subsidi bahan bakar minyak (bbm) agar tepat sasaran,” binus bus. rev., vol. 5, no. 1, pp. 333─343, 2014. [3] international energy agency. “key world energy statistics 2016,” international energy agency, paris, 2016, p. 6. [4] t. jayanthy and p. e. sankaranarayanan. “measurement of dry rubber content in latex using microwave technique,” meas. sci. rev., http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.027 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.027 32 vol. 5, no. 3, pp. 50−54, 2005. [5] s. damanik, m. syakir, m. tasma, and s. siswanto. “budidaya dan pasca panen karet,” pusat penelitian dan pengembangan perkebunan, jakarta, 2010. [6] food and agriculture organization, “the rubber tree,” [online]. available: http://www.fao.org/3/ad221e/ad221e06.htm. [june,7, 2020]. [7] s. subandi. “budidaya tanaman perkebunan (bagian tanaman karet),” gunung djati press, bandung, 2018. [8] dinas kehutanan provinsi sumatera selatan, “potensi,” 2015. [online]. available: http://www.dishutsumsel.go.id/ 2015/09/17/potensi/. [may, 10, 2020]. [9] i. boerhendhy and k. amypalupy. “optimalisasi produktivitas karet melalui penggunaan bahan tanam, pemeliharaan, sistem eksploitasi, dan peremajaan tanaman,” j. litbang pertan., vol. 30, no. 1, pp. 23–30, 2010. [10] h.h. tsang. “uses of scrap rubber tires,” in rubber: types, properties and uses, g. a. popa,ed.. nova science publishers, new york, pp. 1-15, 2010. [11] m. s. ko, d. kwon, j. s. yang, m. j. kwon, s. w. lee, and s. lee. “identifying type of refined petroleum products in environmental media: thin layer chromatography (tlc) as a quick methodology,” water air soil pollut, vol. 225, pp. 2149, 2014. [12] n. s. ekaab, n. h. hamza, and m. t.chaichan. “performance and emitted pollutants assessment of diesel engine fuelled with biokerosene,” case stud. therm. eng., vol. 13, pp. 100381, 2019. [13] i. syauqiah, a. mirwan, a. sulaiman, and d. nurandini. “analisis pengaruh lama penyulingan dan komposisi bahan baku terhadap rendemen dan mutu minyak atsiri dari daun dan batang nilam,” info tek., vol. 9, no. 1, pp. 21–30, 2008. [14] international union of pure and applied chemistry. “compendium of chemical terminology: gold book,” international union of pure and applied chemistry, zurich, 2014. [15] l. cai, “thin layer chromatography,” in current protocols essential laboratory techniques, s. r. gallagher and e. a. wiley, eds. wiley, london, pp. 6.3.1-6.3.18, 2014. [16] a. e. k. salwa, a. h. samia, m. m. h. arief, and f. a.-a. eslam. “production of petroleum – like fractions from waste cooking oil,” egypt. j. chem., vol. 60, no. 1, pp. 147–60, 2017. [17] d. f. lestari. “rubber-tree (hevea brasiliensis) seed oil extraction by adopting traditional method in making coconut oil,” inov. dan pengemb., vol. 2, no. 3, pp. 1–12, 2016. [18] d. blackley. “polymer latices,” science and technology, vol. 2, types of latices,” p. 83, 1997. [19] n juntarachat, n. bouvier, j.p. lepoutre, a. roland, j. sainte-beuve, f. granet, j.m. salmon, p. rigou, and p. chalier. “identification by gc-o and gc-ms of new odorous compounds in natural rubber,” j. appl. polym. sci, vol. 130, pp. 1863–1872, 2013. [20] direktur jenderal minyak dan gas bumi. “keputusan direktur jenderal minyak dan gas bumi nomor 17 k/72/ddjm/1999 tentang standar dan mutu (spesifikasi) bahan bbkar minyak jenis minyak tanah yang dipasarkan di dalam negeri,” indonesia, 1999. [21] u.s. department of health and human services. “toxicological profile for fuel oils,” u.s. department of health and human services, agency for toxic substances and disease registry, atlanta, 1995. [22] f. adesina, a. gbadegesin, a. paul, and o. oyinkepreye. “insight into possibility of producing biokerosene from jatropha curcas plant in nigeria,” covenant j. eng. technol., vol. 1, no. 1, pp. 49–58, 2017. [23] g. ramteke, l. revatkar, r. phadke, and n. chutke. “analysis of petrol: a clarification for purity of petrol,” esr j., vol. 1, no. 1, pp. 1–8, http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.027 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.027 33 2016. [24] m. s. syaripuddin. “utilization of used frying oil as biokerosene fuel,” institut teknologi sepuluh nopember, surabaya, 2009. [25] direktorat jenderal perkebunan. “statistik perkebunan indonesia 2015-2017: karet,” kementerian pertanian indonesia, jakarta, 2017. [26] m. kaltschmitt. “biofuels – on the way to sustainability?,” resd, vol. 2, no. 2, pp. 60–63, 2016. http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.027 4paper2.pdf (p.14-20) journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 197 resd © 2015 http://apc.aast.edu culture independent pathogenic bacterial communities in bottled mineral water hamdy a. hassan environmental biotechnology department, genetic engineering and biotechnology research institute, sadat city university sadat city – egypt abstract bottled mineral water (bmw) is an alternative to mains water and consider it to be better and safer. access to safe bmw from the bacteria involving potential health hazard is essential to health. cultivation-independent technique pcr-based singlestrand conformation polymorphism (sscp) for genetic profiling of pcr-amplified 16s rrna genes was performed using com primer set targeting the 16s rrna genes for detection of pathogenic bacteria in bottled mineral water from the final product of six factories for bmw in wadi el-natron regionegypt. these factories use often ozone technology to treat large quantities of water because of its effectiveness in purifying and conditioning water. a total of 27 single products were isolated from the profiles by pcr reamplification and cloning. sequence analysis of 27 sscp bands revealed that the 16s rrna sequences were clustered into seven operational taxonomic units (otus) and the compositions of the communities of the six samples were all common. the results showed that most communities from phyla alphaproteobacteria and certainly in the sphingomonas sp. culture-independent approaches produced complementary information, thus generating a more accurate view for the bacterial community in the bmw, particularly in the disinfection step, as it constitutes the final barrier before bmw distribution to the consumer keywords bottled mineral water, pathogenic bacteria, cultureindependent, pcr-sscp, 16s rrna genes. i. introduction bottled mineral water (bmw) is often recommended for patients with immune-system deficiencies as well as marketed as ideal for infant nutrition and reconstitution of foods (warburton, 1993). mineral water is an oligotrophic environment; their content of viable bacterial cell is as low as 10cfu ml-1 (ferreira et al., 1994). these lows, count of native organisms are of little concern to the healthy consumer. outbreaks of infectious bacteria via the use of contaminated tap drinking water still pose a serious health threat worldwide, despite that drinking water is one of the most closely monitored and strictly regulated resources. both bottled water and tap water may contain the same microorganisms, which originated from the same sources (papapetropoulou et al., 1997; ahmed et al., 2013). the european union council directive on the quality of water intended for human consumption restricts the presence of e. coli, clostridium perfringens, pseudomonas aeruginosa, enterococci and coliforms and recommends a total heterotrophic colony count only in the case of water offered for sale in bottles or containers (the council of the european union 1998; ahmed et al., 2013). by using conventional cultivation techniques, less than 1% of the bacterial population can be cultivated from oligotrophic systems such as the drinking water distribution system and the related microbial population (kalmbach et al., 1997; falcone-dias et al., 2015). the real significance of of pathogenic bacteria in the drinking water is poorly understood (guzman et al., 2010). sphingomonas spp. are widely distributed in nature and are resistant to many disinfecting and toxic chemicals (laskin and white, 1999), and has been isolated from drinking water and drinking water distribution systems. some sphingomonas strains are well known for metabolizing complex organic pollutants, but some are opportunistic human pathogens as sphingomonas paucimobilis and s. parapaucimobilis (anon, 2000, guzman et al., 2010, gesumaria et al., 2011). a developed protocol was used, which allows the application of single-strandconformation polymorphism (sscp) (orita et al., 1989; hayashi, 1991; gasser et al., 2007) for the culture-independent assessment of microbialcommunity diversity (schwieger and tebbe, 1998; gasser et al., 2007; jean and georges , 2008; http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 198 resd © 2015 http://apc.aast.edu keskes et al., 2012). the sscp method has the potential to be more easily applied (lee et al., 1996) and the sscp produced a number of sharp bands and differentiated the bacterial community structures (tomoyuki et al., 2006). sscp was optimized to analyze only one of the complementary single strands (schwieger and tebbe, 1998; meng-zhi et al., 2008), by preferentially degrading with lambda exonuclease the one strand generated with a phosphorylated primer. this development aims to avoid heteroduplex formations, or overlapping of forward-reverse strands from different amplicons during separation, allowing the separation of mixtures of fragments of identical size but different in sequence. the application of this modified technique was focused on studies of taxonomic shifts in microbial communities by targeting 16s rrna genes (peters et al., 2000; schmalenberger et al., 2001; schwieger and tebbe, 2000, 2003). however, a potential application to assess diversity of functional genes was foreseen (stach and burns, 2002). the aim of this study was to identify the common uncultured bacterial community via sscp in the bmw from the end product of six factories for mineral water located in wadi el-natroon region, which is one of the largest industrial regions for mineral water in egypt. ii. geometry of the model and material properties a. dna extraction from the six water samples six water samples equal volumes each 2 liters were collected from the final product of bmw from six factories in wadi el-natroon region, the filtration was implemented under sterile conditions with a filtering device actuated by a motor driven pump, the filter sandwich with the bacteria was cut into small pieces with a sterile scalpel and transferred to the multimix 2 tissue matrix tub, add 978 µl sodium phosphate buffer and 122 µl mt buffer from fast dna spin kit for soil bio 101 and follow the dna extraction according to the protocol for dna extraction with the fastprep dna kit for soil (bio 101). dna was visualized on 1% agarose gels. yield of genomic dna was determined spectrophotometrically by measuring the absorbance at 260 nm. purity was determined by calculating the ratio of absorbance at 260 nm to absorbance at 280 nm (a pure dna has an a260/a280 the dna extracts from water samples containing approximately 200 ng ml-1 dna were 50or 100-fold diluted in tris-hcl buffer (10 mm, ph 8.0) and used as template dna in pcr. b. sscp for six bmw samples collected from the final product of six factories in wadi el-natroon region the primers com1 (5`cagcagccgcggtaatac3`) targeting the position (519-536) and com2-ph (5`ccgtcaattcctttgagttt3`) targeting the position (907-926) were chosen for the amplification of bacterial 16s rrna genes (schwieger and tebbe 1998). single-stranded dna (ssdna) from pcr products was obtained as previously described (schwieger and tebbe, 1998). briefly, pcr as performed with one of the primers being 5` phosphorylated, each amplification was carried out using 2 ng dna template in a final volume of 50 µl, starting with an initial denaturation for 15 min at 95°c. a total of 30 cycles (30s at 95°c, 30s at 55°c, and 1 min at 72°c was followed by a final elongation for 10 min at 72°c. amplification was achieved using hot star taq dna polymerase (fermentas). pcr products were eluted from agarose gels (see figure. 1), and the phosphorylated strands were digested by lambda exonuclease (neb). the remaining singlestrands were purified with genejet pcr purification kit (fermentas), dried by vacuum centrifugation, resuspended in 6 μl of loading buffer (95% formamide, 0.25% bromophenol blue and 0.25% xylene cyanol), and denatured for 5 minutes at 94 °c, followed by instant cooling on water ice bath for 3 minutes. the separation conditions were standardized in a dcode system for pcr-sscp, optimized running parameters were 120v (10 ma) for 18 h at a constant temperature of 26°c on 20 cm x 20 cm x 0,75 mm 0.6x mde gels in 0.7x tbe (sambrook et al., 1989) as a running buffer. optimal results were obtained when ssdna obtained from 100 400 ng dsdna was loaded onto the gels and a slightly enhanced resolution was achieved when the amplified singlestrands of the reverse primer were subjected to pcrsscp analysis. for nucleic acid detection, gels were silver stained as reported previously (bassam et al., 1991). http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 199 resd © 2015 http://apc.aast.edu single-strand electrophoretic mobilities corresponding to different conformations were excised from dried gels, and dna extracted by the “crush and soak” method (sambrook et al., 1989) pcr reamplification of the excised and eluted single-strands was made with the same primers used to generate the original dsdna fragment. c. data deposition the sequences reported in this paper have been deposited in the genbank database (27 sequences for the independent culture bacteria accession numbers (jf793682jf793708). d. results com primer set were used to amplify the eubacterial 16s rrna gene sequences (see figure 1) including the variable regions yielded complex sscp patterns, sscp community profiling showed highly diverse and distinct microbial communities for the bmw water samples, bmw sample 5 displayed the largest numbers of bands, while bmw sample 6 displayed less numbers of bands ( see figure 2 a, b). by pcr, the opposite strands were regenerated and the products were reamplified. sscp gel electrophoresis was used to evaluate the purities and identities of the reamplified 27 products, as shown for products obtained from pcr targeting the hypervariable samples 16s rrna genes only 27 were appeared (see figure 3). in most cases, reamplification products corresponded to the expected positions in the community patterns and no additional products were observed. these products were then directly used for cloning and dna sequencing. to identify the predominant products by dna sequencing, a total of 27 different dna single strands ("bands") were excised, 27 sequences were in good appearance. by comparing the 27 sequences accession numbers from jf793682jf793708 with the related taxa, revealed 7different operational taxonomic units otus of bacteria, and that the most compositions of the communities of the six bmw samples were all common. the phylogenetic tree (see figure 4) constructed from the partial sequences of the 16s rrna amplicons from the 6 bmw samples showed a predominance of alphaproteobacteria, especially family sphingomonas sp. (table 1). fig .1. pcr with com primers targeting the 16srrna genes for the four dna extracted samples from the six water samples collected from the final product of bmw from six factories in wadi el-natroon region (lanes 1, 2, 3, 4,5,6) , c is the controle without dna and m is 1kb dna ladder generuler™, fermentas. fig .2. (a) sscp on a polyacrylamide gel for the six bmw samples before cutting the bands, (b) after cutting the bands. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 200 resd © 2015 http://apc.aast.edu fig .3. pcr reamplification of the excised and eluted single-strands with the same com primers to generate the original dsdna fragment lans 1-27 are the product of the reamplification, c is the control without any template, m is 1kb dna ladder generuler™, fermentas. fig .4. phylogenetic tree of partial 16s rrna gene sequences for the sscp bands from the six bmw samples and its high similarity. table 1. phylogenetic assignment of sequences of prominent bands in sscp gel profiles of the six bmw samples communities., showed the sample number and the band number i.e 6w1 means bmw sample number 6 and 1 is the band number in this sample. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 201 resd © 2015 http://apc.aast.edu iii. discussion the cultivation independent methods, based on amplification of environmental dna followed by acrylamide gel electrophoresis, separate sequence specific dna fragments of the same length, have the potential for accurate comparison of environmental samples in a short period of time. in this study, we have shown that sscp analysis of 16s rrna genes amplified from directly extracted dna from the six bmw samples from the different end product manufactories can be used to visualize all the community structures included the pathogenic species in the bmw, and also this indicate the high potential of this technique to monitor microbial communities and their variation qualitatively and quantitatively (peters et al., 2000). culture-independent techniques were used for the detection of pathogenic bacteria in bmw at potentially critical control points in the end products of bmw six factories in wadi el-natroon region – egypt. pcrsscp in the bmw from the end product samples. bmw sample number 5 displayed the largest bands than the other bands maybe possibly due to different reasons, because the factory was near from urban but the other factories were a little bit far, and may be also due to the handling of the workers. as more gene sequences become available, pcrsscp-mediated monitoring of different subgroups or microorganisms, due to optimized primer design, will become even more attractive, almost all of these otus from the indirect culture (table 2) in this study are belonging to the phyla alphaproteobacteria (falcone-dias et al. 2015) and certainly related to sphingomonas species, which are widely distributed in nature. sphingomonas have been recovered from sea water (cavicchioli et al. 1999; gesumaria et al., 2011), sea ice (bowman et al. 1997), river water (tabata et al. 1999), waste water (neef et al. 1999), polluted ground water (männistö et al. 1999), mineral water (ferreira et al. 1996; vachee et al. 1997), sterile water' used in hospitals (oie et al. 1998), drinking water (gauthier et al. 1999). the widespread distribution of sphingomonas can be explained by their ability to survive and grow at low temperature, low nutrient concentration and in toxic chemical environments (laskin and white, 1999). because sphingomonas are relatively slow growing (the council of the european union 1998). therefore, the presence of sphingomonas in bmw and also in the drinking water environment may be much more common than has been reported so far and deserves further study not only by culture bacteria but also by cultureindependent bacterial molecular techniques. two species of sphingomonas, s. paucimobilis and s. parapaucimobilis, have been classifed to hazard group 2 in the european community regulations (anon, 2000), all species of sphingomonas contain glycosphingolipids in their cell envelope. glycosphingolipids (kawahara et al., 1999). glycosphingolipids of sphingomonas have been shown to induce tumour necrosis factor and other monokine production in human mononuclear cells (krziwon et al. 1995), stimulate phagosytosis and phagosome lysosome fusion (miyazaki et al. 1995), activate the human complement system (wiese et al. 1996) and inhibit protein kinase c and possibly function as endogenous modulators of cell function and as second messengers (hannun and bell, 1989). these factors may partly explain the pathogenic features of hospital sphingomonas infections. v. conclusion this study provides a better method for understanding the uncultured bacterial community in the bmw and providing new information that might be used for improving bmw quality and safety. the above findings underline the fact that bmw sold in egypt and tested as free from culture pathogenic still have uncultured potential bacterial pathogens. therefore, in a country such as egypt , where the quality of tap water is uncertain, it is recommended that there should be stringent regulation of bottled water quality whilst boiled tap water could be a safe alternative. it is important that consumers are aware that the perception that bottled water is always safer than tap water can be misleading as the former can also contain the same microorganisms commonly found in tap water. this study gives an attention that bmw is not completely safe either for bmw producer to try to solve bmw problems or for the user to be careful during use bmw for infant nutrition and reconstitution of foods. references [1] ahmed, w., yusuf, r., hasan, i., ashraf, w., goonetilleke, a., toze, s., & gardner, t. 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(1999) chemical structure and function of glycosphingolipids of sphingomonas spp. and their distribution among members of the alfa-4 subclass of proteobacteria. journal of industrial microbiology and biotechnology 23: pp. 408413. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 203 resd © 2015 http://apc.aast.edu [20] krziwon, c., zaèhringer, u., kawahara, k., weidemann, b., kusumoto, s., rietschel, e., flad, h. d. and ulmer, a. j. (1995) glycosphingolipids from sphingomonas paucimobilis induce monokine production in human mononuclear cells. infection and immunity 63: pp. 2899-2905. [21] laskin, a.i. and white, d.c. (1999) special issue on the genus sphingomonas. journal of industrial microbiology and biotechnology 23: pp. 231±408 [22] lee, d.h., zu, y.g. and kim, s.j. (1996) nonradioactive method to study genetic profiles of natural bacterial communities by pcr-single strand conformation polymorphism. appl. environ. microbiol. 62: pp. 3112-3120. [23] männistö, m., tiirola, m., salkinoja-salonen, m., kulomaa, m. and puhakka, j. (1999) diversity of chlorophenol-degrading bacteria isolated from contaminated boreal groundwater. archives of microbiology 171, pp. 189±197. [24] meng-zhi, w., hong-rong w., heng-chun c.a.o, guo-xiang l.i and jie z. (2008). effects of limiting amino acids on rumen fermentation and microbial community. in vitro. agricultural sciences in china 7: pp. 1524-1531. [25] miyazaki, y., oka, s., yamaguchi, s., mizuno, s. and yano, i. (1995) stimulation of phagosytosis and phagosome-lysosome fusion by sphingolipids from sphingomonas paucimobilis. journal of biochemistry 118: pp. 271-277. [26] neef, a., witzenberg, r. and kaèmpfer. p. (1999) detection of sphingomonads and in situ identification in activated sludge using 16s rrna-targeted oligonucleotide probes. journal of industrial microbiology and biotechnology 23: pp. 261-267. [27] oie, s., oomaki, m., yorioka, k., tatsumi, t., amasaki, m., fukuda, t., hakuno, h., nagano, k., matsuda, m., hirata, n., miyano, n., and kamiya, a. (1998) microbial contamination of `sterile water' used in japanese hospitals. journal of hospital infection 38: pp. 61-65. [28] orita, m., iwahana, h., kanazawa, hayashi, h. k. and sekyia, t. (1989) detection of polymorphisms of human dna by gel electrophoresis as single-strand conformation polymorphisms. proc. nat. acad. sci. usa 86: pp. 2766-2770. [29] papapetropoulou m., tsintzou, a. and vantarakis, a. (1997) environmental mycolacteria in botled table waters in greece. can. j. microbiology 43: pp. 499 502. [30] peters, s., koschinsky, s., schwieger, f. and tebbe, c. c. (2000) succession of microbial communities during hot composting asdetected by pcr-single-strand-conformation polymorphism-based genetic profiles of smallsubunit rrna genes. appl environ microbiol. pp. 66:930-936. [31] sambrook, j., fritsch, e. f. and maniatis, t. (1989) molecular cloning: a laboratory manual. second edition. cold spring harbor laboratory press, cold spring harbor, new york, usa. [32] schmalenberger, a., schwieger, f. and tebbe, c.c. (2000) effect of primers hybridizing to different evolutionarily conserved regions of the small-subunit rrna gene in pcr-based microbial community analyses and genetic profiling. appl environ microbiol. 67: pp. 35573563. [33] schmalenberger, a. and tebbe, c.c. (2003) bacterial diversity in maize rhizospheres: conclusions on the use of genetic profiles based on pcr-amplified partial small subunit rrna genes in ecological studies. mol ecol. 12: pp. 251-262. [34] schwieger, f., and tebbe, c. c. (1998) a new approach to utilize pcr-single-strandconformation polymorphism for 16s rrna genebased microbial community analysis. appl. environ. microbiol. 64: pp. 4870-4876. [35] schwieger, f. and tebbe, c.c. (2000) effect of field of inoculation with sinorhizobium meliloti l33 on the composition of bacterial communities in rhizospheres of a target plant (medicago sativa) and a non-target plant (chenopodium album)-linking of 16s rrna gene-based singlestrand conformation polymorphism community profiles to the diversity of cultivated bacteria. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 204 resd © 2015 http://apc.aast.edu appl environ microbiol. 66: pp. 3556-3565. [36] stach, j. e. m. and burns, r.g. (2002) enrichment versus biofilm culture: a functional and phylogenetic comparison of polycyclic aromatic hydrocarbondegrading microbial communities. environ microbiol. 4: pp. 169-182. [37] the council of the european union. 1998. council directive on the quality of water intended for human consumption. council directive 98/83/ec 3 november, 1998. the official journal of the european communities l 330, pp. 32-34. [38] tomoyuki h., shin, h., yoshiyuki, u., masaharu, i. and yasuo, i. (2006) direct comparison of single-strand conformation polymorphism (sscp) and denaturing gradient gel electrophoresis (dgge) to characterize a microbial community on the basis of 16s rrna gene fragments. journal of microbiological methods 66: pp.165-169. [39] warburton, d. w. (1993) a review of the microbiological quality of bottled water sold in canada. part 2. the need for more stringent standards and regulations. can. j. microbiology 39: pp. 158–168. [40] wiese, a., reiners, j., brandenburg, k., kawahara, k., zaèhringer, u. and seydel, u. (1996) planar asymmetric lipid bilayers of glycosphingolipid or lipopolysaccharide on one side and phospholipids on the other: membrane potential, porin function, and complement activation. biophysical journal 70: pp. 321-329. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 8 modelling and methodology for window selection with energy efficiency criteria in chile ignacio allende los zarzales 1533, santiago 9270842. chile, ignacio.allende.l@hotmail.com abstract this article presents the development of a methodology associated with the selection of windows with energy efficiency criteria in chile. it provides the optimal option in a housing project, according to specific search parameters by region, commune, orientation, materiality, among others options. at the same time, it is possible to download the technical characteristics of the selected window instantly. according to results obtained on the simulation, s2 showed better energy efficiency performance in the three cities studied (antofagasta, santiago and concepcion). mainly the transmittance value was slightly smaller than s1 solutions. in general, windows with lower thermal transmission (u) achieve better energy efficiency in homes. however, the selection of optimal windows for a project should always be based on the geographical area, the orientation of the facade or wall, the surface of the light, or the visibility to be projected (dimensions), and the thermal transmittance values (u). keywords sustainability, energy efficiency, window, thermal transmission, transmittance values. i. introduction currently, chile has joined multiple sustainable agreement and due to this, chile actively participate such as a member of the organization for economic cooperation and development (oecd), asia pacific economic cooperation (apec) and the united nations framework convention on climate change (unfccc). consequently, a series of national strategies is laid down, for the short and mediumterms, which seeks to favour the transition to a more sustainable and efficient country. [1] [2] [3] for the development of these, the european reality was studied, which had a successful work program and extensive experience. one of the initiatives that stood out in this area was directive 2010 / 31 / eu of the european parliament [4], which is the basis for the energy rating of homes. it also defines the objectives and standards of energy efficiency in buildings by 2020. then, the study and analysis of the different energy sectors of chile began, to know the state of the country in this matter and determine what the gap that exists with high-standard countries is. in this regard, each the residential and the mining sectors represent 15% of the total national energy consumption. this indicates the magnitude of the context, taking and into account the importance of mining in chile. [5] [6] on the other hand, the national energy strategy 20122030 stipulates an energy efficiency action plan 20122020 that aims to achieve a 12% reduction in projected energy demand in the year 2020 [7] [8]. additionally, national law no. 20,257 was also enacted, which states that non-conventional renewable energy sources must generate 10% of the energy by 2024 [9]. notably, the residential sector has sustainable construction standards [10] [11] [12], according to the handbook of housing energy qualification [13] and the general law of urbanism and constructions of chile [14]. as a result, there is a need to innovate in this area, creating a methodology that allows selecting windows with energy efficiency criteria. ii. methodology a. study areas three research areas are involved in the study development, namely laws and standards, market research and technical characteristics. the investigative process is detailed in fig. 1. 1. laws and norms first, all information on national laws and regulations related to window selection was collected, as well as additional information, such as manuals and proposed standards — notably, the general ordinance of urban planning and construction [15]. http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 9 on the other hand, the thermal zones of the cities of chile, they were defined by maps proposed by minvu [16]. alternatively, the minvu update on the communes that have the air decontamination program was incorporated [17] [18]. also, there is complementary information associated with sustainable construction standards [10] [11] [12] according to the handbook of housing energy qualification [13], and climate explorer [19]. after searching for the applicable legal and regulatory information, the parameters for the methodology were established and defined. those parameters are necessary to generate an algorithm that allows simulations of different window configurations. fig .1 flowchart to obtain the methodology for the selection of windows with energy efficiency. 2. market study at this point, the market window that includes recurring characterization patterns in different types of windows available. however, the windows present technical information and tests. these are fully available to be selected by the methodology database to ensure effectiveness during implementation. these involve the articles consulted from minvu [20] [21], as well as suppliers [22]. moreover, it includes a sample of twenty-eight windows, with all the relevant information. subsequently, the windows are added to the methodology and three types are defined; bringing down, sliding and projecting. each of them has a subdivision according to the frame and thermal background. regarding the chilean window market, it is correct to affirm that investments in the real estate sector have been in a constant growth throughout the years [23] [24] producing an increase in the demand for windows. however, the products with the most significant presence in the market are aluminium and pvc. the first is the most frequent for having a lower manufacturing cost, for the number of companies that distribute it and for its age in the market. on the other hand, pvc has only been gaining ground until recently, since public policies use it as a baseline for all their projects in order to generate energy savings in homes, lower maintenance costs, better acoustics [25]. the market distribution is represented by fig. 2, that reflects an approximation of the growth of both over the years. window type amount of money in the window industry per year (m / usd) 2017 2018 2019 aluminium 120,5 126,5 131,5 pvc 31,6 31,0 32,8 total (m / usd) 152,1 157,5 164,3 fig .2 amount of money in the window industry per year. characteristics window type aluminium pvc corrosion resistance high high electrochemical corrosion risk low null vulnerability to thermal bridges half low vulnerability to cuts or scratches half low degradation by saline environment half null risk of condensation inside low null difficulty cleaning low low window weight low high maintenance half low fig .3 factors influencing both durability and window maintenance. on the other hand, the acquisition of a window brings with it a subsequent installation. under this circumstance, the chilean market generally delivers a price to the buyer that includes the installation value. the latter may vary due to the dimensions of the window and the distance or location of the destination. however, the type of window material does not influence this cost, in other words, that a window made up of one material or another will not increase or decrease the installation value. methodology for window selection with energy efficiency criteria in chile laws and norms algorithm development market study typologies to use technical characteristics parameter definition http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 10 nevertheless, in the stage of exploitation or use of the window, there are economic differences related to the material composition. since the durability and maintenance are not the same in all cases, as shown in fig. 3. for this reason, has been used the two most recurring window compositions, aluminium and pvc, have been used to identify the variables that can influence the maintenance costs, as well also as in the useful life of them [26]. the latter being an essential factor in determining when to make a replacement. 3. technical characteristics the methodology explicitly uses the following types of variables; region, commune, thermal zone, facade surface according to orientation, frame material, window type and thermal transmittance (u) [27] [28] [29] [30]. all of these options allow recreating the conditions of the home better. after entering the information, there is an optimal solution for our case through a technical file, which implicitly contains information such as; glass-framed ratio, glass thickness, inner chamber space, the filling inside the chamber, the rail thickness and air permeability [31] [32]. in summary, have to adjust the data at the beginning, to later know in detail the characteristics of windows. additionally, a graphic representation of them allows the user to use as a means for the quotation, manufacture, and implementation of the windows. all this information ensures a correct and quick selection of windows for the case in question. b. methodology of the verification process according to fig. 4, the simulation considers housing in different climatic zones (antofagasta, santiago, concepción) to which improvements are subsequently implemented in its windows. it is important to note that energy demand is calculated based on passive systems and does not include equipment (no hvac). however, the hap program [33] was used to simulate housing, which uses ashrae std. 62.1 2010 [34], ashrae std. 90.1 2010 [35] and leed 2009 [36] as a regulatory framework. fig .4 flowchart to obtain case analysis. 1. characteristics of base cases the base cases are made up of the technical specifications exemplified in figs. 5, 6 and 7. fig .5 general architecture plant for base cases. simulation n°2simulation n°1start base case case of antofagasta solution n°1 solution n°2 case of santiago solution n°1 solution n°2 case of concepción solution n°1 solution n°2 http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 11 city element high (ft) surface (ft2) u (btu/hr/ft2/f) a n to fa g a s ta facade n 7,55 304,62 0,29 facade s 7,55 292,78 0,29 facade e 7,55 248,65 0,29 facade w 7,55 249,72 0,29 roof 1337,95 0,06 floor 0,49 1145,28 0,52 s a n ti a g o facade n 7,55 304,62 0,29 facade s 7,55 292,78 0,29 facade e 7,55 248,65 0,29 facade w 7,55 249,72 0,29 roof 1337,95 0,06 floor 0,49 1145,28 0,52 c o n c e p c ió n facade n 7,55 304,62 0,29 facade s 7,55 292,78 0,29 facade e 7,55 248,65 0,29 facade w 7,55 249,72 0,29 roof 1337,95 0,06 floor 0,49 1145,28 0,52 fig .6 structural elements of the base cases. city element high (ft) width (ft) surface (ft2) u (btu/hr/ft2/f) a n to fa g a s ta p1 6,6 2,8 18,3 0.32 v1 5,2 5,2 27,6 1,02 v2 1,6 1,6 2,7 0,53 s a n ti a g o p1 6,6 2,8 18,3 0.32 v1 5,2 5,2 27,6 1,02 v2 1,6 1,6 2,7 0,53 c o n c e p c ió n p1 6,6 2,8 18,3 0.32 v1 5,2 5,2 27,6 1,02 v2 1,6 1,6 2,7 0,53 fig .7 non-structural elements of the base cases. 2. characteristics of the solutions to simulate the solutions for the simulations appear from replacing the initial windows v1 with others with better performance, through the methodology. as a summary of the improvement selection process, figs. 8 and 9 show all the information necessary to prepare the simulations. city solution n°1 window v1 frame type window opening surface (ft2) u (btu/hr/ft2/f) antofagasta aluminium sidehung 19,4 0,63 santiago aluminium sliding 17,8 0,63 concepción aluminium sliding 12,9 0,63 fig .8 summary of solutions no. 1 to simulate. city solution n°2 window v1 frame type window opening surface (ft2) u (btu/hr/ft2/f) antofagasta pvc side-hung 19,4 0,53 santiago pvc sliding 24,2 0,42 concepción pvc sliding 12,9 0,28 fig .9 summary of solutions no. 2 to simulate. iii. results figure 10 shows the cooling or heating energy required by a window v1. indicating that the cities of antofagasta and concepción have cooling gains with their negative statistics. this is not the case in santiago, whose values show an additional demand for it. as for heating, all windows require other energy input. the window that achieved the best performance was the solution n ° 2 in the city of concepción. since it has a favourable contribution of cooling energy (16 btu / hr) and its heating demand is the lowest (126 btu / hr). figs 11 and 12 indicate the amount of variation and heating energy required by the total windows of the house in comparison with the total area of these houses. in particular, the heating demand values are much higher than the cooling figures, with a difference between them that ranges 87 % and 93 %. on the other hand, the window that obtained better performance in both graphics. is the s2 solution in the city of santiago because it has the smallest reduction in surface area, 11% compared to the base case. also, it manages to reduce the cooling and heating needs by 64% concerning its base case. http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 12 figs 13 and 14 it show the heat that flows per unit of time and surface area (u) in the windows compared to the total demand for cooling or heating energy of the house. the cooling demand values are much higher than those required for heating as there is having a difference between them that ranges between 70% and 86%. moreover, the city that presented the most significant energy demands was that of santiago — reaching differences of up to 9% in cooling and 56% in heating. however, the city that shows the lowest energy savings is antofagasta, decreasing only 1.5% in cooling and having a maximum of 9% in heating. in comparison, the city that achieved the best energy performance was the city of concepcion with solution s2 since it managed to reduce cooling energy by 3% and 12% for heating. fig. 10. cooling vs heating energy required by a v1 window. fig. 11. total surface of the v1 windows vs energy supply for cooling them. s.a.b s.a1 s.a2 s.s.b s.s1 s.s2 s.c.b s.c1 s.c2 cooling trans -38 -16 -14 166 66 60 -127 -37 -16 heating trans 560 244 205 1,148 458 417 980 284 126 -200 0 200 400 600 800 1,000 1,200 1,400 b t u /h r s.a.b s.a1 s.a2 s.s.b s.s1 s.s2 s.c.b s.c1 s.c2 ft2 81 57 57 81 54 72 81 39 39 desing cooling -114 -48 -42 498 198 180 -381 -111 -48 -500 -400 -300 -200 -100 0 100 200 300 400 500 600 0 10 20 30 40 50 60 70 80 90 b t u /h r ft 2 http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 13 fig. 12. total surface of the windows v1 vs energy supply for heating them. fig. 13. thermal transmittance of the window (u) vs total energy demand for cooling. fig. 14. thermal transmittance of the window (u) vs total energy demand for heating. s.a.b s.a1 s.a2 s.s.b s.s1 s.s2 s.c.b s.c1 s.c2 ft2 81 57 57 81 54 72 81 39 39 desing heating 1,680 732 615 3,444 1,374 1,251 2,940 852 378 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 0 10 20 30 40 50 60 70 80 90 b t u /h r ft 2 s.a.b s.a1 s.a2 s.s.b s.s1 s.s2 s.c.b s.c1 s.c2 total desing cooling 67,489 66,481 66,488 69,523 67,856 68,317 65,567 63,527 63,588 u 1.02 0.63 0.53 1.02 0.63 0.42 1.02 0.63 0.22 0.00 0.20 0.40 0.60 0.80 1.00 1.20 60,000 61,000 62,000 63,000 64,000 65,000 66,000 67,000 68,000 69,000 70,000 u = b t u /h r/ ft 2 /f b t u /h r s.a.b s.a1 s.a2 s.s.b s.s1 s.s2 s.c.b s.c1 s.c2 total desing heating 10,227 9,422 9,306 20,964 19,248 18,889 17,897 16,262 15,789 u 1.02 0.63 0.53 1.02 0.63 0.42 1.02 0.63 0.22 0.00 0.20 0.40 0.60 0.80 1.00 1.20 0 5,000 10,000 15,000 20,000 25,000 u = b t u /h r/ ft 2 /f b t u /h r http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 14 iv. conclusion after evaluating the passive energy performance of homes, it is concluded that the highest energy demands were recorded in cooling and they were much higher than those required for heating. as a result, the double airtight glass allows reducing the solar gain but fails to eliminate overheating in hightemperature seasons. other relevant data provided by the simulations correspond to the relationship between the thermal transmittance (u) of the windows and the total energy demand of the house (btu / hr). specifically, when using windows with small values of u in geographic areas where high temperatures prevail, great energy and economic performance are not obtained. radiation control measures are more practical to combat these situations. in geographical areas where low temperatures are recurrent, the strategy is of using very high-quality windows is not always viable. that is to say, using thermal transmittance values that are very low or close to 1.0 btu / hr / ft2 / f. together with decreasing their dimensions, they singularly favour the heating demand reduction. however, this situation is not entirely profitable because the natural light surface is lost, and the implementation costs are too high. in temperate climates, it is where the correct selection of the windows has a higher incidence. because, if windows with u values ranging between 2.0 and 3.0 btu / hr / ft2 / f are used, a considerable reduction in the energy demands of the house is obtained, with a reasonable implementation cost. for example, in cold months, the solar radiation decreases, allowing the double airtight glass to limit heat transfers between the interior and exterior of homes in addition to avoiding condensation in the interior glass. in contrast, in months of high temperatures, the same windows allow cooling through cross ventilation caused by opening them. in the case of having a ventilation, heating and air conditioning system (hvac) the windows with the indicated characteristics allow encapsulating or retaining the comfortable temperature inside the enclosure, avoiding energy loss. in general, it is confirmed that windows with lower thermal transmittance (u) achieve better energy performance in homes. however, the selection of optimal windows for a project should always be based on the geographical area, the orientation of the facade or wall, the surface of light or visibility to be projected (dimensions) and the values of thermal transmittance (u). for example, the simulations showed that the s2 solution obtained a better performance of energy efficiency in the three cities mainly because it had u figures and slightly smaller surfaces than the s1 option. as for the users of homes in chile and around the world, the following inferred; usually, they do not know the energy demand of homes, much less about the selection of doors or windows with excellent performance. because these responsibilities transferred to government authorities, this means that it is the governments that generate the energy efficiency and sustainability strategies, according to the political, social and economic reality that they live. however, the difference is that europe, unlike chile, has more experience and track record on this issue. instead, chile is in the process of transition, since its policies and regulations are recent or in the development stage. about the above and the evidence collected, it is possible to affirm that this methodology can effectively provide support to users, allowing them to know when it is profitable to change their windows for one that has a better performance. on the other hand, the implementation of this in the design stage allows knowing the cost and benefit relationship that exists between the windows, a critical factor in projects where resources are minimal, such as social projects. furthermore, it favours the country's energy transition process in a transversal manner. in other words, it involves all the stages of a project; design, construction, operation and demolition or replacement in this case. it can be implemented free of charge, with high possibilities of application in the market and with national coverage. however, the successful integration of this in the field depends on the improvement of the current legal and technical framework that surrounds it, a modest initial investment, additionally a process of information and standardization of the market. v. acknowledgments dr. david blanco and danny lobos supervised this research at universidad tecnológica metropolitana de http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 15 chile under a master's project from the school of engineering. references [1] oecd and united nations economic commission for latin america and the caribbean, “oecd environmental performance reviews: chile 2016”, secretary-general of the oecd, paris, 2016. [2] apec chile 2019, “apec chile 2019”, 2019, available on: https://www.apecchile2019.cl/apec/acerca-deapec/about-apec. [3] ministerio del medio ambiente de chile, “ministerio del medio ambiente”, 2012, available on: https://sinia.mma.gob.cl/temasambientales/compromisos-internacionales/. [4] eu parliament, directive 2010/ 31/eu, eu parliament, 2010. [5] comisión nacional de energía chile, “anuario estadístico de energía 2018,” ministerio de energía , santiago, 2018. [6] comisión nacional de energía chile, “energía abierta”, 2018, available on: http://datos.energiaabierta.cl/dataviews/253790/ balance-energetico-2018/. [7] ministerio de energía de chile, “estrategia nacional de energía 2012-2030”, santiago, 2012. [8] ministerio de energía de chile, “plan de acción de eficiencia energética 2020”, santiago, 2013. [9] ministerio de economía, fomento y reconstrucción de chile, política energética, ley n ° 20.257, santiago, 2013. [10] ministerio de vivienda y urbanismo. gobierno de chile, estándares de construcción sustentable para viviendas, tomo ii: energía, santiago: división técnica de estudio y fomento habitacional ditec, minvu, 2018. [11] ministerio de vivienda y urbanismo. gobierno de chile, estándares de construcción sustentable para viviendas, tomo iii: agua, santiago: división técnica de estudio y fomento habitacional ditec, minvu, 2018. [12] ministerio de vivienda y urbanismo. gobierno de chile, estándares de construcción sustentable para viviendas, tomo iv: materiales y residuos, santiago: división técnica de estudio y fomento habitacional ditec, minvu, 2018. [13] ministerio de vivienda y urbanismo. gobierno de chile, vol. 2 manual de procedimientos calificación energética de viviendas en chile, santiago: división técnica de estudio y fomento habitacional – ditec, minvu, 2019. [14] ministerio de vivienda y urbanismo. gobierno de chile, ley general de urbanismo y construcciones, santiago, 1975. 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[30] instituto nacional de normalización, nch 3076/2 comportamiento térmico de puertas y ventanas determinación de la transmitancia térmica por el método de la cámara térmica parte 2: ventanas de techumbres y otras ventanas sobresalientes., santiago: instituto nacional de normalización, 2008. [31] instituto nacional de normalización, nch3297 puertas y ventanas permeabilidad al aire método de ensayo., santiago: instituto nacional de normalización, 2013. [32] instituto nacional de normalización, nch3296 puertas y ventanas permeabilidad al aire clasificación., santiago: instituto nacional de normalización, 2013. [33] carrier, “carrier”, 2018, available on: https://www.carrier.com/commercial/en/us/softw are/hvac-system-design/hourly-analysisprogram/. [34] american society of heating, refrigerating and air-conditioning engineers (ashrae), ashrae std. 62.1, atlanta: ashrae, 2010. 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[37] g. p. f. c. p. r. p. andrea gasparellaa, “analysis and modelling of window and glazing systems energy performance for a well insulated residential building,” energy and buildings, 43 (4), pp. 1030-1037, 2011. http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 https://f7b235ff-bd9f-430d-b656-612f8b4c3881.filesusr.com/ugd/2f1e74_c54089853e234e759fbc0c5a4dd8d239.pdf https://f7b235ff-bd9f-430d-b656-612f8b4c3881.filesusr.com/ugd/2f1e74_c54089853e234e759fbc0c5a4dd8d239.pdf https://f7b235ff-bd9f-430d-b656-612f8b4c3881.filesusr.com/ugd/2f1e74_c54089853e234e759fbc0c5a4dd8d239.pdf https://clavelocal.com/ventajas-e-inconvenientes-de-las-ventanas-de-pvc-y-aluminio/ https://clavelocal.com/ventajas-e-inconvenientes-de-las-ventanas-de-pvc-y-aluminio/ https://clavelocal.com/ventajas-e-inconvenientes-de-las-ventanas-de-pvc-y-aluminio/ https://www.carrier.com/commercial/en/us/software/hvac-system-design/hourly-analysis-program/ https://www.carrier.com/commercial/en/us/software/hvac-system-design/hourly-analysis-program/ https://www.carrier.com/commercial/en/us/software/hvac-system-design/hourly-analysis-program/ journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 17 [38] o. aydın, “conjugate heat transfer analysis of double pane windows,” building and environment, 41 (2), pp. 109-116, 2006. 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[42] a. a. castaño, wind seal distribuidora de perfiles de aluminio, santiago: universidad de chile, 2015. http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.057 57 resd © 2019 http://apc.aast.edu modelling and energy analysis of solid oxide fuel cell (sofc) operated by the pv system in the residential sector in australia scarlett allende los zarzales 1533, santiago 9270842. chile, ssallend@uc.cl abstract this paper presents an energy evaluation of a hybrid system composed of a photovoltaic farm, hydrogen consumption and solid oxide fuel cell, which simulation involves the electric demand of a household in the western territory of australia. specifically, the study evidences a significant solar potential that provides 4659kwh/year. however, there is an energy deficit in the period when the load energy is higher than the solar generation. as a result, the fuel cell integration solves the irregularities of solar availability, providing 4567kwh/year load demand and 477827kwh/year of energy delivered to the grid. finally, the configuration of the system generates 50% more than the energy required, which allows enlarging the electric consumption and the possibility to append thermal energy. keywords hybrid system, fuel cell, photovoltaic, hydrogen, residential sector, energy demand. i. introduction the primary purpose of this study is to know the potential of the natural sources of western australia, determine the electricity and hydrogen demand, analyse the integration of the fuel cell into pv system and evaluate the hybrid system performance. overall, australia presents a significant development in the renewable energies due to natural resources available and the target of clean energy regulation existing in different states [1]. particularly, wa has a relevant potential in renewable’s energies, particularly in solar households with 27% of capacity (rooftop solar technology) [2]. the high solar radiation in australia allows getting progress in the industry, especially in the desert areas (northwest and centre), resulting in total solar radiation of 58 million pj. also, due to the policies of clean energy, the government expects to generate 1000mw from solar power, promoting the capacity of electric and thermal technologies, though, the current production of solar energy denotes 0.1% of the total primary energy demand [3] at the same time, australia has expanded the type of renewable resources, such as the hydrogen industry that allows exploring new technologies, including fuel cell development. specifically, the implementation of the fuel cell as an electric generator provides a reliable energy system due to the option of seasonal hydrogen storage and grid stability. furthermore, it’s an alternative to remote area power systems [4]. ii. methodology a. estimating energy demand the annual electric demand was calculated considering the simulator plan of australian energy consumption [5]. the study understands factors that influence electrical use, such as the location, number of people living in the house and the usage of facilities. specifically, the simulation applied in this paper involved the electric consumption of two people, which includes the pool facilities and slab heating system. equivalently, the daily and hourly use were calculated based on the periods of electric usage, considering the distribution of the energy plan simulation on the 8760 hours per year. 1. photovoltaic farm the solar research was in the coordinates -25.69, 116.2, which corresponds to the western territory of australia. the first step of the study involved obtaining the monthly data of temperature and solar irradiation, extracted from the photovoltaic geographical information system [6]. these data correspond to the average hourly of air temperature [°c] and the global and diffuse radiation [kwh/m2] of each month. considering these last two data was possible to estimate the slope radiation [kwh/m2]. fig. 1 explains the sequence of steps done on this methodology. it is important to note that fig. 1 is modified from a similar study [7], where the hourly global and diffuse solar irradiation (kwh/m2) were from the nasa http://dx.doi.org/10.21622/resd.2019.05.2.057 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.057 58 resd © 2019 http://apc.aast.edu database. however, this research considered the pvgis explorer data. the rest of the steps follows the same logic. the resulting diagram explains the sequence of the steps done on this methodology. fig .1 calculation method for the power generation of one pv module. modified from [7]. the cell temperature, efficiency and power generation of one photovoltaic module were calculated considering equation 1, 2 and 3. mainly, the factors are represented by the air temperature obtained from the pvgis explorer (ta); global slope irradiation (gslope); global radiation at the nominal operating cell temperature (gnoct); nominal operating pv cell temperature (tc, noct) [8]; cell efficiency at standard test conditions (nstc); absorptivity of the module (tα); cell temperature at standard testing conditions (tc, stc); temperature coefficient value (αp) [9]; electrical efficiency at standard test conditions (ɳ mod) and area of the pv module surface (a). it is essential to note that some values of the formulas belong to the database of the pv module [10]. tc = ta + ( gslope gnoct ) (tc, noct − ta, noct) (1 − (n stc tα )) [°𝐶] eq .1: cell temperature of pv panel [8]. 𝜂𝑐𝑒𝑙𝑙 = 𝜂𝑠𝑡𝑐 [1 + 𝛼𝑝(𝑇𝑐 − 𝑇𝑐, 𝑠𝑡𝑐)] [%] eq .2: cell efficiency of a photovoltaic module [8]. 𝑃 = ɳ𝑚𝑜𝑑 ∗ 𝐴 ∗ 𝐺𝑡𝑙𝑡 [1 − 0.0045𝑇𝑐 − 298.15][𝑊] eq .3: power generation of pv panel [7]. then the solar farm is determined by the relation between the total electric demanded and the energy provided by a single pv panel. the last function is represented by equation 4, where am is the useful area of the photovoltaic module and itilt is the tilted global irradiance. 𝐸 𝑚𝑜𝑑𝑢𝑙𝑒 = 𝐴𝑚 ∗ 𝜂𝑠𝑡𝑐 ∗ 𝐼𝑡𝑖𝑙𝑡 [𝑘𝑊ℎ/𝑑𝑎𝑦] eq .4: energy of one photovoltaic panel [11]. 2. integration photovoltaic-fuel cell system firstly, it was necessary to estimate the hydrogen consumption of the hybrid system. as a result, equation 5 describes the factors involved, such as the yearly electric demand (e_demand); efficiency of the pv-h2-sofc system and higher heating value of the hydrogen (hhv). 𝐻2𝑑𝑒𝑚𝑎𝑛𝑑 = 𝐸_𝑑𝑒𝑚𝑎𝑛𝑑 𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 ∗ 𝐻𝐻𝑉 [𝑘𝑔] eq .5: amount of hydrogen required in the hybrid system [12]. after getting the energy demand, solar source and hydrogen consumption, it was possible to simulate the system by the fcpower model [13]. additionally, it was necessary to include types of equipment data specification, such as from the pv panel, electrolyser [14] and fuel cell [15] used in the simulation. details of the modelling process are explained in fig. 2. fig .2 flow diagram of the fcpower simulation according to the hybrid system configuration [7]. iii. results a. solar radiation and air temperature according to the database from the photovoltaic geographical information system (pvgis), the air temperature values consider the hourly temperature average of each month, corresponding to the year 2016. notably, the maximum and minimum temperature variation during the year was in november and june with around 14°c and 9°c of difference, respectively. the result of the simulation is detailed in table 1. http://dx.doi.org/10.21622/resd.2019.05.2.057 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.057 59 resd © 2019 http://apc.aast.edu table 1 summary of the monthly ambient temperature [6] month average [°c] max [°c] min [°c] jan 30.83 37.7 25 feb 31.60 37.8 26.1 mar 29.46 35.1 24.3 apr 25.45 30.8 20.7 may 20.89 26.2 16.4 jun 17.16 22 13.5 jul 16.09 21.2 12 aug 18.22 24 13.2 sep 20.10 26.1 14.5 oct 23.58 30.2 17.2 nov 26.03 33 19.4 dec 28.59 35.4 22 analogously, the simulation provides hourly and monthly global horizontal radiation. table 2 indicates that during december produce the highest solar potential with over 800 [w/m2], between the 11 and 15 hours. in contrast, the lowest radiation was in wintertime (june and july), with less of 200 [w/m2]. b. cell temperature, efficiency and output power based on the air temperature values, factors and formulas it was possible to obtain the monthly and hourly cell temperature. the result per month showed that the pv panel increases the heat during the summer season, approximately 2°c. at the same time, fig. 3 describes the result per hour, where the rise appears in the afternoon, with around 3°c of difference. table 2 average of the global radiation per hour and month [w/m2] hour/m onth jan feb mar apr may jun jul aug sept oct nov dec 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0 0 0 5 0 0 0 0 0 0 0 0 0 0 0 0 6 0 0 0 0 0 0 0 0 0 0 27 22 7 47 8 8 0 0 0 0 0 15 95 188 194 8 129 185 210 72 56 49 46 60 201 376 537 567 9 124 257 263 141 64 52 51 89 254 412 560 578 10 157 385 396 245 123 75 88 186 374 547 690 722 11 163 488 495 331 191 129 153 264 460 639 777 821 12 160 552 550 375 235 169 198 313 506 684 821 865 13 162 564 564 386 237 176 204 323 511 682 817 864 14 173 517 535 354 210 152 184 296 472 631 764 821 15 191 425 468 290 150 101 132 235 398 541 667 719 16 162 344 360 196 86 77 82 149 293 417 544 608 17 134 219 224 92 50 37 46 71 170 271 396 465 18 92 125 104 19 0 0 0 15 47 108 224 304 19 38 20 0 0 0 0 0 0 0 0 1 90 20 0 0 0 0 0 0 0 0 0 0 0 0 21 0 0 0 0 0 0 0 0 0 0 0 0 22 0 0 0 0 0 0 0 0 0 0 0 0 23 0 0 0 0 0 0 0 0 0 0 0 0 on the other hand, the relationship between the pv, the cell temperature and the cell efficiency are represented by fig. 4 and 5. principally, this last variable decreases during summer (january and february) with 15% less. furthermore, the period with the lowest performance was between 13 and 15 hours, with almost 14.7% at 9°c. http://dx.doi.org/10.21622/resd.2019.05.2.057 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.057 60 resd © 2019 http://apc.aast.edu fig .3 average of ambient and cell temperature per hour. at the same time, the power generation of the photovoltaic panel was calculated per hour and month, with results manifested in table 3. overall, the peak is concentred in intervals during mornings and evenings of the summer season. for example, december shows the highest power production at the 8 and 18 hours, with 221 and 284 w, respectively. in the rest of the months, the same variation exists but with a lower outpower. fig .4 cell temperature and efficiency per month. fig .5 average of the cell temperature and efficiency per hour. c. determination of pv system regarding the results calculated previously, it was possible to obtain the pv modules quantity required in the hybrid system. in this case, the annual electric demand extracted from the simulator plan of australian energy consumption was of 4610 kwh. additionally, the energy produced by one photovoltaic module was of 89.43 kwh/year. as a result, the total of modules was of 52. details are in table 4. the energy generation of the solar farm was calculated considering the number of pv panels required, and the energy produced by a single 0 5 10 15 20 25 30 35 1 3 5 7 9 11 13 15 17 19 21 23 t e m p e ra tu re [ °c ] hour ambient temperaure cell temperature http://dx.doi.org/10.21622/resd.2019.05.2.057 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.057 61 resd © 2019 http://apc.aast.edu photovoltaic module. this last find was around 90kwh/year. in contrast, the global supplied was of 4659kwh/year, which includes the energy generation of 52 pv panels. as table 5 shows, the month with the highest energy production was december with 996kwh, and the lowest was june with 162kwh. table 4 summary of the monthly ambient temperature [6] e panel kwh/day e panel kwh//yr. total consumption , kwh/yr. pv panels 0.245 89.43 4610 52 table 3 pv module output power [w]. month/ hour jan feb mar apr may jun jul aug sep oct nov dec 1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2.6 2.0 7 71.9 14.8 2.2 0.0 0.0 0.0 0.0 0.0 5.6 36.9 138.8 165.7 8 164.1 67.5 25.7 16.1 20.6 17.9 16.8 20.6 30.6 39.9 139.6 220.6 9 84.5 35.9 29.3 22.1 18.8 19.1 18.7 15.5 28.0 40.9 50.3 111.1 10 50.5 45.8 37.2 30.6 21.7 22.7 21.7 23.7 38.2 49.1 48.4 61.5 11 53.7 49.1 42.5 37.6 27.0 25.7 26.7 28.0 39.9 49.4 50.1 50.4 12 52.7 50.1 42.5 37.9 32.3 30.3 31.0 31.3 39.5 49.8 49.8 53.1 13 53.4 51.7 45.1 39.9 31.3 30.6 30.3 31.3 39.9 49.8 51.7 54.4 14 57.0 55.7 48.8 38.6 31.0 29.7 31.0 30.0 37.6 51.4 53.4 56.0 15 58.3 58.7 46.1 36.6 26.4 25.0 27.0 28.0 34.3 47.8 53.4 68.9 16 100.8 49.8 38.9 29.0 22.4 28.0 24.7 22.7 29.3 40.9 53.3 117.5 17 158.4 66.2 31.0 18.5 17.9 13.5 17.2 18.8 25.0 32.3 109.2 182.8 18 249.2 131.3 19.8 8.4 0.0 0.0 0.0 6.9 15.4 42.2 172.4 283.6 19 21.5 9.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 18.1 20 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 21 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 22 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 23 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 24 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 the design of pv facilities is composed of six rows and seven columns of panels with 45° inclination and orientated towards the north. nevertheless, to reduce the shadow risk, the pv arrows have a prudent distance between them. furthermore, the sizing of pv array considers two inventers for the total of modules. fig. 7 shows the solar farm involved and location. principally, the area distribution includes two aspects; the first one is a useful area that represents the location of the panels, with 322m2. the second factor is around 30% more surface (419m2) intended to a maintenance purpose in the system. similarly, fig. 6 illustrates the distribution of energy consumption and the energy supplied. the electric demand showed steady rises and drops. however, there are significant leaps of the energy provided by the solar system, especially in december. comparatively, during wintertime, the energy demand was higher than the produced. however, this has switched drastically in summer. fig .6 comparison between the energy demand and the energy supplied by the solar farm. the array size involves a voltage dimension of 60v and 49v for the respective maximum and minimum open circuit voltage. furthermore, the maximum current in the photovoltaic module was of 8.4a. analogously, the interval of pv modules per string was between 10 and 5, considering a maximum of voltage and current per line of 600v and 18a, respectively. the design of pv facilities is composed of six rows and 0 200 400 600 800 1000 1200 jan feb mar apr may jun jul aug sep oct nov dec k w h total energy supplied energy demand http://dx.doi.org/10.21622/resd.2019.05.2.057 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.057 62 resd © 2019 http://apc.aast.edu seven columns of panels with 45° inclination and orientated towards the north. nevertheless, to reduce the shadow risk, the pv arrows have a prudent distance between them. furthermore, the sizing of pv array considers two inventers for the total of modules. fig. 7 shows the solar farm involved and location. principally, the area distribution includes two aspects; the first one is a useful area that represents the location of the panels, with 322m2. the second factor is around 30% more surface (419m2) intended to a maintenance purpose in the system. table 5 summary of output energy of photovoltaic module. month energy single module supplied [kwh] total energy module supplied [kwh] jan 15.57 809.8 feb 8.21 426.9 mar 5.42 281.8 apr 4.04 210.0 may 3.3 171.7 jun 3.10 161.7 jul 3.25 168.8 aug 3.40 176.9 sep 4.66 242.1 oct 7.02 365.1 nov 12.47 648.4 dec 19.15 995.5 total 89.589 4658.678 fig .7 location of solar farm. source: (google earth, 2019). d. configuration of the pv-h2-sofc system. the first stage of the hybrid system design involves the solar energy that provides electric generation and hydrogen for the fuel cell system. however, if the hydrogen production is not enough to supply the demand of the system, it is necessary to add the missing hydrogen from an external source. as a result, the pv-h2-sofc configuration has two parties, one from solar energy providing the hydrogen partially to the electrolyser, and the other from the hydrogen storage. as fig. 8 describes, the first scenario exists when the pv generation is lower than the energy consumption. fig .8 design of pv-h2-sofc system [7]. based on the hydrogen calculation and the energy consumption, it was possible to get the comparative variation between both requirements. as fig. 9 describes, the energy demand is proportional to the hydrogen consumption of the fuel cell. for example, the highest and lowest demand for hydrogen and electricity are during summer and spring, respectively. the range of both periods is between 660-780m3 for the hydrogen and 1050-1200kwh for electric consumption. on the other hand, according to the results of the hydrogen produced from pv generation and the hydrogen required, the deficit of hydrogen of the hybrid system was determined. in this case, the highest gap was in the wintertime, with 17.98kg missing hydrogen. in contrast, in the months of summer presented the lowest variation, with a deficit of 9.86kg. the hydrogen distribution is described in fig. 10. http://dx.doi.org/10.21622/resd.2019.05.2.057 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.057 63 resd © 2019 http://apc.aast.edu fig .9 hydrogen demand and electricity required per season. fig .10 hydrogen demand and hydrogen deficit per month. the storage tank was dimensioned considering the highest deficit of hydrogen of the year (18kg/month and 200m3/month) and the values of volume and pressure of the electrolyser and tank. as a consequence, the hydrogen pressurised was 30.8m3, but for safety reasons, it must include a 10% of volume [16], with a final dimension tank of 33.88m3. it is important to note that the location of the tank was underground due to the reduced risk of temperature fluctuation [7]. e. simulation results. the fcpower model provided the modelling results of the pv-h2-sofc system, which started with the annual input specifications data, such as the solar capacity factor and the amount of fuel used in the fuel cell. for example, the yearly system energy output used onsite is the balance between the delivered of electricity (4567kwh), heat (0 kwh), hydrogen (8763kwh), and grid electricity to the building (0 kwh). details of those values are presented in table 6. table 6 energy input of the system, from fcpower model simulation [13]. values specifications 86.801 fuel used in fcs [kwh/kwh] 0.000 fuel used in burner [kwh/kwh] 0.349 ac from solar [kwh/kwh] 0.000 ac from wind [kwh/kwh] 0.000 purchased grid electricity [kwh/kwh] 0.0% purchased grid electricity cost (wtd avg % of base cost) 13,331 system energy output used onsite per year [kwh] at the same time, the model provides the general specification of the fuel cell, considering the range of energy capacity 53.3kwh; combined heat, hydrogen, and power efficiency of 63%; fuel consumed for combined heat and power of 132kwh and the maximum hydrogen generation of 17kw. table 7 shows the data specification of the sofc system. table 7 summary of the fuel cell specifications per hour [13]. specification value units electricity produced 53.33 kw electrical chp efficiency at current electrical power level 0.4047 kw/kw total chp efficiency at current electrical power level 0.6273 kw/kw fuel used for chp operations 131.8 kw chp heat total 29.3 kw max h2 production ability 17.0 kw max h2 over-production ability 11.4 kw h2 production 0.0 kw chp heat used for h2 production 0.0 kw chp heat out total 29.3 kw over-production of h2 0.0 kw fuel used for h2 over-production 0.0 kw total fuel consumption 131.8 kw the hourly output results showed that the electricity delivery was of 0.343kwh per kwh produced by the hybrid system. besides, the hydrogen delivery was 0.657kwh/kwh, which represents the relation between the hydrogen delivered and the yearly system energy output used onsite. analogously, the electricity sold to the grid includes the results of the energy input (13331kwh/year), and the excess of energy intended to the grid (477827kwh). table 8 details the total of power supplied by the pv-h2-sofc system (491158kwh), which considers the values of electricity generated, energy sold, hydrogen production and heat delivered. 950 1000 1050 1100 1150 1200 1250 1300 600 620 640 660 680 700 720 740 760 780 800 820 summer autumn winter spring k w h m 3 electric energy demand hydrogen required 0 5 10 15 20 25 jan feb mar apr may jun jul aug sep oct nov dec k il o g ra m s hydrogen produced hydrogen required http://dx.doi.org/10.21622/resd.2019.05.2.057 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.057 64 resd © 2019 http://apc.aast.edu table 8 energy output of the system, from fcpower model simulation [13]. values specifications 0.343 ac delivered [kwh/kwh] 0.000 heat delivered [kwh/kwh] 0.657 hydrogen delivered [kwh/kwh] 3.58e+01 ac sold to grid [kwh/kwh] 491,158 total energy supplied per year [kwh] finally, the simulation provided different types of efficiencies as explained in fig. 11. principally, the fuel cell efficiency was higher than the electrical performance; for example, in the operating fraction 0.5, the capabilities were 70% and 45%, respectively. furthermore, the capacities of the categories of hydrogen-fuel-cell and electrolyser were significantly similar, with around 52% of the performance at 100% of operation. fig .11 performance of pv-h2-sofc system. modified from [13]. iv. economic analysis according to financial results obtained from fcpower model simulation, the price factors of system net electricity and hydrogen were 0.133 $/kwh and 35.7 $/kwh, respectively. as a result, considering 4567 kwh/year of electricity production from the hybrid system and 8763 kwh of hydrogen required, the total cost of energy generation was 313,446 $/year. however, this cost can be reduced, considering the system electricity sold to the grid of 38,912$/year, whose values includes 477,827 kwh/year of excess and the sold price factor of 0.081 $/kwh. the total cost obtained was 274,534 $/year. analogously, the australian electricity load price is around 0.22 $/kwh [17], which involves a total value of 913 $/year. overall, the electricity cost from the hybrid system was competitive compared to the grid (around 33% cheaper). nonetheless, the deficit of hydrogen increases is considerable to the global cost. on the other hand, one of the main advantages of fuel cell integration was the elimination electric battery into the hybrid system configuration due to the water electrolysis can solve the irregularity of solar availability. therefore, its elimination helps to decrease the operational cost by around 30% [7]. v. conclusion according to the solar power generation, hydrogen and fuel cell modelling, the hybrid system is a viable alternative to supply the electric consumption of one house. therefore, the following points summarise the findings: • the western territory of australia showed an elevated solar source, considering that the highest daily average was in december with a global radiation of 318 w/m2. the rest of the months presented a slight difference between them. • the hourly variation between the cell efficiency and panel temperature did not change significantly as the performance was reduced by 0.2% in the 13 hours. however, the monthly results showed that the efficiency decreased by 1% during summertime. • the solar farm can supply the total annual demand. nevertheless, the distribution of electricity generation was significantly unequal. for example, in the wintertime, solar energy only provides 47% of the total consumption required. as importantly, the integration of the fuel cell helps to supply this deficit. • the electricity generation increases by more than 30% with the integration of the fuel cell. specifically, the photovoltaic energy produced 4658kwh/year, and the solid oxide fuel cell generated 4567kwh/year of electricity load and 477827kwh/year of delivered to the grid. as a result, both renewables sources are 9225kwh/year, which represents 50% more than the energy demand. • the hybrid system presented different efficiencies stages and as a result there are electric and heat losses (unrecoverable energy), associated with http://dx.doi.org/10.21622/resd.2019.05.2.057 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.057 65 resd © 2019 http://apc.aast.edu electrical efficiency and total fuel cell efficiency, respectively. in this case, the fuel cell performance is 42% higher than the electric efficiency. • as a result, the pv-h2-sofc system allows supply a higher electric demand and adds thermal consumption as hot water. furthermore, it has cogeneration benefits, such as the environmental impact due to hydrogen obtained from pv panels, which is used in the fuel cell. also, in this process, there is heat recovery, so it is a closed energy cycle. • despite that the integration of fuel cell into pv system showed an economic disadvantage, there is financial retribution for the sale of the surplus energy, improving the energy cost balance. besides, the system can supply a higher demand for the same cost, 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[36] h. rezkab, e. taha, m. al-dhaifallahe, m.obaidcf, a. hashema, m.el-sayedb, m. ali, and g.olabi. “fuel cell as an effective energy storage in reverse osmosis desalination plant powered by photovoltaic system,” energy, vol. 175, pp. 423-433, 2019. http://dx.doi.org/10.21622/resd.2019.05.2.057 journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 160 resd © 2015 http://apc.aast.edu durability probabilistic evaluation of rc structures subjected to chloride ion han-seung lee1，mohamed a. ismail1,*, mohd warid hussin2 1school of architecture & architectural engineering, hanyang university, ansan, s. korea 2 construction research centre (utm crc), institute for smart infrastructure and innovative construction, universiti teknologi malaysia, 81310 utm johor bahru, johor, malaysia *corresponding author email: mismail@hanyang.ac.kr, phone: +82-314005181, fax: +82-314368169 abstract chloride attack on concrete structures is becoming a primary factor that deteriorates the durability of concrete structures. for this reason, research has been conducted on chloride ion penetration and diffusion. this research produced an accurate durability life prediction through reliability assessments and proposes a prediction method for the chloride ion diffusion coefficient of a concrete applied assessment program for reliability. as a result, test materials were fabricated using different admixtures, and chloride ion diffusion coefficient was calculated by applying an rcpt test at each equivalent age. based on the results, reliability prediction formulas were indicated through the reliability analysis for a durability life design using a monte carlo method. in addition, results were verified through comparisons and analysis using the proposed formula with the investigated data for chloride ion diffusion. keywords evaluation of durability life, chloride ion diffusion coefficient, monte carlo method. i. introduction it is widely known that the ingress of chloride ions constitutes a major source of durability problems affecting reinforced concrete structures that are exposed to saline environments. once a sufficient quantity of chloride ions has accumulated around the embedded steel, pitting corrosion of the metal is liable to occur unless the environmental conditions are strongly anaerobic. in the design of concrete structures, the influence of chloride ingress on service life must be considered [metha 2006; papadakis 2000; nielsen et al. 2003; han 2007; song et al. 2007]. the common service life model for the chloride induced corrosion of reinforcing steel in concrete involves two time periods. the first is the time for chloride diffusion until a sufficient concentration of chlorides is available at the reinforcing bar depth to initiate corrosion. the second is the time for corrosion damage (from initiation to cracking and spalling of the cover concrete) to the end of functional service life. an apparent diffusion process, based on fick’s second law, can be used to model the time for chloride to reach and initiate corrosion, where first repair and rehabilitation at reinforcing steel depths will take place. when solved for the condition of constant surface chloride and a one-dimensional infinite depth, fick’s second law takes the following form [kim et al. 2007]: 0 ( , ) (1 ( / 4 * * )) c c x t c erf x d t  (1) where ( , )c x t is chloride concentration at depth and time; 0 c is surface chloride concentration; cd is apparent chloride ion diffusion coefficient; t is time for diffusion; x is concrete cover depth and erf is statistical error function. when ( , )c x t is set equal to the chloride corrosion initiation concentration and eq. (1) is solved for t , the time for the diffusing chloride ions reaches rebar and initiates corrosion. however, for a given real condition, the values of ( , )c x t , 0 c cd and x are random variables, each with their own statistical distributions, means, and variances. a solution to eq. (1) for the time of diffusion should include the probabilistic nature of the input variables [kirkpatrick et al. 2002; enright and frangopo 1998]. the time for corrosion damage to the end of functional service life is also a random variable and depends on the corrosion rate, concrete cover depth, reinforcing steel bar spacing, and size [liu and weyers 1998]. to predict the whole service life, the probabilistic nature of these variables should also be considered. one common modern statistical technique is called monte carlo simulation. monte carlo is a general class of repeated sampling methods, where a desired response is determined by repeatedly solving a mathematical model using values randomly sampled from probability distributions of the input variables [kalos and whitlock 1986]. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 161 resd © 2015 http://apc.aast.edu ii. summary of chloride penetration test a. experimental program mineral components for improvement of chloride blocking property were tested in the same environment. to examine diffusion blocking properties, rapid chloride penetration test (rcpt) was done. configurations of test are presented in table 1. water-binding material ratio has two levels: 40% and 50%. fly ash (fa), blast furnace slag (bs), silica fume (sf) and meta kaolin (mk) were used in 3 different levels. table 1. dimensions of various fins waterbinding material ratio (%) admixture type admixture replacement ratio (%) measurement item measurement aging (day) 40, 50 non-blending designation compressive strength chlorine ion diffusion coefficient 7, 28, 56, 91 fly ash fa 10, 20, 30 blast-furnace slag bs 30, 50, 70 silica fume sf 5, 10, 15 metakaolin mk 5, 10, 15 table 2 shows composition of the plain concrete, without adding mineral components, to accomplish slump 18 ± 2.5cm and air entrained quantity, high efficiency ae water reducing agent. for the test of chloride penetration, rcpt, which was proposed by tang & nilsson, was referred to as illustrated in fig. 1. accordingly, each side of the cell is filled with 0.3m of sodium hydroxide (naoh) as anode and 3% of sodium chloride (nacl) as cathode. after that 30v was applied to the cell. the test was maintained for 8 hours; then 0.1 n water solution of silver nitrate (agno3) was sprayed after the split test body. as a result, the color of affected area changed. the colored depth was measured by vernier calipers. the chloride ion diffusion coefficient was calculated using eq. (2) based on the measured results. t xax zfu rtl d dd   ( ) 2 1(2 0 1 c c erf zfu rtl a d   ) (2) where: table 2. composition of the plain concrete watercement ratio (%) fine aggregate ratio (%) unit weight (kg/m3) wat er cement fine aggregate coarse aggregate 40 45.6 158 395 793 954 50 47.7 158 316 861 951 d diffusion coefficient (m2/s) z atomic value of ion (z=1 for chloride ion) f faraday constant (96,481.04 j/vmol) u voltage differences between positive and negative pulse (v) r gas constant (8.314 j/kmol) t solution temperature (k) l specimen thickness (m) d x penetration depth of chloride ion (m) t test sustaining time erf error function d c chloride ion density at the section changed in color by agno3 0 c chloride ion density of cell located in a negative pole http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 162 resd © 2015 http://apc.aast.edu fig .1. diagram of chloride ion diffusion test equipment fig. 2 demonstrates the procedure of rapid chloride penetration test to examine chloride ion diffusion coefficient of chloride ion. fig .2. procedure of rapid chloride penetration test iii. evaluation of probabilistic durability life a. in the latent period corrosion in rc structure assumed to have occurred by the attack of salt. in this case, chloride concentration depth is determined by eq. (3); it is also assumed that if chloride concentration is over the limits of (1.2 kg/m3) at steel bar position then it is the end of service for the structure. in this study, durability of the structure in sea environment was statistically analyzed by monte carlo method. table 3 shows the factors of statistical analysis. d0 is determined by rcpt, dm is calculated by eqs. (4a) and (4b) is used with chloride ion diffusion coefficient of chloride on the 28th day. td c c erftx m s cr   )1(2)( 1 (3) )( 1 00 t t n d d m   (t<tc) (4a) n m t t n n t t dd )]( 1 1[ 00 0   (t  tc) (4b) where: table 3. factors of statistical analysis factor average standard deviation d0 test result 1.2 n test result 0.08 d(mm) 40 7 ccr(kg/m 3) 1.2 0.24 cs(kg/m 3) 9 1.8 b. in the progress period progress period means the period that starts after the beginning of corrosion and until the crack begins. in this period, if the corrosion quantity is larger than corrosion quantity when structure cracked, service year will be end. the amount of corrosion in steel bars can be calculated using eq. (5). corr tohfefispew  ])([)2()( 1 3 (5) ( 5.1 ),(025.0 tdci  (6) ccr critical chloride content ion density at the beginning of corrosion (kg/m3) cs chloride ion density at the surface of concrete (kg/m3) dm average chloride ion diffusion coefficient until time t (m2/s) do chloride ion diffusion coefficient at t0 (m2/s) tc perpetual time of chloride ion diffusion coefficient (assumed as 30 years) t time lapse (years) n time dependent coefficient http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 163 resd © 2015 http://apc.aast.edu i m s c td d erfctdc    )) 2 (1(),( )) (7) where: if the shield thickness is considered with factor k, eq. (5) will be expressed as eq. (8). eq. (9a) and eq. (9b) considers diameter and shield thickness to get factor k. c(d, t) is calculated by eq. (7); dm is calculated by (4a) and (4b) as a latent period. ci assumed as 0 and steel bar diameter is assumed as 13 mm. if corrosion calculated by eq. (8) is larger than wcr, which is calculated by eq. (10), it is assumed that its service year has ended. as a process of the latent period, possibility of crack is calculated in the progress period. w = k * w (spe) (8) k = 1.0 (3*d  d) (9a) k = 3 * d/d (3*d < d) (9b) d d wcr 3 02.0  (10) where: iv. test analysis the 28th day compressive strength of this study is found to be between 30~40 mpa, as shown in fig 3, whereas fig. 4 the chloride ion diffusion coefficient of plain concrete for w/c is between 0.4 and 0.5. the estimation of the chloride ion diffusion coefficient dpc, can be produced using eq. (11). dpc = 0.547e3.95w/c (11) fig .3. compressive strength development with time fig .4. diffusion coefficient of plain concrete w/c 0.4 and 0.5 fig .5. diffusion coefficient according to time passage (w/c 0.4 and 0.5) 0 10 20 30 40 50 60 7 28 56 curing duration(days) c o m p re ss iv e s tr en g th (m p a ) 40 45 50 55 30.4m pa 45.7m pa y = 0.547e 3.95w/c 0 1 2 3 4 5 0.3 0.4 0.5 0.6 w/c d if fu si o n c o e ff ic ie n t, d m p c (* 1 0 -1 2 m 2 /s ) 0 1 2 3 4 0 20 40 60 80 100 time (days) d p c (* 1 0 1 2 m 2 /s e c ) w/c 40% w/c 50% 28 days 91 days i corrosion current density (μa/cm2) c(d,t) chloride ion density at the shield d(cm) and time t(year) (kg/m3) w(spe) amount of steel bar corrosion(g/cm2) f faraday constant (96500c/mol) fe(oh)3 molecular weight of fe(oh)3 (ⅲ) (106.9g/mol) tcorr time lapse (years) from the beginning of the time that exceeds the corrosion occurred critical chloride content ion density ci chloride ion density in the early stage (kg/m3)(=0) dm average chloride ion diffusion coefficient at t (year) (m2/s) (eqs. 3a, 3b) w corrosion speed of steel bars k shield parameter that affects corrosion speed d steel bar diameter (cm) d shield thickness (cm) wcr corrosion quantity when cracking begins(g/cm2) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 164 resd © 2015 http://apc.aast.edu in this study, chloride ion diffusion coefficient according to time passage (fig. 5) was determined by rcpt and eqs. (4a) and (4b). with this result, variation of diffusion coefficient was calculated. fig. 6 shows diffusion coefficient ratio when the plain concrete was replaced by admixture. according to fig. 6, equation for determining the diffusion coefficient of each admixture was suggested in table 4. to estimate possibility of failure according to the time dependent coefficient variation, durability failure possibilities according to the service year was calculated when sf15%, time dependent coefficient n=0, 0.4 and 0.8 (fig. 7). chloride ion diffusion coefficient can calculated by eq. (12) when the concrete property according to the time dependent is considered. according to eq. (13), induced by eq. (12) and test result, the variation of time dependent parameter [n] is shown in fig. 8. n t t dotd )()( 0  (12) )(0 )(log td t t don  (13) fig .6. type of admixture and substitution ratio table 4. diffusion coefficient of each admixture component equation(m2/sec) bs dpc·e -0.016·sf fa dpc·e -0.005·sf sf dpc·e -0.016·sf mk dpc·e -0.016·sf fig .7. durability failure possibilities according to the time dependent coefficient fig .8. time dependent parameter by type and quantity of mineral admixture probabilistic durability analysis for the latent period and the progress period were shown in fig. 9. meanwhile fly ash does not have any efficiency to improve durability, wherea blast furnace slag, silica fume and metakaolin do improve durability. fig .9. possibility of durability failure by type and quantity of mineral admixture 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 p la in m k 5 m k 10 m k 15 f a 10 f a 20 f a 30 sf 5 sf 10 sf 15 b s3 0 b s5 0 b s7 0 type of mineral admixture t im e d e p e n d e n t p a r a m e te r n w/b 40 http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 165 resd © 2015 http://apc.aast.edu fig. 10 shows the durability failure possibility according to shield thickness. if the shield thickness of steel bar is increased, distance from concrete surface to the steel is also increased. consequently, resistance of chloride ion is increased and durability failure possibility is decreased. fig. 11 shows durability failure possibility in latent period according to time. it is also replaced by sf 15% and bs 70% is most efficient to improve durability. the point of the possibility of durability failure will be 10% in the 80th year. fig. 12 shows durability failure possibility when admixture type and replacement ratio are different. according to this graph, the deviation of admixture type is smaller than the deviation of replacement ratio. durability failure possibility is also approximately 30% smaller. fig .10. durability failure possibility according to shield thickness fig .11. durability failure possibility according to time fig .12. durability failure possibility of admixture type and replacement variation fig. 13 presents the result of durability failure possibility according to the shield thickness, while fig. 14 shows durability failure possibility in progress period according to time. in the latent period, nothing satisfied the durability failure possibility under 10% when shield thickness was 40mm and over 100 years. however, when replaced by silica fume 15% and blast furnace slag 70%, the durability failure possibility was reduced to 9 % in the progress period, which satisfied possibility under 10%. other parameters have durability failure possibility over 30%. fig .13. durability failure possibility according to shield thickness http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 166 resd © 2015 http://apc.aast.edu fig .14. durability failure possibility according to time v. conclusion in this paper, based on experimental results of chloride diffusion coefficients and monte carlo method, the service of concrete structure incorporating different mineral components, such as fly ash (fa), blast furnace slag (bs), silica fume (sf) and metakaolin (mk) was predicted. the proposed model incorporates the statistical nature of chloride induced corrosion of reinforced concrete and can be used to evaluate the time of first repair and rehabilitation of concrete structures. this study obtained a dpc equation with a w/c using the chloride ion diffusion coefficient and time dependent coefficient (n) calculated by the experiment. it proposes an estimation equation for the chloride ion diffusion coefficient according to the blending ratio of admixtures, using the chloride ion diffusion coefficient of the plain concrete and admixture blended concrete. large differences of 20, 40, and 160 years at a 10 % probabilistic durability failure rate were evident by varying the time dependent index to 0.0, 0.4, and 0.8 under the same conditions of the probabilistic durability life test. it was clear that the time dependent index significantly affected the evaluation of the durability life. thus, it is necessary to precisely calculate the time dependent index. acknowledgement this work was supported by sustainable building research center hanyang university, which was funded by the src/erc program of most (#r112005-056-04003-0). this paper is an extended abstract that was published in korea by aik. references [1] p. kumar metha (2006). concretemicrostructure, properties and materials. magraw-hill, new york. [2] vagelis g. papadakis (2000). effect of supplementary cementing materials on concrete resistance against carbonation and chloride ingress. cem concr res 30: 291-299. [3] erik p. nielsen, mette r. geiker (2003) chloride diffusion in partially saturated cementitious material. cem concr res 33: 133-138. [4] sang-hun han (2007) influence of diffusion coefficient on chloride ion penetration of concrete structure. constr buil 21:370-378. [5] ha-won song, jong-chul jang, velu saraswathy, keun-joo byun (2007) an estimation of the diffusivity of silica fume concrete. bldg envir 42:1358-1367. [6] dongseok kim, hanseung lee, seongmin lee, xiaoyong wang.(2007) a study on the evaluation of probabilistic durability life for rc structures deteriorated by chloride ion, advances in fracture and damage mechanics vi, fdm 2007, portugal, edited by j.alfaiate, m.h.aliabadi, m.guagliano, l.susmei, pp.417421. [7] trevor j. kirkpatrick, richard e. weyers , christine m. anderson-cook, michael m. sprinkel (2002) probabilistic model for the chloride-induced corrosion service life of bridge decks, cem concr res 32 :1943–1960. [8] mchael p. enright and dam m. frangopol (1998) probabilistic analysis of resistance degradation of reinforced concrete bridge beams under corrosion, eng struct 20: 960-971. [9] y. liu, r.e. weyers (1998) modeling the time-tocorrosion cracking in chloride contaminated reinforced concrete structures, aci mater. j.95: 675– 681. [10] m.h. kalos, p.a. whitlock (1986) monte carlo methods: volume i. basics, wiley, new york. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 8 modelling and methodology for window selection with energy efficiency criteria in chile ignacio allende los zarzales 1533, santiago 9270842. chile, ignacio.allende.l@hotmail.com abstract this article presents the development of a methodology associated with the selection of windows with energy efficiency criteria in chile. it provides the optimal option in a housing project, according to specific search parameters by region, commune, orientation, materiality, among others options. at the same time, it is possible to download the technical characteristics of the selected window instantly. according to results obtained on the simulation, s2 showed better energy efficiency performance in the three cities studied (antofagasta, santiago and concepcion). mainly the transmittance value was slightly smaller than s1 solutions. in general, windows with lower thermal transmission (u) achieve better energy efficiency in homes. however, the selection of optimal windows for a project should always be based on the geographical area, the orientation of the facade or wall, the surface of the light, or the visibility to be projected (dimensions), and the thermal transmittance values (u). keywords sustainability, energy efficiency, window, thermal transmission, transmittance values. i. introduction currently, chile has joined multiple sustainable agreement and due to this, chile actively participate such as a member of the organization for economic cooperation and development (oecd), asia pacific economic cooperation (apec) and the united nations framework convention on climate change (unfccc). consequently, a series of national strategies is laid down, for the short and mediumterms, which seeks to favour the transition to a more sustainable and efficient country. [1] [2] [3] for the development of these, the european reality was studied, which had a successful work program and extensive experience. one of the initiatives that stood out in this area was directive 2010 / 31 / eu of the european parliament [4], which is the basis for the energy rating of homes. it also defines the objectives and standards of energy efficiency in buildings by 2020. then, the study and analysis of the different energy sectors of chile began, to know the state of the country in this matter and determine what the gap that exists with high-standard countries is. in this regard, each the residential and the mining sectors represent 15% of the total national energy consumption. this indicates the magnitude of the context, taking and into account the importance of mining in chile. [5] [6] on the other hand, the national energy strategy 20122030 stipulates an energy efficiency action plan 20122020 that aims to achieve a 12% reduction in projected energy demand in the year 2020 [7] [8]. additionally, national law no. 20,257 was also enacted, which states that non-conventional renewable energy sources must generate 10% of the energy by 2024 [9]. notably, the residential sector has sustainable construction standards [10] [11] [12], according to the handbook of housing energy qualification [13] and the general law of urbanism and constructions of chile [14]. as a result, there is a need to innovate in this area, creating a methodology that allows selecting windows with energy efficiency criteria. ii. methodology a. study areas three research areas are involved in the study development, namely laws and standards, market research and technical characteristics. the investigative process is detailed in fig. 1. 1. laws and norms first, all information on national laws and regulations related to window selection was collected, as well as additional information, such as manuals and proposed standards — notably, the general ordinance of urban planning and construction [15]. http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 9 on the other hand, the thermal zones of the cities of chile, they were defined by maps proposed by minvu [16]. alternatively, the minvu update on the communes that have the air decontamination program was incorporated [17] [18]. also, there is complementary information associated with sustainable construction standards [10] [11] [12] according to the handbook of housing energy qualification [13], and climate explorer [19]. after searching for the applicable legal and regulatory information, the parameters for the methodology were established and defined. those parameters are necessary to generate an algorithm that allows simulations of different window configurations. fig .1 flowchart to obtain the methodology for the selection of windows with energy efficiency. 2. market study at this point, the market window that includes recurring characterization patterns in different types of windows available. however, the windows present technical information and tests. these are fully available to be selected by the methodology database to ensure effectiveness during implementation. these involve the articles consulted from minvu [20] [21], as well as suppliers [22]. moreover, it includes a sample of twenty-eight windows, with all the relevant information. subsequently, the windows are added to the methodology and three types are defined; bringing down, sliding and projecting. each of them has a subdivision according to the frame and thermal background. regarding the chilean window market, it is correct to affirm that investments in the real estate sector have been in a constant growth throughout the years [23] [24] producing an increase in the demand for windows. however, the products with the most significant presence in the market are aluminium and pvc. the first is the most frequent for having a lower manufacturing cost, for the number of companies that distribute it and for its age in the market. on the other hand, pvc has only been gaining ground until recently, since public policies use it as a baseline for all their projects in order to generate energy savings in homes, lower maintenance costs, better acoustics [25]. the market distribution is represented by fig. 2, that reflects an approximation of the growth of both over the years. window type amount of money in the window industry per year (m / usd) 2017 2018 2019 aluminium 120,5 126,5 131,5 pvc 31,6 31,0 32,8 total (m / usd) 152,1 157,5 164,3 fig .2 amount of money in the window industry per year. characteristics window type aluminium pvc corrosion resistance high high electrochemical corrosion risk low null vulnerability to thermal bridges half low vulnerability to cuts or scratches half low degradation by saline environment half null risk of condensation inside low null difficulty cleaning low low window weight low high maintenance half low fig .3 factors influencing both durability and window maintenance. on the other hand, the acquisition of a window brings with it a subsequent installation. under this circumstance, the chilean market generally delivers a price to the buyer that includes the installation value. the latter may vary due to the dimensions of the window and the distance or location of the destination. however, the type of window material does not influence this cost, in other words, that a window made up of one material or another will not increase or decrease the installation value. methodology for window selection with energy efficiency criteria in chile laws and norms algorithm development market study typologies to use technical characteristics parameter definition http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 10 nevertheless, in the stage of exploitation or use of the window, there are economic differences related to the material composition. since the durability and maintenance are not the same in all cases, as shown in fig. 3. for this reason, has been used the two most recurring window compositions, aluminium and pvc, have been used to identify the variables that can influence the maintenance costs, as well also as in the useful life of them [26]. the latter being an essential factor in determining when to make a replacement. 3. technical characteristics the methodology explicitly uses the following types of variables; region, commune, thermal zone, facade surface according to orientation, frame material, window type and thermal transmittance (u) [27] [28] [29] [30]. all of these options allow recreating the conditions of the home better. after entering the information, there is an optimal solution for our case through a technical file, which implicitly contains information such as; glass-framed ratio, glass thickness, inner chamber space, the filling inside the chamber, the rail thickness and air permeability [31] [32]. in summary, have to adjust the data at the beginning, to later know in detail the characteristics of windows. additionally, a graphic representation of them allows the user to use as a means for the quotation, manufacture, and implementation of the windows. all this information ensures a correct and quick selection of windows for the case in question. b. methodology of the verification process according to fig. 4, the simulation considers housing in different climatic zones (antofagasta, santiago, concepción) to which improvements are subsequently implemented in its windows. it is important to note that energy demand is calculated based on passive systems and does not include equipment (no hvac). however, the hap program [33] was used to simulate housing, which uses ashrae std. 62.1 2010 [34], ashrae std. 90.1 2010 [35] and leed 2009 [36] as a regulatory framework. fig .4 flowchart to obtain case analysis. 1. characteristics of base cases the base cases are made up of the technical specifications exemplified in figs. 5, 6 and 7. fig .5 general architecture plant for base cases. simulation n°2simulation n°1start base case case of antofagasta solution n°1 solution n°2 case of santiago solution n°1 solution n°2 case of concepción solution n°1 solution n°2 http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 11 city element high (ft) surface (ft2) u (btu/hr/ft2/f) a n to fa g a s ta facade n 7,55 304,62 0,29 facade s 7,55 292,78 0,29 facade e 7,55 248,65 0,29 facade w 7,55 249,72 0,29 roof 1337,95 0,06 floor 0,49 1145,28 0,52 s a n ti a g o facade n 7,55 304,62 0,29 facade s 7,55 292,78 0,29 facade e 7,55 248,65 0,29 facade w 7,55 249,72 0,29 roof 1337,95 0,06 floor 0,49 1145,28 0,52 c o n c e p c ió n facade n 7,55 304,62 0,29 facade s 7,55 292,78 0,29 facade e 7,55 248,65 0,29 facade w 7,55 249,72 0,29 roof 1337,95 0,06 floor 0,49 1145,28 0,52 fig .6 structural elements of the base cases. city element high (ft) width (ft) surface (ft2) u (btu/hr/ft2/f) a n to fa g a s ta p1 6,6 2,8 18,3 0.32 v1 5,2 5,2 27,6 1,02 v2 1,6 1,6 2,7 0,53 s a n ti a g o p1 6,6 2,8 18,3 0.32 v1 5,2 5,2 27,6 1,02 v2 1,6 1,6 2,7 0,53 c o n c e p c ió n p1 6,6 2,8 18,3 0.32 v1 5,2 5,2 27,6 1,02 v2 1,6 1,6 2,7 0,53 fig .7 non-structural elements of the base cases. 2. characteristics of the solutions to simulate the solutions for the simulations appear from replacing the initial windows v1 with others with better performance, through the methodology. as a summary of the improvement selection process, figs. 8 and 9 show all the information necessary to prepare the simulations. city solution n°1 window v1 frame type window opening surface (ft2) u (btu/hr/ft2/f) antofagasta aluminium sidehung 19,4 0,63 santiago aluminium sliding 17,8 0,63 concepción aluminium sliding 12,9 0,63 fig .8 summary of solutions no. 1 to simulate. city solution n°2 window v1 frame type window opening surface (ft2) u (btu/hr/ft2/f) antofagasta pvc side-hung 19,4 0,53 santiago pvc sliding 24,2 0,42 concepción pvc sliding 12,9 0,28 fig .9 summary of solutions no. 2 to simulate. iii. results figure 10 shows the cooling or heating energy required by a window v1. indicating that the cities of antofagasta and concepción have cooling gains with their negative statistics. this is not the case in santiago, whose values show an additional demand for it. as for heating, all windows require other energy input. the window that achieved the best performance was the solution n ° 2 in the city of concepción. since it has a favourable contribution of cooling energy (16 btu / hr) and its heating demand is the lowest (126 btu / hr). figs 11 and 12 indicate the amount of variation and heating energy required by the total windows of the house in comparison with the total area of these houses. in particular, the heating demand values are much higher than the cooling figures, with a difference between them that ranges 87 % and 93 %. on the other hand, the window that obtained better performance in both graphics. is the s2 solution in the city of santiago because it has the smallest reduction in surface area, 11% compared to the base case. also, it manages to reduce the cooling and heating needs by 64% concerning its base case. http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 12 figs 13 and 14 it show the heat that flows per unit of time and surface area (u) in the windows compared to the total demand for cooling or heating energy of the house. the cooling demand values are much higher than those required for heating as there is having a difference between them that ranges between 70% and 86%. moreover, the city that presented the most significant energy demands was that of santiago — reaching differences of up to 9% in cooling and 56% in heating. however, the city that shows the lowest energy savings is antofagasta, decreasing only 1.5% in cooling and having a maximum of 9% in heating. in comparison, the city that achieved the best energy performance was the city of concepcion with solution s2 since it managed to reduce cooling energy by 3% and 12% for heating. fig. 10. cooling vs heating energy required by a v1 window. fig. 11. total surface of the v1 windows vs energy supply for cooling them. s.a.b s.a1 s.a2 s.s.b s.s1 s.s2 s.c.b s.c1 s.c2 cooling trans -38 -16 -14 166 66 60 -127 -37 -16 heating trans 560 244 205 1,148 458 417 980 284 126 -200 0 200 400 600 800 1,000 1,200 1,400 b t u /h r s.a.b s.a1 s.a2 s.s.b s.s1 s.s2 s.c.b s.c1 s.c2 ft2 81 57 57 81 54 72 81 39 39 desing cooling -114 -48 -42 498 198 180 -381 -111 -48 -500 -400 -300 -200 -100 0 100 200 300 400 500 600 0 10 20 30 40 50 60 70 80 90 b t u /h r ft 2 http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 13 fig. 12. total surface of the windows v1 vs energy supply for heating them. fig. 13. thermal transmittance of the window (u) vs total energy demand for cooling. fig. 14. thermal transmittance of the window (u) vs total energy demand for heating. s.a.b s.a1 s.a2 s.s.b s.s1 s.s2 s.c.b s.c1 s.c2 ft2 81 57 57 81 54 72 81 39 39 desing heating 1,680 732 615 3,444 1,374 1,251 2,940 852 378 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 0 10 20 30 40 50 60 70 80 90 b t u /h r ft 2 s.a.b s.a1 s.a2 s.s.b s.s1 s.s2 s.c.b s.c1 s.c2 total desing cooling 67,489 66,481 66,488 69,523 67,856 68,317 65,567 63,527 63,588 u 1.02 0.63 0.53 1.02 0.63 0.42 1.02 0.63 0.22 0.00 0.20 0.40 0.60 0.80 1.00 1.20 60,000 61,000 62,000 63,000 64,000 65,000 66,000 67,000 68,000 69,000 70,000 u = b t u /h r/ ft 2 /f b t u /h r s.a.b s.a1 s.a2 s.s.b s.s1 s.s2 s.c.b s.c1 s.c2 total desing heating 10,227 9,422 9,306 20,964 19,248 18,889 17,897 16,262 15,789 u 1.02 0.63 0.53 1.02 0.63 0.42 1.02 0.63 0.22 0.00 0.20 0.40 0.60 0.80 1.00 1.20 0 5,000 10,000 15,000 20,000 25,000 u = b t u /h r/ ft 2 /f b t u /h r http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 14 iv. conclusion after evaluating the passive energy performance of homes, it is concluded that the highest energy demands were recorded in cooling and they were much higher than those required for heating. as a result, the double airtight glass allows reducing the solar gain but fails to eliminate overheating in hightemperature seasons. other relevant data provided by the simulations correspond to the relationship between the thermal transmittance (u) of the windows and the total energy demand of the house (btu / hr). specifically, when using windows with small values of u in geographic areas where high temperatures prevail, great energy and economic performance are not obtained. radiation control measures are more practical to combat these situations. in geographical areas where low temperatures are recurrent, the strategy is of using very high-quality windows is not always viable. that is to say, using thermal transmittance values that are very low or close to 1.0 btu / hr / ft2 / f. together with decreasing their dimensions, they singularly favour the heating demand reduction. however, this situation is not entirely profitable because the natural light surface is lost, and the implementation costs are too high. in temperate climates, it is where the correct selection of the windows has a higher incidence. because, if windows with u values ranging between 2.0 and 3.0 btu / hr / ft2 / f are used, a considerable reduction in the energy demands of the house is obtained, with a reasonable implementation cost. for example, in cold months, the solar radiation decreases, allowing the double airtight glass to limit heat transfers between the interior and exterior of homes in addition to avoiding condensation in the interior glass. in contrast, in months of high temperatures, the same windows allow cooling through cross ventilation caused by opening them. in the case of having a ventilation, heating and air conditioning system (hvac) the windows with the indicated characteristics allow encapsulating or retaining the comfortable temperature inside the enclosure, avoiding energy loss. in general, it is confirmed that windows with lower thermal transmittance (u) achieve better energy performance in homes. however, the selection of optimal windows for a project should always be based on the geographical area, the orientation of the facade or wall, the surface of light or visibility to be projected (dimensions) and the values of thermal transmittance (u). for example, the simulations showed that the s2 solution obtained a better performance of energy efficiency in the three cities mainly because it had u figures and slightly smaller surfaces than the s1 option. as for the users of homes in chile and around the world, the following inferred; usually, they do not know the energy demand of homes, much less about the selection of doors or windows with excellent performance. because these responsibilities transferred to government authorities, this means that it is the governments that generate the energy efficiency and sustainability strategies, according to the political, social and economic reality that they live. however, the difference is that europe, unlike chile, has more experience and track record on this issue. instead, chile is in the process of transition, since its policies and regulations are recent or in the development stage. about the above and the evidence collected, it is possible to affirm that this methodology can effectively provide support to users, allowing them to know when it is profitable to change their windows for one that has a better performance. on the other hand, the implementation of this in the design stage allows knowing the cost and benefit relationship that exists between the windows, a critical factor in projects where resources are minimal, such as social projects. furthermore, it favours the country's energy transition process in a transversal manner. in other words, it involves all the stages of a project; design, construction, operation and demolition or replacement in this case. it can be implemented free of charge, with high possibilities of application in the market and with national coverage. however, the successful integration of this in the field depends on the improvement of the current legal and technical framework that surrounds it, a modest initial investment, additionally a process of information and standardization of the market. v. acknowledgments dr. david blanco and danny lobos supervised this research at universidad tecnológica metropolitana de http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 15 chile under a master's project from the school of engineering. references [1] oecd and united nations economic commission for latin america and the caribbean, “oecd environmental performance reviews: chile 2016”, secretary-general of the oecd, paris, 2016. 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[37] g. p. f. c. p. r. p. andrea gasparellaa, “analysis and modelling of window and glazing systems energy performance for a well insulated residential building,” energy and buildings, 43 (4), pp. 1030-1037, 2011. http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 https://f7b235ff-bd9f-430d-b656-612f8b4c3881.filesusr.com/ugd/2f1e74_c54089853e234e759fbc0c5a4dd8d239.pdf https://f7b235ff-bd9f-430d-b656-612f8b4c3881.filesusr.com/ugd/2f1e74_c54089853e234e759fbc0c5a4dd8d239.pdf https://f7b235ff-bd9f-430d-b656-612f8b4c3881.filesusr.com/ugd/2f1e74_c54089853e234e759fbc0c5a4dd8d239.pdf https://clavelocal.com/ventajas-e-inconvenientes-de-las-ventanas-de-pvc-y-aluminio/ https://clavelocal.com/ventajas-e-inconvenientes-de-las-ventanas-de-pvc-y-aluminio/ https://clavelocal.com/ventajas-e-inconvenientes-de-las-ventanas-de-pvc-y-aluminio/ https://www.carrier.com/commercial/en/us/software/hvac-system-design/hourly-analysis-program/ https://www.carrier.com/commercial/en/us/software/hvac-system-design/hourly-analysis-program/ https://www.carrier.com/commercial/en/us/software/hvac-system-design/hourly-analysis-program/ journal of renewable energy and sustainable development (resd) volume 6, issue 1, june 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.1.008 17 [38] o. aydın, “conjugate heat transfer analysis of double pane windows,” building and environment, 41 (2), pp. 109-116, 2006. 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[42] a. a. castaño, wind seal distribuidora de perfiles de aluminio, santiago: universidad de chile, 2015. http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.1.008 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.080 80 resd © 2019 http://apc.aast.edu natural gas pre-feasibility study for future lng importing terminal project in morocco 1 firdaous el ghazi, 2 moulay brahim sedra, 3 mahmoud akdi 1 simolab, ibn tofail university, kenitra, morocco, 2 fste, umi moulay ismail university of meknes, morocco, 3 simolab, ibn tofail university, kenitra, morocco, 1elghazi.firdaous@gmail.com, 2 mysedra@yahoo.fr, 3 makerase@gmail.com abstract in recent years, energy debates are increasingly focused on the transition of more ecological energy sources, therefore, morocco is projecting to invest in its first liquified natural gas (lng) importing and storage capacity by 2030. this article comes to establish a pre-feasibility study for the future importation terminal and the objective is to develop a scientific approach to investigate the financial viability of such a project. the main challenge poses on the data estimation methodology and the relevance of the assumptions. besides, the level of uncertainty depends on the stability of the lng international market. the profitability of an investment is generally the most important criterion for the decision-making. even if the combined ecological and industrial benefits of natural gas can sometimes provide enough motivation to invest, a long-term profitability study must be systematically pursued to evaluate the economic impact of such an investment decision. after highlighting the multiple benefits of natural gas, the first step is setting up the financial model to be adopted, which is in this case the net present value (npv) and the discounted payback. therefore, operating and financial assumptions are made based on the benchmark with other similar projects. the prefeasibility study will help to measure the lng terminal capacity to generate revenue. keywords capex, cash flow, discounted payback, gnl, net present value, opex, prefeasibility, profitability.. i. introduction global warming is a phenomenon known and recognized by scientists such as climate change and its adverse effects on the environment [1]. the history of energy between massive pollutions, nuclear disasters, energy resources scarcity and global environmental issues indicates the limitation of the current energy system and calls for a gradual shift towards a sustainable energy mix. the global energetic context makes lng an attractive alternative for electric and industrial generating units that currently run on other polluting, more expensive, and less suitable fuels. as a result, morocco has set itself the goal of building an lng import and storage terminal at jorf lasfar by 2030. in tune with developing a terminal site location and an optimum routing alternative for pipelines [2], this article comes as a follow up to conduct a pre-feasibility study for the future lng importation terminal. the reorientation of energy to lng is a considerable step towards this objective. it is a source of clean energy that translates a strong commitment to: • replace the use of coal and harmful fuels in electricity production. • prepare a favorable economy that can be combined with renewable sources, particularly solar. • contribute to the development of energy efficiency. some countries, particularly morocco, do not dispose of natural gas in their soil. in this case, their commitment is illustrated by an investment decision on lng importing terminal. in the current economic environment, this decision is a decisive step that guides the national strategy. ii. choice of natural gas the development of natural gas is driven not only by its availability as a resource, but also by its preference by consumers. indeed, natural gas has several advantages and combines reliability, availability, cleanliness and safety as compared to nuclear energy. http://dx.doi.org/10.21622/resd.2019.05.2.080 mailto:1mohamed_bekhet@eng.asu.edu.eg journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.080 81 resd © 2019 http://apc.aast.edu a. ecological benefits compared to other fossil fuels, natural gas is considered by excellence the cleanest source of energy; its emissions of sulfur dioxide (so2), carbon dioxide (co2) and nitrous oxide are low compared to coal or oil [3]. in fact, a recent greenpeace study, published in august 2019 and based on data from nasa [4], warns morocco against the risks of air pollution due to the use of coal. fig .1 nasa capture of so2 hot spot, showcasing morocco, 2019 [4] the environmental qualities of natural gas largely justify the growth of its demand. with its high hydrogen content, its combustion is considered perfect and does not produce heavy unburnt. b. industrial benefits natural gas continues to attract electric power plants and industrials because of its simple hydrocarbon composition (mainly methane) [5] whose use offers several advantages: • pure and perfect combustion: immediate and total flammability. • quality and precision of the flame: possibility of reaching very high combustion temperatures. • cleanliness: no emission of heavy polluting particles. • low maintenance: natural gas is not corrosive, it does not damage pipelines. • safety: restricted range of flammability. c. economic benefits the discovery and exploitation of natural gas is relatively newer than many other types of energy, hence its technology is naturally subject to several research development and technical progress. the entire chain of lng, from exploration and drilling to end use, continues to gain efficiency and effectiveness. the moroccan global context makes lng an attractive alternative for sectors currently running on other fossil fuels [6]. the lng price competitiveness and the increasing number of stakeholders are only pulling its operating costs down, making it more and more attractive. iii. financial and profitability criteria the investment decision is one of the strategic and irreversible decisions that engage resources in the long term. to evaluate the profitability of an investment and decide whether it should be retained, several methods can be used such as the net present value (npv) and the payback method. these indicators rely on the estimated cash flows generated in a future environment. the application of these financial techniques to evaluate the profitability of an investment is limited by the difficulty of modeling an economic reality of a distant and random market into a financial equation. admittedly, the financial model of npv is the most appropriate approach to decision making. a. net present value in order to know if a given project is financially acceptable, the decision criterion considered is the npv. like any investment, the construction of an lng terminal requires an investment period, an operating period, and a projected profitability that corresponds to the cash flows generated during the operating period. thus, it is essential to estimate the following elements: • capital required for investment: the amount of funds necessary to conduct the project. • the lifetime of the project: the operational period of the project or its useful life. • the discount rate: the anticipated return of profit for a project which presents a similar risk, also called the cost of the invested capital. http://dx.doi.org/10.21622/resd.2019.05.2.046 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.080 82 resd © 2019 http://apc.aast.edu • the annual cash flows: the remaining profit after revaluating the project’s revenues and expenses. the npv is the difference between the investment and the annual project discounted cash flows. the discount rate corresponds to the required minimum rate of profit. a positive npv indicates that the project is profitable, which means that the cash flows generated make it possible to reimburse the initial investments and generate added value npv = -i0 + ∑ 𝐶𝐹𝑖 (1+𝑡)𝑖 𝑛 𝑖=1 (1) with: i: a year in the project lifetime. i0: initial investment. cfi: cash flow generated during the operating year i. n: project lifetime. t: discount rate. the discount rate is the cost of capital given its composition and the risk of the investment, assuming a discount rate of 9% [7]. b. discounted payback to deepen the analysis, the evolution of the project payback is calculated according to the annual cash flow performed. the payback is the time needed to recover the amount of the investment. this criterion allows to focus on projects quickly amortized, it is defined as the time required to recover the initial investment through cash inflows. this duration corresponds to the value of n for npv = 0. iv. model description and assumptions the investment required to carry out an industrial project of such a large size occupies an important place in the strategic launch decision. the profitability of an investment is completely determined when these two elements are known or at least can be accurately estimated: the amount of the investment also called capital expenditures (capex) and the operating expenses (opex). a. capex inventory several factors can influence the cost of building a terminal, feedback has shown that one of the most important factors is the quality of site environment, which can require some additional investments to limit and contain potential risks [8]. on the other hand, lng storage tanks are generally the most expensive element of a storage terminal. they are also very often the most critical element because of the large surface area they claim, their visual impact that is often deemed unacceptable by the surrounding residents, and their potential risks if poorly managed. 1. lng storage tanks an lng storage tank is particular and different from a hydrocarbon storage tank and has several challenges due to the specifications of the stored product, such as: • the storage tank is intended to contain both vapor and liquid phases of natural gas. • the storage tank must be insulated to minimize heat ingress. the overall storage capacity of the site must meet the projected lng consumption needs assessed by the ministry of energy as follows [9]: table 1 first year annual volume of imported natural gas [9]. year 1 (volume in k m3) volume gas to power 3 500 000 volume gas to industry 1 500 000 total volume 5 000 000 according to the high commission for planning and considering an average growth of electricity consumption of 6% and an economic growth of 3% [10], the 20-year site import forecasts are as follows: http://dx.doi.org/10.21622/resd.2019.05.2.080 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.080 83 resd © 2019 http://apc.aast.edu table 2 lng importing volumes projections. year 1 year 2 year 3 year 4 year 5 year 6 year 7 year 8 year 9 year 10 electricity growth % 5% 5% 5% 5% 5% 5% 5% 5% 5% volume gas to power (k m3) 3 500 000 3 675 000 3 858 750 4 051 688 4 254 272 4 466 985 4 690 335 4 924 851 5 171 094 5 429 649 economic market growth % 3% 3% 3% 3% 3% 3% 3% 3% 3% volume gas to industry (k m3) 1 500 000 1 545 000 1 591 350 1 639 091 1 688 263 1 738 911 1 791 078 1 844 811 1 900 155 1 957 160 total volume (k m3) 5 000 000 5 220 000 5 450 100 5 690 778 5 942 535 6 205 897 6 481 413 6 769 662 7 071 249 7 386 809 year 11 year 12 year 13 year 14 year 15 year 16 year 17 year 18 year 19 year 20 electricity growth % 5% 5% 5% 5% 5% 5% 5% 5% 5% 5% volume gas to power (k m3) 5 701 131 5 986 188 6 285 497 6 599 772 6 929 761 7 276 249 7 640 061 8 022 064 8 423 167 8 844 326 economic market growth % 3% 3% 3% 3% 3% 3% 3% 3% 3% 3% volume gas to industry (k m3) 2 015 875 2 076 351 2 138 641 2 202 801 2 268 885 2 336 951 2 407 060 2 479 271 2 553 650 2 630 259 total volume (k m3) 7 717 006 8 062 539 8 424 138 8 802 573 9 198 645 9 613 200 10 047 121 10 501 336 10 976 817 11 474 585 table 3 supply frequency per year. year 1 year 2 year 3 year 4 year 5 year 6 year 7 year 8 year 9 year 10 liquid gnl volume (km3) 8 333 8 700 9 084 9 485 9 904 10 343 10 802 11 283 11 785 12 311 supply frenquency per year 23 24 25 26 28 29 30 31 33 34 year 11 year 12 year 13 year 14 year 15 year 16 year 17 year 18 year 19 year 20 liquid gnl volume (km3) 12 862 13 438 14 040 14 671 15 331 16 022 16 745 17 502 18 295 19 124 supply frenquency per year 36 37 39 41 43 45 47 49 51 53 the sizing of the storage must allow the reception of the projected volumes and shall also guarantee flexibility in the case of a significant increase of the volumes. natural gas is imported in the liquid phase and occupies 1/600 of its volume [11]. thus, storage must be correctly sized to meet current and future forecast needs. given the many advantages of having multiple storage tanks, the breakdown of the storage would be as follows: table 4 breakdown of the total storage capacity. tank diameter (m) 80 tank height (m) 12 one tank capacity (m3) 60 288 global capacity 6 tanks (m3) 361 728 with useful capacity of the importation terminal estimated at 360 000 m³, the supply frequency starts first with 2 importations per month and reaches on the 20th year 4 importations per month. thus, the possibility of extending the storage remains possible. this storage capacity allows a good flexibility in cargos importation, two or three storage tanks can be used as principal linking distribution sources with the regasification process and the natural gas pipelines. using an average density of lng of 445 kg / m³ and assuming $274/ton as the average world costs [12] for storage tanks, the capex is: http://dx.doi.org/10.21622/resd.2019.05.2.046 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.080 84 resd © 2019 http://apc.aast.edu table 5 storage capex estimation. capacity in m3 density in kg / m³ capacity in ton average cost $/t capex in $ 360 000 445 808 989 274 221 662 921 2. lng storage tanks the cost of the pipeline, on the other hand, can weigh heavily in the project investment amount. its cost depends on several parameters of which are mainly the type, the diameter and the length of the pipeline, the cost of the steel, the nature of the environment and the ground quality of its crossing. assuming that the location of the importation terminal is in jorf lasfar and given the optimum pipeline routing, distance is calculated in the article “study of site location and pipeline routing for future natural gas importing terminal project in morocco” [2]. the shortest distance from jorf lasfar linking all consumption points including the furthest power station is 490 km. given that the investment reference announced for 5660 km of the nigeria morocco pipeline project is estimated at 20 to 50 billion dollars [13] and considering the same pipeline characteristics for 490 km portion of the proposed routing, the pipeline investment can be roughly estimated at 1,8 to 4,5 billion dollars. in order to estimate pipeline cost more accurately, several methods exist. the first is to launch a consultation procedure through a business consultation file; this approach makes it possible to acquire prices closest to the reality of the local market. nevertheless, this approach is time consuming and is only applied at advanced stages of the project. on the other hand, a scientific formula developed by experts in this field can lead to a reliable estimation of the costs. it is a method developed by menon, e._shashi [14]: eq (2) 𝑝ipeline 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙 𝑐𝑜𝑠𝑡 ($) = 0,02463×(𝐷−t) ×l×t×(𝑐𝑝𝑡) with: l: length of the pipe, km d: outside diameter of the pipe, mm t: thickness of the pipe wall cpt: pipe cost, $ / ton considering the american petroleum standard (api spec 5l, iso 3183), based on the united metallurgical company and the pipeline safety trust, the type of steel commonly used in natural gas pipeline construction, [15], the corresponding characteristic is: l = 490 km d = 40 ‘’ t = 9,5 mm 236 kg/ml cpt = 800 $ / ton applying the formula, the estimated capex for pipeline is: 𝑃𝑖𝑝𝑒 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙 𝑐𝑜𝑠𝑡 ($) =0,02463×(𝐷−t) ×l×t×(𝑐𝑝𝑡) = 2 211 352 728 $ many other aspects must be added to the pipeline investment such as: pipeline external coating and wrapping [14] are estimated at 5$ per foot, therefore: pipe coating and wrapping cost = 50 × 0,3048 × 490 000 = 7 467 600 $ compressor station costs [14]: as the gas travels in the pipeline from high pressure areas to low pressure areas, it would be necessity to provide compressor stations which increase the internal pressure at regular intervals along the pipeline. using an installed cost of 2 000$ per compressor station and given that there must a compressor station every 20 km, the: compressor station costs = 2000 × 25 = 50 000 $ scada and telecommunication systems [14], which correspond to the necessary automation and remote monitoring of the pipeline. scada system costs include facilities for monitoring, operating and remote control of the pipeline from a central control center. they are estimated as a percentage of the total project cost from 2% to 5%. environmental and permitting [14]: due to stricter environmental and regulatory requirements, this category includes elements such as environmental impact reports, environmental studies of sensitive areas such as industrial sites and habitat areas. authorization costs would include pipeline construction permits such as crossings of roads and railways. costs related to the environment and authorizations can range between 10% and 15% of total project costs. http://dx.doi.org/10.21622/resd.2019.05.2.080 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.080 85 resd © 2019 http://apc.aast.edu other project costs [14] can cover unforeseen circumstances and design changes, including small diversions to bypass sensitive areas and modifications of facilities not originally planned at the beginning of the project. these costs can represent between 15% and 20% of the total cost of the project. table 6 pipeline cost estimation breakdown. pipe material $2 211 352 728 coating and wrapping $7 467 600 min max scada and telecommunication (2% to 5% of total cost) $60 789 598 $184 901 694 environmental and permitting (10% to 15% of total cost) $303 947 990 $554 705 082 other project costs (15% to 20% of total cost) $455 921 985 $739 606 776 total pipeline cost ($) $3 039 479 902 $3 698 033 881 thus, the global estimated pipeline cost is between 3 billion and 3,6 billion $. it is important to record that the pipeline capex is estimated to extend all capex aspects but cannot be part of the profitability study itself. in fact, the scope of financial study is restricted in this article to the lng importation terminal. b. capex inventory capex estimation is a very important step as every site is specific in terms of capital cost. in general, considering the scope of the terminal alone, the storage tank represents the most important investment after the applicable maritime and process environment such as pump out and vaporizing process. based on the cost allocation for some similar lng terminals conducted in a similar environment [16], the total capex of the terminal is: table 7 capex distribution of the importing terminal. cost distribution capex in $ jetty, topwork, trestle 10% 108 679 393 lng storage 21% 221 662 921 vaporizing, boil-off handling, pump out 39% 418 577 070 utilities, offsites, fire and safety 19% 199 066 216 allowance for land 3% 27 976 874 owner's project management team 4% 43 041 344 allowance for port and break water 5% 57 029 781 total capex ($) 100% 1 076 033 599 regasification itself represents 39% of the total cost of the project. the port equipment and lng tanks are taking the large portion of the investments, with very large disparities related to site conditions. excluding the pipeline, the total capex of the lng importing terminal is estimated at 1 076 033,5 k$. c. operating expenses the specificity of the lng market makes it difficult to estimate the operating expenses. the quantity imported depends on the national future consumption as the purchase prices and sales are very volatile. however, their trend is unpredictable and depends on several variables: currency rate, geopolitical stability, purchase contract or spot purchase, ocean freight, supplier countries, price indexation, etc. the operation costs of an importation terminal are generally made up of the following items: • personnel cost and salaries: it is important to provide an organizational chart, with the estimated human resources and shifts. the wages are in general subject to variation depending on regions. • maintenance cost including corrective and preventive maintenance. • supply reception costs dedicated to lng harbor and cargoes reception. • operating energy consumption. based on the opex data for some similar lng terminals [16], the first year opex is estimated at 2,5% of the project capex, the statistical distribution is then applied to recover the opex items: http://dx.doi.org/10.21622/resd.2019.05.2.046 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.080 86 resd © 2019 http://apc.aast.edu table 8 lng terminal opex distribution cost distribution opex in $ personnel salaries and/or wages 22% 6 033 833 plant maintenance 26% 7 039 472 marine operations maintenance 37% 10 056 389 energy consumption 14% 3 771 146 total first year opex (2,5% of capex) 100% 26 900 840 once the capex and opex are estimated, the profitability study can be perused. v. profitability of the lng project it is nearly impossible to speculate on the evolution of natural gas prices; therefore, a pricing reference is necessary to simulate the production and distribution margin. considering the fluctuation in natural gas prices and according to the national lng law project, gas pricing will be regulated [9]. the prices hypothesis are based on the study on lng prices of the belgian market, published in 2018 [17], the belgium market has many similarities with the med europe quotation market, therefore, the main hypothesis is as follows: natural gas calorific power = 10,83 kw/kg [18] average import price = 14 €/mwh [17] resale to power plants = 17 €/mwh [17] resale price to industrial consumers = 18,9 €/mwh [17] exchange rate 1 € = 1,1 $ a profitability analysis is carried out for the project considering all these factors during a 20 years lifetime. this life expectancy does not reflect the life of lng terminal, but it is an economic life that can be used to evaluate the profitability of the project in the short/medium term. the longer the considered lifetime is, the more uncertain data are collected. the financial calculation makes it possible to express the benefits of lng terminal in monetary terms (profits) by comparing the revenues with the expenses while considering the monetary value of the time (by means of a discount rate). therefore: the net present value (npv) = -i0 + ∑ 𝐶𝐹𝑖 (1+𝑡)𝑖 𝑛 𝑖=1 npv = -176 563 k$ < 0 the project is financially not profitable. other financial indicators can be calculated to help us interpret profitability such as profitability index (pi) and internal rate of return (irr). the profitability index is: 𝐹𝑢𝑡𝑢𝑟𝑒 𝐶𝑎𝑠ℎ 𝐹𝑙𝑜𝑤𝑠 𝐼𝑛𝑖𝑡𝑖𝑎𝑙 𝐼𝑛𝑣𝑒𝑠𝑡𝑚𝑒𝑛𝑡 = 1,29 the internal rate of return is the discount rate that makes the net present value (npv) equal to zero. npv = -i0 + ∑ 𝐶𝐹𝑖 (1+𝐼𝑅𝑅)𝑖 𝑛 𝑖=1 = 0 therefore, irr= 7% the discounted payback period is estimated at 12 year of operation, given a 9% discount rate. fig .2 lng terminal cash flow and discounted payback . a 12-year payback means that the cash flows generated by lng terminal is starting to recover the original investment from the 12th year of operation. it is important to point out that the cost of the distribution pipeline is not included, given the fact that the original pipeline is coming from nigeria through many other countries, who can be participating in financing the pipeline. [2] -1,250,000 -1,000,000 -750,000 -500,000 -250,000 0 250,000 500,000 750,000 1,000,000 1,250,000 1,500,000 in ve st m e n t y e a r 1 y e a r 2 y e a r 3 y e a r 4 y e a r 5 y e a r 6 y e a r 7 y e a r 8 y e a r 9 y e a r 1 0 y e a r 1 1 y e a r 1 2 y e a r 1 3 y e a r 1 4 y e a r 1 5 y e a r 1 6 y e a r 1 7 y e a r 1 8 y e a r 1 9 y e a r 2 0 cumulative cash flow (k$) http://dx.doi.org/10.21622/resd.2019.05.2.080 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.080 87 resd © 2019 http://apc.aast.edu table 9 lng terminal profitability . vi. conclusions an investment in a national lng importing terminal is an important decision requiring a huge investment. after assimilating at first the other non-financial benefits of natural gas, a financial model description and lng market hypothesis were considered and exposed in order to provide a reliable pre-feasibility study regarding the available data now for the moroccan market. at this stage of the project, accuracy of these estimates is believed to be +/-40%. the conducted financial study shows that the project is not profitable within 20 years lifetime, but has estimated payback of 12 years of operation, excluding the pipeline investment. the npv is negative and the irr (7%) is inferior to the discount rate (9%), which reflects that, mathematically, this project will not be profitable enough even after 20 years of operating. these results justify the fact that the profitability of this kind of investment requires government encouragement through subsidies and tax reduction. the environmental qualities of natural gas largely justify the conduction of this project. with its high hydrogen content, gas combustion is considered perfect and does not produce heavy unburnt harmful particles for environment or health. given the tax investment year 1 year 2 year 3 year 4 year 5 year 6 year 7 year 8 year 9 year 10 total capex (k$) -1 076 034 gas to power volume (km3) 3 500 000 3 675 000 3 858 750 4 051 688 4 254 272 4 466 985 4 690 335 4 924 851 5 171 094 5 429 649 gas to industry volume (km3 1 500 000 1 545 000 1 591 350 1 639 091 1 688 263 1 738 911 1 791 078 1 844 811 1 900 155 1 957 160 total gas volume (km3) 5 000 000 5 220 000 5 450 100 5 690 778 5 942 535 6 205 897 6 481 413 6 769 662 7 071 249 7 386 809 operating and distribution margin (k$) resale to power plants (k$) 315 426 331 198 347 758 365 146 383 403 402 573 422 702 443 837 466 029 489 330 resale price to industrial consumers (k$) 151 087 155 619 160 288 165 096 170 049 175 151 180 405 185 817 191 392 197 134 total operating income (k$) 466 513 486 817 508 045 530 242 553 452 577 724 603 107 629 654 657 421 686 464 operating charges (k$) average import price (k$) -371 090 -387 418 -404 495 -422 358 -441 043 -460 589 -481 037 -502 431 -524 814 -548 234 opex k$ (2% inflation) -26 901 -27 439 -27 988 -28 547 -29 118 -29 701 -30 295 -30 901 -31 519 -32 149 total terminal charges (k$) -397 991 -414 857 -432 483 -450 905 -470 161 -490 290 -511 332 -533 331 -556 333 -580 383 net cash flow (k$) -1 076 034 68 522 71 960 75 562 79 336 83 291 87 434 91 775 96 323 101 088 106 081 cumulative cash flow (k$) -1 076 034 -1 007 511 -935 551 -859 989 -780 652 -697 361 -609 927 -518 153 -421 830 -320 742 -214 661 year 11 year 12 year 13 year 14 year 15 year 16 year 17 year 18 year 19 year 20 total capex (k$) gas to power volume (km3) 5 701 131 5 986 188 6 285 497 6 599 772 6 929 761 7 276 249 7 640 061 8 022 064 8 423 167 8 844 326 gas to industry volume (km3 2 015 875 2 076 351 2 138 641 2 202 801 2 268 885 2 336 951 2 407 060 2 479 271 2 553 650 2 630 259 total gas volume (km3) 7 717 006 8 062 539 8 424 138 8 802 573 9 198 645 9 613 200 10 047 121 10 501 336 10 976 817 11 474 585 operating and distribution margin (k$) resale to power plants (k$) 513 796 539 486 566 461 594 784 624 523 655 749 688 536 722 963 759 111 797 067 resale price to industrial consumers (k$) 203 048 209 139 215 413 221 876 228 532 235 388 242 450 249 723 257 215 264 931 total operating income (k$) 716 844 748 626 781 874 816 659 853 055 891 137 930 986 972 686 1 016 326 1 061 998 operating charges (k$) average import price (k$) -572 741 -598 385 -625 223 -653 309 -682 705 -713 472 -745 677 -779 388 -814 677 -851 621 opex k$ (2% inflation) -32 792 -33 448 -34 117 -34 799 -35 495 -36 205 -36 929 -37 668 -38 421 -39 189 total terminal charges (k$) -605 533 -631 833 -659 339 -688 108 -718 200 -749 677 -782 606 -817 056 -853 098 -890 810 net cash flow (k$) 111 312 116 792 122 535 128 551 134 855 141 460 148 380 155 631 163 228 171 188 cumulative cash flow (k$) -103 350 13 443 135 977 264 528 399 383 540 843 689 223 844 853 1 008 081 1 179 270 http://dx.doi.org/10.21622/resd.2019.05.2.046 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.080 88 resd © 2019 http://apc.aast.edu incentives and government conventions planned in morocco to encourage the use of natural gas, the profitability of this investment is guaranteed on a long term. the profitability is generally the most important criterion for the decision-maker, who can also base his judgment on other non-quantitative criteria of an economic or strategic nature, however, investment in ecological energy is a strategic decision that cannot be reduced to a calculation of mathematical expectations. certainly, financial analysis is of paramount importance in the decision-making process, but some non-financial and non-quantifiable criteria must be taken into account. references [1] r. laplante, f. l’italien, n. mousseau, and s. labranche, “how to get out from fossil fuel”. 2nd international summit of research cooperatives in community development, energy transition, university of quebec, available on: http://normandmousseau.com/publications/159.p df [2015] [2] m. akdi, f.el 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institute of strategic studies [2018], available on: https://www.medias24.com/maroc/economie /economie/188546-gazoduc-maroc-nigeriavoici-un-benchmark-de-l-institut-royal-desetudes-strategiques.html [14] systek technologies, inc., usa, transmission, pipeline: calculations and simulations manual, p. 489, [ 2015] [15] jsc “united metallurgical company” and “pipeline basics & specifics about natural gas http://dx.doi.org/10.21622/resd.2019.05.2.080 https://www.wiley.com/en-us/investing+in+energy%3a+a+primer+on+the+economics+of+the+energy+industry-p-9781576603758 https://www.wiley.com/en-us/investing+in+energy%3a+a+primer+on+the+economics+of+the+energy+industry-p-9781576603758 https://www.wiley.com/en-us/investing+in+energy%3a+a+primer+on+the+economics+of+the+energy+industry-p-9781576603758 https://www.wiley.com/en-us/investing+in+energy%3a+a+primer+on+the+economics+of+the+energy+industry-p-9781576603758 https://fr.scribd.com/doc/250255788/plan-national-marocain-de-developpement-du-gaz-naturel-liquefie-gnl%20%20%20%5b2014 https://fr.scribd.com/doc/250255788/plan-national-marocain-de-developpement-du-gaz-naturel-liquefie-gnl%20%20%20%5b2014 https://fr.scribd.com/doc/250255788/plan-national-marocain-de-developpement-du-gaz-naturel-liquefie-gnl%20%20%20%5b2014 https://www.finances.gov.ma/docs/depp/2018/note%20sur%20la%20value%20for%20money%20vf%202016.pdf https://www.finances.gov.ma/docs/depp/2018/note%20sur%20la%20value%20for%20money%20vf%202016.pdf https://www.finances.gov.ma/docs/depp/2018/note%20sur%20la%20value%20for%20money%20vf%202016.pdf https://cnd.hcp.ma/conjoncture-du-08-au-12-juillet-2019_a1440.html https://cnd.hcp.ma/conjoncture-du-08-au-12-juillet-2019_a1440.html https://giignl.org/sites/default/files/public_area/publications/giignl_annual_report_2019-compressed.pdf https://giignl.org/sites/default/files/public_area/publications/giignl_annual_report_2019-compressed.pdf https://giignl.org/sites/default/files/public_area/publications/giignl_annual_report_2019-compressed.pdf https://www.medias24.com/maroc/economie/economie/188546-gazoduc-maroc-nigeria-voici-un-benchmark-de-l-institut-royal-des-etudes-strategiques.html https://www.medias24.com/maroc/economie/economie/188546-gazoduc-maroc-nigeria-voici-un-benchmark-de-l-institut-royal-des-etudes-strategiques.html https://www.medias24.com/maroc/economie/economie/188546-gazoduc-maroc-nigeria-voici-un-benchmark-de-l-institut-royal-des-etudes-strategiques.html https://www.medias24.com/maroc/economie/economie/188546-gazoduc-maroc-nigeria-voici-un-benchmark-de-l-institut-royal-des-etudes-strategiques.html journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.080 89 resd © 2019 http://apc.aast.edu pipelines” available on [2015] https://omksteel.com/upload/iblock/3f9/omk%20l arge%20diameter%20pipes%20catalogue.pdf and http://pstrust.org/wpcontent/uploads/2015/09/2015-pst-briefingpaper-02-natgasbasics.pdf [16] r. tarakad, lng receiving and regasification terminals, an overview of design, operation and project development consideration, houston texas, p. 102, zeus corporation corp, [2003] [17] belgium commission for regulating electricity and gas, “study on prices on the belgian natural gas market in 2017, pp. 9-10, [2018] [18] pickbleu, “comparative table lower caloric energy (pci) of energies”, [2017], available on https://www.picbleu.fr/page/tableau-comparatifpouvoir-calorique-inferieur-pci-des-energies. http://dx.doi.org/10.21622/resd.2019.05.2.046 https://omksteel.com/upload/iblock/3f9/omk%20large%20diameter%20pipes%20catalogue.pdf https://omksteel.com/upload/iblock/3f9/omk%20large%20diameter%20pipes%20catalogue.pdf http://pstrust.org/wp-content/uploads/2015/09/2015-pst-briefing-paper-02-natgasbasics.pdf http://pstrust.org/wp-content/uploads/2015/09/2015-pst-briefing-paper-02-natgasbasics.pdf http://pstrust.org/wp-content/uploads/2015/09/2015-pst-briefing-paper-02-natgasbasics.pdf https://www.picbleu.fr/page/tableau-comparatif-pouvoir-calorique-inferieur-pci-des-energies https://www.picbleu.fr/page/tableau-comparatif-pouvoir-calorique-inferieur-pci-des-energies journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 89 resd © 2015 http://apc.aast.edu numerical analysis of fluid flow and heat transfer for different fin designs and arrangements of ceramic platefin high temperature heat exchanger – part i vijaisri nagarajana, yitung chena*, qiuwang wangb b , ting mab b a department of mechanical engineering, university of nevada, las vegas, nv 89154-4027, usa b key laboratory of thermo-fluid science and engineering, moe, xi’an jiaotong university, xi’an, shaanxi, 710049, china abstract in this study numerical analysis is carried out for four different types of fins namely rectangular, triangular, inverted bolt fins and ripsaw fins for staggered fin arrangement. the obtained results are compared with each other, and the design with best heat transfer and minimum pressure drop is selected. the working fluids used in the model are sulfur trioxide, sulfur dioxide, oxygen and water vapor. the operating pressure is 1.5 mpa and the operating temperature ranges from 973 k to 1223 k. from the results it was found that the ripsaw fin design with thickness of 0.00005 m gives a good heat transfer rate with minimum pressure drop. the inverted bolt fins has the highest pressure drop due to the flow disturbances caused by the arrangement of the fins. the pressure drop and the heat transfer obtained for the rectangular and triangular fins are similar to each other. friction factor, colburn jfactor and dimensionless numbers like nusselt number, schmidt number are calculated for all the models. the average nusselt number obtained for the ripsaw fin design with thickness of 0.00005 m for the top and bottom arrangement is 3.197. the friction factor for the ripsaw fins for the top and bottom arrangement is 0.522. keywords heat transfer enhancement factor, ceramic plate-fin (pfhe) heat exchanger, nusselt number, schmidt number, pressure drop. i. introduction compact heat exchangers (che) plays an important role in the field of aerospace, transportation, nuclear and other industries. the need for lightweight, space saving and economical heat exchangers have driven to the development of compact heat exchangers. surface area density of greater than 700m2/m3 is achieved by incorporating fins, ribs tec. the book by hesselgreaves [1] describes different types of compact heat exchangers like plate-fin heat exchangers, spiral heat exchangers, printed circuit heat exchangers, tube fin heat exchangers etc. a plate-fin heat exchanger is a form of compact heat exchanger made of block of alternating layers of corrugated fins separated by parting sheets. surface interruption prevents the continuous growth of the thermal boundary layer by periodically interrupting it. thus the thicker thermal boundary layer which offers high thermal resistance to heat transfer are maintained thin and their resistance to heat transfer is reduced. in a plate-fin heat exchanger, fins are easily rearranged resulting in cross-flow, counter-flow, cross-counter-flow or parallel flow arrangements. from the research done by kayansayan [2] the effect of the performance of plate-fin and tube cross-flow heat exchangers due to the outer surface geometry was considered. in this study 10 geometrical configurations were tested and the reynolds number was varied from 2,000 to 30,000. the results showed that the heat transfer coefficient strongly depends on the finning factor ε and the value of ε increases with decrease in j-factor. ranganayakaulu & seetharamu [3] carried out an analysis of a cross-flow compact plate-fin heat exchanger for the combined effects of twodimensional longitudinal heat conduction through the exchanger wall, flow non-uniformity and temperature distribution was carried out using the finite element method. the exchanger effectiveness and thermal deterioration due to these effects were studied for various design and operating conditions. wen & li [4] proposed a study in order to enhance the uniformity of flow distribution. in their study an improved header configuration of plate-fin heat exchanger was proposed. the results showed that the fluid flow misdistribution was very severe in the direction of header length for the conventional header used in the industry due to poor header configuration. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 90 resd © 2015 http://apc.aast.edu manglik & bergles [5] studied the heat transfer and pressure drop correlations for the rectangular offset strip-fin compact heat exchanger. the f and j parameters were also found for laminar, transition and turbulent flow regimes. steady state threedimensional numerical model was used to study the heat transfer and pressure drop characteristics of an offset strip-fin heat exchanger by bhowmik & lee [6] three different performance criteria for heat exchangers were tested for different fluids and the appropriate performance criteria for pr = 7 and pr = 50 were found to be jf (thermal-hydraulic performance factor) and j/f1/3. research has been carried out by ma et al. [7] to find heat transfer and pressure drop performances of ribbed channels in the high temperature heat exchanger. from the results it was found that the nusselt number and the friction factor were unsuitable to compare heat transfer and pressure drop performances at different temperature conditions. schulte-fischedick et al. [8] proposed a ceramic high temperature plate-fin heat exchanger for externally fired combustion process. thermal performance and pressure drop in ceramic heat exchanger was evaluated using cfd simulations by monteiro et al. [9]. correlations for the colburn and the friction factors for the reynolds number ranging from 500 to 1500 were evaluated. simulations with conjugate heat transfer were conducted and the results show the influence of mass flow rate on pressure drop and effectiveness of the heat exchanger. ponyavin et al. [10] carried out a numerical analysis on the three-dimensional computational model of the ceramic high-temperature heat exchanger to investigate fluid flow, heat transfer, and chemical reaction and stress analysis within the decomposer. a decomposition rate of 0.515% was achieved for so3 using this design. in this study numerical analysis of ceramic plate fin high temperature heat exchanger was carried out to investigate the fluid flow and heat transfer for different fin designs and fin arrangements. this study is an extension of the work done by nagarajan et al. [11]. in order to save computational space and time a single channel model of the heat exchanger is modeled and studied. the main operating parameters for the heat exchanger design models for the current study are taken from the research done by ponyavin et al. [10]. ii. geometry of the model and material properties in this study three-dimensional study of the fluid flow and heat transfer on four type of fins namely rectangular, triangular, inverted bolt fins and ripsaw fins for top and bottom arrangement is carried out. the computer aided geometry (cad) geometry for all the models are modeled in solid works [12] and simulations are carried out in ansys fluent 14.5. the geometry and dimensions for the current study is taken from the work done by ponyavin et al. [10] and from his study it was found that mass flow rate in all channels can be made almost uniform with a proper design of manifold channels. hence by applying that concept a single channel model is developed to reduce computational time and memory. singlebanking configuration is used where in the hot and the cold plates are stacked alternatively. the current study has hot fluid channel, cold fluid channel and two silicon carbide (sic) solid regions. helium fluid flows through the hot channel placed above the solid region and mixture of sulfur trioxide, sulfur dioxide, oxygen and water vapor flows through the cold fluid channel which is placed between the two solid regions. the flow is counter flow where the hot and the cold fluids enter the model from –x and +x directions and exit in the +x and –x directions, respectively. figure 1 shows the geometry and dimensions of the single channel of plate fin heat exchanger. fig .1. geometry and dimensions of the channel to enhance the thermal performance of the pfhe many fin designs are explored and studied. table 1 shows the dimensions of all the fins http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 91 resd © 2015 http://apc.aast.edu table 1. dimensions of various fins geometry definition rectangular fins height = 0.4 mm, length = 0.4 mm, width = 0.2 mm triangular fins height = 0.3 mm, breadth = 0.2 mm, length = 0.4 mm inverted bolt type fins diameter of top cylinder = 0.2 mm, diameter of bottom cylinder = 0.4 mm ripsaw fins larger height of the rectangle = 0.3 mm, smaller height of the rectangle = 0.15 mm, thickness = 0.05 m in order to avoid backflow and provide entrance zone for each channel no fins are placed near the inlet and the outlet region on the cold channel. a study was carried out by increasing the length of the inlet and outlet to 5, 10 and 15 times the hydraulic diameter. at 10 times the hydraulic diameter the flow becomes fully developed and hence the length of the inlet and outlet are taken to be 10 times the hydraulic diameter. the material properties, boundary and operating conditions are taken from the work done by nagarajan et al. iii. numerical method and algorithm the finite volume method is one of the most versatile discretization techniques used in cfd. the governing equations are solved in the cartesian coordinate system using a control volume finite difference method that is similar to the approach introduced by patankar [14]. ansys fluent [13] a commercial cfd program based on the finite volume method is among the most powerful packages of existing software used for solving fluid flow and heat transfer problems. the pressure-based segregated solution algorithm is used for the given problem. it can be simply described as the process of solving the governing equations in a sequential order as opposed to simultaneously as with a coupled solver. the geometry of the model is meshed in ansys workbench [13] mesh generator. hexahedral elements are used for meshing. the mesh is refined near the walls particularly for the cold flow channel with fins. the mesh refinement near the wall helps in calculating the fluid flow and heat transfer properties accurately. in order to check the mesh dependence on fluid flow and heat transfer properties, the grid independent study was done for both staggered and top and bottom arrangement. from the study, optimum nodes with difference in pressure drop and heat transfer of less than 5% is selected for further study. around 481,558 cells, 1,496,152 faces and 532,599 nodes are selected for further study for all the cases. the friction factor, the colburn factor and the prandtl number are calculated using the formula shown below: 𝑓 = ( ∆𝑃 𝐿 )∗𝐷ℎ (0.5∙𝜌∙𝑈2) (1) 𝑗 = 𝑁𝑢̅̅ ̅̅ 𝑅𝑒∙𝑃𝑟 1 3 (2) 𝑃𝑟 = 𝜇∙𝐶𝑝 𝐾 (3) the schmidt number which is the ratio of the viscous diffusion rate to the mass diffusion rate is calculated based on the average temperature of the reacting channel. the validation of the fluid flow and heat transfer for the rectangular and ripsaw fins was carried out in the previous study done by nagarajan et al. [11]. the friction factor was compared with the published result by manson [15] and the colburn factor was compared with the correlation published by wieting [16]. the obtained cfd result was in good agreement with the published result and the slight offset is due to the difference in the dimensions of the geometry. since the numerical results agree closely with the published results and follow the same trend, further research is carried out for the selected design. iv. results and discussions in this paper studies are done to enhance the heat transfer rate by arranging the fins in the staggered manner. the single channel model with rectangular fins, triangular fins, inverted bolt fins and ripsaw fin with thickness of 0.00005 m are studied in this research. the fluid flow and heat transfer results were discussed in detail in the following. a. staggered arrangement 1. case 1 (single channel model with rectangular fins) the heat transfer surface area for the staggered rectangular fins is 2.25602·10-5 m2 and triangular fins is 2.2058·10-5 m2. the obtained heat transfer rate is high for the staggered arrangement. the obtained http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 92 resd © 2015 http://apc.aast.edu pressure drop for the staggered rectangular and triangular fins is 28.41 pa and 23.07 pa, respectively. due to the staggered arrangement of the fins there is more recirculation and hence higher pressure drop and friction factor are obtained. there is a significant increase in the friction factor for both the fins. the friction factor for rectangular fin is 0.894 and the friction factor for the triangular fin is 0.725. the average nusselt number and the colburn j-factor for the rectangular and triangular fins are 3.205, 0.016, and 3.235, 0.016, respectively. the schmidt number for staggered rectangular and triangular fins is 0.316 and 0.316, respectively. flow over staggered rectangular plates produces recirculation in the wake region. in the wake which is formed downstream of the fin the heat transfer is decreased due to the flow disturbances caused by the fins. relatively low heat transfer distributions are found immediately behind the fin because of flow recirculation with low local velocity. the strong recirculation zone is found behind the fins where the shear layer separates and rolls into vortices. there is no secondary vortex and only one recirculation zone is formed in the wake region. the length of the recirculation region increases with the increase in the reynolds number. the recirculation region is located at 0.00154 m and the reattachment region of the shear layers is located at 0.00210 m. the velocity streamline for the staggered rectangular fins is shown in figure 2. fig .2. velocity streamline for single channel model with staggered rectangular fins along y-plane at y=0.003 m and bottom solid regions the velocity streamline along the z-plane from figure 3 shows the recirculation zone behind the fins. it can be seen that recirculation zone for the first and the third plane are formed at the rear end of the second row of fins or the before the start of the third row of fins. this is due to the staggered arrangement of the fins. the z-plane is created at a distance of threefourth of the first and the third fin and near the edge of the second fin. the recirculation vortex is formed in the wake region immediately behind the first and the third fin. since the fin thickness is very small behind the second fin no vortices are formed behind the second fins. the shear layers continue from the second fin and they separate and form recirculation zone before the start of the third fin for the first and the third z-plane. another vortex is formed in the wake region of the third fin and thereafter the shear layers reattach and the flow becomes stable without much fluctuation. fig .3. velocity streamline for single channel model with staggered rectangular fins along z-plane at z=0.0015 m figure 4 shows the velocity and local heat transfer coefficient for the single channel model with staggered rectangular fins. the velocity of the fluid decreases from 0.800 m/s and it reaches minimum at the stagnation point p1. the velocity at the stagnation point is 0.101 m/s. the velocity reaches maximum at p2 where the fluid flows without any disturbance and is about 0.975 m/s. the velocity decreases as the fluid travels to the wake region of the fins. the velocity starts decreasing from p3 and becomes minimum at p4. again the velocity increases and it becomes maximum at p7. the process repeats till the end of the third fin and then the velocity becomes stable till the fluid reaches the outlet. the heat transfer characteristics influenced by the generation of vortex and wake are observed similar to the uniform arrangement of the fins. the heat transfer coefficient is high at point near to the hot solid wall. the heat transfer rate is greatly enhanced due to the fin arrangement and the flow disturbance caused by http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 93 resd © 2015 http://apc.aast.edu the fins. the heat flux is high near the wall and decrease near the bottom region of the fins. the heat transfer coefficient is low at fluid points near the fin bottom. the reason is due to the points are placed away from the hot solid wall and the heat is dissipated by the moving fluid. the temperature difference is high at points away from the wall and the heat flux is less at these points. after the end of the third fin the heat transfer coefficient increases without much fluctuation till it reaches the outlet. there is increase in heat transfer as the fluid reaches the outlet due to the counterflow arrangement of the heat exchangers. fig .4. velocity and local heat transfer coefficient for single channel model with staggered rectangular fins 2. case 2 (single channel model with inverted bolt fins) the inverted bolt fins gives a good heat transfer rate compared to all the other cases studied here. the obtained pressure drop for inverted bolt fin case is 31.64 pa and the friction factor obtained is 0.996. due to the recirculation and the vortex formed in the fins the obtained pressure drop and the friction factor for the fins are relatively high. the obtained maximum velocity in the fins is 2.027 m/s and the average inlet velocity is 0.8 m/s. the obtained average nusselt number for the staggered inverted bolt fins is 3.418 and the colburn j-factor is 0.017. the obtained schmidt number for the staggered inverted bolt fins is 0.315. the pressure that drives the fluid is the static pressure and the resistance offered to the fluid by the tube causes the pressure drop as the fluid moves towards the exit. the streamline velocity for the staggered inverted bolt fin is shown in figure 5. horseshoe vortices are formed around the cylinder and the pressure increases at the stagnation point. as the fluid flows around the cylinder shear layer separates and forms vortices behind the fins. recirculation zone occurs at the wake region behind the cylinder. the vortices formed on the first and the third rows are symmetrical and there are two vortices one rotating in clockwise and the other in counter clockwise direction. since there are three large cylinders in the second row, the vortices formed are not symmetrical. from figure 5 the vortices can be found in the wake region on the first and third row of the fins but no recirculation is found in the second row of the fins. along the middle z-plane strong recirculation zone is found in the wake region. since there are more recirculation zones found in the staggered arrangement the obtained pressure drop and friction is high compared to the uniform arrangement. the recirculation region of the staggered inverted bolt fins is located at 0.000957 m and the reattachment region of the shear layer is located at 0.00197 m. fig .5. velocity streamlines for the single channel model with staggered rectangular fins at y=0.003 m and z=0.0048 m figure 6 shows the velocity and heat transfer coefficient plot for the staggered inverted bolt fins. the velocity of the fluid decreases and it reaches minimum at p1. p1 is the stagnation point where the pressure is high and the velocity is low. the velocity increases from p2 and it becomes high at p3. the pressure is low at p2 and it starts increasing as the fluid travels to the rear of the cylinder. the velocity is minimum at p4 and the pressure is high at the point due to the adverse pressure gradient. also the increase in pressure is due to the formation of the http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 94 resd © 2015 http://apc.aast.edu recirculation zone in the wake of the fins. again as the fluid moves towards the second fin the velocity increases and the pressure decreases until it reaches the wake region of the fins. the velocity is maximum at the end of the second fin due to the staggered arrangement of the fins and there is more space for the fluid to flow without any disturbance. the local heat transfer coefficient is high at points (p1, p4, etc.) near the top solid wall. the heat flux is high at the top solid wall and it decreases at places away from the top solid wall or near the bottom region of the fins. after p4 the local heat transfer coefficient decreases due to the recirculation formed in the wake region of the fins. the local fluid velocity is low at these points which decrease the heat transfer rate. the temperature and local heat transfer coefficient are low at points (p2, p3 etc.) away from the hot solid wall. after the third fin the local heat transfer coefficient increases without much fluctuation till it reaches the outlet. fig .6. velocity and local heat transfer coefficient for single channel model with staggered inverted bolt fins 3. case 3 (single channel model with staggered ripsaw fin of thickness 0.00005 m) the single channel model with staggered ripsaw fins of thickness 0.00005 m gives a good heat transfer rate with reasonable pressure drop. the obtained pressure drop and friction factor are 16.59 pa and 0.522, respectively. the pressure drop increases by about 1.4 pa between the uniform and the staggered arrangement of the fins. the obtained heat transfer rate for the staggered ripsaw fin is 0.483 w and the average nusselt number is 3.404. the obtained colburn j-factor is 0.017. the average heat transfer coefficient increases from 211.18 w/m2·k to 223.61 w/m2·k. the schmidt number obtained is 0.315. the obtained velocity streamlines show that there is no recirculation formed in the wake region. since the fins are extremely thin and placed close to each other there are no vortices formed in this type of fin arrangement. the heat transfer rate is increased by the increase in the heat transfer surface area. figure 7 shows the velocity streamline along the y and zplanes. fig .7. velocity streamline for single channel model with staggered ripsaw fin with thickness of 0.00005 m at y=0.0037 m and z=0.0047 m figure 8 shows the pressure and local heat transfer coefficient for the staggered ripsaw fins with thickness of 0.00005 m. the pressure changes decreases from the inlet until it reaches the fins at p1. at this point the velocity is low due to the stagnation region and after this point the fluid flow around the fins and the flow separation starts. the pressure is low at p2 since there is no obstacle and the velocity is high at this point. as the fluid reaches the rear of the fins there will be a wake region where the pressure increases. eventhough there is no recirculation zone in this fin arrangement the pressure increases behind the fins and the velocity decreases due to the obstacles and the narrow space between the fins. this process continues until the fluid reaches the third fin and the flow increases till it reaches the outlet. due to the resistance offered to the flow the pressure decreases as the fluid moves from the inlet to the outlet. the local heat transfer coefficient is high at points near the hot solid wall and is low at p2 away from the wall. in between p3 and p4 the local heat transfer coefficient decreases due to the decrease in local fluid velocity. the local heat transfer coefficient does not change a lot after the third fin and till the fluid reaches outlet. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 95 resd © 2015 http://apc.aast.edu fig .8. pressure and local heat transfer coefficient for staggered ripsaw fin with thickness 0.0005 m table 2 shows the fluid flow and heat transfer values for the staggered arrangement of different fins. it has been found that the heat transfer and pressure drop increases for the staggered arrangement of the fins. it can be seen that the heat transfer rate is higher for ripsaw fin with thickness of 0.00005 m compared to the other cases. the obtained average nusselt number is the highest for the inverted bolt fins and least for the ripsaw fins. the rectangular and triangular fins have similar values for the average nusselt number and pressure drop. the schimdt number is calculated based on the average temperature and it is found to be similar for all the cases studied. due to the increase in pressure drop the friction factor is found to be the highest for inverted bolt fins followed by the rectangular fins. the ripsaw fin with thickness of 0.00005 m has the least friction factor. table 2. fluid flow and heat transfer values for the staggered flow arrangement staggered arrangement types rectangle fins triangle fins inverted bolt fins ripsaw fin with thickness 0.00005 m heat transfer rate (w) 0.481 0.478 0.482 0.494 heat transfer surface area (m2) 2.256·10-5 2.205·10-5 2.233·10-5 2.262·10-5 heat transfer coefficient (w/m2·k) 224.16 226.28 239.04 223.61 average nusselt number 3.205 3.235 3.418 3.197 colburn j factor 0.016 0.016 0.017 0.016 schimdt number 0.316 0.316 0.315 0.315 friction factor f 0.894 0.725 0.996 0.522 there is a little increase in pressure drop compared to the uniform arrangement of the fins (nagarajan et al. [11]). the ripsaw and the inverted bolt fins do not have noticeable increase in pressure drop. all the obtained pressure drop values are good for safe operation. due to the smaller heat transfer surface area the effectiveness obtained is also less. there is increase in the effectiveness of the heat exchanger and the ripsaw fin with thickness of 0.00005 m is found to have the highest effectiveness. table 3 shows the pressure drop and temperature values for the staggered arrangement. table 3. pressure drop and temperature difference between the inlet and the outlet for the flow channels δp in reacting flow channel (pa) δt in reacting flow channel (k) δt in helium flow channel (k) temperature gradient in reacting flow channel (k/mm) mass diffusivity in the reacting channel dab (m 2·s1) effectiveness ε rectangular fins 28.41 135.13 55.58 20.90 6.25·10-6 0.544 triangular fins 23.03 132.89 52.72 20.55 6.26·10-6 0.535 inverted bolt fins 31.64 134.22 58.26 20.76 6.27·10-6 0.540 ripsaw fin with thickness of 0.00005 m 16.59 137.35 59.85 21.24 6.28·10-6 0.553 http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 96 resd © 2015 http://apc.aast.edu v. conclusion the obtained average nusselt number is higher for inverted bolt fins which is 3.418 followed by triangular fins which is 3.235. the obtained pressure drop for the rectangular fins is higher compared to the triangular fins for similar heat transfer rate. for similar heat transfer rate the obtained pressure drop which is 16.59 pa is less for the ripsaw fins compared to the other fins. hence ripsaw fin with thickness of 0.00005 m is considered to be the best design with less pressure drop and reasonable heat transfer rate. the inverted bolt fins have the highest average nusselt number followed by the triangular fins. the values of the average nusselt number for the triangular and the rectangular fins are very close. even though the obtained average nusselt number for the ripsaw fin with 0.00005 m thickness which is (nu) ̅ = 3.2 is less compared to the other fins, the obtained pressure drop for the ripsaw fins is the least of all the four fins which is 16.59 pa. hence the ripsaw fin thickness of 0.00005 m is selected as the best design with good heat transfer rate of 0.494 w and minimum pressure drop of 18.73 pa. references [1] hesselgreaves, j. e. (2001). compact heat exchangers selection, design and operation. oxford, uk: elsevier science ltd. [2] kayansayan, n. (1994). heat transfer characterization in plate-fin tube heat exchangers. international journal of refrigeration, 17, pp. 49-57. [3] ranganayakulu, c. & seetharamu. k.n. (1999). the combined effects of wall longitudinal heat conduction, inlet fluid flow non-uniformity and temperature non-uniformity in compact tubefin heat exchangers: a finite element method. international journal of heat and mass transfer, 42, pp. 263-73. [4] wen, j. & liu. (2004). study of flow distribution and its improvement on the header of plate-fin heat exchanger. cryogenics, 44(11), pp. 823831. [5] manglik, r. m. &. bergles, a. e. (1995). heat transfer and pressure drop correlations for the rectangular offset strip fin compact heat exchanger. experimental thermal and fluid science, 10, pp. 171-80. [6] bhowmik, h., &. lee, k. (2008). analysis of heat transfer and pressure drop characteristics in an offset strip fin heat exchanger. international communications in heat and mass transfer, 36(3), pp. 259-263. [7] ma, t., wang, q. w., zeng, m., chen, y., liu, y., & nagarajan, v. (2012). study on heat transfer and pressure drop performances of ribbed channel in the high temperature heat exchanger. applied energy, 99, pp. 393-401. [8] schulte-fischedick, j., dreibigacker, v., & tamme, r. (2007). an innovative ceramic high temperature plate-fin heat exchanger for efcc processes. applied thermal engineering, 27(8-9), pp. 1285-94. [9] monteiro, d. &. b., & batista de mello, p.e. (2012). thermal performance and pressure drop in a ceramic heat exchanger evaluated using cfd simulations. energy, 45, pp. 489496. [10] ponyavin, v., chen, y., mohamed, t., trabia, m.b., hechanova, a.e., & wilson, m. (2012). design of a compact ceramic hightemperature heat exchanger and chemical decomposer for hydrogen production. heat transfer engineering, 33(10), pp. 853-70. [11] nagarajan, v., chen, y., wang, q., & ma, t. (2014). hydraulic and thermal performances of a novel configuration of high temperature ceramic plate-fin heat exchanger. applied energy, 113, pp. 589-602. [12] solidworks 2013., solidworks corp. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 97 resd © 2015 http://apc.aast.edu [13] ansys inc. (2011). ansys 14.5 user's guide. [14] patankar, s. (1980). numerical heat transfer and fluid flow. new york. [15] manson, s. v. (1950). correlations of heat transfer data and friction data for interrupted plate fins staggered in successive rows. washington dc: national advisory committee for aeronautics. [16] wieting, a. r. (1975). empirical correlations for heat transfer and flow friction characteristics of rectangular offset-fin-plate-fin heat exchanger. asme, int j. heat transfer, 97, pp. 480-490. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.068 68 resd © 2019 http://apc.aast.edu comprehensive review of pump as turbine (pat) abdulbasit nasir jemal1, misrak girma haile2 department of mechanical engineering, addis ababa science and technology university, addis ababa, ethiopia . abdulbasitnasir@ymail.com1, misrakmgh@gmail.com2 abstract the turbine is a heart of power generation in a hydro-electric power system. a variety of different turbines are available for that purpose. the common types of hydraulic turbines are; pelton, cross flow, francis, kaplan, and propeller turbine. however, using conventional turbines for low head and flow rate (i.e. micro hydropower) applications are not economically feasible. a low-cost alternative is to use the pump as a turbine. in this paper, existing peer-reviewed articles from (scopus, google scholar, umbrella, etc.) that are directly related to pump running as a turbine are collected and reviewed. theoretical, numerical, and experimental investigations are considered. performance improvement techniques for pat are summarized and research gaps in related works are identified. keywords turbines, pumps, review, pump as turbine, pat. list of abbreviations and symbols bep best efficiency point b2 impeller inlet width (mm) b3 volute outlet width (mm) c absolute velocity of the fluid cfd computational fluid dynamics coefficient of head coefficient of flow rate d1 impeller outlet diameter (mm) d2 impeller inlet diameter (mm) d3 volute base circle diameter (mm) d4 volute inlet diameter (mm) g gravitational acceleration (m/s2) head at best efficiency point (m) pump head (m) theoretical head (m) i turbulence intensity icem integrated computer engineering and manufacturing k turbulent kinetic energy (j/kg) n-s navier-stock specific speed of pump (m, m3/s) specific speed of turbine (m, m3/s) pat pump as turbine pde partial differential equation piso pressure-implicit with splitting of operators hydraulic power (w) mechanical power (w) flow rate at best efficiency point (l/s) pump flow rate (l/s) revolution per minute re reynold’s number rng re-normalization group sst shear stress transport u peripheral/tangential velocity of wheel (m/s) v relative velocity of fluid (m/s) y+ y plus z number of blades α flow angle (0) β1 blade outlet angle (0) β2 blade inlet angle (0) efficiency at best efficiency point pump efficiency (%) μ slip factor for pump operation λ slip factor for turbine operation ε turbulence dissipation ω specific dissipation rate (rad/s) discharge number head number power number i. introduction the turbine is a heart of power generation in a hydroelectric system. a variety of different turbines are available for that purpose. however, using conventional turbines for low head and flow rate (micro hydro power) applications is not economically feasible [1]. a low-cost alternative is to use a pump as turbine (pat). pumps are widely used for irrigation, industrial and domestic applications, transportation of liquid, industrial processes, as well as heating and cooling systems [2]. flow directions of the pump are shown in fig. 1. http://dx.doi.org/10.21622/resd.2019.05.2.068 http://dx.doi.org/10.21622/resd.2019.05.2.068 http://dx.doi.org/10.21622/resd.2019.05.2.068 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.068 69 resd © 2019 http://apc.aast.edu fig .1 flow direction of the pump [2]. in addition to the basic functions, pumps can be used to generate electricity when operating in a reverse way. the basic hydraulic theory of both pump and turbine modes to be is the same, fig. 2. however, the behavior of real fluid flow including friction and turbulence result is different [3]. fig .2 flow direction in pump and turbine modes [4]. pat can be applied to micro-hydropower plants as well as water supply piping and distribution systems [5-9], reverse osmosis systems [10], pressure reducing system [11, 12], energy recovery in irrigation networks and industries [13-22]. pumps have various advantages compared to turbines, such as availability, proven technology, low initial installation and maintenance cost, available for a wide range of heads, and flows [1, 7]. pump impellers have no significant disadvantages in turbine mode, but the efficiency coefficient of a pump in turbine operation is lower [16]. the pump manufacturers do not provide characteristic curves of their pumps working as turbines. this makes it difficult to select a suitable pump to run as a turbine for a specific application [23]. in this paper, existing peer-reviewed articles from (scopus, google scholar, umbrella, etc.), that are directly related to pump running as a turbine, are collected and reviewed. peer-reviewed articles other than review papers are considered. theoretical, numerical, and experimental investigations are studied. performance improvement techniques for pat are summarized and research gaps in related works are identified. pump manufacturers only supply pump mode performance curves and that makes it difficult to predict the performance of the pump working as a turbine. three main ways of conducting researches on the pump running as a turbine are: analytical/theoretical method, the numerical/computational method, and the experimental method. ii. theoretical investigation of pat a theoretical investigation is the study of fluid flow problems analytically, using partial differential equations without any approximations. many attempts have been made to predict pump in turbine mode performance theoretically. a mathematical model was applied to investigate the installation of pat, by solving the system of partial differential equations into ordinary differential equations [7]. it was found that pump impellers have no significant disadvantages in turbine mode and the efficiency coefficient of a pump in turbine operation is hardly lower (in some cases even higher) than in pump operation [16]. the efficiency at the bep in turbine mode corresponds approximately to the efficiency coefficient in pump mode. 𝜂𝑏𝑒𝑝𝑇 = 𝜂𝑏𝑒𝑝𝑃 ± 0.02 (1) if the rotational speeds are the same for both modes, there are equal and opposite heavy line velocities for pump mode and turbine modes based on the infiniteblade theory. consequently, euler head in pump and turbine mode are the same [19,24]. 𝐻𝐸𝑢𝑙𝑒𝑟 = 𝑢1𝑣𝑢1−𝑢2𝑣𝑢2 𝑔 (2) where 𝑉𝑢1and 𝑉𝑢2 represent the peripheral component of velocity at the high-pressure side and low-pressure side, respectively. in equation (2), 𝑣𝑢2 is negligibly small in general and, as a result, the euler head can be as http://dx.doi.org/10.21622/resd.2019.05.2.068 http://dx.doi.org/10.21622/resd.2019.05.2.068 http://dx.doi.org/10.21622/resd.2019.05.2.068 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.068 70 resd © 2019 http://apc.aast.edu 𝐻𝑃 𝐸𝑢𝑙𝑒𝑟 = 𝑢1𝑣𝑢1 𝑔 = 𝐻𝑇 𝐸𝑢𝑙𝑒𝑟 (3) due to slip of finite blade number, pump and turbine theoretical head is given by: 𝐻𝑝 " = 𝜇𝐻𝑝 𝐸𝑢𝑙𝑒𝑟 (4) 𝐻𝑡 " = 𝐻𝑡 𝐸𝑢𝑙𝑒𝑟 /𝜆 (5) where μ is a slip factor for pump operation μ < 1, λ is a slip factor for turbine operation. the slip factor for reverse mode is approximately equal to 1.0 [4]. from the fundamentals of energy transfer in turbines, the output mechanical shaft power and euler turbine head can be represented by [25]: 𝑃 = 𝜌𝑔𝑄𝐻𝑡 − 𝑃𝑚𝑒𝑐ℎ − 𝑃𝑙𝑒𝑎𝑘 (6) 𝐻𝑡 = 𝜎𝐻𝐸𝑢𝑙𝑒𝑟 (7) 𝐻𝐸𝑢𝑙𝑒𝑟 = (𝑈2𝐶𝑢2−𝑈1𝐶𝑢1) 𝑔 = (𝑈2 𝐶𝑚2𝑐𝑜𝑡𝛼2−𝑈1(𝑈1−𝐶𝑚1𝑐𝑜𝑡𝛽1)) 𝑔 = (𝑈2( 𝑄 𝐴2 )𝑐𝑜𝑡𝛼2−𝑈1(𝑈1−( 𝑄 𝐴1 )𝑐𝑜𝑡𝛽1)) 𝑔 (8) pat’s p-q curve is in inverse proportion to the inlet area 𝐴2 . pat’s required pressure head can be represented as the sum of the theoretical head and the losses. pat’s hydraulic efficiency can be represented by: 𝜂ℎ = 𝐻𝑡 𝐻𝑡+ℎ𝑡𝑜𝑡𝑎𝑙 (9) both theoretical head and total hydraulic loss increase with the increase of the blade thickness. in the study of s. barbarelli et al. [26], a statistical method combined with a numerical model for selecting a pump running as turbine in micro-hydro plants is applied. the information of the site (flowrate and head) allow calculating two coefficients, 𝐶𝑄and 𝐶𝐻, respectively. for searching of energy conversion characteristics of pat in detail, theoretical analysis and empirical prediction can only outline the energy conversion characteristics in the macroscopic point of view [27]. by considering the pat’s flow, i.e. the reverse of pump, the theoretical head transferred from the fluid to the runner is smaller than actual head ht between the inlet and exhaust nozzles because of the hydraulic losses z [28]. because of power losses, the power pt available at the coupling of the turbine is smaller than the hydraulic power 𝜌𝑔𝐻𝑄. the pat’s overall efficiency 𝜂𝑇 is: 𝜂𝑇 = 𝑃 𝜌𝑔𝐻𝑄 (10) the basic parameters of pump and turbine mode are specific and deal with (i) geometric characteristics; (ii) flow and geometrical angles, and (iii) hydraulic and power losses. these parameters may be known from pump geometry or can be estimated through an optimization procedure [28]. the effect of variable guide vane numbers on the performance of pump as turbine was analyzed theoretically, having the turbulence kinetic energy under variable working conditions. the asymmetry of the volute and rotor-stator interaction causes turbulence kinetic energy concentration to appear in pump as turbine. theoretically, the turbulence kinetic energy equals half of the product of turbulent velocity fluctuation variance and fluid mass, which generally is expressed by the physical quantity k and can be calculated through the turbulence intensity i [29]. 𝑘 = 3 2 (𝑢𝐼)2 (11) 𝐼 = 0.16𝑅𝑒 −1 8 (12) many attempts have been made to predict turbine mode performance by using analytical/theoretical model but the percentage of deviation is comparatively large compared to the actual performance. it can be concluded that the theoretical method is used to study flow problems with a few variables, while it is difficult to analyze pumps running as a turbine. iii. numerical investigation of pat a numerical investigation is the study of fluid dynamics problem using computer software, in this case approximating partial differential equations into system algebraic equitation. computational fluid dynamics (cfd) is an active design tool for predicting the performance of centrifugal pumps running in turbine mode. http://dx.doi.org/10.21622/resd.2019.05.2.068 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.068 71 resd © 2019 http://apc.aast.edu flow conditions for pats operating in parallel was performed using the cfd model [1]. the kε turbulent model is adopted, the domain has 713,954 cells. variables, such as mass flow rate, outlet pressure, and rotational speed, and rotating zone are specified in fig. (3). when the flow is different from the normal rated conditions, two pats in parallel can better cover it. fig .3 pat’s system set-up [1]. the behavior of the pressure distribution when pat installing in a water network was analyzed [11]. the pat model was built in solidworks, then simulated by using cfd, the boundary conditions are specified and the number of elements is about 100,000. the global variables are simulated in the cfd model and used to evaluate the overall pat characteristics. results of numerical and experimental values do relatively not agree. the pressure fluctuation characteristic of the hydraulic turbine at a single rotational speed with guide vane was analyzed [13]. unlike others in this work, the piso algorithm is adopted to solve the navier-stokes equations. rng k-ε turbulence model was used for this specific purpose. the grid independence is verified. the final grid number is 1,042,502. in the impeller blade region, the pressure fluctuation in the pressure surface is lighter than that of the suction surface. the slip phenomenon was investigated and the effective value of slip factors for both direct and reverse modes is obtained. pump and turbine head impeller can be predicted by computational fluid dynamics [19]. 𝐻𝑝 = 𝐻𝑝 𝜂ℎ𝑝 (13) 𝐻𝑡 = 𝐻𝑡 ∗ 𝜂ℎ𝑡 (14) ansys-cfx was selected for the solution. a grid sensitivity analysis was performed. the final elements number of the fluid volume was 4,154,084. testing different turbulence models, and rng kε model confirms a good accuracy in the performance prediction of pat. at bep the effective value of slip is 0.28 for pump and 0.24 for turbine mode. pump and pat can be related 𝐻𝑡 𝐻𝑝 = 1−𝑠𝑡 1−𝑠𝑝 1 𝜂ℎ𝑡𝜂ℎ𝑝 (15) a performance prediction method for three different pumps as turbines using a computational fluid dynamic modeling approach was presented [23]. results have been first confirmed in pumping mode using data supplied by pump manufacturers. then, the model results have been compared to experimental data for pat. the analyzed pumps have three different specific speeds. the main characteristics are summarized in table (1). from the cfd model results, the specific head, capacity, power, and efficiency have been evaluated and the best efficiency point of all the analyzed pumps was found. table 1 characteristics of different pumps [23] impeller diameter (mm) delivery outlet diameter (mm) 𝐻𝑏𝑒𝑝(𝑚) 𝑄𝑏𝑒𝑝 ( 𝑚3 ℎ ⁄ ) (𝑁𝑠 37.6) 190 80 39 148 (𝑁𝑠 20.5) 200 70 60 45.4 (𝑁𝑠 64.0) 120 80 3.9 54 for all cases, the maximum value is lower than the pump mode value. for low specific speed pumps, this maximum value is roughly equal to the pump mode, while for high specific speed pumps, it is different. model results for pump 1 at 2900 rpm are shown in fig. 4 and the pressure distribution at the bep in the 0–9 bar pressure range is presented. fig .4 pressure distribution of model results for pump 1 (ns = 37.6) at 2900 rpm [23]. it is clear that maximum pressure is applied in reverse mode. this indicates that blade modification is required when using the pump as a turbine. http://dx.doi.org/10.21622/resd.2019.05.2.068 http://dx.doi.org/10.21622/resd.2019.05.2.068 http://dx.doi.org/10.21622/resd.2019.05.2.068 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.068 72 resd © 2019 http://apc.aast.edu a single-stage centrifugal pump was selected for energy conversion characteristic of pump as turbine [27]. the centrifugal pump design parameters are: flow rate q = 12.5 m3/h, head h= 30.7 m, rotating speed n = 2900 rev/min, specific speed ns = 48, and the shape of the blade is cylindrical. the impeller is divided into six regions as shown in fig. (5) by the radius. fig .5 schematic diagram of the impeller division of the pat [27]. icem was used to generate a structured hexahedral mesh for each part. the grid number is about 1.1 million. the ansys-fluent was selected to calculate pde. the standard k–e turbulence model was chosen. the results show that the front and middle part of the impeller i.e. (0.6–1.0) d2) are significant parts for energy conversion; in the rear area of the impeller. thus, the pat blades need to be optimized to improve the performance, especially in the impeller blade rear area. turbulence model has its own influence on the accuracy of the result. in the numerical method, a variety of turbulence models are available, among them rng k-ε [13, 19], standard k-ω [22], and standard kε [1, 6, 11, 23, 25, 27, 29 and 30] are used to predict the effects of turbulence on the system. because of the irregularity shape of impeller unstructured mesh found to be the best one, but the result of review indicates, many researchers used structured mesh. pressure fluctuations are very vital characteristics in pump turbine’s operation. 3d numerical simulations using sst k-ω turbulence model was carried out to predict the pressure fluctuations distribution in a prototype pump-turbine at pump mode [31]. three operating points with different flow rates and different guide vanes openings were simulated. the numerical results show how pressure fluctuations at blade passing frequency and its harmonics vary along with the whole flow path direction, as well as along the circumferential direction. a complete numerical detail for a selection of centrifugal pump as turbine with a rotational speed of 2880rpm for micro-hydro power plants was provided [32]. the maximum power output is 17.78 kw. the bep of centrifugal pump operated in pump mode was observed as 70% of that to turbine mode was 35.45%. it was clear that the pump relatively operated as a turbine is with lower efficiency. the future work focuses on the further development of pat performance. hydraulic design and optimization of a modular pumpturbine runner were performed [33]. a mesh discretization study was performed and found that convergence was reached around a nine million cell mesh. the runner’s performance was characterized in both the pump and turbine modes for its designed working conditions for both the initial and optimized design. numerical simulations were done to predict the distribution of pressure fluctuations with different numbers of runner blades in turbine mode using the k ω turbulence model [34]. the two factors that influence the distribution of pressure fluctuations found to be the flow rate and a number of blades, especially at blade passing frequency along the circumferential direction. the power loss and radial force characteristics of the pump as a hydraulic turbine under gas-liquid twophase condition was studied [35]. based on the n-s equation and standard k-e turbulence model, computational fluid dynamics technology was used to simulate the flow field in a hydraulic turbine. the result illustrates that the gas content has a serious effect on pat performance. under the two-phase condition, the fluid velocity distribution in turbine mode is uneven, and the power loss is not uniform enough when the gas content is lower. mesh refine [1, 6, 11, 19, 22, 23 and 25] especially at the boundary and the inlet of the pipe is used to: • save memory capacity • decrease computational time in all cases, the value of the numerical result is higher than the experimental one. this indicates that numerical methodology is not enough to determine the exact solution of pump running as a turbine. iv. experimental investigation of pat the experimental investigation is the study of fluid flow problem using physical laboratory. knapp (1941) http://dx.doi.org/10.21622/resd.2019.05.2.068 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.068 73 resd © 2019 http://apc.aast.edu published the complete pump characteristics for a few pump designs based on experimental investigations [36]. two equal pats working in parallel and single-mode were performed [1]. several experimental tests at a different flow rate (200 to 1150) were carried out for the two configurations by regulating the flow rate. during each test, the data were recorded. the performance in parallel design conditions illustrates a peak efficiency with less shock losses within the impeller. the hydraulic facility, composed of one closed pipe, an air-vessel tank (allows to regulate the flow and pressure in order to reach the steady flow conditions) a recirculating pump, an open free surface tank, ball valves, an electromagnetic flowmeter, two pressure transducers were used to determine the behavior of the pressure distribution along the pat [11]. the pressure fluctuation characteristic of a hydraulic turbine with guide vane using the test bench fig. 6 was studied [13], with different flow rate. the pressure fluctuation is also different, the greater the flow rate, the more serious the pressure fluctuation. fig .6 test bench for hydraulic turbine [13] three centrifugal pumps with different heads and flow rates have been modeled and tested in the test bench [13], unitless parameters are calculated. head number 𝛹 = 𝑔ℎ 𝑛2𝐷2 (16) discharge number 𝜙 = 𝑄 𝑛𝐷3 (17) power number 𝜋 = 𝑝 𝜌𝑛3𝐷5 (18) efficiency 𝜂 = 𝑃 𝜌𝑄𝐻 (19) experimental investigations and laboratory measurements on the hydraulic machine are conducted at a turbine test rig to validate the theoretical work that is used to predict the behavior of a centrifugal stainless-steel pump in turbine operation [16]. a centrifugal multistage end-suction pump chosen for experimental investigation [17]. the test rig consists of the pump with a synchronous motor, two pressure transducers, a magnetic flow meter, a watt meter, and an optical speedometer. the focus of the study was comparing direct and indirect water supply a network and direct pumping found to be considered to be more efficient than indirect pumping. equation 16 through 19 used to determine the characteristics of the pump running as a turbine. a laboratory model of pat test rig was used to conduct research on energy conversion characteristics of the pump as a turbine [27]. the main equipment composed of an electric motor, a feed pump, a control valve, an electromagnetic flow meter, a differential pressure transducer, a pat, a torque meter, and an energy dissipation pump. the characteristics of energy transformation, especially within impeller, plays significant roles for further optimum design of the pump as turbine, the area of (0.6–1.0) d2) are important parts for energy conversion; in the rear area of the impeller, this at least shows that the pat blades need to be optimized to improve the performance, especially in the impeller blade rear area. the feasibility study of using pumps in turbine mode in small hydroelectric stations was presented [37]. to regulate the power applying variations in the turning speed of the turbine-generator set. the study of a. carravetta et al. [38] affinity law for the evaluation of the behavior of a single machine under variable speed. the study shows that the use of performance curves calculated using affinity law and suter parameters produces a limited error in the evaluation of the head drop, granting the satisfaction of the correct hydraulic constraint (pressure level within the network). meanwhile, the error in terms of mechanical efficiency is greater but still acceptable in a limited range of velocity difference between a prototype and simulated machine. an end suction centrifugal pump with a specific speed of 15.36 (m, m3/s) was tested experimentally, to determine the performance characteristic of the pump in reverse mode. the result showed that a centrifugal pump can satisfactorily be operated as a turbine without any mechanical problems. the best efficiency http://dx.doi.org/10.21622/resd.2019.05.2.068 http://dx.doi.org/10.21622/resd.2019.05.2.068 http://dx.doi.org/10.21622/resd.2019.05.2.068 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.068 74 resd © 2019 http://apc.aast.edu point (bep) for pat was found to be lower than bep in pump mode [39]. there are some variations between numerical and experimental results in the case of pat. as recommended by many researchers the variation can be minimized through development by using a fine grid and introducing appropriate turbulence models. the solution of the pump running as a turbine highly depends on different conditions like flow rate, head, impeller diameter, and rotational speed. tasting and measuring pat output with various parameters as done by many investigators is very important to predict a relatively more accurate solution. v. modification in pat the result of the study shows the efficiency of pat is 12.4 % [12], 4% [21], 34.55% [32], 19 % [39] lower than direct pump mode. the result of all investigations shows that the pump has low efficiency in turbine mode, geometric modification is required to improve the efficiency pump working as a turbine. the influence of the different number of blades (10-13) with guide vane on the performance of pat was investigated numerically and experimentally [22]. to perform the numerical simulation, applying ansys cfx and k-ω the turbulence model was used. meshing is performed by icem. the grid independence is verified. the total number of grids is 15.287 million. the pat test bench consists of a model pat, an overrunning clutch, an electric motor, a centrifugal pump, throttle valves, and bypass valves, and a pool is used to validate relationship curves among the head, efficiency, power, and flow rate of the pat, which are drawn and compared with the simulation result. results show that when the number of blades is 10 at the same flow rate, the highest efficiency is achieved and the internal flow becomes stable. pat covering different specific speeds was designed to explore the effects of blade thickness on the performance [25]. numerical and experimental methodologies are applied. icem-cfd was used to generate the structured hexahedral grid for the components. a grid-independent test was performed. the final mesh number is over 1 million and the standard k-ε model was applied. after modification, a new impeller was manufactured and verified in the test rig. the efficiency decreases with increasing blade thickness. using the thinner blades with sufficient strength to obtain higher efficiency was recommended. based on the founding of research appropriate material selection is an important factor for the improvement of pat. energy conversion characteristic of pump as turbine by considering a single-stage and single-suction centrifugal pump running in the reverse model as the turbine was selected [27]. the centrifugal pump design parameters are: flow rate q = 12.5 m3/h, head h= 30.7 m, rotating speed n = 2900 rev/min, specific speed ns = 48, and the shape of the blade is cylindrical. the result of the study shows that pat blades need optimization to enhance the performance, especially in the impeller blade rear area. blade profile optimization by using a numerical approach was performed [30]. coordinate values of the control point 1-8 in fig. 7 were selected as the optimization design variables. the control point 9 remains unchanged. fig .7 blade parameterization (30). the ansys-fluent software is used to calculate the selected model in the numerical method. n-s equations to describe the inner flow of the pat, the standard k–e turbulence model is used. icem was used to generate the structured grid of computational domain. the final mesh number is 1,178,560. the result shows that the efficiency of the optimized pump as turbine under the optimum operating condition increased by 2.91%. through optimization of the blade, the hydraulic loss in the impeller decreased, the hydraulic loss in the volute and outlet pipe has a certain increase, whereas the total hydraulic loss decreased. further investigation is required to control the hydraulic loss in the volute and outlet pipe. http://dx.doi.org/10.21622/resd.2019.05.2.068 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.068 75 resd © 2019 http://apc.aast.edu one original impeller and three modified impellers of an industrial centrifugal pump with a specific speed of 23.5 m, m3 /s were tested numerically and experimentally. in this work, the shape of blades was redesigned to reach a higher efficiency in turbine mode using a gradient-based optimization algorithm coupled by a 3d navier–stokes flow solver. also, another modification technique was done by rounding the leading edges of blades and hub/shroud interface in turbine mode [40]. the result of the study shows modifications on the impeller lead to achieving maximum efficiency in reverse mode. a comparison between centrifugal impeller pumps mode [41] and turbine mode [42], with and without splitter blades in terms of suction performance, is presented by experimental tests and numerical analyses. the efficiency of pat is improved when splitter blades are added to impeller flow passage. multi-objective optimization to improve the hydrodynamic performance of a counter-rotating type pump-turbine operated in pump and turbine modes was illustrated [43]. the inlet and outlet blade angles of impellers/runners with four blades, which were extracted through a sensitivity test, were optimized using a hybrid multi-objective genetic algorithm with a surrogate model based on latin hypercube sampling. three-dimensional steady incompressible reynoldsaveraged navier-stokes equations with the shear stress transport turbulence model were discretized via finite volume approximations and solved on a hexahedral grid to analyze the flow in the pump-turbine domain. for the major hydrodynamic performance parameters, the pump and turbine efficiencies were considered as the objective functions. the result shows that the arbitrarily selected optimal designs in the pareto-optimal solutions were increased as compared with the reference value. many researchers have reported that the efficiency of pump in turbine mode can be improved by simple modification such as rounding impeller tips, installation of splitter blades, reducing impeller thickness, increasing number of blades, applying of guide vane, and optimizing blade profile . table 2 summarizes the outcome of the modifications different researchers made. table 2 summary of modification result proposed by different researchers. among the various techniques attempted by different investigators for performance improvement of pump as turbine, rounding of impeller inlet and blade profile optimization is found to be the most promising technique. testing of more than one modification techniques per system is important to further improvement. vi. research gaps in related literature when the pump is operating in the turbine mode, the direction of flow is reversed; therefore, the pattern of loss distribution is not the same as in the pump mode. to improve performance, one of the important factors is to identify the causes of losses that may occur in turbine mode. many researchers have studied performance improvement of pat focusing on shock loss, while other losses such as diffusion and hydraulic losses should be considered when using pump as turbine. guide vane is an important part of a turbine, but centrifugal pumps have no guide vane. an extra row of fixed blades called inlet guide vane are required to direct the water at the correct angle onto the pat blade; therefore, testing and using different guide vane angle are important to improve the efficiency of the system. there is a need for studies that focus on the multistage multi-flow pumps to increase the power output from pump as turbine (pat). furthermore, a comparative study is needed to provide information on the various turbulence models then finding out the best one. author shi et al. [22] yang et al. [25] feng xia shi et al. [29] s. miao et al. [30] s. derakhshan et al. [40] p. singh and f. nestmann [44] method number of blades blade thickness guide vane number blade profile optimization rounding of inlet optimization impeller rounding rise in efficiency (η%) ≈1.75 ≈1.6 ≈2 ≈2.91 ≈5.5 ≈2.75 ≈2 http://dx.doi.org/10.21622/resd.2019.05.2.068 http://dx.doi.org/10.21622/resd.2019.05.2.068 http://dx.doi.org/10.21622/resd.2019.05.2.068 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.068 76 resd © 2019 http://apc.aast.edu the velocity triangle is one of the fundamental tools to analyse turbomachinery problems. after each modification, the velocity triangle of the modified blade should be specified. cavitation is caused by local vaporization of the liquid. it usually occurs in hydraulic machines and it is a cause of different potential problems. optimum design is required to avoid the effect of cavitation. vii. conclusion in various parts of this review paper, it has been recognized that extensive studies have been carried out on pump as turbine. from the entire study, it can be concluded that commercial centrifugal pump, i.e. pat, will provide an attractive alternative for power generation in off-grid areas. the limitations of pat can be further reduced by selecting a proper pump for a specific site. the characteristics of the pump running as a turbine can be predicted by a theoretical, numerical, and experimental approaches. the efficiency can be increased by using various modification techniques. among the various techniques attempted by different researchers is rounding of impeller inlet and blade profile optimization, which were found to be the most promising techniques. for future research, in addition to introducing new modifications, a study on the importance of applying existing techniques should be carried out. references [1] m. simão, m. pérez-sánchez, a. carravetta, and helena m. ramos, “flow conditions for pats operating in parallel: experimental and numerical analyses,” energies, vol. 12, pp 901, 2019. doi:10.3390/en12050901 [2] val s. lobanoff, and robert r. ross, “centrifugal pumps design & application”. 2nd ed. united states of america: gulf publishing company, 1992. [3] s. derakhshan, and a. nourbakhsh, “theoretical, numerical and experimental investigation of centrifugal pumps in reverse operation,” elsevier, experimental thermal and fluid science, vol. 32, pp. 1620–1627, 2008. doi:10.1016/j.expthermflusci.2008.05.004 [4] j. chapallaz , p. eichenberger , and g. fischer, “manual on pumps used as turbines” mhpg series; vol. 11; germany, friedr. vieweg & sohnverlagsgesellschaftmbh, 1992. 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“theoretical, numerical and experimental prediction of pump as turbine performance,” elsevier, renewable energy, vol. 48, pp. 507513, 2012. doi:10.1016/j.renene.2012.06.002 [25] s. yang, c. wang, k. chen, and x. yuan. “research on blade thickness influencing pump as turbine.” hindawi publishing corporation, advances in mechanical engineering, 8 pages, volume 2014. doi:10.1155/2014/190530 [26] s. barbarelli, m. amelio, g. florio, and n.m. scornaienchi. “procedure selecting pumps running as turbines in micro hydro plants,” 72nd conference of the italian thermal machines engineering association, ati2017, 6-8 http://dx.doi.org/10.21622/resd.2019.05.2.068 http://dx.doi.org/10.21622/resd.2019.05.2.068 http://dx.doi.org/10.21622/resd.2019.05.2.068 https://doi.org/10.1016/j.renene.2018.01.053 https://doi.org/10.2507/ijsimm17(3)443 http://dx.doi.org/10.1016/j.renene.2012.06.002 http://dx.doi.org/10.1155/2014/190530 journal of renewable energy and sustainable development (resd) volume 5, issue 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[37] j. fernandez, e. blanco, j. parrondo, m. t. stickland, and t. j. scanlon. “performance of a centrifugal pump running in inverse mode.” journal of power and energy. vol. 4, pp. 265-271, 2004. doi:10.1243/0957650041200632 [38] a. carravetta, o. fecarotta, r. martino, and l. antipodi. “pat efficiency variation with design parameters,” 12th international conference on computing and control for the water industry, ccwi2013, procedia engineering 70, pp. 285 – 291, 2014. doi:10.1016/j.proeng.2014.02.032 [39] n. raman, i. hussein, k. palanisamy, and b. foo. “an experimental investigation of pump as turbine for micro hydro application,” iop conference series: earth and environmental science, 16, 012064. 2013. doi:10.1088/17551315/16/1/012064 [40] s. derakhshan, b. mohammadi, and a. nourbakhsh. “efficiency improvement of centrifugal reverse pumps,” journal of fluids engineering, vol. 131 / 021103-1, 2009. doi:10.1115/1.3059700 [41] g. cavazzini, g. pavesi, a. santolin, g. ardizzon, and r. lorenzi. “using splitter blades to improve suction performance of centrifugal impeller pumps,” journal of power and energy, vol. 229(3), pp. 309–323, 2015. doi:10.1177/0957650914563364 [42] y. sun-sheng, k. fan-yu, f. jian-hui, and x. ling. “numerical research on effects of splitter blades to the influence of pump as turbine,” hindawi publishing corporation, international http://dx.doi.org/10.21622/resd.2019.05.2.068 http://dx.doi.org/10.1155/2014/923937 http://dx.doi.org/10.1016/j.enconman.2015.01.037 http://dx.doi.org/10.1243/0957650041200632 journal of renewable energy and sustainable development (resd) volume 5, issue 2, december 2019 issn 2356-8569 http://dx.doi.org/10.21622/resd.2019.05.2.068 79 resd © 2019 http://apc.aast.edu journal of rotating machinery, 9 pages, volume 2012. doi:10.1155/2012/123093 [43] k. jin-woo , s. jun-won , c. young-seok , l. kyoung-yong , k. joon-hyung , t. kanemoto, and k. jin-hyuk. “simultaneous efficiency improvement of pump and turbine modes for a counter-rotating type pump-turbine.” advances in mechanical engineering, vol. 8, pp. 1-14, 2016. doi:10.1177/1687814016676680 [44] p. singh, and f. nestmann. “internal hydraulic analysis of impeller rounding in centrifugal pumps as turbines,” elsevier, experimental thermal and fluid science, vol. 35, pp. 121-134, 2010. doi: 10.1016/j.expthermflusci.2010.08.013 http://dx.doi.org/10.21622/resd.2019.05.2.068 http://dx.doi.org/10.21622/resd.2019.05.2.068 http://dx.doi.org/10.21622/resd.2019.05.2.068 journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 81 resd © 2015 http://apc.aast.edu pitch angle control for variable speed wind turbines mouna ben smida, anis.sakly research unit: industrial systems study and renewable energy (esier), key the national engineering school of monastir (enim), university of monastir, av. ibn el jazzar skanes (5019), tunisia. abstract pitch control is a practical technique for power regulation above the rated wind speed it is considered as the most efficient and popular power control method. as conventional pitch control usually use pi controller, the mathematical model of the system should be known well.this paper deals with the operation and the control of the direct driven permanent magnet synchronous generator (pmsg). different conventional strategies of pitch angle control are described and validated through simulation results under matlab\simulink. keywords variable-speed wind turbine; mppt; pitch control; pmsg. nomenclature – pmsg permanent magnet synchronous generator hawt horizontal-axis wind turbines vawt vertical axis wind turbines tsr tip speed ratio mppt maximum power point tracking pwm pulse width modulation pi proportional integral i. introduction traditional energy resources, especially from fossil origins, will break off in the following few decades, which predict an energy shortage in the world. in addition, the energy consumption, in its various forms, increased in an exponential way. to satisfy these needs, it was necessary to solve this problem. actually, there was a simple way to do so, since there were inexhaustible renewable energy resources, which can be easily and properly exploited [1-3]. nevertheless, being neglected for a long time, power extraction techniques of these resources requires more researches and developments aiming to make the manufacturing costs reliable and lower and to increase the energy efficiency [4-5]. in this general context, this study was interested in the wind energy which seems to be one of the most promising energies with a very high rate growth in the world. today, the wind power has become a reality with the increase of the installed power all over the world a significant proportion of this type of energy is available in windy areas. recently, pitch-adjusting variable-speed wind turbines have become the dominating type of installed wind turbines.pitch angle control method is a basic approach to improve the performance of the power generation system including different types of wind turbines. although a wind turbine can be built in either a vertical-axis or horizontal-axis configuration, we focus on horizontal-axis wind turbines (hawts) because they dominate the utility-scale wind turbine market. at the utility scale, hawts have aerodynamic and practical advantages [6]. smaller vertical axis wind turbines (vawts) are more likely to use passive rather than active control strategies. in fact, generally for vertical axis wind turbine, which consists of several blades rotating about axis in parallel direction, the cycloid blade system and the individual active blade control system are adopted. both methods are variable pitch system. for cycloid wind turbine, aerodynamic analysis is carried out by changing pitch angle and phase angle based on the cycloid motion according to the change of wind speed and wind direction. and for more efficient wind turbine, individual pitch angle control of each blade is obtained by maximizing the tangential force in each rotating blade at the specific rotating position, optimal. therefore, generally for the variable-speed wind turbines two controllers are used. below rated value, in low wind speed, the speed controller can continuously adjust the rotor speed to maintain the tip speed ratio constant at the level which gives the maximum power coefficient, so the efficiency of the turbine will be significantly increased. pitch angle regulation is necessary in conditions above the rated wind speed when the rotational speed is kept constant which can have a dramatic effect on the power output. the purpose of the pitch angle control might be expressed as follows [7-8]: http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 82 resd © 2015 http://apc.aast.edu  optimizing the wind turbine power output. below rated wind speed, the pitch setting should be at its optimum value to give maximum power.  preventing the mechanical power input to beat the design limits. above rated wind speed, pitch angle control provides an effective method of regulating the aerodynamic power and loads produced by the rotor.  minimizing fatigue loads of the turbine mechanical component. it is clear that the action of the control system can have a major impact on the loads experienced by the turbine. the design of the controller must take into account the effect on loads, and the controller should ensure that excessive loads will not result from the control action. it is possible to go further than this, and explicitly design the controller with the reduction of certain fatigue loads as an additional objective. in this paper, conventional pitch angle control strategy in which various controlling variables may be used is discussed. ii. wind turbine modeling in order to simulate the behavior of the wind turbine, it is necessary to determine the torque exerted on its shaft.the mechanical power extracted from the wind turbine is expressed by [9-10]: )( 2 31 2 w w p p r v cr p l b= , (1) the power coefficient cp depends on the pitch angle of rotor blades  and the tip speed ratio (tsr)  , with [11]: (2) where: i 3 1 1 0.003 0.02 1 l l b b = + (3) w r v w l = (4) the turbine torque is then defined as the ratio of the mechanical power to the rotational speed: w m p t w = (5) the mechanical speed of the turbine is determined from the fundamental equation of the dynamics as: m em d j t t f dt w w= (6) the wind turbine speed is controlled in order to extract the maximum power from the wind. according to the betz theory, the maximum power extractable from a wind turbine is 59.3% of the available wind power, which corresponds to the betz limit with a power coefficient of 0.593 [12]. for the wind turbine modeled in this study, the curve of cp versus  with b =0, represented in fig. 1, shows an optimum value of the tsr ( opt 8l = ) corresponding to a maximum value of the power coefficient (cpmax =0.473). fig .1. cp versus l curve a. control of the wind generator the control of the generator power is obtained by the control of the pmsg electromagnetic torque tem. the role of the pitch control system is to limit the rotational speed of the shaft, the reference electromagnetic torque tem-ref, can be developed in this method [13]: the strategy of an operating at maximum power, goals to develop the turbine aerodynamic output, aiming to extract the maximum of wind power derived when the turbine operates at maximum power coefficient. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 83 resd © 2015 http://apc.aast.edu equation 7 gives the expression of the maximum power obtained using the maximum power point tracking (mppt) strategy which adjust automatically the ratio speed at its optimum value , opt l , in order to attain the maximum power coefficient cpmax, the equation below indicates the relationship between turbine power and turbine speed at maximum power. when regulating the system under the specification of maximum power, it must be considered that turbine power must never be upper than generator rated power. the output power must be limited when generator rated power is attained at rated wind speed. 3 mppt opt p k  (7) 5 max 3 1 2 p opt opt r c k r p l = (8) in the case of high wind, it is necessary to limit the rotational speed to avoid the damage of the turbine and the electric machine. this limitation is obtained by the control of the pitch angle  . fig .2. turbine model b. wind turbine operating regions the typical power control regions of wind turbine are shown in figure 3. three wind speeds are considered as limits of this division, the cut-in wind speed vcut-in, the rated wind speed vrated and the cut-out wind speed vcut-out. for the wind turbine model considered in this study the values of vcut-in, vrated and vcut-out respectively are 6m/s, 10m/sand 13m/s. in region i, the wind turbine is at stop state and the pitch angle usually is set to90°. in the partial load region, region ii, the wind speed is limited between vcut-in and vrated. the main objective of the control in this region is maximizing power generated by the wind turbine. the principle control objective in the full load region, region iii, is maintaining the generator power g p around the rated generator power g rated p , . in fact, in the case of high wind, it is necessary to limit the rotational speed to avoid the damage of the turbine and the electric machine. this limitation is obtained by the control of the pitch angle b .in region iv where the wind speed is upper than vcut-out, the wind turbine must be shut down in order to protect wind turbine against the stresses and fatigue damages. in this case, the pitch angle usually is set to 90° and power generation is stopped. the focus of this paper is on full load region (region iii) to design an optimal pitch controller. fig .3. wind turbine operating regions iii. pitch angle control the pitch control method is a basic approach for controlling the rotational speed of wind turbine. the conventional blade pitch angle control strategies are developed in this part. the pitch angle reference ref b , is controlled by the input values, which may be as follows:  wind speed, as shown in fig. 5(a). perfectly, the pitch angle reference can be illustrated from the curve of the pitch angle versus wind speed, as shown in fig.3. the direct measure of the wind speed makes this control strategy simple; however this is not a pertinent procedure, because it is difficult to measure the wind speed precisely.in fact, when the rotor speed exceeds the maximum rotor speed of turbine ωtn, the pitch angle is increased to reduce the turbine torque ct. 0 5 10 15 0 1 000 2 000 3 000 3 600 4000 w ind speed (m/s) p o w e r (w ) v ratedvcut-in vcut-out http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 84 resd © 2015 http://apc.aast.edu fig .4. reference pitch angle  generator rotor speed, as shown in fig. 5(b). the controlling rotor speed is compared with its reference. the error signal is then sent to the pi controller and produces the reference value of the pitch angle.  generator power, as shown in fig. 5(c). the error signal of the generator power is sent to a pi controller. the pi controller produces the reference pitch angle ref b . for variable-speed wind turbines, a mechanical actuator is generally used to adjust the pitch angle of the blades in order to decrease the power coefficient cp and maintain the power at its rated value. by linearization of the model to order 1 [14-16], the torque has been considered proportional to rotational speed of the turbine. the control strategy implemented is as follows: (9) with is the initial pitch angle (optimal value) and (rad/s) is the nominal mechanical turbine speed. taking into account the blades orientation system which can be hydraulic or electric type, a transfer function of the first order is introduced in order to control the position of the blades according to a reference. 1 1 ref b s b b t = + (10) (a) (b) (c) fig .5. pitch control strategy.(a) wind speed; (b) generator rotor speed; (c) generator power iv. permanentmagnetic synchronous generator and rectifier a. modeling of the pmsg in this study a pmsg park model is used, only the fundamental harmonic of the flux distribution in the airgap of the machine is considered and the homopolar component is neglected, so the theory of the space vector gives the dynamic equations of the stator currents as follows: (11) where the phase resistance of the stator winding (ω), the stator cyclic inductance (h), φ is is the flux of the permanent magnetic (wb), sdv and sqv are the d-q components of the stator voltages respectively (v), sd i and sq i are the d-q components of the stator currents respectively (a), and finally p is the number 0 2 4 6 8 10 -2 0 2 4 6 8 10 12 wind speed(m/s) r e fe re n c e p it c h a n g le (° ) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 85 resd © 2015 http://apc.aast.edu of pairs of poles the electromagnetic torque is given by: em sq c pφi= (12) b. modeling of the rectifier for the dynamic model of the system, we will divide the study of the converter to three parts: the alternative part, the discontinuous part which is composed by switches and the dc side. in this context, the function of switches is to establish a connection between the ac side and the dc bus; these switches are complementary, their state is defined by the following function: for s=a,b,c (13) then, the input phase voltages and the output current may be written in function of sj, udc and input currents ia, ib, ic. ba c i i i 0+ + = (14) the phase between the input pwm rectifier voltages can be described by: ( ). ( ). ( ). sab a b dc sbc b c dc sca c a dc u s s u u s s u u s s u = = = (15) the voltage equations of the system can be written as follows: (16) avec: 2 . 3 2 . 3 2 . 3 a b c sa dc b a c sb dc c a b sc dc s s s u u s s s u u s s s u u = = = (17) finally, we deduce the equation coupling between ac and dc sides by: dc a a b b c c du c s i s i s i dt = + + (18) fig .6. diagram of msappwm rectifier c. control for variable-speed wind turbine, the maximum power is a cubic function of rotational speed. the development of the generator torque is based on the stator q-axis current component, but a freedom degree remains to set direct current. in order to minimize current for a given torque, and therefore, minimize resistive losses the direct-axis current component can be set at zero [17]. thus, the control of the generator torque depends directly of the quadrature current component. the schematic diagram of the control loops of the permanent-magnet generator-side converter is illustrated on fig. 7.the required d–q components of the rectifier voltage vector are determinate from two proportional plus integral (pi) current controllers: the first one is controlling the d-axis component of the current and the other one is controlling the q-axis component. in order to improve the dynamic response, compensation terms are added.the control requires the measurement of the stator currents, dc voltage, and rotor position. fig .7. pmsg and converter control http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 86 resd © 2015 http://apc.aast.edu 0 50 100 150 200 250 300 7 8 9 10 11 12 time (seconds) w in d ( m /s ) 0 50 100 150 200 250 300 0.25 0.3 0.35 0.4 0.45 0.5 time (seconds) p o w e r c o e f f ic ie n t 0 50 100 150 200 250 300 -2 0 2 4 6 8 time (seconds) pi tc h an gl e (° ) power regulator rotor speed regulator wind curve method d. simulation results and discussion pitch angle control systems of the wind turbine were simulated using matlab/simulink tool to test the control strategy and evaluate the performance of the system. the wind model is necessary to obtain realistic simulations of the power control of the wind turbines [18]. during 300 s, we have applied to the wind turbine model a variable wind profile between 6 and 12 m/s with an average value of 10 m/s. this sequence is obtained by adding a turbulent component to a slowly varying signal represented in fig.8. fig .8. wind speed fig .9. output power fig .10. mechanical speed fig .11. pitch angle curve fig .12. power coefficient fig .13. electromagnetic torque the wind turbine is dimensioned to provide a nominal power at a nominal speed of 10 ms-1. beyond this wind, it is necessary to protect the wind turbine against mechanical failures; therefore, we must limit its speed. this limitation will be obtained by a pitch control. the mechanical speed of the turbine represented in fig. 10 is obtained next to the variation of the pitch angle illustrated in fig. 11. the more the pitch angle increases, the more the power coefficient decreases (fig. 12). the comparisons of different strategies illustrated in the simulation results show that pitch angle control strategy where the generator power is used as the controlling variable has a rapid pitch angle respond to the wind speed variation and minimum power ripples. 0 50 100 150 200 250 300 0 1000 1500 2 000 2500 3 000 3500 4 000 time (seconds) po we r ( w) power regulator rotor speed regulator curve method 100 200 300 3595 3600 0 50 100 150 200 250 300 100 110 120 130 140 150 160 time (seconds) s p e e d (r a d /s ) 0 50 100 150 200 250 300 0 5 10 15 20 25 time (seconds) e le c tr o m a g n e ti c t o rq u e s ( n .m ) tem tem ref http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 87 resd © 2015 http://apc.aast.edu the response of the second strategy where rotor speed is used as the controlling variable has a squared error evaluated of 0.79 and the error of the response obtained next to the wind curve pitch control method is evaluated of 0.95, these results highlight the robustness of the strategy of the generator power controller. v. conclusion in order to handle the pitch control in wind turbines, in this paper conventional methods are proposed. in fact, pitch angle control has an effect on the aerodynamic loads which may be controlled by the controller to achieve lower torque peak as well as lower fatigue loads.the simulation results show that the power controller has lower torque peak and lower power peak. references [1] lior, n. (2008) energy resources and use: the present situation and possible paths to the future, energy, 33(6): pp. 842-57. [2] lund, p.d, (2009) effects of energy policies on industry expansion in renewable energy, renew energy, 34(1): pp. 53-64. [3] østergaard p.a, (2009) reviewing optimization criteria for energy systems analyses of renewable energy integration, energy, 34(9):1236-45g. [4] w en, j., zheng, y., donghan, f. (2009) a review on reliability assessment for wind power, renew sustain energy review, 13(9): pp. 2485-94. [5] chowdhury m.a, hosseinzadeh n, shen w.x. (2012) smoothing wind power fluctuations by fuzzy logic pitch angle controller. renewable energy; 38: pp. 224-233. [6] pao, l. y., and johnson, k. e. (2011) control of wind turbines: approaches, challenges and recent development, ieee control systems magazine april. [7] duong, m.q., grimaccia, f., leva, s., mussetta, m., and ogliari, e. (2014) pitch angle control using hybrid controller for all operating regions of scig wind turbine system. renewable energy, 70:pp. 197203. [8] suryanarayanan, s. (2005) a. dixit, control of large wind turbines: review and suggested approach to multivariable design, proc. of the american control conference, portland, usa, pp. 686-690. [9] firdaus, a. a. (2014) design and simulation of neural network predictive controller pitchangle in permanent magnetic synchronous generator wind turbine variable pitch system. in information technology, computer and electrical engineering (icitacee), 1st international conference on (pp. 346-350). ieee. [10] yuan, x., & li, y. (2013) control of variable pitch and variable speed directdrive wind turbines in weak grid systems with active power balance. iet renewable power generation, 8(2), pp. 119-131. [11] w ang, z., cai, c., & jia, k. (2013, july). neural network adaptive control for constant output power of variable pitch wind turbine. in vehicular electronics and safety (icves), 2013 ieee international conference on (pp. 165-170). ieee. [12] muhando, e.b., senjyua, t., urasakia, n., yonaa, a. k,,and funabashi, t. (2007) gain scheduling control of variable speed wtg under widely varying turbulence loading, renew energy;32(14): p.2407 [13] courtecuisse,v. supervision d’une centrale multisources a base d’éoliennes et de stockage d’énergie connectée au réseau electrique. [14] leclercq, l. (2004) apport du stockage inertiel associé a des eoliennes dans un réseau electrique en vue d’assurer des services systèmes thèse de doctorat : génie electrique : université des sciences et technologies de lille, villeneuve d’asq, , 171 p, n°3563. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 88 resd © 2015 http://apc.aast.edu [15] melício r, mendes, v.m.f., catalão j.s. (2011) transient analysis of variablespeed wind turbines at wind speed disturbances and a pitch control malfunction, applied energy; vol.88; pp.1322-1330 [16] rodriguez-amenedo, j. l., arnalte, s. et burgos, j. c. automatic generation control of wind farm with variable speed wind. [17] kesraoui m, korichi n, belkadi a. (2011) maximum power point tracker of wind energy conversion system. renewable energy; 36: pp. 2655-2662. [18] xing g. (2011) research on application of fuzzy pid in collective pitch control system. control, automation and systems engineering (case): pp. 1–4. appendix  wind turbine dry friction torque : cs = 953 nm number of blades : 3 viscous friction coefficient : f = 10-3n.m.s.rad-1 total inertia of the mechanical transmission: j =99 10-4 kg.m2  pmsg nominal power: pn = 3.6kw number of pole pairs: p=4 self-inductance: ls = 15.1 mh permanent magnetic flux: φa = 0.5 nm/a stator resistance: rs = 0.82ω http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 236 modeling and simulation of a wind turbine driven induction generator using bond graph a. ramdane *, a. lachouri *, m. krikeb * *team leader in automatic laboratory, electrical engineering department, faculty of technology, university of 20 august 1955, skikda. 21000, algeria, id, 83844-1133, usa., e-mail: adlene_soft2005@yahoo.fr, alachouri@yahoo.fr, krikeb@yahoo.fr abstract this paper deals with the modelling and simulation of wind turbine driven by induction generator. usually in mechatronic systems, several types of energy are involved. by its nature of a power conserving description of a system, the bond-graph method is especially practical when several physical domains have to be modeled within a system simultaneously. this is certainly the case in wind turbine systems where mechanical and electrical systems in several combinations are present. this work presents an implementation of the wind turbine model in bond graph approach. simulation results are carried out by means of simulation in 20-sim software environment. keywords wind turbine, modelling, bond graph, induction generator. i. introduction energy consumption has increased considerably in recent years with the technology evolution. this has increased the demand for fossil fuels and has made firstly, electrical energy more expensive and secondly, the fossil fuels have a several disasters on the environment protection by the emissions of greenhouse gases and undesired particles into the atmosphere. because of such reasons, it is necessary to focus on other forms of energy production to meet the growing needs of today's world. furthermore, the wind energy, being one as an efficient source of alternative and cleanest sources of electricity, has emerged as one of the most preferred sources for electricity generation. the wind energy is the kinetic energy of the flowing air mass per unit time. therefore, when performing wind power integrated network planning or analysis of the operation, the engineers have put a lot of effort in modelling the wind rather than focusing on the problem itself. thus, a wind model compatible with the analytical tools of commercial power system is in imminent need. in electromechanical engineering, the global analysis of systems is difficult because of their heterogeneity and their multi-domains nature. nevertheless, this system approach is essential because it underlines couplings between elements of different physical fields. to facilitate this analysis, the unified formalism bond graph is used. this modelling method illustrates the energetic transfers in the system. moreover, this methodology offers interesting solutions in terms of system analysis. much research has been done on the modelling and control of wind turbines [2], [4], [6] and [7]. most of this research has been done using simple wind mechanical and aerodynamic models that overlook a number of important features. research on wind turbines based on more sophisticated mechanical and aerodynamic models was made only with relatively simple models of electric generator, its controllers, and model of the power system. this is because most researchers who have studied the wind power, they are focusing on aspects either electrical or mechanical part, without paying attention to the operation of the complete electromechanical system. there are many types of wt models, ranging from single mass, one state model to multiple mass models. in a simulation point of view, it is desirable that the model is as simple as possible and can capture as much of the dynamics that appear in reality. in this context, our study is interested in the wind turbine system. this document is based on modelling and simulation method with bond graph (bg) applied to the wind turbine driven by generator induction. this method becomes a powerful tool when the complex interaction of subsystems of different types should be evaluated. the paper is organised as follows: the section 2 gives a brief introduction on bond graph methodology then, on finds in section 3 a modelling of different parts of wind turbine system and their journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 237 bond graph in 20-sim software is presented. in section 4 is illustrated the simulation results and theirs discuss. a conclusion is given at the end of this paper. ii. bond graph a. bond graph methodology the methodology of the bond graph modelling is based on the characterization of power exchange phenomena within a system. the idea of the bond graph modelling is the representation of dissipated power as the product flow and effort to bind the various junctions to reproduce the system. the bond graph is a powerful tool in modelling systems; especially in cases where subsystems of different physical character (mechanical, electrical, thermal, hydraulic …) are interact. the exchange of energy between the subsystems of a more complex system in bond graph modelling is of an essential significance. bond graph is therefore a directed graph whose nodes represent subsystems and arrows the transfer of energy between the subsystems. b. bond graph elements in bg modelling, there are a total of nine different elements. we will first present the basic elements of bg and introduce the causality assignments. source element: there are two type of 1-ports source: the effort source and the flow source. in each case, an effort or flow is assumed to be maintained constant independent of the power supplied; the constitutive relation and causality is showing in fig.1. fig .1. sources elements resistive element: is an element in which the effort and flow variables at the single port are related by a static function fig2. inertia element: the inertia port corresponds to the electrical inductors, the momentum p is related the flow f. there are two choices for the causality assignment for the i-element fig2. compliance element: is an element that relates effort e and displacement q. the power flows into the port and a sign convention similar to that used for the resistor is adopted fig.2. fig .2. resistance, inertia and compliance elements transformer and gyrator: the transformer and gyrator can work in two ways; transformer transforms a flow to another flow or an effort to another effort. the gyrator transforms a flow into an effort or transforms the effort into a flow. fig .3. transformer and gyrator elements junctions: there are two different types of junctions that connect the different parts in bg, the 0-junction and 1-junction. junctions are power conserving at each instant and the power transport of all bonds add up to zero at all times. the junction elements represent the two types of connections, which, in electrical terms, are called the series, and parallel connections iii. model description fig .4. wind turbine model description in this section, the dynamic simulation model is described for the proposed wind turbine energy conversion. the block diagram of the integrated overall system is shown in fig.4. afterwards, each sub-model of the wind turbine is presented and journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 238 combined to obtain a complete model of the wind turbine. the all parts of system modelling in 20-sim software is showing in fig.5. fig .5. system parts modelling in 20-sim software a. aerodynamic model wind turbine electrical generation systems power comes from the kinetic energy of the wind. thus, it can be expressed as the kinetic power available in the stream of air multiplied by a cp factor called power coefficient or betz’s factor. the cp mainly depends on the relation between the average speed of the air across the area covered by the wind wheel and its angular speed and geometric characteristics of the turbine. the power extracted by the wind turbine has the following expressions [2]:. 𝑃𝑤 = 1 2 .𝜌.𝐴.𝐶𝑝.𝑉𝑊 3 (1) 𝐴 = 𝜋.𝑅3 (2) where 𝑃𝑤 is the air stream kinetic power, ρ the air density assumed to be constant, 𝐴 is the surface covered by the wind wheel and 𝑉𝑊 the average wind speed. the power that wind turbine can catch from wind is: 𝑇𝑊 = 𝑃𝑤 ω (3) there have been different approaches to model the power coefficient ranging from considering it to be constant for steady state and small signal response simulations to using lookup tables with measured data. another common approach is to use an analytic expression [2]: 𝐶𝑝 = 0.22( 116 𝜆′ − 0.4𝛽 − 5)𝑒 −12.5 𝜆′ (4) with: 1 𝜆′ = 1 𝜆+0.08𝛽 − 0.035 𝛽3+1 (5) where λ is so called tip-speed ration and it is defined as λ = ω𝑅 𝑉𝑤 (6) and β is the pitch angle. fig .6 power coefficient of wind turbine in general the 𝐶𝑝 coefficient is represented by the graph which depends on the tip-speed ratio λ and the pitch angle β. the bond graph of aero-dynamical part of wind turbine model implemented in 20-sim software from [4] is show in fig.4. fig .7 the bloc diagram model of aero-dynamical part of wind turbine model in 20-sim software b. mechanical part the mechanical part of the wind turbine system includes all the mechanical elements of systems (blades, lock rotor, shafts, speed multiplier (gear box) journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 239 ... etc.).this multiplier is modelled mathematically in [3] for the following equations: 𝑪𝒓 = 𝑻𝒎 𝑮 (7) 𝛀𝒕𝒖𝒓𝒃𝒊𝒏𝒆 = 𝛀𝒎𝒆𝒄 𝑮 (8) g: the speed multiplier gain 𝑱 = 𝑱𝒕𝒖𝒓𝒃𝒊𝒏𝒆 𝑮𝟐 + 𝑱𝒓 (9) the fundamental equation of dynamics used to determine the evolution of the mechanical speed from the total mechanical torque (𝑪𝒎𝒆𝒄) applied to the rotor: 𝑱 𝒅𝛀𝒎𝒆𝒄 𝒅𝒕 = 𝑪𝒎𝒆𝒄 (10) 𝐽 the total inertia appears on the generator rotor. the mechanical torque depends on the electromagnetic torque (𝑪𝒆𝒎) produced by the generator, the torque of viscous friction (𝑪𝒗𝒊𝒔) and load torque (𝑪𝒓). 𝑪𝒎𝒆𝒄 = 𝑪𝒓 − 𝑪𝒆𝒎 − 𝑪𝒗𝒊𝒔 (11) the viscous torque is modelled by. 𝑪𝒗𝒊𝒔 = 𝒇.𝜴𝒎𝒆𝒄 (12) 𝒇: is the viscous friction coefficient. c. three masses model the equivalent model of a wind turbine drive train is presented in fig 6. the masses correspond to a large mass of the wind turbine rotor, masses for the gearbox wheels and a mass for generator respectively. fig 6. three-mass model of a wind turbine drive train. the inertia of the low-speed shaft also includes the inertia of the rotor, while the friction component includes bearing frictions. the dynamics of the lowspeed shaft is: 𝑻𝒘𝒕 − 𝑻𝟏 − 𝑩𝒘𝒕𝛀𝒘𝒕 = 𝑱𝒘𝒕 𝒅𝛀𝒘𝒕 𝒅𝒕 (13) where: 𝐵𝑤𝑡 is the viscous friction of the low-speed shaft [nm/(rad/s)], 𝐽𝑤𝑡 is the moment of inertia of the low-speed shaft [kgm2], 𝑇𝑤𝑡 is the torque acting on the low-speed shaft [nm], 𝜃𝑤𝑡 is the angle of the low-speed shaft [rad], the inertia of the high-speed shaft also includes the inertia of the gearbox and the generator rotor. the friction coefficient covers bearing and gear frictions. the dynamics of the high-speed shaft is: 𝑻𝒉 − 𝑻𝒈𝒆𝒏 − 𝑩𝒈𝒆𝒏𝜴𝒈𝒆𝒏 = 𝑱𝒈𝒆𝒏 𝒅𝜴𝒈𝒆𝒏 𝒅𝒕 (14) where: 𝐵𝑔𝑒𝑛: the viscous friction of the high-speed shaft [nm/(rad/s)]; 𝐽𝑔𝑒𝑛 : the inertia moment of the high-speed shaft [kgm 2]; 𝑇𝑔𝑒𝑛 : the generator torque [nm]; 𝑇ℎ : the torque acting on the high-speed shaft [nm]; 𝜃𝑔𝑒𝑛 : the angle of the high-speed shaft [rad]; the remaining part of the gearbox modeling is to apply a gear ratio, as defined below. 𝑻𝒉 = 𝑻𝟏 𝑲𝒈𝒆𝒂𝒓 (15) 𝐾𝑔𝑒𝑎𝑟 is the drive train gear ratio. the torsion of the drive train is modelled using a torsion spring and a friction coefficient model, described according to: 𝑻𝟏 = 𝑲𝒘𝒕𝜽∆ + 𝑫𝒘𝒕�̇�∆ (16) 𝜽∆ = 𝜽𝒓 − 𝜽𝒈𝒆𝒏 𝑲𝒈𝒆𝒂𝒓 (17) where: 𝐷𝑤𝑡 is the viscous friction of the low-speed shaft [nm/(rad/s)] 𝐾𝑤𝑡 is the torsion stiffness of the drive train [nm/rad] 𝜃∆is the torsion angle of the drive train [rad] 𝑻𝟏(𝒕) = 𝑲𝒘𝒕 (𝜽𝒓 − 𝜽𝒈𝒆𝒏 𝑲𝒈𝒆𝒂𝒓 ) + 𝑫𝒘𝒕 (𝜴𝒘𝒕 − 𝜴𝒈𝒆𝒏 𝑲𝒈𝒆𝒂𝒓 ) (18) after simplification and substituting equations obtains journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 240 { 𝑱𝒘𝒕 𝒅𝛀𝒘𝒕 𝒅𝒕 = 𝑻𝒘𝒕 − 𝑲𝒘𝒕 (𝜽𝒓 − 𝜽𝒈𝒆𝒏 𝑲𝒈𝒆𝒂𝒓 ) − (𝑫𝒘𝒕 + 𝑩𝒘𝒕)𝛀𝒘𝒕 + 𝑫𝒘𝒕 𝑲𝒈𝒆𝒂𝒓 𝛀𝒈𝒆𝒏[𝑵𝒎] 𝑱𝒈𝒆𝒏 𝒅𝛀𝒈𝒆𝒏 𝒅𝒕 = 𝑲𝒘𝒕 𝑲𝒈𝒆𝒂𝒓 (𝜽𝒓 − 𝜽𝒈𝒆𝒏 𝑲𝒈𝒆𝒂𝒓 ) + 𝑫𝒘𝒕 𝑲𝒈𝒆𝒂𝒓 𝛀𝒘𝒕 − ( 𝑫𝒘𝒕 𝑲𝒈𝒆𝒂𝒓 + 𝑩𝒈𝒆𝒏)𝛀𝒈𝒆𝒏 − 𝑻𝒈𝒆𝒏[𝑵𝒎] �̇�∆ = �̇�𝒘𝒕 − �̇�𝒈𝒆𝒏 𝑲𝒈𝒆𝒂𝒓 [𝒓𝒂𝒅 𝒔⁄ ] (19) three first order differential equations have been derived in this section in order to describe the behavior of the drive train. in the next section, the effect on the tower from the aerodynamic thrust is considered. bond graph bloc diagram model of three masses system is showing in fig.8. fig 8. multi masses system model d. electrical part the generator used for the wind system is an asynchronous squirrel-cage generator whose parameters are quoted in table1. the model of the asynchronous machine is deduced from the twophase machine by supposing that the variables are expressed in a reference frame x-y turning at the speed of the electric field. the results obtained by simulation illustrate the behaviour of this generator and give the par values of operation. the induction machine equations are [2]: { 𝑈𝑠𝑥 = 𝑅𝑠𝐼𝑠𝑥 + 𝑆ψ𝑆𝑋 − 𝜔𝑆. ψ𝑆𝑌 𝑈𝑠𝑦 = 𝑅𝑠𝐼𝑠𝑦 + 𝑆ψ𝑆𝑦 − 𝜔𝑆. ψ𝑆𝑥 0 = 𝑅𝑟𝐼𝑟𝑥 + 𝑆ψ𝑟𝑥 − (𝜔𝑆 − 𝜔𝑟)ψ𝑟𝑦 0 = 𝑅𝑟𝐼𝑟𝑦 + 𝑆ψ𝑟𝑦 − (𝜔𝑆 − 𝜔𝑟)ψ𝑟𝑥 𝐶𝑒 = 𝑃. 𝐿𝑠𝑟(𝐼𝑠𝑦. 𝐼𝑟𝑥 − 𝐼𝑠𝑥. 𝐼𝑟𝑦) ψs = ls. is + lsr. ir ψr = lr. ir + lsr. is (20) this system can be presented as follows: { 𝑆ψ𝑠𝑥 = 𝑈𝑠𝑥 − 𝑅𝑠. 𝐼𝑠𝑥 + 𝜔𝑠. ψ𝑠𝑦 𝑆ψ𝑠𝑦 = 𝑈𝑠𝑦 − 𝑅𝑠. 𝐼𝑠𝑦 + 𝜔𝑠. ψ𝑠𝑥 𝑆ψ𝑟𝑥 = 𝑅𝑟. 𝐼𝑟𝑥 + (𝜔𝑆 − 𝜔𝑟)ψ𝑟𝑦 𝑆ψ𝑟𝑦 = 𝑅𝑟. 𝐼𝑟𝑦 + (𝜔𝑆 − 𝜔𝑟)ψ𝑟𝑥 𝐶𝑒 = 𝑃. 𝐿𝑠𝑟(𝐼𝑠𝑦. 𝐼𝑟𝑥 − 𝐼𝑠𝑥. 𝐼𝑟𝑦) 𝐼𝑠 = lr.ψs+lsr.ψr ls.lr−lsr 2 𝐼𝑟 = ls.ψr+lsr.ψs ls.lr−lsr 2 (21) 𝑈𝑆𝑋 ,𝑈𝑠𝑦 : the stator voltage components expressed in x-y reference. 𝐼𝑆𝑋 , 𝐼𝑠𝑦 : the stator current components expressed in x-y reference. 𝑅𝑆 : stator resistance; 𝑅𝑟 : rotor resistance; 𝐿𝑆 : stator inductance; 𝐿𝑟 : rotor induction; 𝐿𝑆𝑟 : mutual inductance; 𝑃 : number of pole pairs; 𝐶𝑒 : electromechanical torque; 𝜔𝑆 : speed of the electric field; 𝜔𝑟 : electric rotor speed; the bond graph of induction machine in 20-sim software using library developed in [5] is showing in fig.9. fig 9. induction generator bond graph model iv. simulation results simulation step is done on a specific bond graph software 20-sim, which is an object oriented hierarchical modelling software. it allows users to create models using bond graph, block-diagram and equation models. a list of numerical values of wind turbine system parameters used in this simulation is presented in table-1. ce omega2 omega1 omega3 constant1 1 0.00875 s linearsystem2 1 0.004375 s linearsystem1constant2 constant3 20 s linearsystem3 k gain 1 0.004375 s linearsystem4 20 s linearsystem5 k gain1 journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 241 table 1. model parameters nominal power pn=180kw rotor diameter d=23.2m rotor speed ω=42tr/min multiplier coefficient 23.75 number of blades 3 air density ρ=1kg/m3 turbine moment inertia jt=102,8kgm 2 generator moment inertia jg=4,5kgm 2 rigidity coefficient k12=2700nm/rad damping coefficient b12=0.1nms/rad number of pairs p=3 stator resistance rs=0.0092ω rotor resistance rr=0.0061ω stator mutual inductance lls=186μh (ls= lls+ lm) rotor mutual inductance llr=427μh (lr= llr+ lm) magnetizing inductance lm=6.7mh (lsr= lm) the fig.5 shows all parts of system modelling implemented in 20-sim software. the fig.6 presents the power coefficient 𝐶𝑝 evolution function of tipspeed ration (λ). through this figure, we can easily see that the evolution of the 𝐶𝑝 retrieve its maximum at the 𝜆𝑜𝑝 = 3. the fig.7 illustrated a bond graph bloc diagram model of aero-dynamical part of wind turbine and fig.8 presents a bond graph of multi mass model under 20-sim software. the fig.9 depicts induction generator bond graph model. the fig.10 and fig.11 show the mechanical power and torque curves respectively of the wind turbine. they occur the maximum point at the 𝜆𝑜𝑝 = 3 . the fig.12 shows the power coefficient with blade pitch 𝛽 and its maximum value at 𝜆𝑜𝑝 = 3. with regard to the instantaneous torque (fig.13), we can indicate the presence of oscillations in magnitude for a very short time at start up, and then these oscillations are cleared. figures (fig.14-16) show the curves velocities of multi-mass model. they have strong oscillations during the transient regime during 0.02s, and converse to its nominal speed at 157rad /s. fig 10. mechanical power in 20-sim software fig 11. mechanical torque in 20-sim software fig 12. power coefficient fig 13. torque characteristic fig 14. first mass speed fig 15. second mass speed 0 2 4 6 8 10 12 14 lamda 0 50000 100000 150000 200000 pm(w) 0 0.5 1 1.5 2 2.5 3 time {s} -10 0 10 20 30 ce (n.m) 0 0.5 1 1.5 2 2.5 3 time {s} 0 50 100 150 200 omega3(rad/s) 0 0.5 1 1.5 2 2.5 3 time {s} 0 50 100 150 200 omega1(rad/s) journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 242 fig 16. third mass speed v. conclusion in this paper, a power conversion system was studied with a “system viewpoint methodology” by using a bond graph technique. however, the different fields of energy conversion, the nonlinearity and the different dynamics of the system involve the use of a global unified formalism for studying the global system. the software ‘‘20-sim’’ permit to implemented the bond graph system model’s. the simulation results from this approach confirm one of the benefits of bg as a generally usable approach to modelling mechatronic systems and offers interesting solutions in terms of system diagnosis and analysis. references [1] a.djeziri, r. merzouki, b. ould bouamama, g. dauphin-tanguy. ‘bond graph model based for robust fault diagnosis’ ieee, 2007, 1-42440989-6/07. [2] sanae rechka, gillesroy, sébastien dennetiere et jean mahseredian,’modélisation de systèmes électromécanique multi-masses à base de machines asynchrones, à l’aide des outils matlab et emtp,avec application aux éoliennes ,juillet 2004. [3] f. kendouli, k. nabti, k. abed et h. benalla,’ modélisation, simulation et contrôle d’une turbine éolienne à vitesse variable basée sur la génératrice asynchrone à double alimentation ‘ revue des energies renouvelables vol. 14 n°1 (2011) 109 – 120. [4] j.g. slootweg, s.w.h.h polinder and w.l. king, ‘general model for representing variable speed wind turbines in power systems dynamics simulations’, ieee transaction on power system, vol 18, no. 1, february 2003, pp. 144-151. [5] sergio junco, gonzalo dieguez, facundo ramirez, ‘ une librairie 20-sin pour la simulation basée bond graphs de système de commande des machines électrique ‘cifa_2008_t18-i-070338. [6] lucian mihet-popa, frede blaabjerg, ion boldea,’ wind turbine generator modeling and simulation where rotational speed is the controlled variable’,ieee transactions on industry applications, vol. 40, no. 1, january/february 2004. [7] b. chittibabu , k.b. mohanty,’ doubly-fed induction generator for variable speed wind energy conversion systemsmodeling & simulation', international journal of computer and electrical engineering, vol. 2, no. 1, february, 2010 ,1793-8163. [8] tore bakka and hamid reza karimi,’ wind turbine modeling using the bond graph’, 2011 ieee international symposium on computeraided control system design (cacsd),part of 2011 ieee multi-conference on systems and control denver, co, usa. september 28-30, 2011. 0 0.5 1 1.5 2 2.5 3 time {s} 0 50 100 150 200 omega2(rad/s) journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 01 resd © 2015 http://apc.aast.edu power electronics and renewable energy systems – a perfect match for a sustainable society prof. frede blaabjerg the energy consumption is steadily increasing very rapid due to more people on the earth, better living conditions as well as we are trying to live in areas where the energy demand is high. the economy growth in the last century has not been possible without low prize of energy which has been achieved by fossil fuels. looking into the future – the fossil fuel resources have a time limit – which can appear faster than expected – both because of the limited resources but also because the market can suddenly increase the prize. therefore there is a demand to come up with sustainable energy solutions for energy production like wind turbines, hydro power as well as photovoltaics. at the same time it is evident that by the use of new technology it is possible to make energy saving. in both situations power electronics are making this possible – we are using power electronics to interface renewable sources to maximize the energy yield from wind turbines and photovoltaics as well as smoothly integrate it to the grid. also in many applications we use power electronics to interface a load with the grid and control the behavior of the electrical equipment according to the demand. in many cases power electronics is able to ensure a large amount of energy saving like in pumps, compressors as well as in ventilation systems. also the transportation gain a lot of using electricity instead of fossil fuel – clearly made possible due to the power electronics. denmark is one of the societies which have been the frontier of implementing the renewable technology and has today covered more than 50 % of the electrical energy consumption by means of renewable and has as ambition to be fully independent on fossil fuels in 2050. already in 2035 100 % of the electricity will be covered by renewables. at the same time the energy consumption has not really increased for 20 years despite the gdp has grown by more than 60 % much is enabled by energy efficient technologies based on power electronics. so renewables and power electronics are a perfect tool for a sustainable society. about prof. frede blaabjerg frede blaabjerg (s’86–m’88–sm’97–f’03) was with abb-scandia, randers, denmark, from 1987 to 1988. from 1988 to 1992, he was a ph.d. student with aalborg university, aalborg, denmark. he became an assistant professor in 1992, an associate professor in 1996, and a full professor of power electronics and drives in 1998. his current research interests include power electronics and its applications such as in wind turbines, pv systems, reliability, harmonics and adjustable speed drives. he has received 15 ieee prize paper awards, the ieee pels distinguished service award in 2009, the epepemc council award in 2010, the ieee william e. newell power electronics award 2014 and the villum kann rasmussen research award 2014. he was an editor-in-chief of the ieee transactions on power electronics from 2006 to 2012. he has been distinguished lecturer for the ieee power electronics society from 2005 to 2007 and for the ieee industry applications society from 2010 to 2011. he is nominated in 2014 by thomson reuters to be between the most 250 cited researchers in engineering in the world. he has more than 1000 publications and more than 37000 citation in google scholar. journal of renewable energy and sustainable development (resd) volume 7, issue 2, december 2021 issn 2356-8569 http://dx.doi.org/10.21622/resd.2021.07.2.043 43 http://apc.aast.edu analysis of the economic viability of the installation of a photovoltaic system at jorge de abreu regional hospital in sinop-mt matheus holzbach *¹, carla carol silva e carvalho ¹, adriana sousa rezende ¹ ¹ faculty of exact and technological sciences, university of mato grosso state, sinop, brazil e-mail: matheus.holzbach@unemat.br renewable energy sources are emerging technologies on the current world stage that have become a sustainable alternative for the production of electricity. it is estimated that renewable energies already occupy about 83% of the brazilian energy matrix, according to the speech of the secretary of energy planning and development of the ministry of mines and energy, reive barros [10]. although energy sources that use fossil resources, such as oil, have large stocks, they are not renewable yet, not to mention the significant degradation of the environment they cause. due to this, the sources with unlimited resources have been gaining prominence in the market, because in extension to the guarantee of not being resources that will be exhausted in nature, they are still relatively clean, decreasing the negative impacts to the environment. one of the most widespread examples today is photovoltaic energy, which through a system of capturing solar rays through photovoltaic cells, is able to convert the irradiation collected into electric current by means of the so-called photovoltaic effect, thus supplying energy to the consumer unit in which it was installed. in this type of system, the energy produced can be connected to the network, configuring the system as on-grid, or it can be stored in stationary batteries, configuring the system as offgrid [20]. in the system connected to the network, the conceived energy is lowered in the energy account and the surplus generation is converted into credits for the consumer, and can be used in up to 60 months, in an agreement with the contracted concessionaire, this is known as the system of “solar energy credits” regulated by aneel (national electric energy agency), for captive consumers who install this specie of system. for the analysis of the viability of the installation of a photovoltaic system it was obtained as a basis researches in the municipality of sinop, observing the enormous potential of the territory considering the incidence of solar rays which have an average of 5.00 kwh/m². day [7]. in this perspective, through review of previous works regarding solar energy in the city, it was also noted that the presence of photovoltaic systems is growing every day, however, only in the year 2019 there was a growth of 84% of all the facilities abstract brazilian consumers have the possibilit y to produce their ow n energ y using renewable sources or qualified cogenerat ion and even provide the surplus for the distribut ion net work of their localit y, as determined by normat ive resolut ion no. 482/2012 issued by the nat ional electric energ y agenc y (aneel). in view of this, the use of photovoltaic systems for electricit y generat ion has g row n surprisingly reaching the mark of 8 gigawatts of installed power on brazilian soil in the year 2021 [1]. in brazil, public agencies represent 0.1% with 4.7m w installed [1], and 0.38% in the state of mato grosso [14]. thus, aiming at the rise of electricit y generat ion in public buildings due to the possibilit y of reducing the electric bill costs, the present work deals with the dimensioning, budget quotat ion and economic feasibilit y analysis regarding the installat ion of a g rid-connected photovoltaic power generat ion system to meet the energ y demands of jorge de abreu regional hospital in the cit y of sinop, mato grosso state, brazil. after carr y ing out the necessar y research based on the techniques present in the economic sciences, as minimum attract iveness rate (mra), net present value (npv), internal rate of ret urn (irr) and calculat ion of payback, the present work considered a g rid-connected solar energ y generat ion system of 585 kw to supply the hospital’s average monthly consumpt ion of 93.829 kwh/month. the invest ment analysis showed that the project for the implementat ion of the photovoltaic system will have its npv viable as of the 4th year of installat ion and the payback (ret urn on invest ment), obser ving the monetar y correct ions, of approximately four years and five months, thus config uring the system as economic financially. index terms: distributed generat ion, economic indicators, photovoltaic energ y, renewable sources, sustainabilit y. received on, 25 may 2021 accepted on, 15 july 2021 published on, 10 november 2021 i. introduction http://dx.doi.org/10.21622/resd.2021.07.2.043 http://apc.aast.edu mailto:matheus.holzbach@unemat.br journal of renewable energy and sustainable development (resd) volume 7, issue 2, december 2021 issn 2356-8569 http://dx.doi.org/10.21622/resd.2021.07.2.043 44 http://apc.aast.edu of the locality, not to mention the significant increase of 514,35% compared to the year 2018, thus making the market quite diversified and accessible [14]. based on the aforementioned factors this structure was implemented in a public institution, namely the jorge de abreu regional hospital, which was inaugurated in december 2014 and is a reference for health in the region, serving as shelter for more than 430,000 people and having a large unit with care for several clinical sectors [11]. in this way, by reason of the large expenses that the hospital has to bear, the alternative of generating its own energy is an attractive option in terms of the reduction of expenses, since solar energy has an investment that returns after a certain period and that in this case, would return in a short time if compared to the years of operation of the entity. based on this assumption, the main objective is to analyze the feasibility of implementing a photovoltaic system in this building, the jorge de abreu de sinop regional hospital, considering aspects such as the cost of projects, equipment and installation. in addition, there will be the use of definitions of economic studies such as npv (net present value), irr (internal rate of return) and payback to prove the importance of the installation of the system. a. photovoltaic system photovoltaic energy is the production of electrical energy through the capture of solar rays by means of a semiconductor material, more commonly silicon, which will establish the phenomenon of direct conversion of solar radiation into electric current, known as photovoltaic effect [5]. according to castro [5], at present, this system can be used in a wide range of applications, for example in medium-power employment covering electrification in rural or remote regions without access to the distribution network, and dispersed productions connected to the network. as well as in low power applications ranging from clocks and calculators to road signs or parking meters. the photovoltaic system can be subdivided into two categories: off-grid and on-grid. the offgrid type, most of the time, is adopted in locations that have no connection with the power utility, thus causing the need to use stationary batteries in the storage of the generated energy. in the on-grid type, there is no use of these batteries, which makes this system economically viable compared to the previous one, and in turn needs to be connected to the network. there are still hybrid photovoltaic systems, which supports integrating a battery-powered energy storage system at the same time that it is connected to the electrical grid. this ensures greater autonomy and security for the user, also aiming at the financial benefit in the acquisition of this infrastructure [5]. b. analysis of economic viability the analysis of economic viability is a process that encompasses several studies on the market and qualifies the effectiveness of an investment over a given time. to verify the efficiency of the installation of a photovoltaic system, some economic terms have been adopted which are listed in the subsequent sections, including the formulas presented, all taken from the digital practical guide “financial indicators for investment analysis” by author renata freitas de camargo [4]. 1) minimum attractiveness rate: the acronym mra, the minimum attractiveness rate, is a percentage that corresponds to the minimum that an investor proposes to earn, or the maximum that someone proposes to pay when making a loan. it is considered an excellent tool especially when choosing among the various investment options available. at both strategic and financial levels, mra is one of the first tools to assess the attractiveness of an investment. the investment analysis of mra is estimated on the basis of the main interest rates practiced by the market, the researchers can mention for example those that currently have the most impact: tmf: basic financial rate; tr: reference rate; tjlp: long-term interest rate; selic: special settlement and custody system 2) net present value: net present value (npv) is an internationally accepted method by finance professionals and widely used to plan long-term investments as it is one of the best-known methods when dealing with analysis of the viability of investment projects [4]. the method consists of bringing to zero date all the cash flows of an investment project and adding them to the value of the initial investment, using as discount rate the minimum attractiveness rate (mra) of the company or project. with the calculation of the net present value, it is possible to make adjustments, discounting the interest rates to get the true notion of the value of money in the future. for this reason, the npv not only compares ii. literary review http://dx.doi.org/10.21622/resd.2021.07.2.043 http://apc.aast.edu journal of renewable energy and sustainable development (resd) volume 7, issue 2, december 2021 issn 2356-8569 http://dx.doi.org/10.21622/resd.2021.07.2.043 45 http://apc.aast.edu the investment with the expected return, but also takes into account the capital appreciation over time by calculating the real investment gain. the npv formula is expressed as follows: (1) where, npv is the net present value, fc is the cash flow, t is the time when the cash flow occurred, i is the discount rate (or minimum attractiveness rate) and n = time period. for the analysis of the result obtained by calculating the npv there are three possible situations: negative npv: expenditure greater than revenue, that is, the project is unviable; positive npv: revenue greater than expenditure, that is, the project is viable; npv zero = income and expenditure are equal, that is, the decision to invest in the project is neutral. 3) internal rate of return: the internal rate of return also known as the irr, is the rate that will equal the anticipated cash flow to the value of the investment. this rate is nothing more than an indicator, greatly used to assess the attractiveness of a project or investment. its calculation is given by the formula described below: (2) where, vp is the present value, capital is the investment value, n is the amount of periods, ft is the capital inflow in period t and i is the internal rate of return. when the researchers analyze the irr, they should compare it with the minimum attractiveness rate (mra), because if its percentage is lower, the investment is economically unviable. already if the irr is larger than the mra, the investment is considered viable. 4) payback: the recovery time of the investment, or popularly known as payback, is another risk indicator, being an important indicator within the investment decision-making process. it represents the number of periods necessary for the flow of benefits to exceed the invested capital. although it is a simple calculation, it is essential that all variables linked to the cash flow are analyzed for a correct execution of the payback calculation, since the entered values and the discounted expenses must faithfully represent the planned scenario, so that it does not present unwanted surprises. iii. methodology this work addresses the analysis of the financial viability of the investment aiming at the installation of a photovoltaic power generation system to meet the consumption needs of the regional hospital of sinop mt. in a first moment the researchers will deal with the dimensioning of the photovoltaic system, the researchers will calculate the variables that directly impact the generation and they will carry out the quotation of the equipment, project and labor costs. after that, the researchers will perform the investment analysis to evaluate its implementation. the two consumer units that serve the jorge de abreu de sinop regional hospital were considered; the first one located at number 2799, avenue of itaúbas, called emergency room, and the second unit located in street of caviúnas, without number, center, called regional hospital. both units are three-phase, served on average voltage with a 127/220v secondary voltage lowering transformer and belonging to tariff group a. for the preparation of this study, it is worth noting that some analyses could not be performed due to the location of the equipment installation not having been decided. in this sense, it is worth emphasizing that the resistance of the roof for the installation of the panels was not verified, the study of the coverage that allows the analysis of the interference of the shading throughout the year in the place of accommodation of the modules was not contemplated, and the calculations of losses by the voltage drop and heating of the inverter could not be calculated. for the purposes of carrying out the work, the researchers estimate, in comparison with other systems installed in the city of sinop-mt, that the total losses of the solar energy plant will not exceed 10%, assuming a general efficiency of the system of 90%. thus, the calculations presented should be reviewed and adjusted when the definition of points is solved and due technical studies are carried out. a. energy consumption of the jorge de abreu de sinop-mt regional hospital determining the consumer’s energy consumption is fundamental to the design of the photovoltaic solar system. the consumption considered is the arithmetic average contained in the electric energy bills provided by the head of the financial department of the jorge de abreu regional hospital of the city of sinop, mato 01 02 http://dx.doi.org/10.21622/resd.2021.07.2.043 http://apc.aast.edu journal of renewable energy and sustainable development (resd) volume 7, issue 2, december 2021 issn 2356-8569 http://dx.doi.org/10.21622/resd.2021.07.2.043 46 http://apc.aast.edu grosso. the analyzed period comprises from january to december 2020 and the mean value obtained was 93,829 kwh/month. consumption throughout the year showed oscillations mainly in the months of february to july in relation to the months of august to january. for this purpose, the standard deviation of consumption of 28.340kwh/ month was determined in relation to the period observed. given that the volume of energy demanded may vary according to the number of patients in need of services and the increased use of air conditioners in the excessive heat months of the region, it is not possible to present a linear consumption condition, justifying such a variation. b. dimensioning of the photovoltaic system the consumers of group a have hourly charges, that is, at certain hours the researchers call peak hours, when the electric system acts with greater intensity due to the high demand of industries and large trades, the cost of kwh consumed is higher. with a view on this, the researchers considered the methodology presented by kikomoto [15] present in equations 3, 4 and 5, where they prioritize the reduction of the monthly demand for electric energy in the same period (end-to-end). if there are leftovers, this balance will be used to reduce consumption in the other tariff post, provided that it is conditioned to a correction of the value attributed by the adjustment factor, according to the formula below: (3) where, fa is the adjustment factor, tp is the fare on the end and tfp is the off-edge fare. therefore, the generation required is calculated in order to meet the need for injected energy for peak and off-peak periods, using the adjustment factor: (4) where, gn is the generation needed, cmfp is the average off-peak consumption and cmp is the average consumption at the end. from the solar radiation data of the region and the definition of the photovoltaic module, the researchers can determine with its characteristics the number of modules needed to generate customer consumption. equation 5 shows as follows: (5) where, is is the average solar irradiation of the region, am is the contact area of the photovoltaic module, em is the percentage of efficiency of the photovoltaic module, es is the efficiency of the generation system and de the number of sunny days in the year. in this way the system dimensioned to supply the energetic demands of the hospital requires a system composed of approximately 1,858 photovoltaic modules, resulting in a solar plant of 817.52 kwp of power generation. the budget quotation for the one that meets such needs was carried out next to the main supplier of equipment of this branch, according to the study of the company greener, and the labor was quoted in the local trade. the final cost of the equipment is r$ 2,057,924.00 and labor of r$ 899,859.44. totaling the amount of r$ 2,957,823.44. it should also be noted that the quotation considered that the system will be installed on the roof of the building with fixing structures for trapezoidal metal tiles. the cost of adapting the current electrical infrastructure was not included in this study, because it would be necessary to have the prior definition of the places of installation of the equipment by the interested party. c. specification of the equipment considered the present study took into consideration the system with the best cost that attended the dimensioning, conferred by the technical professional of the responsible area for the company where the quotation of the labor costs was accomplished, being indicated the set of equipments of 585 kw of power of invertors and 817,52 kwp of power of the photovoltaic modules, composed by: 7 three-phase solar photovoltaic inverters of the growatt brand of nominal power of 75kw, model max75ktl3-lv, output voltage ac 220/380v, with 7 independent mppts and maximum dc input power of 112500w and efficiency of 98.3%; 1 three-phase solar photovoltaic inverter from growatt, 60kw nominal power, model mac60ktl3lv, 220/380v ac output voltage, with 3 independent mppts and maximum dc input power of 90000w and efficiency of 98.5%; 1858 monocrystalline photovoltaic modules from jinko brand composed by 120 cells, model jkm440m60hl4-v, with maximum power of 440w and efficiency of 20.39%. 3000 meters of nexans 40023 energyflex afitox 0.6/1kv 1500v dc solar cable black. 3000 meters of nexans 40023 energyflex afitox 0,6/1kv 1500v dc red solar cable. 240 staubli mc4 connector 320016p0001-ur pvkbt4/6ii-ur female coupler. 240 staubli mc4 connector 320016p0001-ur pv03 04 05 http://dx.doi.org/10.21622/resd.2021.07.2.043 http://apc.aast.edu journal of renewable energy and sustainable development (resd) volume 7, issue 2, december 2021 issn 2356-8569 http://dx.doi.org/10.21622/resd.2021.07.2.043 47 http://apc.aast.edu kbt4/6ii-ur male coupler. 465 solar structures solar romagnole 412012 2 pairs aluminium profile 240cm 4 modules t. metalic trapezoidal. d. maintenance expenditures and reduction in system efficiency according to galdino [9], over the course of its system life some preventive maintenance is necessary to maintain the proper functioning of the system, this maintenance varies annually between 0.5 and 1% of the initial value of the structure. for the study of this research, the value of 1% was used. the efficiency of photovoltaic modules varies according to their lifetime, this reduction in system performance varies between 0.5% and 1% per year [18]. the supplier brings together the technical data sheet of the product that its performance degradation is 2% in the first year and a linear decrease of 0.55% for the next 25 years. e. annual average readjustment index of the cost of electricity the adjustment of the annual electricity tariff is made according to the variation of the cost of purchasing energy, transport cost by high voltage lines, social charges, market inflation, operating costs and losses. based on the data provided by the national electric energy agency, the average readjustment in the last five years of the cost per kwh consumed in the state of mato grosso was approximately 8.32%, which the researchers will use in this work. according to the climatic data of the region, made available by cresesb [7] the researchers can estimate the energy generated by the photovoltaic system and also taking into account the expenditures for maintenance, efficiency of panels and average annual readjustment of energy, and consequently the savings generated by this system. an important factor to be observed in this case is that the consumer units of the sinop regional hospital have contracted demand for electricity. when the power of the photovoltaic inverters is increased, this contract must be modified, since the sum of the nominal power of the inverters will be higher than the current one. the tariff paid today by kwh hired by the consumer is r$ 19,26, and this value is affected by the annual average readjustment of the cost of electricity. the sum of the nominal power of the inverters is 585kw. taking into account all the factors addressed in this research, according to table i, the researchers can analyze the generation and savings forecast generated (without monetary correction) by the system over the first 5 years. iv. results table i generation forecast and savings generayed by the system over the initial five years variables/year 1st year 2nd year 3rd year 4th year 5th year performance of panels (%) 100% 98% 97,5% 96,9% 96,4% annual solar generation (kwh/year) 1.126.010,17 1.103.489,97 1.197.296,91 1.091.103,86 1.084.910,80 average energy readjustment (%) 8,32% 8,32% 8,32% 8,32% 8,32% energy cost (kwh/r$) 0,68 0,74 0,80 0,87 0,94 cost of maintenance (r$) 6.338,60 6.699,36 7.207,12 7.752,99 8.339,81 cost of demand contracts (r$) 135.205,20 146.454,27 158.639,27 171,838,06 186.134,98 economy generated in the year (r$) 627.521,15 663.236,50 713.504,42 767.545,84 825.640,70 accumulated economy (r$) 627.521,15 1.290.757,64 2.004.262,06 2.771.807,90 3.597.448,60 http://dx.doi.org/10.21622/resd.2021.07.2.043 http://apc.aast.edu journal of renewable energy and sustainable development (resd) volume 7, issue 2, december 2021 issn 2356-8569 http://dx.doi.org/10.21622/resd.2021.07.2.043 48 http://apc.aast.edu a. analysis of the economic viability of the investment 1) minimum attractiveness rate: the central bank of brazil (bacen) [3] is the authority responsible for ensuring financial stability in brazil, which confers power over the referenced interest rates traded in the country. the researchers will use the savings income index of the year 2020 of 2.11%, disclosed by bacen, as reference to the minimum rate of attractiveness, becauseboth financial applications are considered low risk. 2) net present value: from the rate defined in the previous item and using equation 1 defined in this work, the researchers can determine the net present value (vlp) of the financial investment. for this study the researchers considered the first 25 years of operation of the system because the manufacturer only informed the degradation rate for this period. table ii shows the discounted cash flow and its respective npv for each year considered. table ii discounted cash flow and calc ulated npv for each year year discounted cash flow year (r$) net gift value (r$) 1st year 614.554,06 -2.343.269,38 2nd year 636.109,47 -1.707.159,91 3rd year 670.180,58 -1.036.979,33 4th year 706.043,10 -330.936,23 5th year 743.788,10 412.852,71 6th year 783.514,50 1.196.367,20 7th year 825.320.98 2.021.688,19 8th year 869.314,57 2.891.002,76 9th year 915.606,66 3.806.609,42 10th year 964.314,10 4.770.923,51 11th year 1.015.559,46 5.786.482,97 12th year 1.069.471,29 6.855.954,26 13th year 1.126.184,38 7.982.138,64 14th year 1.185.840,05 9.167.978,69 15th year 1.248.586,45 10.416.565,14 16th year 1.314.578,88 11.731.144,02 17th year 1.383.980,08 13.115.124,10 18th year 1.456.960,59 14.572.084,69 19th year 1.533.699,08 16.105.783,77 20th year 1.614.382,71 17.720.166,48 21th year 1.699.207,52 19.419.374,00 22th year 1.788.378,78 21.207.752,78 23th year 1.882.111,49 23.089.864,22 24th year 1.980.630,49 25.070.494,71 25th year 2.084.171,44 27.154.666,14 in addition, in figure 1, it is possible to observe graphically its performance over the 25 years covered in the study. http://dx.doi.org/10.21622/resd.2021.07.2.043 http://apc.aast.edu journal of renewable energy and sustainable development (resd) volume 7, issue 2, december 2021 issn 2356-8569 http://dx.doi.org/10.21622/resd.2021.07.2.043 49 http://apc.aast.edu fig. 1. npv performance over the obser ved period. 3) internal rate of return: the internal rate of return (irr) was calculated for 5, 15 and 25 years of operation in order to perform a comparative. it was obtained respectively: 7% for the first five years, 27% for the initial 15 years of operation and 28% for the total period analyzed. 4) payback: the payback of the investment addressed has been calculated on the basis of the forecast cash inflows and discounted cash flow that takes into account the monetary correction of the inflows based on the benchmark rate. for the first case the researchers get the simple payback of four years and three months. in the second case, the researchers take for analysis the discounted payback with the value of four years and five months. in figure 2, the researchers graphically analyze the behavior of payback discounted over the analyzed period. fig. 2. payback in relat ion to the init ial invest ment and discounted cash flow. initially, the researchers can observe the high start cost required to install the system estimated at r$ 2,957,823.44, because of the high consumption present in the energy bills considered. however, when observing the expected calculation of generation and economy provided by the system, the impact is noted as the years evolve. in the proposed financial viability analysis, by taking into account the net present value (npv), it can be seen that the investment has an unworkable return on investment in the first four years and is therefore considered viable. the internal rate of return (irr), calculated for the three cases described, is analyzed as accessible, v. discussion http://dx.doi.org/10.21622/resd.2021.07.2.043 http://apc.aast.edu journal of renewable energy and sustainable development (resd) volume 7, issue 2, december 2021 issn 2356-8569 http://dx.doi.org/10.21622/resd.2021.07.2.043 50 http://apc.aast.edu since all percentages are higher when compared to the minimum attractiveness rate (mra) of 2.11%. the values of payback portray the moment when the initial investment is recovered being in approximately four years and five months, that is, the exact moment when the investment will obtain financial return. vi. conclusion paying attention to the fact that the structure will be installed in a public building of social character and will be active for several years, it is understood that the installation of such a photovoltaic power generation system is viable and that in the long term its generated economy will make it possible to invest in other needs of the hospital, such as the acquisition of equipment and the opening of new medical treatment beds for the population. the analyses carried out and the results obtained are based on the laws in force in the current brazilian energy scenario, and any additional taxation will directly impact the data calculated for this study. one should also observe the dollar value (r$ 5.58 quotation of march 2021), because the equipment of a photovoltaic power generation system is imported and negotiated according to the import and export guidelines. moreover, it is left as a research suggestion, the technical analysis and implementation study of this system within the structural limitations of the hospital regional jorge de abreu, exploring the existing electrical installations, available area for installation of the panels and structural report, being possible as a result of this, to calculate in fact the losses by shading, voltage drop in the cabling and heating of the system. furthermore, other research can be carried out employing different methodologies to compare or complement the data obtained in this article, such as the levelized cost of energy (lcoe) which allows one to determine if one should go ahead with the project or as a means of comparing different strategies, and can be used for example to analyze the location of the installation of the photovoltaic modules on ground or roof structures. vii. acknowledgements the researchers really appreciate the mato grosso research foundation for their support and encouragement in carrying out this research and the secretary of state for health of mato grosso for providing the necessary data. references [1] brazilian photovoltaic solar energy association, “brazil exceeds 5 gw mark in photovoltaic capacity”, 2021, available: https://www.absolar. o r g . b r /n o t i c i a /e n e r g i a s o l a r f o t o v o l t a i c a sup era-8-gw-e-traz-r-40-bi-de-investimentosao-brasil [may 01, 2021]. 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[26] c.a. olivati, photovoltaic effect and photoconductivity in polymeric devices, m. sc. thesis, ifsc, http://dx.doi.org/10.21622/resd.2021.07.2.043 http://apc.aast.edu http://www.sinfra.mt.gov.br/-/15391191-sinop-comemora-46-anos-com-obras-em-infraestrutura-saude-e-educacao http://www.sinfra.mt.gov.br/-/15391191-sinop-comemora-46-anos-com-obras-em-infraestrutura-saude-e-educacao http://www.sinfra.mt.gov.br/-/15391191-sinop-comemora-46-anos-com-obras-em-infraestrutura-saude-e-educacao https://doi.org/10.1590/1806-9126-rbef-2017-0342 https://doi.org/10.1590/1806-9126-rbef-2017-0342 https://www.coner.com.br/submissao-trabalho/resumo/nw96u1jpy1l6amhqeemrafl3n2k5dz09 https://www.coner.com.br/submissao-trabalho/resumo/nw96u1jpy1l6amhqeemrafl3n2k5dz09 https://www.coner.com.br/submissao-trabalho/resumo/nw96u1jpy1l6amhqeemrafl3n2k5dz09 https://canalsolar.com.br/dimensionamento-de-sistemas-fotovoltaicos-para-o-grupo-a https://canalsolar.com.br/dimensionamento-de-sistemas-fotovoltaicos-para-o-grupo-a http://m.sc https://repositorio.ufsc.br/bitstream/handle/123456789/130919/327988.pdf?sequence=1&isallowed=y https://repositorio.ufsc.br/bitstream/handle/123456789/130919/327988.pdf?sequence=1&isallowed=y https://repositorio.ufsc.br/bitstream/handle/123456789/130919/327988.pdf?sequence=1&isallowed=y https://essentiaeditora.iff.edu.br/index.php/bolsistadevalor/article/view/4706 https://essentiaeditora.iff.edu.br/index.php/bolsistadevalor/article/view/4706 http://scholar.google.coscholar?hl=en&btng=search&q=intitle http://scholar.google.coscholar?hl=en&btng=search&q=intitle http://scholar.google.coscholar?hl=en&btng=search&q=intitle cnhttp://scholar.google.com/scholar?hl=en&btng=search&q=intitle cnhttp://scholar.google.com/scholar?hl=en&btng=search&q=intitle http://www.cresesb.cepel.br/publicacoes/download/artigo/iii-cbens/68946.pdf http://www.cresesb.cepel.br/publicacoes/download/artigo/iii-cbens/68946.pdf http://www.cresesb.cepel.br/publicacoes/download/artigo/iii-cbens/68946.pdf https://teses.usp.br/teses/disponiveis/76/76132/tde-02092010-083031/publico/clarissadealmeidaolivatim.pdf https://teses.usp.br/teses/disponiveis/76/76132/tde-02092010-083031/publico/clarissadealmeidaolivatim.pdf https://teses.usp.br/teses/disponiveis/76/76132/tde-02092010-083031/publico/clarissadealmeidaolivatim.pdf https://teses.usp.br/teses/disponiveis/76/76132/tde-02092010-083031/publico/clarissadealmeidaolivatim.pdf cnhttp://scholar.google.com/scholar?hl=en&btng=search&q=intitle cnhttp://scholar.google.com/scholar?hl=en&btng=search&q=intitle http://www.cresesb.cepel.br/publicacoes/download/artigo/iii-cbens/68946.pdf http://www.cresesb.cepel.br/publicacoes/download/artigo/iii-cbens/68946.pdf http://www.cresesb.cepel.br/publicacoes/download/artigo/iii-cbens/68946.pdf journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 editorial articles journal of renewable energy and sustainable development prof. yasser gaber a. dessouky energy is one of the basic needs of humanity and, for ages, the sun seemed to be the main source of all energy in the universe and that is why the ancient egyptians used to venerate it. many wastes and corpses – under pressure and heat – have been converted throughout the years inside the earth into the oil on which recent development is totally based to support humans’ life, particularly in transportation and power generation. as time passes, it has been proven that oil will vanish. for the first moment, it seemed like mankind will certainly suffer due to such a hard situation and some people thought that we will get back to stone ages when oil no longer exists. thanks for the renewable energy scientist who has looked at the issue from a different prospective, that is, even if oil vanishes, the main reason of its existence is still there, that is the sun . the sun has the capability to still make people enjoy their life not only by enjoying the sunny weather in many places of the world and having good times on the beach for those who live by the sea but also the sun can still provide man with required energy and cause the wind to blow, the waves to raise, the plants to be converted to biomass, and the earth to store its geothermal energy. as long as life goes on, the sun will always rise and will always grant its energy to mankind. it is the clean, renewable and sustainable energy, which guarantees sustainable development. because of the high correlation between renewable energy and sustainable development, the editorial team of this journal thought of offering a hub to researchers interested in these two important fields to present their work and share it with others who have the same interest in such a wide area of research . thanks to the academy publishing center, ‘apc’ owned by the arab academy for science, technology and maritime transport ‘aastmt’ for hosting this international journal. we call upon researchers in this area to share their thoughts and their work through this journal, free of charge through the online submission system, and have it on hard copy through a print on demand ‘pod’ base. last but not least, we would like to thank the authors of the four editorial articles which were useful to researchers in the field of renewable energy and sustainable development. 1 resd © 2015 http://apc.aast.edu http://apc.aast.edu/ http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 about prof. yasser gaber a. dessouky professor yasser gaber dessouky graduated from alexandria university in 1991. he got his phd from heriot watt university, uk in 1998. he is a professor at the department of electrical and control engineering, arab academy for science, technology and maritime transport (aastmt) since 2006. currently, he is the dean of scientific research and innovation in the aastmt. he is the chair of industry relations subcommittee, ieee alexandria. he is a renewable energy expert in the escwa of the un and he is a member of the world renewable energy network (wren) uk and the desertech university network (dun) hamburg germany. he is also a member of the research, development and innovation network (rdin) and the egyptian science, technology and innovation observatory (estio). professor dessouky is an editorial board member of many journals and a consultant for many industrial companies. he is a peer reviewer in many transactions, periodicals and conferences. he has a patent from the patent office in uk. he is leading technology, innovation and commercialization office (tico) in the aastmt. he is also leading many research projects funded by the eu such as erafrica project entitled, 'development of a high-efficient power-generation from hybrid-fuel supplies', 2014-2017 and a tempus project, 'highway and traffic engineering', 2013-2016. 2 resd © 2015 http://apc.aast.edu http://apc.aast.edu/ http://apc.aast.edu/ paper title (use style: paper title) journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 30 resd © 2015 http://apc.aast.edu a review of indirect matrix converter topologies lazhar rmili 1 , salem rahmani 1 , kamal al-haddad 2 1 laboratory of biophysics and medical technology (bmt), istmt of the university of tunis el-manar, tunisia av. dr. zouhaier essafi, 1006, tunisia rmili_lazhar@yahoo.fr, rsalem02@yahoo.fr 2 canada research chair in energy conversion and power electronics crc-ecpe, école de technologie supérieure, 1100 notre-dame, montréal, québec h3c 1k3, canada kamal@ele.etsmtl.ca i. introduction matrix converter is a new generation of the direct power converter controlling the output voltage, amplitude and frequency. it has an adjustable power factor to control the input, regardless of the load. the absence of heavy and susceptible-tofailure capacitors, matrix converters can perform operations at high temperature, gain reliability, control input and output current and adjust voltage sine waves with an adjustable phase shift. these are considered some advantages of this type of converters. the controlling of output voltage, amplitude and frequency represents one more advantage over the previously mentioned advantages and over other types of converters as well. those advantages promote the integration of this new topology in several areas of industrial applications. for example, aerospace industries have a great interest in that converter [1], [2], marine propulsion industries, electrical drive machines with variable speed [3]-[10], embedded systems and other fields of renewable energy which are based on wind and fuel cells [11]-[14]. various research works on the topologies of matrix converters, led to the discovery of appropriate structures that minimize the number of semiconductors. two types of topologies for the matrix converter have been established by researchers including direct and indirect matrix converter topologies [15]-[26]. it has been shown that the indirect topology is handled easier. other studies have been published on the design of multilevel and z-source matrix converters. in previous work [24], authors showed the primary concerns of the mcs on bidirectional switches as well as the direct mc topologies and associated modelling. in this paper, the indirect topologies for mcs are investigated. various features of those topologies are studied and a brief summary of the research will be shown at the end. ii. indirect matrix converter topology a new topology, developed in the early 2000s, can be proposed as an alternative to the matrix converter. this configuration consists of a combination of two conventional converters through a fictitious intermediate floor without capacitive storage element. it is called "double stage converter". the first floor is a controlled rectifier directly connected to the second floor, which consists of a voltage inverter, traditionally used in variable speed ac machines as presented in figure 1. this indirect converter topology has two stages: rectifier stage and inverter stage the rectifier stage is formed of two switching cells, denoted (r) and (r'), modeled by the (1). one switch is closed at each switching time for both cells; this condition is expressed by the relation (2). (1) (1) where …. is the connection matrix of the rectifier. abstract— matrix converter (mc) is a modern direct ac/ac electrical power converter without dc-link capacitor. it is operated in four quadrants, assuring control of the output voltage, amplitude and frequency. the matrix converter has recently attracted significant attention among researchers and it has become increasingly attractive for applications of wind energy conversion, military power supplies, induction motor drives, etc. recently, different mc topologies, which have their own advantages and disadvantages, have been proposed and developed. matrix converter can be classified as direct and indirect structure. in this paper, the indirect mcs are reviewed. different characteristics of the indirect mc topologies are mentioned to show the strengths and weaknesses of such converter topologies. keywords— matrix converter; ac/ac conversion; topologies; bidirectional switches; journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 31 resd © 2015 http://apc.aast.edu (2) the operation of the rectifier is described by (3) and (4). (3) (4) the inverter stage of the indirect matrix converter consists of three switching cells called a, b, c as shown in figure 1. this floor is modeled by equation (5) and satisfies the constraints described by (6). (5) where … is the connection matrix of the inverter stage. p o ia ib ic va vb vc vp vo udc idc -idc sa sb sc s’a s’b s’c sa sb sc s’a s’b s’c cell r cell r’ cell a cell b cell c va vb vc ia ib ic fig. 1. dual-stage indirect matrix converter every rectifier switch may be one of the following switches fig. 2 (6) the inverter operation is set by the relations (7) and (8). transistors with common emetters transistors with common collectors transistor associated with a diode bridge rb-igbt structure (a) (b) (e) (c) (d) : (f ) (g) hybride strcture transistor and diode in series transistor and diode in series fig.2. different topologies of the bidirectional switches (7) (8) the connection matrix of two-stage matrix converter named is obtained by the product of the connecting matrices of the inverter and rectifier, as shown in equation (9). (9) a tie between two matrices connections can be established as shown in (10). (10) in the same manner as the direct matrix converter, (9) (10) journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 32 resd © 2015 http://apc.aast.edu a formulation based on modulation of the switches may also be set for the dual stage matrix converter. the equations described above in "connection function" are transposed in "modulation function" and the conversion matrices defined by the modulation functions of each stage of "dual-stage" matrix converter are described by (11), (12) for the rectifier stage and (15), (16) for the inverter stage. where represents the conduction time of switch ( ) during the commutation period . (11) (12) the laws of conversion of electrical values, whatsoever voltage/voltage or current/current are set by relations (13), (14) for the recovery block and (17), (18) for the inverter stage. (13) (14) (15) (16) (17) (18) product conversion matrices of inverter and rectifier stages are the conversion matrix of "double stage" matrix converter, denoted it is expressed by (19). as explained before; there is a relationship between "modulation functions" of the direct matrix converter and the indirect matrix converter, which is the equality of two conversion matrices according to (20). where represents the conduction time of switch ( ) during the commutation period . matrix converter « dual-stage » ultra-sparsevery-sparsesparseindirect with inverter stage with igbt switch two antiparallel rb-igbt rb-igbt and igbt in antiparallel with rb-igbt switch fig. 3. different indirect mc topologies this two-stage indirect matrix converter structure developed by “j.w. kollar” has a major advantage which is the ability to minimize the number of power transistors. the different topologies derived from indirect dual-stage mc have been shown in figure 3. based on the two-stage indirect mc configuration, the following topologies have been derived: a. indirect matrix converter: the configuration shown in figure 4 includes a rectifier stage comprising six bidirectional switches connected to a common emitter or common collector. this configuration generates less switching and conduction losses compared to other (19) (20) journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 33 resd © 2015 http://apc.aast.edu configurations. it has a complex control for the number of switches to handle. all this leads to the development of other configurations with the aim of reducing the number of required transistors which facilitates the monitoring and control of the matrix converter. inverter stagerectifier stage fig. 4. indirect matrix converter (19) b. sparse matrix converter: the configuration shown in figure 5, leads to remove an igbt from each arm of the rectifier, so three components will be eliminated totally compared to the previous configuration, which facilitates the development of control algorithm of the converter. conduction losses will be greater than those generated by the first configuration since three transistors and diodes are working during the feeding phase of the load as well as two transistors and two diodes in the feedback phase to the network. fig. 5. sparse matrix converter c. very-sparse matrix converter: the structure of this topology illustrated in figure 6 is based on the implementation of bidirectional igbt switches connected to a diode bridge, where the number of the controlled components in the rectifier is reduced compared to the two configurations mentioned above. each active element of the rectifier requires the activation of a transistor with two diodes in each commutation phase, the rectifier requests two transistors and four diodes, bearing in mind that conduction losses are then a matter of importance. fig. 6. very-sparse matrix converter d. ultra-sparse matrix converter: in this configuration, the least number of switches is employed. there is a single switch via input phase as shown in figure 7. in each arm, one transistor and two diodes are controlled. this structure generates similar conduction losses to those produced by the "verysparse" structure. yet, this configuration does not allow bi-directional power flow which limits its practical application. fig. 7. ultra-sparse matrix converter e. matrix converter "to inverter stage" the first stage of this configuration includes a rectifier in cascade with an inverter circuit as shown in figure 8. this structure has many controlled components than the "sparse" topology. it creates additional switching losses and has a high complexity level in control. consequently, this configuration will not be an objective study. fig. 8. matrix converter with rectifier stage f. matrix converter based on rb-igbt: the structure shown in figure 9 incorporates rbigbts into the rectifier stage with advantages like reduction of conduction losses. the poor diode recovery behavior of the rb-igbt is of less concern here than in a matrix converter because it is possible journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 34 resd © 2015 http://apc.aast.edu to switch the rectifier stage at zero current as soft switching pattern. at low switching frequencies, a matrix converter built with rb-igbts will be more efficient than the one built with igbts. fig. 9. matrix converter or rectifier unit switches are based on rbigbt g. matrix converter based hybrid switches: the topology of matrix converter using hybrid bidirectional switches in the rectifier stage (as shown in figure 10), provides low conduction losses in motoring operation as well as soft turn-on commutation of the rb-igbts, whereas in the rectifier stage the standard igbts and diodes provide low switching losses in regenerative operation. fig. 10. matrix converter or rectifier unit switches are based on a rb-igbt on anti-parallel to an igbt with a series diode table 1 shows the summary of the abovementioned mc topologies considering various points including some elements such as a number of components, power losses, control strategy complexity and reversibility. iii. simulation results the simpowersystem toolbox of matlab has been used as the simulation tool. the simulation results before and after compensation of the threelevel sparse matrix converter feeding an rl load as illustrated in fig.11, also shown in figs.12 to 17. table ii gives the system parameters used in the simulations. va vb vc lin-f lo-f cin-f co-f load r-l ie vs is fig. 11. three-level sparse matrix converter table 1. summary of the indirect topologies features figs.12 (a)-(b) show the phase a input current (ie) and its harmonic spectrum, respectively. the input current has a thd of 75.33%. the output voltage (vs) of phase (a), and its harmonic spectrum (output voltage thd of 92.21%) are shown in figs.13 (a)-(b), respectively. figs.14 (a)-(b) show the phase (a) output current (is) and its harmonic spectrum. the output current thd is 2.43%. an input and output lc filters are necessary to compensate the highfrequency ripple from the input currents and output voltages. thus, an lc filter is connected at the input side to avoid overvoltage and to filter the highfrequency ripple from the input currents. similarly, on the other side, an output lc filter is connected between the converter and the load which allows controlling the output voltage and mitigates its harmonics. figs. 15 (a) and (b) show the phase (a) input current and its harmonic spectrum after filtering. the measured thd of the input current in phase (a) is reduced from 75.33% before compensation to 1.78% after compensation. it is important to notice that the input current is kept free of harmonics. topology numbe r of transist ors number of diodes energetic losses reversibi lity power control indirect matrix 18 18 low yes fairly complic ated sparse 15 18 important yes fairly complic ated verysparse 12 12 low yes easy ultrasparse 9 18 low no easy with stage inverter 14 14 important yes complic ated based on rb-igbt 18 18 low yes fairly complic ated based-on hybrid switches 18 18 average yes easy journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 35 resd © 2015 http://apc.aast.edu 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 -20 0 20 time (s) ie ( a ) 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 100 120 harmonic order fundamental (50hz) = 13.45 , thd= 75.33% m a g ( % o f f u n d a m e n t a l) (a) 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 -20 0 20 time (s) ie ( a ) 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 100 120 harmonic order fundamental (50hz) = 13.45 , thd= 75.33% m a g ( % o f f u n d a m e n ta l) (b) fig. 12. (a) waveform of phase a input current (ie) of three-phase three-level sparse matrix converter before filtering, (b) harmonic spectrum of input current. 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 -400 -200 0 200 400 time (s) v s ( v ) 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 100 120 harmonic order fundamental (50hz) = 205 , thd= 92.21% m a g ( % o f f u n d a m e n ta l) (a) 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 -400 -200 0 200 400 time (s) v s ( v ) 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 100 120 harmonic order fundamental (50hz) = 205 , thd= 92.21% m a g ( % o f f u n d a m e n ta l) (b) fig. 13. (a) waveform of phase a output voltage (vs) of threephase three-level sparse matrix converter before filtering, (b) harmonic spectrum of output voltage 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 -20 0 20 time (s) i s ( a ) 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 100 120 harmonic order fundamental (50hz) = 19.56 , thd= 2.43% m a g ( % o f f u n d a m e n t a l ) (a) 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 -20 0 20 time (s) is ( a ) 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 100 120 harmonic order fundamental (50hz) = 19.56 , thd= 2.43% m a g ( % o f f u n d a m e n ta l) (b) fig. 14. (a) waveform of phase a output current (is) of threephase three-level sparse matrix converter before filtering, (b) harmonic spectrum of output current. 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 -20 0 20 time (s) ie ( a ) 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 100 120 harmonic order fundamental (50hz) = 26 , thd= 1.78% m a g ( % o f f u n d a m e n ta l) 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 -20 0 20 time (s) ie ( a ) 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 100 120 harmonic order fundamental (50hz) = 26 , thd= 1.78% m a g ( % o f f u n d a m e n ta l) (b) fig. 15. (a) waveform of phase a input current of three-phase three-level sparse matrix converter after filtering, (b) harmonic spectrum of input current. the waveforms and harmonic spectra of output voltage and current waveforms after filtering are shown in (figs.16 and 17) respectively. the output filter reduces the thd in the output voltage from 92.21% to 0.26%. the thd of the output current in phase (a) is therefore reduced from 2.43% without output filter to 0.15% after filtering. these results show the output lc filter capability to compensate harmonics of output voltages and output currents. 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 -200 0 200 time (s) v s ( v ) 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 100 120 harmonic order fundamental (50hz) = 265.3 , thd= 0.26% m a g ( % o f f u n d a m e n ta l) (a) 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 -200 0 200 time (s) v s ( v ) 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 100 120 harmonic order fundamental (50hz) = 265.3 , thd= 0.26% m a g ( % o f f u n d a m e n ta l) (b) fig.16. (a) waveform of phase a output voltage of three-phase three-level sparse matrix converter after filtering, (b) harmonic spectrum of output voltage 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 -20 0 20 time (s) is ( a ) 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 100 120 harmonic order fundamental (50hz) = 25.31 , thd= 0.15% m a g ( % o f f u n d a m e n t a l) (a) 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 -20 0 20 time (s) is ( a ) 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 100 120 harmonic order fundamental (50hz) = 25.31 , thd= 0.15% m a g ( % o f f u n d a m e n ta l) (b) fig.17. (a) waveform of phase a output current of three-phase three-level sparse matrix converter after filtering, (b) harmonic spectrum of output current (a) journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 36 resd © 2015 http://apc.aast.edu table 2. specification parameters circuit specifications value input side , load , input filter , , output filter , , output side , ratio 0.825 switching frequency iv. conclusion this paper proves that the dual stage mc topology has been studied and analyzed. different topologies based on dual stage configuration of mc have been illustrated. the brief summary at the end shows some facts and characteristics of the aforementioned topologies which would be useful for future applications on mc topologies and control aspects. as mentioned before, mc has two main topologies including direct and indirect ones. the comparison between these two topologies made it clear that the two-stage matrix converters have advantages over the direct or conventional ones. for example, the possibility of reducing the number of switches forming the converter enables consumers to reduce the switching power losses and manufacturing cost as well. less switching difficulties occurs because switches of the input stage (rectifier) can be turned on by the application of the zero vector current. the second stage is controlled as a standard inverter and the clamp circuit can be simplified only by a capacitor in series with a diode which is not compatible with the direct matrix converter topology. simulation results for an rl load supplied via a sparse matrix converter with the pwm modulation show that output voltage is controllable with corresponding improvements in power quality and the unity displacement power factor is achieved at the input stage. eventually, these studies offer a very wide field of research, especially in the study of reliability, maintainability, availability; faults tolerances and stability of these types of converters. references [1] alesina, a. and venturini, m. 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[10] klumpner, a., nielsen, p., boldea, i. and blaabjerg, f. (april 2002) a new matrix converter motor (mcm) for industry applications, ieee transactions on industrial electronics, vol. 49, pp. 325 – 335. [11] changliang, x., yan, y., song, p. and tingna, s. (january 2012) voltage disturbance rejection for matrix converter-based pmsm drive system using internal model control, ieee transactions on industrial electronics, vol. 59, no. 1, pp. 361-372. [12] ortega, c., arias, a., caruana, c., balcells, j. and asher, g. m. (june 2010) improved waveform quality in the direct torque control of matrixconverter-fed pmsm drives, ieee transactions on industrial electronics, vol. 57, no. 6, pp. 2101-2110. [13] daning, z., sun, k., huang, l., and sasagawa, k. (2005) a novel commutation method of matrix converter fed induction motor drive using rbigbt, fourtieth. ieee ias industry applications society annual meeting, pp. 2347-2354. [14] casadei, d., serra, g., tani, a., trentin, a. and zarri, l. (october 2005) theoretical and experimental investigation on the stability of matrix converters, ieee transactions on industrial electronics, vol. 52, no. 5, pp. 1409-1419. [15] yue, f., wheeler p., and clare, j. (march 2006) relationship of modulation schemes for matrix converters, 3rd iet international conference on power electronics, machines and drives, pp. 266270. [16] rodriguez, j., rivera, m., kolar, j. and wheeler, p. (january 2012) a review of control and modulation methods for matrix converters, ieee transactions on industrial electronics, vol. 59, no. 1, pp. 58-70,. [17] domes, d., hofman, w.and lutz, j. (september 1114, 2005) a first loss evolution using a vertical sicjfet and a conventional sic-igbt in the bidirectional journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 37 resd © 2015 http://apc.aast.edu matrix converter switch topology, european conference on power electronics and application. [18] hojabri, h., mokhtari, h. and chang, l. (march 2011) a generalized technique of modeling, analysis, and control of a matrix converter using svd, ieee transactions on industrial electronics, vol. 58, no. 3, pp. 949-959. [19] mahlein, j. , weigold , j. , and simon,o. (november 29-december 2, 2001) new concepts for matrix converter design, the 27th annual conference of the ieee industrial electronics society iecon, vol.2, pp 1044-1048. [20] ibarra, i., kortabarria, j. , andreu, i., martin, m. l. and ibañez, p. (january 2012) improvement of the design process of matrix converter platforms using the switching state matrix averaging simulation method, ieee transactions on industrial electronics, vol. 59, no. 1, pp. 220-234. mahlein,j., bruckmann , m., and braun, m. (april 2002) passive protection strategy for drive system with matrix converter and induction machine, ieee transactions and industrial electronics, vol. 49, no. 2, pp. 297-303,. [21] ishiguro, a., furuhashi, t., and okuma, s. (1991) a novel control method for forced commutated cycloconverters using instantaneous values of input lineto-line voltage, ieee transactions on industrial electronics, pp.166-172,. [22] schafmeister f. and kolar, j. (january 2012) novel hybrid modulation schemes significantly extending the reactive power control range of all matrix converter topologies with low computational effort, ieee transactions on industrial electronics, vol. 59, no. 1, pp. 194-210. [23] rmili, l., rahmani, s., vahedi, h. and al-haddad, k. (june 2014) a comprehensive analysis of matrix converters: bidirectional switch, direct topology, modeling and control, in proc. 23rd ieee international symposium on industrial electronics, ieee-isie, [24] huang,x., goodman, a., gerada, c., fang, y. and lu, q. (september 2012) a single sided matrix converter drive for a brushless dc motor in aerospace applications, ieee transactions on industrial electronics, vol. 59, no. 9, pp.3542-3552. [25] wheeler, p., clare, j.c., empringham, l., apap, m., bradley, k., whitley c. and towers, g. (june 2004) a matrix converter based permanent magnet motor drive for an aircraft actuator system, proceedings of ieee international electric machines and drives conference, vol. 2, pp. 1295 – 1300. journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 1 http://dx.doi.org/10.21622/resd.2022.08.1.001 http://apc.aast.edu a scoping review of adopter attributes, motivations, and barriers of solar home systems adoption: lessons for sub-saharan africa tiyamike ngonda1 department of mechanical and mechatronic enginering, cape peninsula university of technology, cape town, south africa ngondat@cput.ac.za most governments in sub-saharan africa (ssa) struggle to provide their populations with access to affordable and clean energy, one of the united nations’ 17 sustainable development goals [1]. one of the forms of clean energy whose usage has grown globally over the past two decades is solar photovoltaic (pv). solar pv generation has seen rapid increases, reaching 821 terawatt-hours in 2020, 3.1% of global electricity generation [2]. most of this increase has been from china, the united states and europe. the gains were driven by policy interventions such as subsidy-driven deployment, tax credits and feed-in metering [2]. in the absence of similar interventions, africa has lagged in generating electricity from renewable sources and access to electricity [3]. at 20% in 33 of the 49 ssa countries, the region has the lowest electricity access in the world [4]. in addition to access, ssa suffers from low-quality electricity supply, as evidenced by the frequent electricity shortage problems, often resulting in unannounced load shedding to keep grids from instability [5], [6]. this frequent load shedding has forced middle-class households in ssa to self-generate electricity using diesel generators, thereby contributing to co2 emissions. this approach is not sustainable. it does not consider the renewable energy sources available in the african continent. instead, a more sustainable system would be electricity micro-generation using solar thermal, solar photovoltaics, and heat pumps which would be exploited if reliance on fossil fuels is to be reduced [7]. however, africa’s electricity generation from renewables is increasing slowly, only growing by 6% between 1985 and 2020 [3]. the contribution of solar generation is even more minor, only 2.23% as of 2020, despite having excellent conditions for pv electricity [3], [8]. ssa’s long term daily power output achievable by pv exceeds 4.5 kilowatt-hours per installed kilowatt peak (kwh/kwp) [8]. as the continent with the lowest abstract the diffusion of solar home systems in sub-saharan africa would reduce the prevalent energ y pover t y in the region. however, the adopt ion of solar home systems faces significant barriers that have hampered the adopt ion process. this paper presents a scoping review that invest igates non-inst it ut ional factors influencing the solar home systems diffusion process. the st udy searched three databases, scopus, sciencedirect and web of science, for conference papers and journal ar t icles that focused on barriers and mot ivat ions for adopt ing solar home systems. the search produced 116 records. after apply ing the exclusion criteria, 14 papers were included in the themat ic analysis. the analysis revealed that affordabilit y and inadequate informat ion on solar home systems are significant barriers to adopt ion. the analysis fur ther showed that solar home system adopters, t ypically highly skilled and educated highincome individuals, are mot ivated by the peer effect, energ y securit y and independence, monetar y saving and desire to protect the environment. finally, the findings suggest that government inter vent ion is essent ial for the widespread diffusion of solar home systems in sub-saharan africa. index terms: barriers, diffusion, mot ivat ions, photovoltaic, solar home systems, sub-saharan africa i. introduction received on, 26 december 2021 accepted on, 03 february 2022 published on, 27 april 2022 journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 2 http://dx.doi.org/10.21622/resd.2022.08.1.001 http://apc.aast.edu access to electricity, this high pv electricity potential suggests potential in ssa for future growth of solar home systems (shs) installations. shs are solar pv systems that are used in the microgeneration of electricity in individual houses. they could contribute to energy security and autonomy by reducing dependency on the grid [9]–[13]. in addition, shs installations could mitigate climate by reducing the dependence on biomass for cooking. the use of biomass for cooking and water heating contributes to deforestation and emissions of co2 [14]. unlike china, the united states and european countries, most african countries cannot solely depend on institutional level financial incentive approach to fasten shs adoption. this scoping review investigates non-institutional factors influencing the shs diffusion process. it builds on a previous review of shs in ssa [15] by focusing on household-level factors influencing shs adoption, particularly those relevant to ssa. the findings and recommendations would assist policymakers, academics, and other energy stakeholders in ssa to develop interventions that would promote the adoption of residential shs. in addition, increasing shs installations is crucial for ssa countries to ease the pressure on their electricity grids and provide access to off-grid communities. ii methodolgy this scoping review followed the five-step framework developed by arksey and o’malley [16]. a. step 1: identifying the research question the following question guided this scoping review of the barriers and enablers of the adoption of shs: what household-level factors facilitate or constrain the adoption of shs? b. step 2: identifying relevant studies the author searched the three databases, scopus, sciencedirect and web of science. the searches were performed on 24 november 2021 and targeted the fields, title, abstract, and keywords. the author used search string (solar photovoltaic or pv) and (resident ial or home or domest ic) and (bar riers or enablers) and (ow nership or adopt ion). c. step 3: study selection the scoping review included all conference papers and journal articles published up to november 2021. the scope of the review encompassed literature focussing on the barriers and enablers of the adoption of shs. this included articles focusing on electricity generation from solar for cooking, lighting, and other domestic electricity usage. all records were selected without a time limit. the titles and abstracts of the records were screened to exclude those that fit the exclusion criteria. the study excluded literature that was not published in english, which focused on policy, commercial electricity users, community solar projects or solar pv as part of microgrids. also, literature focusing on post-installation issues such as payback period and installed system efficiency was removed. finally, after eliminating duplicates and initial screening, the full texts were imported in mendeley reference manager for eligibility screening and to streamline the review process. the screening process is summarised in figure 1, and fourteen publications were considered relevant for inclusion in the analysis. fig. 1. modified prisma flow diag ram illust rat ion of the st udy sc re ening pro cess. journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 3 http://dx.doi.org/10.21622/resd.2022.08.1.001 http://apc.aast.edu d. step 4: data charting process the included studies were imported into nvivo for thematic synthesis and analysis. study characteristics, including the publication type, setting, year, were input as file classifications and attributes in nvivo to facilitate data display and comparison. the author performed the data extraction, and a peer reviewer audited the process for confirmability. the thematic synthesis comprised three concurrent flows of activity: (1) data condensation through coding, (2) data display through charts, maps and diagrams and (3) theme development and verification [17]. this process was conducted by the author and audited by a peer reviewer. e. step 5: summarising results the results are reported according to prisma guidelines extension for scoping review [18]. iii. results the searches returned 116 journal papers and conference papers, 42 in scopus, 45 in sciencedirect, and 29 in the web of science. table i summarises the characteristics of the studies included in the scoping review. most of the reviewed studies were conducted in united states (n = 4), the remaining in sweden (n = 2), pakistan (n =2), australia (n = 1), finland (n = 1), new zealand (n = 1), vietnam (n = 1), united kingdom (n = 1) and nigeria (n = 1). the earliest was conducted in 2013, and the highest number was three studies in 2017, 2019 and 2020. there was one each in 2014 and 2018, two in 2016 and no studies in 2015 and 2021.the synthesis included a thematic analysis process that uncovered four themes: household attributes that influence shs adoption, household-level barriers to shs adoption, motivations for shs adoption and outcomes of shs adoption. the themes and their subthemes are presented in table ii, and their overviews are presented in the following sections. table i synthesis of included studie journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 4 http://dx.doi.org/10.21622/resd.2022.08.1.001 http://apc.aast.edu journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 5 http://dx.doi.org/10.21622/resd.2022.08.1.001 http://apc.aast.edu table ii the themes and subthemes that emerged from thematic analysis of included studies a. household attributes that influence shs adoption most of the studies found that adopters shared similar attributes. they were older than average [7], [25], [27], professionally skilled or highly educated [7], [20], [23]–[25], [27], [28], had a higher household income, were energy efficiency literate [10], [21], [23], [25] and were interested in environmental issues [24], [25]. it is worth noting that there was one contrary finding on the age of adopters. an australian study by zander [28] found that younger people, motivated by environmental concerns, also adopt shs. the adopters were generally interested in environmental issues and technologies that developed over time [24], [25]. as a result, their interest was broader than shs, covering broader renewable energy issues and politics. this broader interest was shown in their co-adoption journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 6 http://dx.doi.org/10.21622/resd.2022.08.1.001 http://apc.aast.edu of renewable technologies [7], [12], [20], [21], [23], [27]. they co-adopted efficient heating/cooling systems, solar thermal systems, hydro, wind turbines, battery storage, and smart thermostats. these other technologies had been adopted either prior, simultaneously or after adopting shs. qureshi et al. (2017) and ugulu and aigbayboa (2019) found a different co-adoption pattern in pakistan and nigeria. the shs adopters coadopted fossil fuel-driven power generators. the studies suggest that adopters and rejectors have similar income and education statuses, whereas considerers have lower incomes. it is worth noting that although adopters and rejectors share several traits, j. palm and eriksson [25] found that rejectors had relatively lower knowledge of energy efficiency technologies. also, rejectors had different motivations than adopters. for example, j. palm and eriksson [25] report that rejectors in their study were more concerned about the impact of shs on the esthetics of their houses and of whether their neighbours would approve of shs installations. b. household-level barriers to shs adoption the studies showed that households are deterred from adopting shs by affordability high capital investment [12], [13], [19], [21], [28] and high maintenance costs – components such as batteries need to be replaced at some intervals [12], [13], [21], [28], inadequate and untrustworthy shs information[7], [19], [21], [23], [25], [26], scepticism about benefits of shs[12], [21], [23], [27], [28] and complex administrative requirements for shs installation [19], [20]. the two elements of affordability, high initial costs and the cost of batteries, are related [12]. however, it is possible to have an shs without incorporating energy storage through batteries. although this would reduce the initial cost of shs, it would mean that some of the electricity generated would not be used unless there is some feed-in to the grid. having a feed-in system when the household energy demand is lower than selfgenerated electricity then recouping this when household demand is high would eliminate the need for batteries. unfortunately, this is beyond the control of households and depends on the energy policies of countries [21], [28]. with or without battery storage, there is consensus among adopters, considerers and rejectors [13] that high initial costs are the most significant barrier to shs adoption [12]. in zander’s study [28], owners ranked high initial costs as almost two times more important than the second rated barrier. also, balcombe et al. [7] found that for considerers and adopters, the high initial costs were 50% more significant than any cost saving that they would make from installing shs. shs adoption is also constrained by a lack of clear, impartial, and trustworthy technical and financial information on shs viability [7]. because of the significant initial capital investments, households want real tax incentives, feed-in tariffs and future electricity pricing estimates. however, when potential adopters have difficulty processing the available information, they become sceptical of potential financial and environmental benefits of installing shs or prolong the period they take to move from considerer to adopter [26]. do et al. [19] showed that households are also concerned about the lack of credible information about the quality and reliability of shs and service providers. this is a challenge because most of the information on shs is provided by service providers. some studies suggest that this anxiety is reduced if the information on shs was provided by a government entity, the utility companies or the potential adopter’s peers [24]–[26]. in some cases, the barrier of the lack of credible information on shs was accompanied by the scepticism of shs financial benefits, often associated with the uncertainties of calculating the payback period for shs installations [21]. in their study, karjalainen et al. [23] reported that the payback period for shs installations is often long, 15 to 25 years. this long payback deters older potential adopters. in addition, there are uncertainties in the estimates of payback for such long periods because the future pricing of electricity is unknown. furthermore, zander [28] reported that some potential adopters are sceptical of the environmental benefits of solar panels. c. motivations for shs adoption the included studies showed that shs adopters are motivated by the desire for energy security [7], [21], [28], energy autonomy [10], [12], [13], [21], journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 7 http://dx.doi.org/10.21622/resd.2022.08.1.001 http://apc.aast.edu [28], saving money from reduced electricity bills [10], [20], [28], environmental protection [7], [12], [23], [28] and the peer effect [12], [22]–[24], [26], [27]. the respondents in most of the cited protection from futures rise in electricity prices and protection from load shedding as critical motivators of shs adoption. most shs adopters, notably those older, indicated that they needed protection against future rises in electricity prices [21]. this motivation was cited by those who had retired or were near retirement and those who became off-grid. the past rises in electricity costs informed the stance of these households. for example, one adopter from the study by ford et al.[21] indicated that they installed shs because electricity prices had gone up by 24% over the previous three years. shs adopters, particularly those in developing countries, also mentioned protection from loading shedding as a critical motivator for their adopting shs [10], [12], [13]. in a nigerian study by ugulu and aigbayboa [10], 80% of shs adopters cited energy security in the form of reliable energy supply as the main reason they adopted shs. these shs adopters co-adopted power generators with shs installations, further signalling the importance of reliable energy supply, even more, important than improving the environment. khalil et al. [13] suggested that the co-adoption with power generators might sign of distrust in standalone shs. another frequently stated motivation for adopting shs was protecting the environment. however, the relative importance of adopting shs to preserve the environment is unclear. for example, the study by balcombe et al. [5] ranked protecting the environment as the fourth most crucial motivator, less important than saving or earning money. despite this, the study found that shs adopters were more inclined to present their shs installation to others to indicate their environmental commitment. the study by zander [27] ranked protecting the environment as the third overall. however, they found that it was the dominant reason among younger adopters. several studies suggested that some shs adopters were influenced by their peers [12], [22], [24], [27] or by the desire to inspire others to produce clean energy [7], [23]. graziano et al. [22] suggested that these peer effects are effective in the short range as potential adopters as vicariously influenced by their neighbour shs installations. also, it is efficacious for potential adopters could seek information on the quality and economics of shs installations from people in their community other than from outsiders. finally, a. palm [24] extended the peer effect beyond the same neighbourhood blocks to include potential adopters’ co-workers and friends. peer effects are essential for raising potential shs adopters’ interest and speeding the decision time between considering and adopting [22], [24], [26], [27]. a. palm [24] categorised peer effects into active, where there is direct interpersonal contact, and passive, where there is vicarious influence. a. palm’s study [24] found that passive peer effects were less influential than active peer effects in the shs diffusion process. as a result, they were less likely to lead to direct contact with shs adopters. potential adopters use direct communication to obtain and verify shs information and confirm that shs adoption would be a sound choice. according to rai and robinson [26], direct contact with shs adopters is the single most effective strategy to spending up decision time between considering and adopting. they found that direct contact can shorten decision times by as much as 4.6 months. d. outcomes of shs adoption most respondents indicated that they found the potential financial return of shs adoption challenging to establish because of uncertainties of computing the shs payback period study [23]. however, the shs adopters realised monthly savings in electricity bills [20]. the included studies showed that shs adoption has other non-monetary outcomes. shs adoption often contributes to energy behaviour change, such as using high power-consuming appliances when solar energy is available. also, shs adopters coadopt other renewable energy interventions, monitor their energy consumption and purchase more efficient appliances [12], [23], [27]. furthermore, some shs adopters gain new awareness and interest in energy politics; shs adopters often talk about energy policies and energy-saving technologies, thereby contributing to peer effects [23]. journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 8 http://dx.doi.org/10.21622/resd.2022.08.1.001 http://apc.aast.edu iv. discussion this scoping review provides an overview of household-level factors that influence shs diffusion that might potentially influence shs diffusion in sub-saharan africa, thereby extending the work of kezilcec and parikh [15], a general review of shs diffusion in sub-saharan africa. although the review aims to inform policy on shs diffusion in sub-saharan africa, the included studies were not geographically limited to maximise the factors that would be uncovered. the review found that the shs diffusion is influenced by household attributes, including income, age, and education status of potential shs adopters. shs adopters are motivated by monetary, environmental, energy security and independence concerns. also, peer effects influence shs adoption. on the other hand, affordability arising from high capital and maintenance costs was found to be a major barrier to shs adoption. the other barriers are inadequate and untrustworthy information on shs, the complex administrative approval process for shs installations and scepticism about the potential benefits of shs adoption. a. practical implications for sub-saharan africa the findings suggest that government support is required for the widespread adoption of shs in regions such as ssa because most potential adopters have low incomes and are not highly educated. increasing shs uptake would be the most productive way of minimising the energy poverty prevalent in ssa. for this to be done, there is a need to reduce the barriers to shs adoption, particularly the significant barriers of affordability and availability of quality shs information. minimising the affordability barrier is crucial for shs adoption in ssa as most households cannot afford the high one-off payment for shs [4]. therefore, there is a need for ssa countries to develop financing systems for shs installations. one approach is the pay-as-you-go (payg) system was tried in kenya [29], [30]. payg approach eliminates the initial costs of shs, thereby allowing homes to make payments based on their electricity. however, the disadvantage of the payg approach is that the household will never become owners of the shs, thereby limiting their direct economic benefits of ownership. other approaches include supporting hire purchase of shs through access to governmentsupported microfinancing, subsidies for purchasing shs and generous feed-in tariffs. shs ownership in ssa is unsustainable without government support due to payback period uncertainties and high repayment due to most banks’ preference for short loan periods [4]. short loan periods require higher repayments, making shs financing less attractive for most ssa households who live below the poverty line. thus, ssa governments need to subsidise or finance shs loans to mitigate this challenge. examples from other developing countries such as laos and vietnam show that if properly implemented, financing and cost recovery of shs installations through generous feed-in tariffs could contribute to ssa’s rapid electrification [4], [19]. for sustainable and rapid adoption of shs, the challenge of the availability of clear and trustworthy information needs to be addressed [19], [21], [23], [25]. evidence from the scoping review suggests that the barrier of inadequate information might be more potent in ssa as most people in ssa are not as educated as the participants in the included studies. a multisector approach to shs information dissemination might be more appropriate to counter the barrier. governments, shs experts and the private sector could collaborate to provide information on various options of shs and to champion shs adopters. these stakeholders would also facilitate joint ordering of shs, a proven effective strategy speeding the shs diffusion in finland [23]. b. limitations and future research the scoping review is not without limitations. the review inadvertently excluded other relevant literature by limiting the search to publications indexed in scopus, sciencedirect and web of science. for example, the study excluded reports from entities such as the world bank and the international energy agency, which potentially contribute to the subject. in addition, the literature search was not geographically limited, and as a result, some of the nuanced contextual issues relevant to ssa might not have been captured. therefore, this limitation needs to be addressed in future research to determine journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 9 http://dx.doi.org/10.21622/resd.2022.08.1.001 http://apc.aast.edu which factors highlighted in this study apply to ssa. further, future research needs to quantify the relative importance of each of the identified factors to ssa countries. this information would facilitate more targeted interventions to fasten shs adoption in the region. v. conclusion the findings of this scoping review suggest that widescale diffusion of shs cannot happen in ssa without government support. the included studies showed that a typical adopter of shs is a highly skilled and educated high-income individual who is energy efficiency literate and environmentally cognisant. this profile is opposite to that of a typical resident of subsaharan africa, indicating that it is unlikely that household driven shs adoption would happen in ssa. the profile of residents of ssa makes the two main barriers, the affordability and information barriers, more potent. therefore, ssa governments would need to intervene to mitigate the influence of these barriers. the reviewed papers highlight gaps for further research. further research is needed to uncover which factors are relevant for ssa and quantify their relative importance in the shs adoption process. this information is essential for developing targeted interventions to mitigate the barriers and promote shs adoption in the region. in addition, speeding up shs adoption is crucial for eliminating energy poverty prevalent in the region. this review contributes by uncovering the factors that need to be considered in developing shs diffusion policy. references [1] united nations, (2021, dec. 19). sustainable development goals: ensure access to affordable, reliable, sustainable and modern energy. 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[29] g. adwek et al., “the solar energy access in kenya: a review focusing on pay-as-you-go solar home system,” environment, development and sustainability, vol. 22, issue. 5. springer, pp. 3897–3938, jun. 2020. [30] p. yadav, a. p. heynen, d. palit, “pay-as-you-go financing: a model for viable and widespread deployment of solar home systems in rural india,” energy for sustainable development, vol. 48, pp. 139–153, feb. 2019. journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 9 resd © 2015 http://apc.aast.edu energy mix between renewable energy and nuclear energy prof. yousri abusahdy energy is the backbone of any development in any state. renewable energy (wind, solar and biomass) appears currently as a major strategic energy source for a sustainable development particularly for developing or under developing societies. use of renewable energy will challenge major technological changes, by achieving energy production and saving. in particular by replacing fossil fuel, a significant cut of environmental impact and green house gas emission (ghg) could be achieved. in addition renewable energy could offer a sustainable development for different societies particularly those in rural area (e.g. desert or isolated islands). the significant technical renewable energy tool developments in developed states could be much easier to be transferred to or copied in developing states . due to the lack of continuity of energy production throughout the entire days for solar and wind resources, it would either need an important increase in their cost to save energy from the hours it works to use it during the dead production period, or to use a base-load other energy source. one of the best clean and relatively sustainable is the nuclear energy. the use of energy mix between renewable energy and nuclear energy could offer the best energy strategy for a developing state like egypt. the issue of a journal for renewable energy and sustainable development from the arab academy for science and technology and maritime transport in alexandria is an important step to address many scientific and technical researches and technical applications in the field and could offer an important reference to national and international affiliations and academic researches. i wish all success to the new journal in its important field. about prof. yousri abusahdy prof. yousri abusahdy was awarded his bsc, msc and phd in nuclear engineering from alexandria university and france. he was former head of the nuclear engineering department (ned), alexandria university till 1982. prof. abushady is an international expert in the field of energy, nuclear energy and designing reactors, in particular. he is also a senior inspector at the international atomic energy agency (iaea) and former head of its safeguards operation section. prof. abusahdy assumed duty at iaea since 1984 till 2009 (for 25 years) during which he was assigned several tasks, held various positions and took part in inspection of hundreds of nuclear facilities in more than 40 countries. prof. abusahdy was awarded several honorary rewards and certificates of merit, atop of which is the nobel peace prize in 2005 jointly awarded with the iaea, as well as the international iaea distinguished award for excellence in work in 2003 in addition to alexandria university encouragement award in 1981. he also chaired and took part in various international and local scientific conferences and seminars, has a multiplicity of scientific research papers, publications, references and a number of books and articles. furthermore, he was able to design and manufacture the first prototype of an egyptian nuclear reactor in collaboration with ten bsc students as their graduation project at the nuclear energy department, alexandria university in 2012-2013 supported by an egyptian national factory. now, he is a member of the egyptian council for foreign affairs (acfa), member of pugwash international association that is countering nuclear weapons. recently, he is a visiting professor at a number of egyptian universities. journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 126 resd © 2015 http://apc.aast.edu a brief introduction to building information modeling (bim) and its interoperability with trnsys a. boukaraa & a. naamaneb a école nationale supérieure d'architecture de marseille, l’unité de recherche project[s] email: abdelaziz.boukara@marseille.archi.fr b aix marseille université, cnrs, ensam, université de toulon, lsis umr 7296, 13397, marseille france, email: aziz.naamane@lsis.org abstract hand-drafted print, sketching and hand modeling were the standard for building designs before the advent of computer aided design (cad) systems. nowadays cad systems are better understood, their adoption increased until the 2d, 3d cad system and the virtual reality system have become the norm. their natural evolution has given rise to a new and more complex generation of building design tools known as building information modeling, or bim. there is insufficient clarity about what bim is, although this is improving, and there is much shared understanding. there is agreement that bim is not just software. bim is not just cad, or geometric data. bim is a collaboratively generated and maintained data rich information source for the life of the design process and beyond. in this paper, we present briefly the greatest value derived from bim in the use and maintenance of buildings and the use of trnsys with bim. nomenclature – bim building information modeling cad computer assisted design mep mechanical, electrical & plumbing trnsys transient simulation program i. introduction wikipedia defines building information modeling (bim) as the process of generating and managing building data during its life cycle using threedimensional, real-time, dynamic building modeling software to decrease wasted time and resources in building design and construction. this process produces the building information model (also abbreviated bim), which encompasses building geometry, spatial relationships, geographic information, and quantities and properties of building components, including the life-cycle processes of construction and facility operation. building information modeling (bim, the process) began as a common name for a variety of activities in objectoriented computer-aided design (cad) that support the representation of building elements in terms of their 3d geometric and non-geometric (functional) attributes and relationships[2]. ii. what is bim? bim is an intelligent model-based process that provides insight to help you plan, design, construct, and manage buildings and infrastructure. so bim goes further than traditional cad drawings by providing intelligence to individual building components (e.g. windows, walls or chillers) as well as providing systemand building-wide information and awareness (system flows or building loads) in addition to simple spatial relationships. the bim process involves participants from the entire project life cycle (architect, engineer, contractor, owner, facilities management, etc.) who all contribute and communicate with bim designers, who are asked to provide more accurate energy modelling data. it is important to not consider and think that bim is a software; bim should be considered as the process of creating and using digital models for design, construction and/or operations of building projects. these models combine intelligent 2d and 3d objects used to define a building design, along with external factors, such as geographic location and local conditions, into a virtual building database that provides a single, integrated source for all information associated with that building’s design. the “intelligence” attributed to the objects includes parametrically-defined graphical and non-graphical information, giving the architects, mep engineers, and contractors the ability to represent geometric and functional relationships between building elements. this information feeds an integrated database, which in turn feeds all design documents and schedules for http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 127 resd © 2015 http://apc.aast.edu the building project. when a change is made to the building model, all graphical views (plan, elevation, detail, and other construction drawings), as well as non-graphical views, such as the design documents and schedules, automatically reflect the change. therefore, the main advantages of bim are: a. improved information flow because a digital model represents a unified description of a building, it can significantly improve the flow of information in every stage of the design, construction, and life cycle of a building the digital model can be accessed by the architects, mep engineers, contractors, facilities managers, and owners at different phases in the building life cycle to add, extract, or modify information in support of their role. a clear vision of the project is maintained to promote informed decisions, reduce errors, and improve productivity[5]. b. better design visualization the ability to predict how occupants, visitors, and neighbors will react to and interact with a building is a crucial part of the design process for architects and engineers. however, the virtual building model created during the bim process also provides an important benefit in helping mep engineers optimize the layout of the hvac system within the space constraints of the building design [2]. whether placing an air handler in a mechanical room, or routing piping or ductwork, the ability to virtually build the hvac system and visually examine it in 3d can provide added assurance that all components will fit when construction begins [3]. c. improved cost estimating bim can simplify and help provide better cost estimates because of the depth and precision of the information it provides. the relative ease with which material and assembly quantities can be extracted from the model can increase the speed and accuracy of estimates, providing a better gauge of the impact of design changes so that budget concerns can be dealt with proactively. d. improved energy analysis here again, bim can simplify and improve the accuracy of energy analysis because the data required to perform such analysis is resident in the digital building model [4]. e. reduced construction costs clash detection can be used long before construction begins to show where parts of the design occupy the same space. this can reduce or eliminate the need for changes in the field during construction. bim models can also be used to help prefabricate building components, such as duct or pipe runs, with confidence. this can save in costs associated with assembly and installation. f. building history as a building passes through design, construction, and into occupancy, the digital model can serve as an important information library for owners and service contractors. for example, if a building component fails, the building information model can be used to identify its location, manufacturer, model number, performance specifications, and other pertinent data to most efficiently repair or replace that component. if a portion of the building is being remodeled, the building information model can be used to identify concealed components, such as piping, ductwork, and electrical equipment to promote informed decisions on the remodel design[6]. fig .1 bim environment iii. trynsys and bim trnsys is a complete, modular, and expansible simulation environment for the transient simulation of thermal systems including multi-zone buildings [1], [8]. it is used by engineers and researchers around the world to validate new energy concepts, from simple solar domestic hot water systems to the design and simulation of buildings and their equipment, including control strategies, occupant behavior, alternative energy systems (wind, solar, photovoltaic, hydrogen systems), etc. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 128 resd © 2015 http://apc.aast.edu one of the key factors in trnsys’ success over the last 25 years is its open, modularstructure. the source code of the kernel as well as the component models is delivered to theusers. this simplifies extending existing models to make them fit the user’s specific needs. no single computer application can support all of the tasks associated with building design and production. interoperability depicts the need to pass data and knowledge between applications, allowing multiple types of experts and applications to contribute to the work at hand. interoperability has traditionally relied on file -based exchange formats, such as dxf (drawing exchange format, or another type of date as dwg and more) and iges that exchange only geometry. in this part, we present how trnsys is used in bim framework. iv. study case: dynamic thermal simulation of a building the project consists of 8 buildings as shown on the below ground plane. the study will focus on building e. the objective is to analyze the thermal behaviour of the building and evaluate the impact of technical or architectural choices in order to justify the proposed solution. in this case, the standard building, initially defined without insulation on the external envelop was modified by taking into account the glazing surface in the building. the simple glazing was changed to a double glazing layer incorporated with argon. a dynamic thermal simulation with trnsys software was conducted. the simulation results are presented as output data, hour by hour: temperature, moisture, powers of air conditioning, energy consumption, and so forth, related to the building behaviour and its occupants. the different steps carried out in the simulation are the following: a. step 1 the building is obtained on a graphical format compatible with sketch up environment fig .2 cad format fig .3 sketchup view using trns3d (open studio) plugin b. step 2 thermophysical properties are affected to the external envelop once the operation has been completed the file is saved in an appropriate format idf. this enables to make the connection between sketchup and trnsys. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 129 resd © 2015 http://apc.aast.edu fig .4 opening the idf format on simulation studio trnsys is loaded with features that allow making the link between the geometric modeling and thermal modeling, so it minimizes the time and the loss of the data; this interface returns fully under the bim approach.the tool that is used to set all the thermophysical, properties and in this case the different consumption and internal inputs as a function of the scenarri is trnbuild. the latter allows thermophysical modifications at the level of the envelope and its properties. fig .5 trnbuild environment heat transfer calculations are made in trnbuild and forwarded to the studio simulation environment in which the building is being updated (data). fig .6 managing the project on open studio environment v. simulation results after making several parametric simulations, we obtained the following results concerning the comfort temperature and energy consumption (summer comfort) parameters. fig .7 simulation results (type 65, online plotter) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 130 resd © 2015 http://apc.aast.edu over a period of 20 years, the building designed by the project management team will allow an economy of exploitation of €326 529, or an average of €16 326 / year. such building designed by the project management team will enable a saving of 82 257 kwh of electricity / year. v. conclusion those who have adopted bim continue to tell us about the real benefits it delivers. for the design team, there are clear benefits of collaboration, visualisation, coordination and information retrieval. this readily translates into increased cost efficiencies and profitability. the use and sophistication of bim will continue to grow as more of the benefits of the technology have become evident. the number of buildings designed using the technology and the number of bim users has grown dramatically over the past few years, and this trend is expected to continue. the benefits of bim adoption depend on all parties being able to engage and collaborate in a well-informed way. in the bim world all participants depend on each other to succeed. there may be a lot of focus on technology, but bim is also about people and processes. people need to understand the opportunities offered by technology and make choices about how to use it. references [1] klein, s. a., beckman, w., mitchell, j. w., duffie, a. j., duffie, n. a., freeman, t. l., mitchell, j. c., braun, j. e., evans, b. l., kummer, j. p., urban, r. e., fiksel, a., thornton, j., blair, n. j.,williams, p. m., bradley, d. e., mcdoweel, t. p. & kummert, m. 2004. trnsys 160a transient system simulation program, user manual, adison, solar energy laboratory, university of isconsinmadison. [2] laine, t., et al., 2010. energy and thermal performance management through utilisation of building information models nbdm, neutral building data model, http://nbdm.org/ [3] nytsch-geusen, c. et al., 2003. integration of caad, thermal building simulation and cfd by using ifc data exchange format, eigth international ibpsa conference, eindhoven, netherland. [4] bazjanac, v. 2008. ifc bim-based methodology for semi-automated building energy performance simulation. in l. rischmoller (ed.), cib w78, proc. 25th conf. [5] ford, s., aouad, g., kirkham, j., brandon, p., brown, f., child, t., cooper, g., oxman, r., young, b., 1995. an information engineering approach to modelling building design, automation in construction 4(1), pp. 5-15. [6] sacks, r., eastman, c.m., lee, g., 2004. parametric 3d modeling in building construction with examples from precast concrete, automation in construction 13(3), pp. 291-312. [7] migilinskas, d., ustinovichius, l., 2006. computer-aided modelling, evaluation and management of construction project according plm concept,lecture notes in computer science 4101, pp. 242-250. [8] eastman, c., teicholz, p., sacks, r., listo, k., 2008. bim handbook: a guide to building information modeling for owners, managers, designers,engineers, and contractors. hoboken (new jersey): wiley, p. 490. http://apc.aast.edu/ volume 1, issue 2, december 2015 issn 2356-8569 journal of renewable energy and sustainable development (resd) 235 resd © 2015 http://apc.aast.edu sustainable development is the only path to achieve the green economy eng. ahmed abou elseoud sustainable development is the management of renewable resources for the good of the entire human and natural community. built into this concept is an awareness of the animal and plant life of the surrounding environment .the goal of sustainable development is to provide resources for the use of present populations without compromising the availability of those resources for future generations, and without causing environmental damage that challenges the survival of natural ecosystems. consequently, sustainable economies cannot be based on the use of non-renewable resources. ultimately, sustainable economies must be supported by the use of renewable resources such as biological productivity, and solar, wind, geothermal, and biomass energy sources. however, even renewable resources may be subjected to overexploitation and other types of environmental degradation. central to the notion of sustainable development is the requirement that renewable resources are utilized in ways that do not diminish their capacity for renewal, so that they will always be present to sustain future generations of humans. on the other hand, egypt welcomes the concept of the green economy to achieve sustainable development ,within the framework of respect for national priorities of each country, in order to achieve more decent work opportunities, and developments continued, and use environmental resources. egypt have passed already in the implementation of a number of pilot projects in this regard, and look forward to witnessing the next stage for more cooperation with development. the energy is the main driver of economic and social development with the necessity to development of primary energy resources and the proper management and use of the most important policies and development strategies egypt depends in achieving economic development and technological several sources of energy available to a power and petroleum and natural gas, but that recently egypt has seen a severe lack of energy due to the following reasons increased energy consumption rate lower crude oil and gas production rates in the country some electricity production plants with low efficiency increasing proportion of commercial wasteslow expansion of the use of alternative energy .in this sense the ministry of environment has searched for alternative sources of energy assessing its environmental impact and its economic and social impact at the same time and take measures and actions that would raise sustainable proportion of renewable energy in the egyptian energy mix and working to reduce the pressures of climate change where can these measures can contribute to maximize the utilization of alternative energy resources and traditional such as the use of solid waste as well as alternative fuels and use them as a form of alternative energy. about eng. ahmed abou elseoud currently the chief executive officer, egyptian environmental affairs agency, ministry of environment. he has over 29 years of experience in different aspects and phases of water environmental management. he also has a significant expertise in computer modelling, management information systems, decision support systems and environmental quality monitoring and analysis including oversight of biomonitoring and environmental flow monitoring to eu water framework directives, in egypt, armenia, azerbaijan and georgia. eng abou elseoud has served as water resources planner in the egyptian ministry of water resources and irrigation for 15 years and moved to the ministry of environment where promoted to be the first deputy secretary head of the central department for environmental quality in the egyptian ministry of environment. he is a member of the management board of the egyptian electricity holding company, cairo, charged with reviewing annual strategic planning, investment project and tariff structures for electricity in egypt. http://apc.aast.edu/ 48 journal of renewable energy and sustainable development (resd) http://dx.doi.org/10.21622/resd.2020.06.2.048 submitted on | 05 june 2020 accepted on | 01 october 2020 published on | 12 november 2020 volume 6, issue 2, december 2020 issn 2356-8569 ___________________________________ _____________________________________________________________________________________________________________________________ green supply chain practices framework for petrochemicals in egypt karim soliman, ghada elkady arab academy for science, technology & maritime transport, egypt, karim.mohamed@aast.edu, ghada-elkady@aast.edu abstract the aim of this study is to determine the extent of green supply chain management (gscm) practices used by shell and co-operation (co-op) petroleum companies in egypt and to evaluate the effect of gscm practices on the operational performance of both companies. a conceptual framework was developed to link the gscm practices and operational performance. the framework consisted of three gscm practices (green procurement, green manufacturing, and reverse logistics) as independent variables and four operational attributes (quality, safety, delivery, and flexibility) as dependent variables. the data were collected through on-site surveys, using eighteen-item-questionnaire with the relevant departments in both companies from the three managerial levels (i.e. strategic, tactical, and operational). further, the results, based on benchmarking, were statistically analyzed by fischer analysis. the results offer guidelines to petroleum and lubricant manufacturers to enhance their operational performance and customer satisfaction while employing gscm practices throughout their entire supply chain (sc). keywords green supply chain management, operational performance, reverse logistics, green procurement, green manufacturing. i. introduction the increase in greenhouse gas emissions, global warming and environmental pollution by companies has increased the need for organizations to reorganize their sc processes to improve the operational performance of enterprises and thus products in accordance with the requirements of environmental regulations [1]). furthermore, environmental pollution and the increase in greenhouse emissions have led to an increased demand for organizations to reorganize sc operations, thereby conserving scarce resources. the gscm is an important organizational philosophy to achieve corporate profit and market share objectives by reducing environmental risks and impacts while improving the ecological efficiency of these organizations and their partners [2]. as a synergistic joining of environmental and supply chain management (scm), the competitive and global dimensions of these two topics cannot go unnoticed by organizations. likewise, the rise in environmental missions and concerns lead to the need to reduce environmental pollution resulting from industrial development with scm [3]). moreover, monshiwa [4] acknowledged that any competitive advantage obtained or can be obtained by applying the green approach and accordingly, this creates pressure on companies not to ignore these green initiatives. with the increase in environmental concerns during the past decade, a consensus is growing that environmental degradation issues accompanying industrial development should be addressed together with scm, thereby contributing to gscm [5]). egypt is one of the developing countries in the world and is becoming increasingly industrialized and this makes egypt faces a heavy burden on the environment. likewise, multinational organizations and developed countries use the developing countries as a point of disposal of endemic products and this has environmental impact [6]. for this reason, this research attempts to answer the following questions: (1) what are the current state of gscm practices adoption by shell and co-op petroleum companies in egypt? (2) how have the gscm practices affected the operational performance at shell and co-op petroleum companies? and (3) what are the drivers of gscm practices in shell and co-op petroleum companies? hence, this research will help local companies operating in the lubricant industry, such as co-op petroleum company, to be more involved in http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 49 implementing the gscm concept. additionally, the management will be able to identify gscm practices that will develop and improve the operational performance of the co-op company besides all local companies operating in this controversial area. besides, how these companies can benefit from the implementation of shell's gscm practices and their effective impact on their operational performance. it has been noted that previous studies on the evaluation of operational performance and the effect of implementing gscp in this field are few, especially in developing countries, such as egypt. thus, this research is urgently needed to determine how the operational performance of companies in the lubricant industry is affected by the implementation of gscm practices. the remainder of the paper is organized as follows. in section 2, the literature is briefly discussed. in section 3, the methodology section is introduced. then in section 4, the analysis and findings are presented. finally, sections 5 and 6 conclude the study, including the theoretical contributions and managerial implications of the findings. ii. literature review environmentally sustainable gscm has emerged as organizational philosophy to achieve corporate profit and market share objectives by reducing environmental risks and impacts while improving the ecological efficiency of these organizations and their partners [7];[2]. likewise, it is necessary to integrate the organizational environmental management practices into the entire sc to achieve a sustainable sc and maintain a competitive advantage [8]; [9]. the gscm practices should cover all the sc activities, from green purchasing to integrate lifecycle management, through to manufacturer, customer, and closing the loop with reverse logistics [10]. thus, the literature review section presents an overview on all the previously mentioned concepts and thoughts and is divided into two main sections: gscm concepts and paradigms, and the gscm practices and operational performance, all discussed respectively. 1. green supply chain management practices the full concept of gscm was first proposed by the michigan state university manufacturing research association (mrc) in 1996 to comprehensively consider environmental impacts and improve the resources of manufacturing chains (handfield, 1996). this means that it aims to reduce the environmental impacts of products at the end of use by tracking and controlling purchases of raw materials, in order to ensure compliance with environmental rules and regulations. furthermore, awareness of environmental pollution has increased among people around the world, making them curious about protecting the environment. as a result, people are planning to buy green products, and the concept of gscm is becoming more popular and gradually became the new concept of sustainable development of enterprises. the first series of green scs emerged in the context of 1989 when [1] first published how to develop an ideal forecasting system for organizations to predict reusable products, and the first book of green design literature came into context in 1991. later, the article, published by [11] was the first to examine the need for green design to reduce the impact of waste products. while [2] came to context and expanded the green design framework. according to beamon [12] , wastes from industrialization and the use of natural resources contribute to environmental pollution. in addition, scarcity of resources is another factor that enterprises and industrial companies must study. therefore, the gscm is the only way to deal with these environmental problems because gscm has its primary role in dealing with environmental degradation, for example, the contraction of raw material resources, the lack of scientific and professional treatment with waste, and the increasing level of pollution [13]. the gscm practices is frequently used for various activities implemented by any company to diminish the negative impacts on the environment [14]. these activities vary from green purchasing to integrated scs flowing from suppliers to the manufacturer, to customers and reverse to logistics, which is named as “closing the loop” [8] as shown in figure 1. fig .1 the areas of literature associated with grsc source: zhu and sakris, 2006. [8] when empirical studies on gscm are assessed, it has been found that there are several gscm dimensions http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 50 discussed by different researchers, such as green purchasing, green manufacturing, green logistics, green packaging, green marketing, green building, green education, investment recover, eco-design, etc. [15]; [8]; [16]; [17]; [18]. in light of this researches, three dimensions were selected to be included in this study as shown in table 1 and further will be briefly described in the next sub-sections. table 1. gscm dimensions. dimension definition author(s) green purchasing the integration of environmental efforts, purchasing activities and environmental objectives of the firm foo [19] et al., 2019 ; zhang [20] et al., 2018 green manufacturing the planning and implementation of energy-saving resources in the production process to produce environmentally friendly products with the least resources ma et al., 2018 [21]; karimi et al., 2019 [22] reverse logistics managing how products and/or materials are returned to the original manufacturer or agent for reuse, recycling or re-manufacture. bottani et al., 2019 [10]; bai and sakris, 2019 [23] a. green purchasing the green purchasing implicates a company evaluating the environmental performance of their vendors, which requires these vendors to implement all necessary operation measures to ensure the environmental quality [7]. furthermore, this step is considered to be the first step in the value chain that positively affect the operational performance of the entire chain [24]. [18] acknowledged that green purchasing entails all organizations in the entire chain to get attention towards the eco-labeling of all purchased items, supplier’s cooperation to attain the environmental objectives, supplier’s environmental audit, supplier’s international standards organization (iso) 14000 accreditation, supplier’s environmentally friendly practice assessment, and finally, providing the required environmental design specification to the suppliers. chen [25] also points out that green procurement has beneficial effects on the corporate pollution control system and can promote the successful implementation of the company's quality and environmental standards. likewise, [24] signified that green purchasing involves a procurement function through various sc activities, such as life cycle analysis (lca) and 3r model reduction, reuse, and recycling that belong to the product design and process part. the first is to reduce waste received from products and to guide consumers to reduce their waste by purchasing their own needs only and purchasing goods made from recyclable materials rather than nonrecyclable materials. the second r is to reuse any wastes to reduce environmental pollution and global warming. finally, the third r is to recycle the disposed waste by segregating the materials from each other. b. green manufacturing the green manufacturing is considered the significant step in all gscm activities in any industry to continuously improve their operational performance such as reducing cost, the quality of the products, and the environmental risks, all of which bring a competitive advantage to the product [22]. sezen [26] affirmed that pollution can be reduced or mitigated through continuous improvement strategies that focus on green design and manufacturing. nevertheless, dubey [27] added that green manufacturing is a system that connects all problems associated with the design, planning, and manufacturing matters efficiently to control the emerged waste amounts to be consistent with the environmental standards and procedures. c. reverse logistics as reverse logistics is gaining increasing interest and relevance, the question becomes whether it is enough to limit greening efforts to one segment of the sc and single companies or choosing to expand these efforts to the entire chain. greening can start right at the source with supply conditions and can work its way through storage and packaging practices to distribution and end-consumers [28]. however, the reversed flow can take different forms, from collection to return shipments into the distribution channel, followed by disassembly and re-use of selected parts. alternatively, used goods could be shredded and scrapped and reentered into production as raw materials. returned goods, or elements of the product, could even be returned to suppliers and supply chain partners for them to re-manufacture [23]. those possible sc applications should be taken into consideration. one step further, dis-assembly operations in the reversed http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 51 flow might call for a proactive design for dis-assembly right in the initial product design stage of both supplier and customer [10]. of all green activities, it is relatively easier to repair existing products and run renovations. more and more companies pay attention to yield management or product recovery management. reverse logistics aims to ensure the return of materials and products from the user to the product for reuse, recycling, and regeneration [29]. however, for most companies, they do not put reverse logistics in their planning strategies initially, although they will take action to respond to the requirements of customers or members of the final channel. 2. the relationship between gscm practices and operational performance there are several impacts of gscm practices on performance outcomes. generally, the adoption of gscm practices by manufacturing organizations lead to improved environmental performance and economic performance, and on operational performance [18]. laws, procedures, standards, and incentives regulated by regulatory institutions make corporate responsibility more environmentally friendly [30]. sarkis [31] discussed the impact of persistent pressures through laws and regulations on improving awareness in developed countries such as the united states of america where large industrial companies often face scrutiny by environmental activists [7]. thus, companies and organizations are under pressure from their competitors, forcing companies to implement green supply chain practices to reduce competition and make them competitive [32] . additionally, consumers are increasingly aware of the environmental impacts, which leads to the selection of the goods they receive and ask companies to apply the minimum green standards in their product design and thus to preserve the environment [33]. companies take societal responsibilities into society as companies believe they must commit themselves to society to conform to expectations and standards that lead to accepted business behaviors [34]. thus, implementation of gscm practices can result in a set of advantages for the company itself, for procurement and supply, and for the community itself. green procurement and supply can be improved to the extent that green supply facilitates information exchange and flow and cooperative relationships in the supply chain [35]; [36]. the benefits of green supply to society begin with a green environment, reduce hazardous and harmful substances, use scarce resources more efficiently, and avoid waste. green supply also helps to spread environmental knowledge through green marketing and best practices. environmental initiatives in the industrial supply chain should focus on the production and processing processes used by the supplier [37]. according to [33], the operational performance was summarized in four factors: • quality: evaluate the product or service that meets customer satisfaction and expectations. • safety: evaluate both the health and the working environment of the staff. • delivery: evaluate the business unit with its achievement in a proper time based on customer requirement. • flexibility: this means that this requires a great deal of flexibility in different processes, such as reducing the number of back orders, lost sales, and late orders. additionally, [5] indicated the positive relationship between the gsc and multi-operational performances in cost, delivery, quality, and flexibility. while [38] signified the impact of customers’ involvement in green practices on improving the customer satisfaction. additionally, [39] affirmed that the gscm practices lead to significant operational performance increase in terms of quality, cost, and flexibility, however, it does not have any impact on the delivery aspect. accordingly, for this study, figure 2 presents the initial conceptual framework to link the three gscm practices previously identified and the four operational performance attributes adopted by [33]. iii. methodology benchmarking is an assessment process on best performing corporate goods, services and procedures [40]. benchmarking concept is also associated with individual corporations' attempts to recognize and emulate best practices in their own industry. moreover, benchmarking has also been cited as an effective method to constantly enhance organizational performance, overall management of quality and competitive advantage [2]; [41]. benchmarking as a mechanism to identify operating performance measures and compares scs in relation http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 52 to selected measures. accordingly, this study used descriptive research design by using benchmarking between shell and co-op companies in egypt. in this study, descriptive research design based on two types of benchmarking; best-in-class and operational benchmarking. in order to achieve this aim, both approaches were used to explain the relationship between the gscm practices and operational performance by benchmarking the factors that influence the impact of effective gscm between shell and co-op companies in egypt. the performance measurement methodology is defined as an effective tool for managing change; it can be described as an ongoing process to identify, understand and evaluate industry best practices to improve the performance of an organization [42]. this is usually done by studying other organizations that carry out similar operations [43]. in contrast, performance measurement is an external activity that can enable the organization to move away from tradition. however, standard measurement and comparative analysis should not be confused. in the comparative comparison group, the metrics for similar elements are compared between organizations or within the organization, and this is simply one step in the normative assessment process [44]. fig .2 initial conceptual framework to link gscm practices and operational performance source: developed by the authors shell and co-op companies have been chosen for the purpose of this study as one of them is a multinational company operating in egypt (i.e. shell), and the other was a local egyptian company (i.e. co-op). the reason behind that is to drill down into performance gaps to recognize areas for improvement [42]. figure 3 presents the overall research design. 1. data collection this study focuses on the relationship between gscm practices, and the sc operational performance. the target sample was managers in both companies from the three managerial levels (i.e. strategic, tactical, and operational). accordingly, the targeted departments were procurement, production, marketing, quality assurance, and logistics departments. there was an intention to engage a larger sample, however, if a large sample is used, data may become repetitive [45]. owing to the nature of this benchmarking study, saturation was not applied on less than 25 face-to-face conducted questionnaires. the data collection was conducted in person for four months from august 2019 to november 2019. ethical issues have been considered through gaining well-versed consent and making confirmation that the data will be treated as confidential to be used only for research purpose. all surveys were conducted on-site, using an eighteenitemquestionnaire for collecting data and were guided by the objectives of the study. the questionnaire scale was in the range from – to ++++ where respondents required to indicate their views on this scale. this scale was chosen by the researcher because it allowed the respondents to express their views more clearly and openly. at the beginning, the survey questions were assessed by five professors from the sc management field. then a pilot test was conducted with seven sc management consultants and industry experts. minor modifications were received from the experts. however, most of the remarks were related to the wording of the questions, so they were re-written to be easily understood. the questionnaire consisted of two sections: section i; included, practices of gscm, and section ii; the operational performance with regards to implementation of gscm practices. 2. data analysis researchers are indeed concerned in recognizing significant cells relationships following a statistically valid chi-squared test [46]. two test statistics are widely used to test the value of each cell. the first test is a http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 53 standardized residual that is measured as a raw residual divided by a square root of the expected value, where the raw residual is defined. the discrepancy between the observed value and the predicted value. the second test shall be modified residual: raw residual divided by its standard error. both experiments adopt the normal standard distribution asymptotically. in this study, statistical analysis was performed using a statistical program (gmp for windows version 5.1, sas institute, cary, nc, usa). for data analysis, use the fisher's exact test to compare shell and the co-op company to gsc; green procurement, green manufacturing, reverse logistics and operational performance; quality, safety, delivery and, flexibility. data were analyzed as = 0, + = 25, ++ = 50, +++ = 75, ++++ = 100. at the end, the results were considered significant at p <0.05 which is considered acceptable to achieve the objectives of the study. the reason behind using fisher’s exact test in data analysis is that in case of small samples, the fisher exact test is considered an effective tool used instead of the chi square test for 2 in 2 tables. fig. 3. overall research design source: developed by the authors . iv. analysis and findings this study was carried out to determine the effect of green supply chain practices on operational performance of benchmarking study between shell egypt and co-op petroleum company working in the lubricant industry. the study had two objectives. the first is to determine the extent of gscm practices used by shell and co-op petroleum company in egypt; the second objective is to establish the relationship between green supply chain management practices and operational performance of shell and the co-op petroleum company in egypt. accordingly, in the subsequent sections, the detailed descriptive analysis of the questionnaires conducted was analyzed using fisher’s exact test. 1. green procurement the results of extent the firm practice green procurement are demonstrated in table 2. the results showed that suppliers are required to have iso 14001, shell company had significantly higher extent the firm practice green procurement than the co-op company (p < 0.0001). likewise, for purchasing materials that contain green attributes, the results revealed that shell company had significantly higher extent firm practice green procurement than the coop company (p < 0.00001). furthermore, the fisher’s exact test results unveiled that evaluate suppliers on specific environmental criteria, shell company has significantly higher extent the firm practice green procurement than the co-op company (p< 0.0001). likewise, the results showed that procure products that are made using recycled packages, shell company had a significantly higher extent the firm practice green procurement than the co-op company (p< 0.0001). http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 54 the sc network starts in shell egypt with the suppliers who are mainly raw material suppliers (base oil and additives) and packaging materials. suppliers are evaluated based on their commitment to environmental standards according to the rider center for sc management (2008) that protects the environment from all aspects (as mentioned earlier). base oils are supplied to the plant by refineries either inside or outside of egypt. additives are delivered to the lubricant oil blending plant (lobp) through alexandria port from europe. all packaging material supply is locally supplied to the plant. these raw and packaging materials are used to manufacture a wide range of portfolio of products. once products are produced, they are shipped to the distribution center in 6th of october waiting its turn to be shipped to the customers. thus, the results revealed that co-op company was not committed to environmental standards according to the regulations that protects the environment from all aspects. table 2. the extent at which the firm practices green procurement. green procurement practices shell co-op requiring suppliers to have iso 14001 75*** 25 purchasing materials that contain green attributes 75*** 0 evaluating suppliers on specific environmental criteria 75*** 0 procuring products that are made using recycled packages 75*** 0 source: research data (2019) by using fisher's exact tes. table 3. extent at which the firm practices green manufacturing. green manufacturing practices shell co-op producing products that have packages which can be recycled 75*** 25 using life cycle assessment to evaluate environmental load 75 75 replacing hazardous substances with that which are environmentally friendly 66*** 33 minimizing the use of materials in packaging 75*** 0 encouraging reuse of products and recycled materials 75*** 25 reducing the size of packaging 75*** 0 cooperating with suppliers to standardize packaging 75*** 0 source: research data (2019) by using fisher's exact test. 2. green manufacturing results of the extent at which the firm practices green manufacturing are shown in table 3. the fisher’s exact test results revealed that produce products that have packages which can be recycled, shell company has significantly higher extent the firm practice of green manufacturing than the co-op company (p<0.0001). likewise, the result of using life cycle assessment to evaluate environmental load showed non-significant difference between both companies. furthermore, the results of replacing hazardous substances which are environmentally friendly showed that shell company has significantly higher extent to which the firm practices green manufacturing than the co-op company (p<0.0001). moreover, concerning the minimization of the use of materials in packaging, it was clear that shell company had a significantly higher extent at which the firm practices green manufacturing than the co-op company (p< 0.0001). on the other hand, shell company has significantly higher extent at which the firm practices green manufacturing than the co-operation company (p< 0.0001) in encouraging the reuse of products and recycled materials. likewise, concerning reducing the size of packaging, it was found that shell company had significantly higher extent at which the firm practices green manufacturing than the co-operation company (p< 0.0001). finally, the results indicated that shell company has significantly higher extent at which the firm practices green manufacturing than the co-op company (p<0.0001) in cooperating with suppliers to standardize packaging. in shell, the inputs are divided into two main groups; raw materials (base oils and additives) and packaging material (bottles, packs, drums, caps, pallets, pails, stretch wrap and cartons). all these materials are recycled and reused. these inputs are discharged into main storage holding tanks (base oil and additives) and warehouses (packing material) to be used later on throughout the whole manufacturing cycle. the base oil and additives are blended with certain percentages according to the final product’s bill of materials (bom) and required a specification for each product. after blending, the mixed product is pumped through a system of pipelines that transfers it to the filling lines. the product is then dispensed in the designated packaging containers to be then transported to the finished products warehouse for storage until being shipped outside the facility to customers lobp. it is notably to mention that using life cycle assessment in co-op company is under the responsibilities petro trade company. concerning replacing hazardous http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 55 substances, shell company is concerned with recycling both the used oil and packages, while the co-op is concerned basically with recycling the used oil only. 3. reverse logistics the results of the extent of the firm practices of reverse logistics are shown in table 4. the results of dealing with disposal indicated that shell company had significantly higher extent as regards the firm practice of reverse logistics than the co-op company (p< 0.0001). regarding the processing of returned merchandise, the results showed that shell company has significantly higher extent of the firm practice of reverse logistics than the co-op company (p< 0.00001). finally, the analysis results revealed that shell company had significantly higher extent of the firm practice of reverse logistics than the co-op company (p<0.0001) in repackaging product. shell’s sc is adopting the lean strategy as it is always working on minimizing if not eliminating the waste. this includes all types of daily wastes with the concentration on inventory reduction on both the raw materials side as well as the finished product side. there are lots of efforts exerted in this area especially qualifying six sigma professionals to be able to assist in the company’s strategy and be even leaner according to [47]. on the contrary, co-op company (and all local companies) are charged of collecting used oil from distributing companies. thus, establishing petro trade company to collect used oil from all resources to increase the amount of collected oil will be a significant recommendation besides obliging service stations to establish land tanks for collecting used oil. table 4. extent of the firm practices of reverse logistics. reverse logistics shell co-op dealing with disposal 66*** 33 processing returned merchandise 75*** 25 repackaging product 75*** 0 source: research data (2019) by using fisher's exact tes. 4. operational performance with regards to implementation of gscm practices the results of operational performance with regards to implementation of gscm practice are shown in table 5. the result indicated that the quality at shell company has significantly higher extent in green procurement practices than the co-op company (p< 0.0001). furthermore, the safety at shell company revealed significantly higher extent of the firm practice of green procurement than that of co-op company (p< 0.00001). additionally, the delivery at shell company had significantly higher extent the firm practice green procurement than the co-op company (p< 0.0001). finally, the flexibility at shell company had a significantly higher extent the firm practice green procurement than that of the co-op company (p< 0.0001). finally, as shown in the table 5, the overall effects of gscm practices on operational performance reflected on quality, safety, delivery and flexibility. the competency relies always to the delivery on time of their wide range of portfolio as well as providing several after-sales technical support services which made them currently the market leader lubricants’ supplier for eight years in a row. nevertheless, shell is the highest spender on research and development reaching an annual spend of 1.3 billion dollars to be able to come up with the products that fulfill today’s customers’ needs. as mentioned above, the majorities of the raw materials supplied to the sc in egypt as well as other countries are imported goods and have strict environmental specifications. moreover, sometimes finished goods themselves are imported (or exported from other plants in the world) to satisfy a certain need in another operating unit. it is worth mentioning that planning is based on the historical statistical forecast of the products’ range. in other words, based on the finished product forecast, the material requirement planning (mrp) tools are used to explore the bill of materials (bom) and accordingly know the requirements from all bom components. based on the forecast as well, the company usually plans for all its capacities and requirements. accordingly, a sourcing plan with the companies' suppliers is constructed to fulfill the requirements of the customers. the raw and packaging materials are then converted to the finished product during the manufacturing stage. after this step, the finished product is sent to the distribution center to and be arranged and then sent to customers. in case of any faulty delivery, the company accepts returns from customers as per the service level agreement with the customer. http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 56 table 5. operational performance with regrads to implementation og gscm practices. impact shell company co-op quality 75*** 25 safety 66*** 33 delivery 75*** 25 flexibility 75*** 0 source: research data (2019) by using fisher's exact tes. 5. discussion of theoretical and managerial implications according to [48], gscm is increasing expanding enthusiasm among specialists and professionals of operations and scm. the developing significance of gscm is driven principally by the expanding crumbling of nature; that is, reducing crude material assets, flooding waste locales and expanding levels of contamination. actually, the gscm is a business esteem driver and not a cost focus [45];[17]. a successful way for sc managers to strengthen the reliability of scs is to complete a benchmarking exercise to assess how well their sc is performing. in order to complete such an exercise, a benchmarking approach for gsc performance can help benchmark scs based on their impact on the operational performance factors. based on the data collected and analyzed, figure 4 presents the refined conceptual framework for gscm practices for petrochemical companies in egypt. fig. 4. conceptual framework for gscm practices for petrochemical companies in egypt. source: developed by the authors . http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 57 the empirical results fulfilled the objectives of the study and generated adequate evidence for practitioners and decision makers to understand the various kinds of gscm practices and to what extent the adopted practices influence the operational performance. moreover, the research strongly supported the view that to green the environment requires collective responsibility and cross-functional cooperation for environmental improvements by the petrochemical’s companies. likewise, this study specifies several empirical evidences for the impact of three dimensions of gscm practices (green purchasing, green manufacturing, and reverse logistics) on four operational performance dimensions (quality, safety, delivery, and flexibility) and customer satisfaction. based on the analysis of the comebacks collected from the respondents of the study, shell egypt has already begun to implement gscm practices such as deliberating suppliers‟ iso 14000 certification; purchasing materials that contain green attributes; evaluating the suppliers on specific environmental criteria; replacing hazardous substances with those that are environmentally friendly, etc. consistent with the current literature, gscm practices drives the entire chain stakeholders to deal effectively with environmental problems, from the beginning of product design, development, and production, to reach the end user [22]; [7] . thus, these implications offer guidelines to petroleum and lubricant manufacturers to enhance their operational performance and customer satisfaction while employing gscm practices throughout their entire sc. v. conclusions and recommendations this study was carried out to determine the effect of gsc practices on operational performance using a benchmarking study between shell egypt and co-op petroleum company working in the lubricant industry. the study had two objectives. the first was to determine the extent of gsc practices used by shell and co-op petroleum company in egypt; the second objective was to establish the relationship between green sc management practices and operational performance of shell and the co-op petroleum company in egypt. the study showed that shell egypt, which operates in the lubricant industry, appreciates the role of green supply chain practices. the company practices green procurement. most practices are to ensure that suppliers comply with their environmental goals, purchase green materials, purchase energy-saving equipment, and other green manufacturing practices adopted by shell. furthermore, shell also uses recycling and collaboration with suppliers to standardize packaging and then reduce package size. shell has faced challenges in implementing green supply chain practices but has access to the tools and techniques needed to measure the performance of green supply chain management. this corresponds to the challenges identified by the rider center for supply chain management (2008). the three independent variables of gscm practices have clearly improved recycling and reuse opportunities, as well as improved operational performance and thus customer loyalty. as for the co-op petroleum company, it is clear that they used raw materials and packaging materials that cannot be recycled and that are non-reusable, although the co-op company has realized the importance of gscm practices. environmental issues are not used in the selection criteria of suppliers because of the company's lack of appropriate technology, which is a major challenge. it also lacks the gscm, which had a direct negative impact on customer loyalty. therefore, gscm is an operational innovation that petrochemical firms may adopt to address environmental concerns, such as, complying with stringent environmental regulations, addressing the environmental concerns of their suppliers and customers, and to mitigating the environmental impact of their production and service activities. in the future, implementing a gsc will be even more important than it is today. reasons for this are: concentrating on more government legislation, growing awareness of environmental issues and motivating consumers to be more sustainable. thus, greening the sc is not an alternative, it is becoming a norm. the area of gscm is relatively young and is still suffering from a shortage of information. this research will help to bring forth unknown information in the petroleum industry that will go a long way in facilitating further understanding of gscm practices adoption. future researchers will empirically test the relationships suggested in this paper in different companies to enable comparative studies. a larger sample would also allow detailed cross-sectoral comparisons which are not possible in the context of this study. to be efficient and effective in gscm, collaboration among important stakeholders in the petroleum marketing firms supply chain must be http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 58 strongly concerned. this study recommends the creation of awareness of the role of gscm practices for the benefit of all the stakeholders and for sustainable economic and environment development. references [1] hsu, c.-w. and a.h. hu, green supply chain management in the electronic industry. international journal of environmental science & technology, 2008. 5(2): p. 205-216. 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[29] agrawal, s. and r.k. singh, analyzing disposition decisions for sustainable reverse logistics: triple bottom line approach. resources, conservation and recycling, 2019. 150: p. 104448. [30] bohas, a. and n. poussing, an empirical exploration of the role of strategic and responsive corporate social responsibility in the adoption of different green it strategies. journal of cleaner production, 2016. 122: p. 240-251. [31] sarkis, j., q. zhu, and k.-h. lai, an organizational theoretic review of green supply chain management literature. international journal of production economics, 2011. 130(1): p. 1-15. [32] canning, l. and s. hanmer‐lloyd, modelling the adaptation process in interactive business relationships. journal of business & industrial marketing, 2002. [33] tate, w.l., l.m. ellram, and j.f. kirchoff, corporate social responsibility reports: a thematic analysis related to supply chain management. journal of supply chain management, 2010. 46(1): p. 19-44. [34] singh, a. and a. trivedi, sustainable green supply chain management: trends and current practices. competitiveness review, 2016. [35] sarkis, j. and y. dou, green supply chain management: a concise introduction. 2017: routledge. [36] wu, a. and t. li, gaining sustainable development by green supply chain innovation: perspectives of specific investments and stakeholder engagement. business strategy and the environment, 2020. 29(3): p. 962-975. [37] liu, z., v. jayaraman, and y. luo, the unbalanced indirect effects of task characteristics on performance in professional service outsourcing. international journal of production http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 60 economics, 2017. 193: p. 281-293. [38] yang, j., et al., the influence of environmental management practices and supply chain integration on technological innovation performance—evidence from china’s manufacturing industry. sustainability, 2015. 7(11): p. 15342-15361. [39] famiyeh, s., et al., green supply chain management initiatives and operational competitive performance. benchmarking: an international journal, 2018. [40] andersen, b. and r.c. camp, current position and future development of benchmarking. the tqm magazine, 1995. [41] simatupang, t.m. and r. sridharan, a benchmarking scheme for supply chain collaboration. benchmarking: an international journal, 2004. [42] sueyoshi, t. and m. goto, data envelopment analysis for environmental assessment: comparison between public and private ownership in petroleum industry. european journal of operational research, 2012. 216(3): p. 668-678. [43] nunes, b. and d. bennett, green operations initiatives in the automotive industry: an environmental reports analysis and benchmarking study. benchmarking: an international journal, 2010. 17(3): p. 396-420. [44] sharif, a.m., benchmarking performance management systems. benchmarking: an international journal, 2002. [45] glasser, b. and a.l. strauss, the development of grounded theory. chicago, il: alden, 1967. [46] cox, m.k. and c.h. key, post hoc pair-wise comparisons for the chi-square test of homogeneity of proportions. educational and psychological measurement, 1993. 53(4): p. 951-962. [47] eckes, g., six sigma team dynamics. the elusive key to project, john wiley& sons inc., new jersey, 2003. [48] srivastava, s.k., green supply‐chain management: a state‐of‐the‐art literature review. international journal of management reviews, 2007. 9(1): p. 53-80. http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 6paper4.pdf (p.35-47) 230 resd © 2015 http://apc.aast.edu volume 1, issue 2, december 2015 issn 2356-8569 journal of renewable energy and sustainable development (resd) sustainability and energy self-sufficiency; overcoming the barriers ass. prof. rania abdel galil engendering more positive attitudes to renewable energy is by no means a simple feat. renewable energy technologies are viewed as radical innovations which necessitate substantial changes in production and consumption patterns, hence often met with resistance from both institutions and individuals. yet action is needed; global energy consumption is expected to rise by 41% and global carbon dioxide emissions by 29%, with most of the demand and rise coming from emerging economies (bp energy outlook 2035). further, countries need to meet objectives of reduction of ghg under the united nations framework convention on climate change. renewable energy share in the global energy mix needs to significantly increase in order to reach supply sufficiency, energy security, energy equity and environmental sustainability. meeting demands of energy is critical for the economic and social development of any country; energy must be secure, accessible and affordable at all levels of society, and any negative impact of energy production and energy use on the environment must be minimized. middle east energy consumption is expected to grow by 69% whilst production to grow by 32%, with 97% of demand still met by fossil fuels by the end of the 2035. energy investment of $316 billion will be required in the middle east and north africa (mena) between 2015 and 2019 to meet its growing demand for power (apicorp, 2014). diversifying energy sources is indeed of interest in the mena region, spurred by growing demand for power and desalinated water, fluctuating fuel price, ghg emission reduction targets, depleting fossil fuel reserves and advances in renewable energy technology. however, there are many barriers that hinder the adoption of renewable energy technologies worldwide, but more so in the mena region. these barriers are political, economic, social and technological. with a focus on europe and mena, it can be said that these barriers have much in common albeit framing the struggle on the micro level in europe and on the macro level in mena. on a political level, renewable energy policies in europe are criticized as being uncoordinated, unstrategised and based on multiple interests, generally favouring macro level and inadequate to stimulate widespread adoption at the micro level. similarly, in the mena region, there is a lack of coordination between sustainable energy policies with other policy fields, namely economic, financial, environmental and social policy, with a lack of expertise in renewable energy policies and supportive policies for private investment. on an economic level, in europe, sourcing and accessing finance is a major barrier for communities, with a lack appropriate organizational structures, the volatility of grant regimes and uncertain infrastructural costs perhaps associated with the near monopolistic position of some grid companies. whereas in the mena region, there are no incentives for economical use of energy, there is a lack of funding in public utilities in most countries, the investment climate is less attractive and a monopoly position of most electricity producers exists. http://apc.aast.edu/ 231 resd © 2015 http://apc.aast.edu journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 technically, on a national level in europe, a problem of the incompatibility of the new technologies with the current infrastructure (grid connection and capacity) are often identified as barriers, whilst on a community level, the lack of data on the efficiency of techniques, lack of technical skills and experience to implement renewable energy solutions act as barriers. in mena, technologies involving the use of renewables have barely become established on the market and there is a significant lack of knowledge in the areas of technology transfer, marketing and the development of services within the energy sector. finally, on a social level, the picture in the mena region is bleaker. in europe, governments and communities are well aware of the challenges laying ahead in terms of energy and some are well underway in achieving targets on the energy sustainability front (wec, 2013). that is not to say that social barriers do not exist. they are manifested in the hindrance of knowledge transfer between social actors including misinformation, inadequate public consultation, and lack of inertia, access to relevant professional services, expertise and skills. also, community concern over aesthetics, environmental issues and a perception of unequal distribution of benefits. however, in the mena there is barely any awareness on the issue of energy security, equity and sustainability among individuals and the society, with lack of education and information on production and consumption, and no incentives for change. the rate of adoption, although not homogenous across the region, has been slow to date. policy makers will not be persuaded to change, as a bottom-up approach is unlikely and the market will not develop accordingly, for lack of demand. also, top-bottom approaches will be ineffective as the adoption of new systems are often met with resistance and the uptake will require change of entrenched practices and incentives for adoption. challenges to the wider adoption of renewable energy lie in two areas; provision and choice. the later can be overcome by awareness campaigns, incentive-based initiatives, and involving and empowering individuals and local communities in the development of renewable energy solutions. there is an urgent need to support initiatives in the mena region to collaborate on environmental and energy related issues, build capacities to enable civil society engagement in the context of developing and implementing national energy plans and increase awareness on the needed shift towards a sustainable energy future. meaningful global price for carbon is but one example to provide incentives for everyone to play their role in meeting the world’s increasing energy needs whilst combating climate change and maintaining good air and water quality. to conclude, a quote by the united nations secretary-general ban ki-moon comes to mind: “energy is the golden thread that weaves together economic growth, social equity, and environmental sustainability”. if sustainable development is to be realized, if there is to be a universal access to modern energy services and energy self-sufficiency, the share of renewable energy sources and the global rate of improvement in energy efficiency need to intensify, in addition to a strong shift of attitudes and policy towards cleaner choices of energy. about ass. prof. rania abdel galil associate professor rania abdel galil has graduated from alexandria university, faculty of engineering. she was appointed in the arab academy for science, technology and maritime transport (aastmt) till present. she received her phd from sheffield university, united kingdom in 2007. following her phd, she accepted an appointment in the department of town and regional planning, sheffield university, uk, where she taught for two years. during that time, she was a member in a winning bid for a research commissioned by the parliamentary commissioner for the environment, new zealand. she is now an associate professor in the department of architectural engineering and environmental design, aastmt. besides teaching, she acted as riba coordinator over the last 5 years and currently liaises for international relations and training opportunities. rania has presented in many international conferences, has been a member of the scientific and organizing committees and actively participated in numerous workshops and symposiums. she is the associate-editor of the journal of renewable energy and sustainable development (egypt) and an editorial board member of the international development planning review journal (uk). she is a peer reviewer in several journals, supervised numerous phd and msc theses and has published over 20 research papers. her research interests are in sustainability and the north/south divide. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 146 resd © 2015 http://apc.aast.edu sustainable management of climate change: the case of the middle east and north africa region adel m. al taweel1*, v. ismet ugursal1 and donnie boodlal2 1 dalhousie university, halifax ns, canada 2 the university of trinidad and tobago, point lisas campus, trinidad and tobago wi, * corresponding author: al.taweel@dal.ca abstract climate change is one of the major environmental challenges facing the world. particularly vulnerable are arid and low-laying coastal areas, conditions that prevail through most of the middle east and north africa [mena]. this region is an economically diverse one, including both the oilrich economies in the gulf and countries that are resource-scarce in relation to their population. however, with about 23 percent of mena’s population living on less than $2 a day, it is imperative that the climate change management strategies adopted be cost-effective and emphasize economic, social and human development while addressing the concerns arising from anthropogenic climate change. over the past decades several national and international mechanisms were developed in an attempt to reduce the emissions considered to be mainly responsible for climate change, and to assist in coping with the adverse effects that are beginning to occur as a result of climate change. unfortunately, many of these approaches are presently associated with economic penalties that often adversely affect the socio-economic welfare of the populace, particularly in low-, and medium-income countries. in this regard, it is informative to note the experience recently gained by trinidad and tobago [t&t] in its attempt to reduce ghg emissions without affecting the competitiveness of the industrial and agricultural sectors. using appropriate decision making tools and a policy environment based on a combination of regulations and incentives, the environmental challenges can be turned into a vehicle for sustainable development. this paper discusses the factors that need to be considered while developing a sustainable climate change management approach for the mena region and develops some recommendations that may be essential for achieving the desired climate change mitigation/adaptation actions while minimizing social disruption.greenhouse gas emissions keywords climate change, mena region, global and regional energy production/consumption trends, energy and wealth, need for adaptation, managing ghg emissions, sustainable development, building local capacity. nomenclature – cebc clean energy business council of the middle east and north africa cer certified emission reductions cng compressed natural gas eu european union gcc gulf cooperation council gdp gross national product gni gross national income hdi human development index led low emission strategies lng liquefied natural gas maps mitigation action plans and scenarios pcgdpi per capita gross gdp ppp purchasing power parity tpa tonne per annum t&t trinidad and tobago un united nations i. introduction energy is one of the key commodities required to sustain human existence and advancement and is one of the largest components of the world economy. consequently, global energy consumption has been rapidly increasing over the past two centuries but the pace of change has recently accelerated due to the increase in the total world’s population and the rapid improvement in the standard of living in a large segment of the world’s populace. however, the negative environmental aspects associated with the increasing consumption of energy necessitate that such trends be properly managed for the overall benefits of humanity (brundtland et al. 2010). climate change is a multi-faceted problem that requires the numerous stakeholders to contribute knowledge, skills and energy to plan for the impacts of a warmer planet and to take action to mitigate rising ghg http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 147 resd © 2015 http://apc.aast.edu emissions. such actions must however be based on meeting the socio-economic challenges faced in any particular country/region yet help in achieving the overall objectives of protecting the global environment. nowhere are the climate change and sustainability issues more acute than in the mena countries which are likely to be severely affected by climate change. the predicted rise in temperature and sea level may affect coastal areas, while the current severe water stress is likely to be exacerbated (cherfane 2010, ghaddar 2010). water supply sources in mena – two-thirds of which originate outside the region— are being stretched to their limits threatening to lead to national confrontations over this vital resource. adapting to climate change is not a new phenomenon for the nema region. for thousands of years, the people in this region have coped with the challenges of climate variability by adapting their survival strategies to changes in rainfall and temperature. but over the next century global climatic variability is predicted to increase, and nema countries may experience unprecedented extremes in climate (world bank mena region, 2007). this paper discusses the factors that need to be considered while developing a sustainable climate change management approach for the mena region. some of the recommendations developed in this paper may be essential for achieving the desired climate change mitigation/adaptation actions while minimizing social disruption particularly in low-income countries. ii. the impact of energy production and utilization on the socioeconomic conditions in mena countries the evolution of population, prosperity, and energy consumption has been substantially different in different parts of the world, resulting in large disparities amongst nations and regions in terms of wealth and the state of human development. this is particularly evident in the middle east and north africa, a region which includes both the energy-rich economies in the gulf as well as countries that are amongst the poorest in the world. figure 1 clearly illustrates this phenomenon where the 22 mena countries considered in this investigation (algeria, bahrain, egypt, eritrea, iraq, israel, jordan, kuwait, lebanon, libya, mauritania, morocco, oman, palestine, qatar, saudi arabia, somalia, sudan, syria, tunisia, uae, yemen) were organized in ascending order in accordance with their economic wealth using the world bank data for the annual per capita gross domestic product (pcgdp). although the cost of living variation between the different countries is already taken into consideration through the purchasing power parity [ppp] factor, the value of the per capita gdp was found to vary between these countries by a factor of up to about 150, thus creating a very difficult situation in which it is virtually impossible to develop a singular strategy that meets the needs of the whole region. conversely, the presence of countries depicting a wide spectrum of developmental stages can create an opportunity for complementary/synergistic action that can benefit the population of both the wealthy and poor countries. appropriate strategies and frameworks are however needed in order to achieve such goals. the discrepancy between the various countries in the mena region becomes less sever when one utilizes more comprehensive indicators of the socio-economic development stage for any particular country. the human development index [hdi] used in figure 2 is a composite indicator introduced by the un in 1990 and provides a better measure of the socio-economic state of development of the populace by combining three basic dimensions: life expectancy, educational attainment (through literacy index and registration combined index) and economic performance (through per capita ppp gni in international dollars) (undp, 2010). the use of this more appropriate indicator reduced the inter-country discrepancy within the mena region to about 3-fold. fig .1. – intra-region variation of the per capita gdp http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 148 resd © 2015 http://apc.aast.edu (source of data: world bank databank, ppp 2011) however, it is worthwhile to note that whereas only three countries in the region have achieved a high stage of human development (hdi ≥ 0.8), five countries can be considered as still being in a low stage of human development (hdi < 0.5), with the remaining 14 countries being in the moderate stage of human development (0.5 ≤ hdi < 0.8). fig .2. – regional variation in the human development index (2011) the scale used for labeling the countries in fig. 2 resulted in half of the countries being omitted in the formatted version a significant part of the gdp generated by prosperous mena countries can be attributed to the production and utilization of non-renewable energy resources (energy-related revenues can be as high as 55% of the gdp for countries that are primarily oil exporters). two-thirds of the organization of petroleum exporting countries (opec) are thus located in the mena region, which has 57% of the world’s proven conventional oil reserves and 41% of proven conventional natural gas resources. these reserves generated an estimated us$ 785 billion in revenues in 2011 (fattouh and el-katiri, 2012) and sovereign investment funds are being increasingly considered as means for ensuring the prosperity of future generations in countries presently endowed with large non-renewable natural resources. the importance to the energy sector in determining the state of prosperity in mena countries becomes very clear when one considers the per capita level of ghg emissions and its variation amongst the different countries of the region (figure 3). with the exception of israel, the most prosperous mena countries are those with abundant energy resources and energy-based industries (e.g. the processing of petroleum and natural gas as well as petrochemicals).however, the activities associated with the extraction, processing and export of the oil and gas resources, and the rapidly-expanding energy-based industrial sector, are large ghg emitters. continued development of these energy resources along historic lines is therefore expected to result in exasperating the level of ghg emissions unless certain measures are taken to reduce the overall environmental impact of such development. on the other hand, any viable ghg emission reduction strategy will have to consider the fact that the near-term demand for fossil fuels is predicted to increase as a result of the increase in the world’s population, and the increased per capita demand particularly in the rapidly expanding economies such as china, india, and indonesia. policies and procedures aimed at implementing cleaner energy extraction/production/utilization are therefore urgently needed, particularly in the wealthy energy-rich countries. such measures can strongly reduce the environmental impacts of present and future development of energy resources in the region. fig .3. – regional variation in ghg emissions (source of data: world bank databank) previous studies confirmed the existence of strong correlation between the wealth of the citizens of a country and their energy consumption pattern (sütterlin 2012, floyd 2012, estiri et al. 2013), a situation that applies to all countries regardless of their state of human development. prosperous and developed countries thus have a high level of energy consumption that is used for the production of goods and services, to support the transport and telecommunications sectors, and to achieve a high level of comfort for the citizens. a large part of their 0 0.2 0.4 0.6 0.8 1 human development index 2010 http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 149 resd © 2015 http://apc.aast.edu energy demand is presently supplied (directly and indirectly) by fossil fuels whereas a significant part of the energy demand in low-income countries is supplied by traditional biomass (wood and charcoal). unfortunately, the increasing use of biomass for energy purposes in middle and low-income mena countries is one of the major forces driving the desertification process and is driven by the local availability of relatively inexpensive biomass in a world where the price of fossil fuels is relatively high. as shown in figure 3, the same qualitative relationship exists in the mena region. the average fossil fuel energy consumption in the major oil and gas producers (bahrain, iraq, libya, qatar, saudi arabia, and uae) are more than 300-fold higher than that in the low-income countries in the region. unfortunately, these emission levels are also manyfold higher than the present day world-average emission levels (4.6 tpa co2 equivalent) as well as the emission levels in developed countries that are strongly dependent on the exploitation of natural resources (canada = 15.2 tpa co2 equivalent; australia = 18.2 tpa co2 equivalent). amongst the factors contributing to this state of affairs are: the heavy dependence of affluent mena countries on energy-intensive industries, the export of raw materials with limited local value-added (e.g. crude oil and lng), and the limited contribution of the agricultural and service sectors to the overall prosperity of the citizens. concerted efforts have been ongoing to change this situation, but is recommended that special attention be given to the use of low-emission-development routes (e.g. energy efficiency and waste minimization) in order to ensure that the increase in the level of local value added does not result in further exasperating the environmental problems. the heavy dependence of a country’s prosperity and the level of energy resource utilization is reflected in the essentially linear relationship between the per capita gdp and the level of ghg emissions in mena countries (figure 4). this is mainly caused by the heavy dependence of affluent mena countries on energy-intensive industries, the export of raw materials with limited value-added processing, and the limited contribution of the agricultural and service sectors to the welfare of the citizens. iii. energy consumption, power generation and the standard of living accepting that most countries do not want to suffer a reduction in their prosperity level while attempting to address the climate change challenge, the question becomes how the level of fig .4. the relationship between pcgdp and the ghg emissions level (source of data: world bank databank, mena region) ghg emissions can be reduced while maintaining the prosperity at its present level or even higher. an indication the efficiency by which energy is utilized to generate wealth can be obtained by calculating the amount of ghg emissions associated with every $ 1,000 ppp gdp produced. this indicator which is frequently used for benchmarking purposes is based on the fact that most of the world’s large consumers of energy still rely heavily on fossil fuel for power generation. the large intra-regional variation in the energy use per unit gdp is clearly evident from the results depicted in figure 5. an in-depth investigation of the factors contributing to this phenomenon (e.g. internal strife, the contribution of the service sector, the emphasis on high-value added production, the role of the agricultural sector, the role of hydro power) is needed to develop better understanding of the factors hindering the accelerated development of this region as a whole, and to identify novel means by which the prosperity of the region can be enhanced. it is however noteworthy that the prosperous mena countries are about 3-7 fold less efficient in converting their energy resources into national wealth than it is the case in the usa and eu (figure 6). thus, whereas the generation of a $1,000 -5 0 5 10 15 20 25 30 35 40 45 0 20 40 60 80 p e r ca p it a g h g e m is si o n s (t p a c o 2 ) per capita gdp ($ 1,000 http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 150 resd © 2015 http://apc.aast.edu of gdp in the former group is associated with the emission of 700-1000 kg of co2 equ., the same is achieved while emitting 100-180 kg of co2 equ. in more developed societies. this suggests that there is a substantial potential for improving the efficiency by which energy resources are converted into revenuegenerating economic activities in the prosperous, hydrocarbon-rich mena countries. on the other hand, the high energy utilization efficiencies exhibited by the poorest three mena countries are not indicative of high energy utilization efficiencies but are typical of their developmental stage (hdi < 0.5) where energy (fossil fuels in particular) plays a less significant role in determining the gdp. the very low energy utilization efficiency observed in the case of iraq in 2009 could most probably be attributed to the internal strife in the country and its negative impact on the gdp. in that regard, it is important to note that although china has been rapidly increasing its power generation capacity to cope with the escalating demand, it has been able to achieve a remarkable increase in the energy use efficiency of energy utilization over the past 30 years. this is largely due to the use of better manufacturing technologies and the gradual shift towards the production of high-value added products and services. fig .5. regional variation in energy utilization efficiency fig .6. evolution of energy use per unit of gdp (source of data: world bank databank) iv. energy consumption, power generation and the standard of living in order to develop sustainable mena-focused strategies for coping with the problem of climate change it is important that, in a fashion similar to other rapidly-developing regions of the world, the mena region assumes its responsibility with respect to reducing its ghg emissions while undertaking unquestionably necessary adaptation projects (verner, 2012). in the meantime, it should also attempt to achieve two important socioeconomic objectives:  avoid socially disruptive situations by reducing the large discrepancy in prosperity levels of the citizens within the mena region.  address the need for securing long-term prosperity for the citizens of the countries whose present prosperity levels depend on exhaustible non-renewable energy resources. the question is how these apparently contradictory demands can concurrently be met particularly by governments that have limited funds and need to spend them in a fashion that addresses urgently needed socio-economic challenges while trying to reduce emissions?. considering the fact that about 23% of the population in mena lives below the poverty level of less than $2 a day, a concerted effort aimed at improving the standard of living in the region as a whole is desperately needed if social turmoil is to be minimized. it is however imperative that the strategies adopted emphasize economic, social and human development objectives while addressing the concerns arising from climate change. however, the financial and human resources needed for such an effort can be limiting factors considering the multifaceted needs in the region in a period of budgetary constraints throughout much of the world. in a recent study based on data from 112 countries (ugursal, 2013), it was noted that the relationship between the hdi and energy consumption depends very much on the country’s developmental stage (figure 7). thus, for example, a substantial increase in the per capita energy consumption is needed before any significant improvement can be noted in the human development level can be noted for countries with hdi < 0.5. on the other hand, http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 151 resd © 2015 http://apc.aast.edu significant reductions in the energy consumption levels can be achieved without substantial reduction in the standard of living in countries with hdi ≥ 0.8; while, small increases in energy consumption result in substantial increases in the hdi of countries within the moderate hdi range (0.5-0.8). fig .7. relationship between a country’s hdi and its per capita energy consumption rate (ugursal, 2013). it is therefore projected that substantial investment in power generation and utilization will be needed in most of the 19 countries having hdi less than 0.8. such a massive undertaking will adversely affect climate change with the impact being mitigated if low emission development [led] strategies are adopted in the new projects and measures for improving the efficiency of existing operations are adopted (clapp et al., 2010). considering the fact that the population of the region is in excess of 330 million with an average per-capita ghg emission of 5.85 tpa co2 equivalent per year, the full impact of unplanned development is equivalent to adding a ghg emitter that is equivalent to 2/3 that of the usa (until recently, the world’s largest emitter). innovative means for the planning, financing, execution, and managing of such a major undertaking are therefore needed in order to avoid the adverse impact of combined social, economic, and environmental upheavals. the concept of “sustainable development” with its emphasis on balancing the needs of the society with those of the environment in an economically viable fashion represents one of the most promising avenues for achieving the aforementioned balanced objectives. however, the challenge of managing this global problem in a sustainable fashion is quite daunting particularly considering the conflicting interests of the various regions and countries, particularly those at radically different stages of development. the increase in ghg emissions associated with the accelerated development of low-, and mediumincome mena countries can be partially compensated by improving the environmental efficiency of the enormous oil and gas sector operating in various mena countries. many such countries (e.g. algeria, egypt, iraq, kuwait, libya, oman, qatar, saudi arabia, and uae) have very large oil and gas operations, a situation that offers the opportunity for achieving significant reductions in ghg emissions at little, or even negative, costs. a review of the ghg mitigation efforts in most of the mena countries was recently given by abdel gelil (2009). once identified, the private sector may be interested in profitable emission reduction schemes but some additional incentives may be needed for high-risk border line cases. typical examples are:  reducing the wasteful release of undesired energy by-products (e.g. flares).  replacing high-carbon fuels with low-cost lowemission alternatives.  enhancing the efficiency of power generation plants and power transmission systems,  enhancing the efficiency of energy utilization in large industrial operations, and  identifying opportunities for reusing some of the co2 captured in the many petrochemical plants present in the region for enhancing oil recovery in nearby fields. it is hard to overemphasize the importance of energy efficiency as an economically-viable tool for mitigating ghg emissions. the experience in many european countries, combined with the recent financial crunch, resulted in the recent adoption by the eu of “directive 2012/27/eu” on energy efficiency. this directive establishes a common framework of the promotion of energy efficiency within the eu in order to ensure the achievement of its 2020 target on energy efficiency, and to pave the way for further energy efficiency improvements beyond that date. it also lays down rules designed to remove barriers in the energy market and overcome market failures that impede http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 152 resd © 2015 http://apc.aast.edu efficiency in the supply and use of energy, and provides for the establishment of indicative national energy efficiency targets for 2020 marginal mena cases may be eligible for financial support through various international programs, such as the clean development mechanism [cdm] program and the global environment facility fund. it is however imperative that such border-line project meet the sustainability criteria and urgently addresses the socio-economic needs of the population. the potential for significantly reducing ghg emissions at little or no cost is not a situation that is unique to mena and was identified to exist in several countries. for example, it is estimated that a significant reduction in australian ghg emissions can be achieved (30% below 1999 levels by 2020) can be achieved without major technological breakthroughs or lifestyle changes. these reductions can be achieved by using existing approaches and by deploying mature or rapidly developing technologies to improve the carbon efficiency of the australian economy (gomer and lewis, 2008) it is, however, essential to redress the imbalance presently existing in the various methodologies used to estimate ghg emissions. for example, equitable mechanisms may have to be developed by which the ghg emissions associated with the production, export, and transport of natural gas (10-12% of the carbon content in the case of lng) can be split between the exporting counties and those which use it to replace coal in power generating plants. v. an example of a sustainable climate change mitigation effort over the past few years, several national and international mechanisms were developed in an attempt to reduce ghg emissions and to assist in coping with the adverse effects that are beginning to occur as a result of climate change. unfortunately, many of these approaches are presently associated with economic penalties that often adversely affect the socio-economic welfare of the populace particularly in low-, and medium-income countries. in this regard, it is informative to note the experience recently gained by trinidad and tobago [t&t] in its attempt to reduce ghg emissions without affecting the competitiveness of its industrial and agricultural sectors. although the ghg emissions of trinidad and tobago are not very large when compared to larger countries (estimated at 53 m tonne co2 equivalent per year in ), it is one of the world’s largest ghg emitters per capita (40 tpa co2 equivalent in 2009). initial attempts were made to meet its international obligations, focused on policies/measures similar to those used in developed economies (energy efficient cars, replacing incandescent bulbs etc.). however, a recent inventory of the sources of ghg emissions clearly showed the inability of such simple measures to achieve substantial reductions in ghg emissions (figure 8), since more than 80% of the ghg emissions are generated by industrial activities. fig .8. sources of ghg emissions in t&t, 2010 (adapted from boodlal and al taweel, 2013) conventional environmental management concepts were applied to identify means by which ghg emissions can be reduced without significantly affecting the value of the welfare of the country (figure 9). based on the results of an inventory of ghg emissions in t&t, and the costs associated with each ghg reduction option, an indigenous action plan was proposed (boodlal and al taweel, 2013) which includes identification of the optimal carbon reduction opportunities in the country (figure 10). fig . 9. identifying the most sustainable ghg reduction strategies http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 153 resd © 2015 http://apc.aast.edu fig . 10. cost associated with the various options for reducing ghg emissions in t&t (adapted from boodlal and al taweel, 2013) very conservative cost estimates were used in this study since its primary purpose is to serve as a policy development tool rather than for profitability analysis; yet several negative-cost opportunities were identified (figure 10). this suggests that the implementation of such measures will be beneficial for the country’s economy while, simultaneously, reducing its ghg emissions. a policy environment based on a combination of regulations and incentives was also recommended to attract investment to cost-effective emission reduction measures. in this way, environmental challenges can be turned into economic opportunities and a vehicle for sustainable development. to achieve this goal it is, however, necessary to use appropriate decision-making tools and adopt innovative site-specific solutions that take into consideration the socio-economic welfare of the disadvantaged segment of the population. the most financially attractive option for reducing ghg emission in t&t is the replacement of liquid fuels (diesel and gasoline) by compressed or liquefied natural gas. for the past several decades, diesel and gasoline have been heavily subsidized in t&t in order to facilitate the transport of individuals and goods, particularly for the low-income citizens. the price of liquid fuels has been fixed for many years at the fixed prices of: tt$ 1.50/liter of diesel, tt$ 2.60/liter of regular gasoline, and tt$ 4.20/liter of premium gasoline (6.5 tt$ = 1 us$). in addition to encouraging energy-wasteful behaviour, the annual subsidy for these fuels was about us$ 500 per person with large quantities of the subsidized diesel fuel being illegally exported. significant savings can therefore be achieved by converting cars and trucks so that they can use natural gas instead of the aforementioned liquid fuels. in addition to the financial benefits accrued by such conversions, the air quality is expected to improve as a result of using the cleanburning fuel and the ghg emissions are lower than those achieved when using the conventional heavier fuels. the need for promoting such a conversion has been recognized many years before and both cng and lng are easily available as a by-product of the existing lng production facility (used to export 58% of all the natural gas produced in t&t). however, the progress achieved on that front has been slow because of the lack of a concerted effort to promote such conversion and the limited number of re-fueling stations equipped to handle cng. following the drop in the price of natural gas and its impact on the country’s royalties, this issue is being more seriously addressed. the price of premium gasoline was recently raised to tt$ 5.75 and a plan for increasing the number of stations equipped to handle cng is being implemented. a growing number of public transport buses are being converted to cng while the environmental management authority has launched a programme to convert its vehicle fleet to cng. this approach is not a novel one since natural gas is a commonly used alternative fuel used by trucks and transit bus fleet operators interested in reducing the cost and environmental impact of their operations. many factory-built natural gas vehicles are available, which incorporate engine technologies that have been designed specifically for natural gas with power, torque, and fuel efficiency similar to diesel engines. warranty coverage is also comparable to what is available on diesel engines. natural gas presently powers more than 15 million vehicles around the world and the number of natural gas fueled vehicles has been increasing by more than 15% a year over the past decade (ngv global, 2012). there are more than 20,000 refueling stations in use globally, with the majority of these stations dispensing cng, although lng projects have been announced in several countries for both on-road truck and marine use. the trend of using cng/lng to power vehicles is expected to grow as the price differential between natural gas and liquid fuels increases as a result of the abundant availability of natural gas in the market place (figure 11). the development of a cost-effective natural-gas http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 154 resd © 2015 http://apc.aast.edu based alternate to lpg (liquefied petroleum gases that are extensively used in the region for cooking and heating purposes) could similarly benefit nema countries that are heavily dependent on the use of this type of fuel for domestic purposes. fig . 11. price ratio of crude oil to natural gas (u.s. energy information administration) vi. balancing climate change abatement measures against developmental needs global climate change is projected to result in a set of diverse and regionally-specific impacts on natural ecosystems and human societies. a growing literature suggests that while mitigation strategies are necessary, those alone are unlikely to be sufficient to cope with these changes. therefore, pursuing a complementary strategy of enabling countries to adapt to global change and negate many of the expected adverse impacts is equally, if not more, urgent (burton et al., 2002; verner, 2012). however, with about 23% of mena’s population living on less than $2 a day, it is imperative that the climate change management strategies adopted be cost-effective and emphasize economic, social and human development, while addressing the environmental concerns arising from anthropogenic climate change. poverty alleviation is often linked to economic development resulting in job creation, increased energy production and consumption, gdp growth, energy security, and reducing all of inequality, which usually translates into increased emissions levels. policy makers in low-income countries are therefore faced with the dilemma of having to allocate limited resources in an attempt to alleviate poverty while, at the same time, try to slow down ghg emissions. the need for integrating the environment in development planning has been strongly promoted for many years (tolba m. k., 2008) and it may be now necessary to emphasize the need for integrating development into environmental planning particularly for lowand middle-income countries over the past few years, several tools have been developed to facilitate rational decision making and achieving a balance between development needs and protecting the environment. (e.g. low-emission development strategies [leds], and mitigation action plans and scenarios [maps]). a detailed discussion of these tools is beyond the scope of this investigation but a quick introduction to their recent application to developing countries was given by clapp et al. (2010) and boyd (2013). though no formally agreed definition exists, leds are generally used to describe forward-looking national economic development plans and strategies that encompass low-emission and/or climate-resilient economic growth. leds can serve multiple purposes but are primarily intended to help advance national climate change and development policy in a more coordinated, coherent and strategic manner. by providing integrated economic development and climate change planning, an leds can provide valueadded to the myriad of existing climate change and development related strategies and reports that already exist. because of its benefits, the copenhagen accord recognised that a leds is indispensable to sustainable development. vii. financing sustainable integrated development projects with climate change mitigation/ adaptation components achieving sustainable development goals that integrate climate change adaptation/mitigation measures within a holistic framework requires that announced commitments be translated into strategies, policies and actions. the scale of such anticipated efforts in the mena region requires massive multi-billion dollar financing that needs to be secured from internal and external sources. the financial aspects of climate change issues in the mena region has recently received much attention from a large number of investigators (abaza, 2008; babiker and m. fehaid, 2011; fattouh and el-katiri, 2012; nakhooda et al., 2012; saidi, 2012) whose findings provide valuable insight into the real state of affairs. a high level of investment in climate change related projects by resource-rich mena countries is http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 155 resd © 2015 http://apc.aast.edu already underway, largely supported with domestic and private sector financing. many large-scale wind and solar energy projects are also investing in for both domestic use and export, while significant investments are being planned in energy efficiency and carbon reduction projects. however, the financing of similar projects in resource-limited mena countries faces many challenges. climate change funding by international agencies has been rather limited in the mena region. although about us$ 1 billion in finance has been dedicated since 2004, less than us$ 200 million was approved as grants in support of a large number of relatively small-scale projects, which are concentrated in 12 mena countries (nakhooda et al., 2012). similarly, the region’s share of the cdm funding is less than 2% of the global cer market in spite of the multitude of oil, gas, and petrochemical operations that are spread throughout the region and usually offer good opportunities for cdm support. to further complicate matters, prices for cers collapsed from about us$20 a tonne in 2008 to less than us$ 1 by the end of 2012. this is mainly driven by the eurozone debt crisis reducing the industrial activity and the over-allocation of emission allowances under the european union emissions trading scheme” . furthermore, some of the projects contemplated for support can hardly be considered as being “sustainable” when, for example, the citizens of a developing country end up supporting the development of a promising technology by substantially subsidizing the cost of the power generated over the project’s life span (typically 20-30 years in this case). on the other hand, there exists excellent opportunity for drawing upon the substantial financial resources that are generated within the mena region itself. these can be utilized to accelerate the development of equitable, holistic, and sustainable climate change projects in the region, provided that a proper framework is developed that secures the equity, longterm viability, and security of such financing efforts. a similar example is presently being considered for the case of the five major emerging national economies of: brazil, russia, india, china and south africa [brics], where the need for financial cooperation in the five-nation bloc has led to a recent agreement to establish a brics development bank, which could properly utilize the huge savings pool of the bloc countries. in this regard, it is worthwhile to note that the high oil and gas prices have generated an extraordinary level of international assets and liquidity in the hydrocarbon exporting countries of the mena region, with gross foreign assets forecast to reach some usd 2.3 trillion by end-2012 (saidi, 2012). consequently, governments and corporations in such countries have traditionally been cash rich and not reliant on market financing. however, the global financial crisis, the contagion effects of the eurozone's continuing crisis and retrenchment of eu banks, along with growing financial sophistication of both the public sector and private businesses in the gcc countries, changed their financial strategy, particularly since the gcc countries are keen to lead in innovative finance as they develop financial centers and diversify their economies (saidi, 2012). in this context, sukuk (tradable financial instruments that comply with the islamic law and its investment principles, which prohibit the charging of and/or paying interest) may be a suitable investment instrument for the mena region, as it would meet the investment requirements of investors from the gcc, asia and other shariah-compliant global institutional investors. several organizations, such as the green sukuk working group, the clean energy business council of the mena region and the gulf bond and sukuk association, were formed to address this need (climatebonds, 2015). in light of the above, the clean energy business council of the middle east and north africa (cebc), the climate bonds initiative and the gulf bond and sukuk association have launched a green sukuk working group. the group aims to channel market expertise to develop best practices and promote the issuance of sukuk for climate change solutions investments, such as renewable energy and clean tech projects (saidi, 2012). green sukuk are shariah securities and investments that use criteria for climate solutions developed by the international climate bond standards scheme. the cebc plans to help investors more easily identify shariah-compliant opportunities while assisting in providing the investment capital for clean energy and other climatefriendly projects in the region. another financing option to be considered is based on the development of a framework by which mena http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 156 resd © 2015 http://apc.aast.edu countries with high per capita ghg emissions can gain credit in exchange for financing climate change mitigation/adaptation projects within lowand intermediate-income countries in the region. viii. building the capacity to manage climate change and development challenges in mena the development of sustainable solutions to the multitude of climate change issues facing the mena region requires in-depth knowledge of site-specific conditions prevalent in the various countries and the ability to identify/develop appropriate solutions that can meet the socio-economic needs of the local population. much of the expertise needed is already available in the region but is scattered amongst many countries, ministries, universities and ngos. it is therefore necessary to develop a regional network of institutions that have the knowledge and ability to accomplish such goals, and equip it with a project management team that can coordinate the efforts of the various individuals. this network should encourage flexibility in problem-solving, the development of cost-effective innovative approaches, and emphasize the importance of addressing the needs of the various stakeholders and the balance of power among the various interest groups. such a network can also draw upon the world-wide pool of expertise, but the translation of the experience of others into a mena-specific plan of action could best be handled on the local level where the active participation by the various stakeholders (particularly the most vulnerable sectors of the population) is a necessary condition for the success of any sustainable development program. ix. conclusion based on the analysis presented in this investigation it can be concluded that:  socioeconomic analysis of the mena countries and their ghg emissions shows that they can be split into three categories: the affluent resourcerich countries, the middle-income countries, and a few low-income countries. the former group of countries has the world’s highest level of per capita ghg emissions while the latter has almost negligible emissions. although the variation in per capita gdp amongst these countries is very high, this does not reflect in a similar disparity of human development level.  massive investments are needed to accelerate the pace of economic development in lower-and middle income countries in order to improve the standard of living and minimize social disruption. such efforts will be accompanied by an increase in the emission levels that can be minimized by adopting low emission development strategies and by implementing cost effective means for reducing the emissions associated with the development of the oil/natural gas/petrochemical sectors.  with about 23% of mena’s population living on less than $2 a day, it is imperative that the climate change management strategies adopted be cost-effective and emphasize economic, social and human development while addressing the concerns arising from anthropogenic climate change. this will avoid duplicating efforts, minimize the capital requirements, and facilitate the acceptance of such measures by the population at large.  the carbon reduction experience of t&t clearly identified several negative-cost opportunities for reducing carbon emissions. the savings accrued by implementing such measures can be used for adaptation or economic development purposes. in this fashion, environmental challenges can be turned into economic opportunities and a vehicle for sustainable development.  converting cars and trucks so that they can use natural gas instead of gasoline or diesel reduces the ghg emissions and improves the air quality in urban centres. significant financial benefits can also be accrued by such conversions due to the large difference in the cost per unit energy of the two fuels and the elimination of the subsidies needed to make transportation more affordable. it is, however, essential that such conversion plans be carefully implemented in a fashion that renders it the natural choice of the consumer rather than the socially disruptive price hikes.  the extent of financial support received from international agencies by mena countries for http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 157 resd © 2015 http://apc.aast.edu mitigation/adaptation measures is relatively low. this is most probably driven by the financial difficulties through which some of the world’s leading economies are presently going through, a situation, which is not predicted to change in the near future. the region should therefore rely primarily on internally-generated financing driven by intelligent self-motivated interests.  there apparently is a growing interest in developing shariah-compliant financing istruments that can be used for climate change solutions investments. this is driven by the high liquidity levels prevalent in the public and private sectors in many resources-rich mena countries and the desire of the gcc countries to diversify their economies and develop financial centers that lead in innovative finance. this approach is similar to that recently adopted the recent agreement by the brics countries to establish their own development bank, which could utilize their huge savings pool to enhance their collective interests.  an alternate financing scheme may be achieved by having large ghg emitters gain credit for financing climate change mitigation/adaptation projects within lowand intermediate-income countries in the region. although no single formula can apply to a collection of countries as diverse as those in the nema region, it is recommended that the various mena countries undertake the initial four steps needed to create a low-emission development strategy [leds] which entail:  development of vision/goal: an over-arching vision or goal is needed to help guide in the development of long-term policy decisions related to economic development and climate change priorities.  assessment of current situation: a clear understanding of major ghg emitting sectors and the socio-economic indicators is fundamental to determining the path forward.  emission projections, mitigation potential and costs: planned pathways for business-asusual emissions can help provide a sense of the national emission trajectory, while mitigation potential and costs associated with the various emission reduction options are needed as a first step towards identifying promising mitigation actions.  vulnerability assessment: indications of how a country or region may be impacted by climate change can help engage stakeholders, including the general public, and can help identify adaptation needs and the range of possible cost-effective adaptation outcomes. much of this information is already available in the many mena-related studies conducted by several local and international agencies. what is needed is to collect and update the information and ensure its correctness, fill in any gaps, and analyse the findings in a fashion that allows for the identification of costeffective projects that emphasize economic, social and human development while addressing the environmental concerns arising from anthropogenic climate change. acknowledgement the financial support of the natural sciences and engineering research council of canada is gratefully acknowledged. the stimulating intellectual input and contribution of all the members of the trinidad and tobago carbon reduction strategy task force is greatly appreciated. references [1] abaza h., 2008, financing of environment programmes: private-public partnership, in arab environment: future challenges, m. k. and n. w. saab edit., report of the arab forum for environment and development, 2008. 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[23] undp, 2010, http://hdr.undp.org/en (last accessed may 20th, 2015) http://apc.aast.edu/ http://www.mapsprogramme.org/normalising-apples-and-oranges-comparing-trade-offs-for-pro-poorhttp://www.mapsprogramme.org/normalising-apples-and-oranges-comparing-trade-offs-for-pro-poorhttp://www.mapsprogramme.org/normalising-apples-and-oranges-comparing-trade-offs-for-pro-poorhttp://www.mapsprogramme.org/normalising-apples-and-oranges-comparing-trade-offs-for-pro-poorhttp://www.climatebonds.net/tags/green-sukuk-working-group http://www.climatebonds.net/tags/green-sukuk-working-group http://hawkamah.org/wp-content/uploads/2014/10/harnessing-green-sukuk-for-sustainable-development.pdf http://hawkamah.org/wp-content/uploads/2014/10/harnessing-green-sukuk-for-sustainable-development.pdf http://hawkamah.org/wp-content/uploads/2014/10/harnessing-green-sukuk-for-sustainable-development.pdf journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 159 resd © 2015 http://apc.aast.edu [24] ugursal v. i., 2013, energy use and energy conservation. chapter 21 in the world scientific [25] handbook of energy, edited by gerard m crawley, world scientific publishing co., 2013. [26] verner d. ed. 2012. adaptation to a changing climate in the arab countries. washington, dc: world bank. doi: 10.1596/978-0-8213-9458-8. [27] wingqvist g. ö. and o. drakenberg, 2010, environmental and climate change policy brief mena1 [28] world bank databank, 2013. http://databank.worldbank.org/ (last accessed march 18, 2013). [29] world bank mena region, 2007, sustainable development sector department (mnssd) regional business strategy to address climate change preliminary draft for consultation and feedback. http://apc.aast.edu/ 48 journal of renewable energy and sustainable development (resd) http://dx.doi.org/10.21622/resd.2020.06.2.048 submitted on | 05 june 2020 accepted on | 01 october 2020 published on | 12 november 2020 volume 6, issue 2, december 2020 issn 2356-8569 ___________________________________ _____________________________________________________________________________________________________________________________ green supply chain practices framework for petrochemicals in egypt karim soliman, ghada elkady arab academy for science, technology & maritime transport, egypt, karim.mohamed@aast.edu, ghada-elkady@aast.edu abstract the aim of this study is to determine the extent of green supply chain management (gscm) practices used by shell and co-operation (co-op) petroleum companies in egypt and to evaluate the effect of gscm practices on the operational performance of both companies. a conceptual framework was developed to link the gscm practices and operational performance. the framework consisted of three gscm practices (green procurement, green manufacturing, and reverse logistics) as independent variables and four operational attributes (quality, safety, delivery, and flexibility) as dependent variables. the data were collected through on-site surveys, using eighteen-item-questionnaire with the relevant departments in both companies from the three managerial levels (i.e. strategic, tactical, and operational). further, the results, based on benchmarking, were statistically analyzed by fischer analysis. the results offer guidelines to petroleum and lubricant manufacturers to enhance their operational performance and customer satisfaction while employing gscm practices throughout their entire supply chain (sc). keywords green supply chain management, operational performance, reverse logistics, green procurement, green manufacturing. i. introduction the increase in greenhouse gas emissions, global warming and environmental pollution by companies has increased the need for organizations to reorganize their sc processes to improve the operational performance of enterprises and thus products in accordance with the requirements of environmental regulations [1]). furthermore, environmental pollution and the increase in greenhouse emissions have led to an increased demand for organizations to reorganize sc operations, thereby conserving scarce resources. the gscm is an important organizational philosophy to achieve corporate profit and market share objectives by reducing environmental risks and impacts while improving the ecological efficiency of these organizations and their partners [2]. as a synergistic joining of environmental and supply chain management (scm), the competitive and global dimensions of these two topics cannot go unnoticed by organizations. likewise, the rise in environmental missions and concerns lead to the need to reduce environmental pollution resulting from industrial development with scm [3]). moreover, monshiwa [4] acknowledged that any competitive advantage obtained or can be obtained by applying the green approach and accordingly, this creates pressure on companies not to ignore these green initiatives. with the increase in environmental concerns during the past decade, a consensus is growing that environmental degradation issues accompanying industrial development should be addressed together with scm, thereby contributing to gscm [5]). egypt is one of the developing countries in the world and is becoming increasingly industrialized and this makes egypt faces a heavy burden on the environment. likewise, multinational organizations and developed countries use the developing countries as a point of disposal of endemic products and this has environmental impact [6]. for this reason, this research attempts to answer the following questions: (1) what are the current state of gscm practices adoption by shell and co-op petroleum companies in egypt? (2) how have the gscm practices affected the operational performance at shell and co-op petroleum companies? and (3) what are the drivers of gscm practices in shell and co-op petroleum companies? hence, this research will help local companies operating in the lubricant industry, such as co-op petroleum company, to be more involved in http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 49 implementing the gscm concept. additionally, the management will be able to identify gscm practices that will develop and improve the operational performance of the co-op company besides all local companies operating in this controversial area. besides, how these companies can benefit from the implementation of shell's gscm practices and their effective impact on their operational performance. it has been noted that previous studies on the evaluation of operational performance and the effect of implementing gscp in this field are few, especially in developing countries, such as egypt. thus, this research is urgently needed to determine how the operational performance of companies in the lubricant industry is affected by the implementation of gscm practices. the remainder of the paper is organized as follows. in section 2, the literature is briefly discussed. in section 3, the methodology section is introduced. then in section 4, the analysis and findings are presented. finally, sections 5 and 6 conclude the study, including the theoretical contributions and managerial implications of the findings. ii. literature review environmentally sustainable gscm has emerged as organizational philosophy to achieve corporate profit and market share objectives by reducing environmental risks and impacts while improving the ecological efficiency of these organizations and their partners [7];[2]. likewise, it is necessary to integrate the organizational environmental management practices into the entire sc to achieve a sustainable sc and maintain a competitive advantage [8]; [9]. the gscm practices should cover all the sc activities, from green purchasing to integrate lifecycle management, through to manufacturer, customer, and closing the loop with reverse logistics [10]. thus, the literature review section presents an overview on all the previously mentioned concepts and thoughts and is divided into two main sections: gscm concepts and paradigms, and the gscm practices and operational performance, all discussed respectively. 1. green supply chain management practices the full concept of gscm was first proposed by the michigan state university manufacturing research association (mrc) in 1996 to comprehensively consider environmental impacts and improve the resources of manufacturing chains (handfield, 1996). this means that it aims to reduce the environmental impacts of products at the end of use by tracking and controlling purchases of raw materials, in order to ensure compliance with environmental rules and regulations. furthermore, awareness of environmental pollution has increased among people around the world, making them curious about protecting the environment. as a result, people are planning to buy green products, and the concept of gscm is becoming more popular and gradually became the new concept of sustainable development of enterprises. the first series of green scs emerged in the context of 1989 when [1] first published how to develop an ideal forecasting system for organizations to predict reusable products, and the first book of green design literature came into context in 1991. later, the article, published by [11] was the first to examine the need for green design to reduce the impact of waste products. while [2] came to context and expanded the green design framework. according to beamon [12] , wastes from industrialization and the use of natural resources contribute to environmental pollution. in addition, scarcity of resources is another factor that enterprises and industrial companies must study. therefore, the gscm is the only way to deal with these environmental problems because gscm has its primary role in dealing with environmental degradation, for example, the contraction of raw material resources, the lack of scientific and professional treatment with waste, and the increasing level of pollution [13]. the gscm practices is frequently used for various activities implemented by any company to diminish the negative impacts on the environment [14]. these activities vary from green purchasing to integrated scs flowing from suppliers to the manufacturer, to customers and reverse to logistics, which is named as “closing the loop” [8] as shown in figure 1. fig .1 the areas of literature associated with grsc source: zhu and sakris, 2006. [8] when empirical studies on gscm are assessed, it has been found that there are several gscm dimensions http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 50 discussed by different researchers, such as green purchasing, green manufacturing, green logistics, green packaging, green marketing, green building, green education, investment recover, eco-design, etc. [15]; [8]; [16]; [17]; [18]. in light of this researches, three dimensions were selected to be included in this study as shown in table 1 and further will be briefly described in the next sub-sections. table 1. gscm dimensions. dimension definition author(s) green purchasing the integration of environmental efforts, purchasing activities and environmental objectives of the firm foo [19] et al., 2019 ; zhang [20] et al., 2018 green manufacturing the planning and implementation of energy-saving resources in the production process to produce environmentally friendly products with the least resources ma et al., 2018 [21]; karimi et al., 2019 [22] reverse logistics managing how products and/or materials are returned to the original manufacturer or agent for reuse, recycling or re-manufacture. bottani et al., 2019 [10]; bai and sakris, 2019 [23] a. green purchasing the green purchasing implicates a company evaluating the environmental performance of their vendors, which requires these vendors to implement all necessary operation measures to ensure the environmental quality [7]. furthermore, this step is considered to be the first step in the value chain that positively affect the operational performance of the entire chain [24]. [18] acknowledged that green purchasing entails all organizations in the entire chain to get attention towards the eco-labeling of all purchased items, supplier’s cooperation to attain the environmental objectives, supplier’s environmental audit, supplier’s international standards organization (iso) 14000 accreditation, supplier’s environmentally friendly practice assessment, and finally, providing the required environmental design specification to the suppliers. chen [25] also points out that green procurement has beneficial effects on the corporate pollution control system and can promote the successful implementation of the company's quality and environmental standards. likewise, [24] signified that green purchasing involves a procurement function through various sc activities, such as life cycle analysis (lca) and 3r model reduction, reuse, and recycling that belong to the product design and process part. the first is to reduce waste received from products and to guide consumers to reduce their waste by purchasing their own needs only and purchasing goods made from recyclable materials rather than nonrecyclable materials. the second r is to reuse any wastes to reduce environmental pollution and global warming. finally, the third r is to recycle the disposed waste by segregating the materials from each other. b. green manufacturing the green manufacturing is considered the significant step in all gscm activities in any industry to continuously improve their operational performance such as reducing cost, the quality of the products, and the environmental risks, all of which bring a competitive advantage to the product [22]. sezen [26] affirmed that pollution can be reduced or mitigated through continuous improvement strategies that focus on green design and manufacturing. nevertheless, dubey [27] added that green manufacturing is a system that connects all problems associated with the design, planning, and manufacturing matters efficiently to control the emerged waste amounts to be consistent with the environmental standards and procedures. c. reverse logistics as reverse logistics is gaining increasing interest and relevance, the question becomes whether it is enough to limit greening efforts to one segment of the sc and single companies or choosing to expand these efforts to the entire chain. greening can start right at the source with supply conditions and can work its way through storage and packaging practices to distribution and end-consumers [28]. however, the reversed flow can take different forms, from collection to return shipments into the distribution channel, followed by disassembly and re-use of selected parts. alternatively, used goods could be shredded and scrapped and reentered into production as raw materials. returned goods, or elements of the product, could even be returned to suppliers and supply chain partners for them to re-manufacture [23]. those possible sc applications should be taken into consideration. one step further, dis-assembly operations in the reversed http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 51 flow might call for a proactive design for dis-assembly right in the initial product design stage of both supplier and customer [10]. of all green activities, it is relatively easier to repair existing products and run renovations. more and more companies pay attention to yield management or product recovery management. reverse logistics aims to ensure the return of materials and products from the user to the product for reuse, recycling, and regeneration [29]. however, for most companies, they do not put reverse logistics in their planning strategies initially, although they will take action to respond to the requirements of customers or members of the final channel. 2. the relationship between gscm practices and operational performance there are several impacts of gscm practices on performance outcomes. generally, the adoption of gscm practices by manufacturing organizations lead to improved environmental performance and economic performance, and on operational performance [18]. laws, procedures, standards, and incentives regulated by regulatory institutions make corporate responsibility more environmentally friendly [30]. sarkis [31] discussed the impact of persistent pressures through laws and regulations on improving awareness in developed countries such as the united states of america where large industrial companies often face scrutiny by environmental activists [7]. thus, companies and organizations are under pressure from their competitors, forcing companies to implement green supply chain practices to reduce competition and make them competitive [32] . additionally, consumers are increasingly aware of the environmental impacts, which leads to the selection of the goods they receive and ask companies to apply the minimum green standards in their product design and thus to preserve the environment [33]. companies take societal responsibilities into society as companies believe they must commit themselves to society to conform to expectations and standards that lead to accepted business behaviors [34]. thus, implementation of gscm practices can result in a set of advantages for the company itself, for procurement and supply, and for the community itself. green procurement and supply can be improved to the extent that green supply facilitates information exchange and flow and cooperative relationships in the supply chain [35]; [36]. the benefits of green supply to society begin with a green environment, reduce hazardous and harmful substances, use scarce resources more efficiently, and avoid waste. green supply also helps to spread environmental knowledge through green marketing and best practices. environmental initiatives in the industrial supply chain should focus on the production and processing processes used by the supplier [37]. according to [33], the operational performance was summarized in four factors: • quality: evaluate the product or service that meets customer satisfaction and expectations. • safety: evaluate both the health and the working environment of the staff. • delivery: evaluate the business unit with its achievement in a proper time based on customer requirement. • flexibility: this means that this requires a great deal of flexibility in different processes, such as reducing the number of back orders, lost sales, and late orders. additionally, [5] indicated the positive relationship between the gsc and multi-operational performances in cost, delivery, quality, and flexibility. while [38] signified the impact of customers’ involvement in green practices on improving the customer satisfaction. additionally, [39] affirmed that the gscm practices lead to significant operational performance increase in terms of quality, cost, and flexibility, however, it does not have any impact on the delivery aspect. accordingly, for this study, figure 2 presents the initial conceptual framework to link the three gscm practices previously identified and the four operational performance attributes adopted by [33]. iii. methodology benchmarking is an assessment process on best performing corporate goods, services and procedures [40]. benchmarking concept is also associated with individual corporations' attempts to recognize and emulate best practices in their own industry. moreover, benchmarking has also been cited as an effective method to constantly enhance organizational performance, overall management of quality and competitive advantage [2]; [41]. benchmarking as a mechanism to identify operating performance measures and compares scs in relation http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 52 to selected measures. accordingly, this study used descriptive research design by using benchmarking between shell and co-op companies in egypt. in this study, descriptive research design based on two types of benchmarking; best-in-class and operational benchmarking. in order to achieve this aim, both approaches were used to explain the relationship between the gscm practices and operational performance by benchmarking the factors that influence the impact of effective gscm between shell and co-op companies in egypt. the performance measurement methodology is defined as an effective tool for managing change; it can be described as an ongoing process to identify, understand and evaluate industry best practices to improve the performance of an organization [42]. this is usually done by studying other organizations that carry out similar operations [43]. in contrast, performance measurement is an external activity that can enable the organization to move away from tradition. however, standard measurement and comparative analysis should not be confused. in the comparative comparison group, the metrics for similar elements are compared between organizations or within the organization, and this is simply one step in the normative assessment process [44]. fig .2 initial conceptual framework to link gscm practices and operational performance source: developed by the authors shell and co-op companies have been chosen for the purpose of this study as one of them is a multinational company operating in egypt (i.e. shell), and the other was a local egyptian company (i.e. co-op). the reason behind that is to drill down into performance gaps to recognize areas for improvement [42]. figure 3 presents the overall research design. 1. data collection this study focuses on the relationship between gscm practices, and the sc operational performance. the target sample was managers in both companies from the three managerial levels (i.e. strategic, tactical, and operational). accordingly, the targeted departments were procurement, production, marketing, quality assurance, and logistics departments. there was an intention to engage a larger sample, however, if a large sample is used, data may become repetitive [45]. owing to the nature of this benchmarking study, saturation was not applied on less than 25 face-to-face conducted questionnaires. the data collection was conducted in person for four months from august 2019 to november 2019. ethical issues have been considered through gaining well-versed consent and making confirmation that the data will be treated as confidential to be used only for research purpose. all surveys were conducted on-site, using an eighteenitemquestionnaire for collecting data and were guided by the objectives of the study. the questionnaire scale was in the range from – to ++++ where respondents required to indicate their views on this scale. this scale was chosen by the researcher because it allowed the respondents to express their views more clearly and openly. at the beginning, the survey questions were assessed by five professors from the sc management field. then a pilot test was conducted with seven sc management consultants and industry experts. minor modifications were received from the experts. however, most of the remarks were related to the wording of the questions, so they were re-written to be easily understood. the questionnaire consisted of two sections: section i; included, practices of gscm, and section ii; the operational performance with regards to implementation of gscm practices. 2. data analysis researchers are indeed concerned in recognizing significant cells relationships following a statistically valid chi-squared test [46]. two test statistics are widely used to test the value of each cell. the first test is a http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 53 standardized residual that is measured as a raw residual divided by a square root of the expected value, where the raw residual is defined. the discrepancy between the observed value and the predicted value. the second test shall be modified residual: raw residual divided by its standard error. both experiments adopt the normal standard distribution asymptotically. in this study, statistical analysis was performed using a statistical program (gmp for windows version 5.1, sas institute, cary, nc, usa). for data analysis, use the fisher's exact test to compare shell and the co-op company to gsc; green procurement, green manufacturing, reverse logistics and operational performance; quality, safety, delivery and, flexibility. data were analyzed as = 0, + = 25, ++ = 50, +++ = 75, ++++ = 100. at the end, the results were considered significant at p <0.05 which is considered acceptable to achieve the objectives of the study. the reason behind using fisher’s exact test in data analysis is that in case of small samples, the fisher exact test is considered an effective tool used instead of the chi square test for 2 in 2 tables. fig. 3. overall research design source: developed by the authors . iv. analysis and findings this study was carried out to determine the effect of green supply chain practices on operational performance of benchmarking study between shell egypt and co-op petroleum company working in the lubricant industry. the study had two objectives. the first is to determine the extent of gscm practices used by shell and co-op petroleum company in egypt; the second objective is to establish the relationship between green supply chain management practices and operational performance of shell and the co-op petroleum company in egypt. accordingly, in the subsequent sections, the detailed descriptive analysis of the questionnaires conducted was analyzed using fisher’s exact test. 1. green procurement the results of extent the firm practice green procurement are demonstrated in table 2. the results showed that suppliers are required to have iso 14001, shell company had significantly higher extent the firm practice green procurement than the co-op company (p < 0.0001). likewise, for purchasing materials that contain green attributes, the results revealed that shell company had significantly higher extent firm practice green procurement than the coop company (p < 0.00001). furthermore, the fisher’s exact test results unveiled that evaluate suppliers on specific environmental criteria, shell company has significantly higher extent the firm practice green procurement than the co-op company (p< 0.0001). likewise, the results showed that procure products that are made using recycled packages, shell company had a significantly higher extent the firm practice green procurement than the co-op company (p< 0.0001). http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 54 the sc network starts in shell egypt with the suppliers who are mainly raw material suppliers (base oil and additives) and packaging materials. suppliers are evaluated based on their commitment to environmental standards according to the rider center for sc management (2008) that protects the environment from all aspects (as mentioned earlier). base oils are supplied to the plant by refineries either inside or outside of egypt. additives are delivered to the lubricant oil blending plant (lobp) through alexandria port from europe. all packaging material supply is locally supplied to the plant. these raw and packaging materials are used to manufacture a wide range of portfolio of products. once products are produced, they are shipped to the distribution center in 6th of october waiting its turn to be shipped to the customers. thus, the results revealed that co-op company was not committed to environmental standards according to the regulations that protects the environment from all aspects. table 2. the extent at which the firm practices green procurement. green procurement practices shell co-op requiring suppliers to have iso 14001 75*** 25 purchasing materials that contain green attributes 75*** 0 evaluating suppliers on specific environmental criteria 75*** 0 procuring products that are made using recycled packages 75*** 0 source: research data (2019) by using fisher's exact tes. table 3. extent at which the firm practices green manufacturing. green manufacturing practices shell co-op producing products that have packages which can be recycled 75*** 25 using life cycle assessment to evaluate environmental load 75 75 replacing hazardous substances with that which are environmentally friendly 66*** 33 minimizing the use of materials in packaging 75*** 0 encouraging reuse of products and recycled materials 75*** 25 reducing the size of packaging 75*** 0 cooperating with suppliers to standardize packaging 75*** 0 source: research data (2019) by using fisher's exact test. 2. green manufacturing results of the extent at which the firm practices green manufacturing are shown in table 3. the fisher’s exact test results revealed that produce products that have packages which can be recycled, shell company has significantly higher extent the firm practice of green manufacturing than the co-op company (p<0.0001). likewise, the result of using life cycle assessment to evaluate environmental load showed non-significant difference between both companies. furthermore, the results of replacing hazardous substances which are environmentally friendly showed that shell company has significantly higher extent to which the firm practices green manufacturing than the co-op company (p<0.0001). moreover, concerning the minimization of the use of materials in packaging, it was clear that shell company had a significantly higher extent at which the firm practices green manufacturing than the co-op company (p< 0.0001). on the other hand, shell company has significantly higher extent at which the firm practices green manufacturing than the co-operation company (p< 0.0001) in encouraging the reuse of products and recycled materials. likewise, concerning reducing the size of packaging, it was found that shell company had significantly higher extent at which the firm practices green manufacturing than the co-operation company (p< 0.0001). finally, the results indicated that shell company has significantly higher extent at which the firm practices green manufacturing than the co-op company (p<0.0001) in cooperating with suppliers to standardize packaging. in shell, the inputs are divided into two main groups; raw materials (base oils and additives) and packaging material (bottles, packs, drums, caps, pallets, pails, stretch wrap and cartons). all these materials are recycled and reused. these inputs are discharged into main storage holding tanks (base oil and additives) and warehouses (packing material) to be used later on throughout the whole manufacturing cycle. the base oil and additives are blended with certain percentages according to the final product’s bill of materials (bom) and required a specification for each product. after blending, the mixed product is pumped through a system of pipelines that transfers it to the filling lines. the product is then dispensed in the designated packaging containers to be then transported to the finished products warehouse for storage until being shipped outside the facility to customers lobp. it is notably to mention that using life cycle assessment in co-op company is under the responsibilities petro trade company. concerning replacing hazardous http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 55 substances, shell company is concerned with recycling both the used oil and packages, while the co-op is concerned basically with recycling the used oil only. 3. reverse logistics the results of the extent of the firm practices of reverse logistics are shown in table 4. the results of dealing with disposal indicated that shell company had significantly higher extent as regards the firm practice of reverse logistics than the co-op company (p< 0.0001). regarding the processing of returned merchandise, the results showed that shell company has significantly higher extent of the firm practice of reverse logistics than the co-op company (p< 0.00001). finally, the analysis results revealed that shell company had significantly higher extent of the firm practice of reverse logistics than the co-op company (p<0.0001) in repackaging product. shell’s sc is adopting the lean strategy as it is always working on minimizing if not eliminating the waste. this includes all types of daily wastes with the concentration on inventory reduction on both the raw materials side as well as the finished product side. there are lots of efforts exerted in this area especially qualifying six sigma professionals to be able to assist in the company’s strategy and be even leaner according to [47]. on the contrary, co-op company (and all local companies) are charged of collecting used oil from distributing companies. thus, establishing petro trade company to collect used oil from all resources to increase the amount of collected oil will be a significant recommendation besides obliging service stations to establish land tanks for collecting used oil. table 4. extent of the firm practices of reverse logistics. reverse logistics shell co-op dealing with disposal 66*** 33 processing returned merchandise 75*** 25 repackaging product 75*** 0 source: research data (2019) by using fisher's exact tes. 4. operational performance with regards to implementation of gscm practices the results of operational performance with regards to implementation of gscm practice are shown in table 5. the result indicated that the quality at shell company has significantly higher extent in green procurement practices than the co-op company (p< 0.0001). furthermore, the safety at shell company revealed significantly higher extent of the firm practice of green procurement than that of co-op company (p< 0.00001). additionally, the delivery at shell company had significantly higher extent the firm practice green procurement than the co-op company (p< 0.0001). finally, the flexibility at shell company had a significantly higher extent the firm practice green procurement than that of the co-op company (p< 0.0001). finally, as shown in the table 5, the overall effects of gscm practices on operational performance reflected on quality, safety, delivery and flexibility. the competency relies always to the delivery on time of their wide range of portfolio as well as providing several after-sales technical support services which made them currently the market leader lubricants’ supplier for eight years in a row. nevertheless, shell is the highest spender on research and development reaching an annual spend of 1.3 billion dollars to be able to come up with the products that fulfill today’s customers’ needs. as mentioned above, the majorities of the raw materials supplied to the sc in egypt as well as other countries are imported goods and have strict environmental specifications. moreover, sometimes finished goods themselves are imported (or exported from other plants in the world) to satisfy a certain need in another operating unit. it is worth mentioning that planning is based on the historical statistical forecast of the products’ range. in other words, based on the finished product forecast, the material requirement planning (mrp) tools are used to explore the bill of materials (bom) and accordingly know the requirements from all bom components. based on the forecast as well, the company usually plans for all its capacities and requirements. accordingly, a sourcing plan with the companies' suppliers is constructed to fulfill the requirements of the customers. the raw and packaging materials are then converted to the finished product during the manufacturing stage. after this step, the finished product is sent to the distribution center to and be arranged and then sent to customers. in case of any faulty delivery, the company accepts returns from customers as per the service level agreement with the customer. http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 56 table 5. operational performance with regrads to implementation og gscm practices. impact shell company co-op quality 75*** 25 safety 66*** 33 delivery 75*** 25 flexibility 75*** 0 source: research data (2019) by using fisher's exact tes. 5. discussion of theoretical and managerial implications according to [48], gscm is increasing expanding enthusiasm among specialists and professionals of operations and scm. the developing significance of gscm is driven principally by the expanding crumbling of nature; that is, reducing crude material assets, flooding waste locales and expanding levels of contamination. actually, the gscm is a business esteem driver and not a cost focus [45];[17]. a successful way for sc managers to strengthen the reliability of scs is to complete a benchmarking exercise to assess how well their sc is performing. in order to complete such an exercise, a benchmarking approach for gsc performance can help benchmark scs based on their impact on the operational performance factors. based on the data collected and analyzed, figure 4 presents the refined conceptual framework for gscm practices for petrochemical companies in egypt. fig. 4. conceptual framework for gscm practices for petrochemical companies in egypt. source: developed by the authors . http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 57 the empirical results fulfilled the objectives of the study and generated adequate evidence for practitioners and decision makers to understand the various kinds of gscm practices and to what extent the adopted practices influence the operational performance. moreover, the research strongly supported the view that to green the environment requires collective responsibility and cross-functional cooperation for environmental improvements by the petrochemical’s companies. likewise, this study specifies several empirical evidences for the impact of three dimensions of gscm practices (green purchasing, green manufacturing, and reverse logistics) on four operational performance dimensions (quality, safety, delivery, and flexibility) and customer satisfaction. based on the analysis of the comebacks collected from the respondents of the study, shell egypt has already begun to implement gscm practices such as deliberating suppliers‟ iso 14000 certification; purchasing materials that contain green attributes; evaluating the suppliers on specific environmental criteria; replacing hazardous substances with those that are environmentally friendly, etc. consistent with the current literature, gscm practices drives the entire chain stakeholders to deal effectively with environmental problems, from the beginning of product design, development, and production, to reach the end user [22]; [7] . thus, these implications offer guidelines to petroleum and lubricant manufacturers to enhance their operational performance and customer satisfaction while employing gscm practices throughout their entire sc. v. conclusions and recommendations this study was carried out to determine the effect of gsc practices on operational performance using a benchmarking study between shell egypt and co-op petroleum company working in the lubricant industry. the study had two objectives. the first was to determine the extent of gsc practices used by shell and co-op petroleum company in egypt; the second objective was to establish the relationship between green sc management practices and operational performance of shell and the co-op petroleum company in egypt. the study showed that shell egypt, which operates in the lubricant industry, appreciates the role of green supply chain practices. the company practices green procurement. most practices are to ensure that suppliers comply with their environmental goals, purchase green materials, purchase energy-saving equipment, and other green manufacturing practices adopted by shell. furthermore, shell also uses recycling and collaboration with suppliers to standardize packaging and then reduce package size. shell has faced challenges in implementing green supply chain practices but has access to the tools and techniques needed to measure the performance of green supply chain management. this corresponds to the challenges identified by the rider center for supply chain management (2008). the three independent variables of gscm practices have clearly improved recycling and reuse opportunities, as well as improved operational performance and thus customer loyalty. as for the co-op petroleum company, it is clear that they used raw materials and packaging materials that cannot be recycled and that are non-reusable, although the co-op company has realized the importance of gscm practices. environmental issues are not used in the selection criteria of suppliers because of the company's lack of appropriate technology, which is a major challenge. it also lacks the gscm, which had a direct negative impact on customer loyalty. therefore, gscm is an operational innovation that petrochemical firms may adopt to address environmental concerns, such as, complying with stringent environmental regulations, addressing the environmental concerns of their suppliers and customers, and to mitigating the environmental impact of their production and service activities. in the future, implementing a gsc will be even more important than it is today. reasons for this are: concentrating on more government legislation, growing awareness of environmental issues and motivating consumers to be more sustainable. thus, greening the sc is not an alternative, it is becoming a norm. the area of gscm is relatively young and is still suffering from a shortage of information. this research will help to bring forth unknown information in the petroleum industry that will go a long way in facilitating further understanding of gscm practices adoption. future researchers will empirically test the relationships suggested in this paper in different companies to enable comparative studies. a larger sample would also allow detailed cross-sectoral comparisons which are not possible in the context of this study. to be efficient and effective in gscm, collaboration among important stakeholders in the petroleum marketing firms supply chain must be http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 journal of renewable energy and sustainable development (resd) volume 6, issue 2, december 2020 issn 2356-8569 http://dx.doi.org/10.21622/resd.2020.06.2.048 58 strongly concerned. this study recommends the creation of awareness of the role of gscm practices for the benefit of all the stakeholders and for sustainable economic and environment development. references [1] hsu, c.-w. and a.h. hu, green supply chain management in the electronic industry. international journal of environmental science & technology, 2008. 5(2): p. 205-216. 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[48] srivastava, s.k., green supply‐chain management: a state‐of‐the‐art literature review. international journal of management reviews, 2007. 9(1): p. 53-80. http://apc.aast.edu http://dx.doi.org/10.21622/resd.2020.06.2.048 6paper4.pdf (p.35-47) journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 60 resd © 2015 http://apc.aast.edu the vsas approach gives the best mppt for solar energy sources (res) nacer k.1, m’sirdi n. k.2, rabhi a.3, nehme b.4 1laboratory of systems and information sciences of aix marseille university (lsis amu), 2cnrs umr 7296, domaine universitaire saint-jerome, avenue escadrille normandie-niemen, 13397 marseille cedex 20, france. 3mis, laboratory of modeling, information and systems, university of picardie jules verne amiens, france authors are members of the hyres lab and the rmei network. 4 département de génie électrique et électronique, faculté d’ingénierie, université saint-esprit de kaslik, b.p. 446 jounieh, mont liban – liban. abstract more and more mppt (maximum power point tracking) algorithms are in competition to maximize energy extracted from pv systems. this paper shows how to get the best algorithm (the most simple, fast and robust). vsas (variable structure automatic systems) control methodology is applied to develop the control algorithm, to clarify the rationale behind and get the best optimization algorithm. keywords maximum power point tracking, renewable energy sources, perturb and observe, inccond, hill climbing. i. introduction the pv system operation principle needs a polarization depending on the weather to fix the operation point leading to extraction of the maximum power. the renewable energy systems (res) include commutations and discontinuities; this is one kind of variable structure system (vss). however, the behaviour of the conversion systems of this kind of renewable energy is vsas (variable structure automatic systems)[msirdiefea14] and highly dependent on variations in climate parameters, such as temperature and irradiation. the mppt algorithms are necessary to maximize, at each time instant, the produced power. several techniques have been designed to search this optimal maximum power point (mpp). in the literature, more and more mppt (maximum power point tracking) algorithms are in competition to maximize energy extracted from pv systems. the maximum performance of a photovoltaic system depend, of course, on good weather conditions, but needs also appropriate mppt algorithm [mutoh, nianchun]. the great majority of mppt control strategies are based on the (steady state) characteristics of pv panels, such as i-v or p v plots, the duty cycle ratio control and sometimes using look-up tables [amei]. a lot of mppt techniques are well established in the literature. there are several methods: voltage feedback method, perturbation and observation method, linear approximation method, incremental conductance method, hill climbing method, actual measurement method, fuzzy control method and so on [ting-chung, tavares, hua lin, fangrui, chihchuanhua, weidong]. in general, there exist four types of mppt techniques:  the pv operation point perturbation and observation (po) based algorithms in order to get the direction of tracking the mpp.  the hill-climbing algorithm which makes a perturbation in duty cycle to reach the apex of the characteristics.  the incremental conductance (incond) algorithm which periodically checking heslope (conductance) of the p-v curve [liu].  the constant voltage algorithm based on keeping constant the ratio between the pv voltage at the maximum power and the open circuit voltage (voc) value; in this method the effect of solar irradiance variations is neglected [hohm]. in[ibrahimhoussiny, amei], ibrahim and houssing use a look-up table to track, when other author prefer the use of a dynamic mpp tracker to pv appliances [midyakerin]. a single-stage mpp controller using the slope the power versus voltage, like has been done in [kuoliangchen]. in [hua lin] a http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 61 resd © 2015 http://apc.aast.edu dsp chips is used to implement the po mppt in order to get maximum power. they, also try to improve the efficiency of the po and hc methods. in [fangrui], the time response of po [chihchuanhua]and hc methods [fangrui, weidong, hohm]are compared for a grid connected system. the po method can fail under rapidly changing atmospheric conditions. several research activities have been carried out to improve the traditional hillclimbing and p&o methods. reference [xiao] proposes to use three measurement points to compute mpp. the method compares the obtained power measurement to the two preceding points before choosing the perturbation sign. in [kuoliangchen] the authors propose a two stage algorithm that offers faster tracking in the first stage and more accurate tracking in the second stage. to prevent divergence from mpp, they use a modified adaptive algorithm. table 1. parameters definition symbol units definition q q=1.6.1 0 −19 c the electron charge n diode non-ideality factor k b 1.38065·1 0 −23 n.m/k the boltzmann’s constant stc at (1kw/m2, 25°c) standard test condition i sc a short circuit current i sc,stc a short circuit current at stc v oc v open circuit voltage k 0 % calculated for isc temperature coefficient g w/m2 solar radiation t in kelvin °k the cell temperature t 1,ref at 1kw/m2, 298k (25°c) reference temperature t 2,ref k temperature at 2nd stc v ref vref =5v reference voltage in [tina]tina et. al. proposed a mathematical model for the electrical-thermal coupling of a pv module with ambient temperature, wind speed, wind direction, relative humidity and electrical operating point (voltage and current values). an mpp tracking based on dual boost converter is developed using fuzzy logic in [veerachary]. artificial neural network (ann), trained offline with a gradient descent algorithm using a back-propagation have been used by kaiser et. al. [kaiser] to generate (online) the reference voltage for mppt control, in a solar electric vehicles. another approach based on variable structure control is applied to a buck converter in [miaojie]. in [tingchung], the authors study and compare three maximum power point tracking (mppt) algorithms, under different climate conditions, in a photovoltaic simulation: the algorithms of perturbation and observation (po), incremental conductance (inc) and hill climbing (hc), respectively (see also [hohm]). they show that the photovoltaic simulation can track the maximum power accurately using the three mppt algorithms. po algorithm has fast dynamic response and well regulated pv output voltage than hc algorithm. since the inc algorithm is more complex, the time response of inc is a little longer. all of the mppts are based on the convex nature of the power characteristic curve and ignore that the characteristic can change in time when the temperature or irradiation changes[shaefer, kim]. as the weather conditions change during time, the maximum power point varies also with time. the maximum power point (mpp) changes from one curve to another, with solar irradiation or load variations. the paper is organized as follows. section 1 gives the problem formulation and recalls most used algorithms used for mppt. the second section presents pv system equations and features. section three introduces our new algorithm design approach. we compare their results with the widely used mppt algorithms; performance is evaluated considering different actual solar irradiation measured variations. the fourth section gives a conclusion and proposes perspectives. fig .1. equivalent circuit model of pv panel http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 62 resd © 2015 http://apc.aast.edu ii. pv systems control a. solar energy sources in this section we present the models of the pv systems. the simulation of the energy behavior of res (renewable energy source) is developed and several control methods and parameters can be analyzed. the goal is to obtain a good model of the process and to achieve a realistic simulation to enable us to check and validate our approach of optimal mppt and control. 1. the solar irradiation model the electric power operating by a pv panel depends on the irradiation intensity of the sun shining, and the temperature of the pv cells. the simplest solar radiation, perturbation free, model that can be used is the following, from (roughly) 7h19h, the period of sunshine. at the top of the sinusoid, the maximum power is assumed to be 1kw/m², at the time 13 hours. the sunless period is 19h-31h [schijndel1, sallem]. note that the wave is assumed piecewise sinusoidal. the solar radiation is represented by the following expression: g𝑆 = {g𝑆−𝑝𝑖𝑐sin( 2πt 3600 ) if t ∈ [ 7h,19h ] (1) the electric diagram is equivalent to an average pv cell as shown in figure 1 (a) (b) fig .2. a) measurement of solar irradiance taken for a day; b) temperature taken for a day 2. photovoltaic systems model and characteristics a photovoltaic generator consists of a group of pv modules electrically connected in series or parallel or series-parallel combinations with each other in a res to generate required currents and voltages [msirdiefea14, liu]. the model is a photo-current source il one diode with as reverse saturation current i0 , and a serial resistance rs , representing the pv cell resistance. the circuit is connected to the load ( r l ) trough a converter in order to adjust (adapt) the operating voltage and current of the pv panel at optimal values to maximize the harnessed power and transmit it. the control has to tracks the maximum power point. the equations describing the i(v) relationship between the current and voltage of a solar cell are given by (2), with the parameters defined in table1 [shaefer, hsiao, walker]. 𝐼 = 𝐼𝐿 − 𝐼0 [exp( 𝑞(𝑉−𝑅𝑠𝐼 𝑛𝐾𝐵𝑇𝑠 ) − 1] − 𝑉+𝑅𝑠𝐼 𝑅𝑃 (2) 𝐼0 = 𝐼0(𝑇1)[exp( 𝑉𝑂𝐶(𝑇1,𝑟𝑒𝑓) 𝑛𝐾𝐵𝑇1,𝑟𝑒𝑓/𝑞 ) − 1] (3) the internal serial resistance rs relative to one cell in open circuit voltage voc is: 𝑅𝑆 = − 𝑑𝑉 𝑑𝐼 ⎥𝑉𝑂𝐶 − ( 𝑛𝐾𝑜𝑇1,𝑟𝑒𝑓 𝑞 ) / 𝐼0(𝑇1,𝑟𝑒𝑓)exp( 𝑉𝑂𝐶(𝑇1,𝑟𝑒𝑓) 𝑛𝐾𝐵𝑇1,𝑟𝑒𝑓/𝑞 ) (4) the pv output voltage of the serial cells can be expressed as v: 𝑉 = 𝑁𝑆 𝑛𝐾𝐵𝑇 𝑞 𝑙𝑛( 𝐼𝑆𝐶−𝐼 𝑞𝐼0 ) (5) il varies as a function of the ambient temperature t and of the solar radiation g as: 𝐼l= 𝐼l(𝑇1,𝑟𝑒𝑓)+ 𝐾𝑜(𝑇 − 𝑇1,𝑟𝑒𝑓) (6) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 63 resd © 2015 http://apc.aast.edu with 𝐾𝑜 = 𝐼𝑆𝐶(𝑇2,𝑟𝑒𝑓)−𝐼𝑆𝐶(𝑇1,𝑟𝑒𝑓) 𝑇2,𝑟𝑒𝑓−𝑇1,𝑟𝑒𝑓 (7) 𝐼l= 𝐼stc(𝑇1,𝑟𝑒𝑓,𝑆𝑇𝐶) 𝐺𝑆 𝐺𝑆𝑇𝐶 (8) the pv system exhibits a nonlinear i(v) characteristic which depend on the temperature and the solar radiation which vary during a day, for exemple, as shown by the figure tempradiation; where a) and b) show the profile of real irradiation measured and temperature for one day. the photovoltaic panel considered, in this paper, contains 36 photovoltaic cells connected in series. to track the maximum power point (mppt) and achieve the optimum matching, a good control of the dc-dc is necessary. as the temperature, insulation and load vary, an algorithm is used to ensures that the pv module always operates at its maximum power point. the boost converter operation principle is the one of variable structure system (vss). the switching frequency of the boost igbt (changing s) is in general around fsw = 1/ts =20khz . we will try to use, in the comparative analysis different frequency values. fig .3 shows the electric circuit diagram of a pv panel connected to a dc/dc converter with the mppt control circuit based on po. b. the mppt controls for pv systems this part reviews 3 of the most frequently used control algorithms to get the maximum power. as presented previously, an mppt controller is used to increase the pv system efficiency. the principle is to calculate the optimal reference output voltage and/or current which ensures that the pv system operate at its mpp. these techniques are different from each other in many aspects, including simplicity, convergence speed, hardware implementation, sensors required, cost, range of effectiveness and need for parametrization (see eg [shaefer] for a survey). 1. perturb and observe methods http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 64 resd © 2015 http://apc.aast.edu the most commonly used mppt algorithm is the perturbation and observation (po) due to its easy implementation. it uses the p-v characteristics ppv=f(v) of the pv module. note that, for constant weather conditions, the operating power point p(n)=v(n)i(n) is obtained when the condition dp/dv=0 is accomplished. we can calculate the slope (dp/dv) using consecutive outputs measurements (voltages and output): 𝑑𝑃 𝑑𝑉 (𝑛) = 𝑃(𝑛)−𝑃(𝑛−1) 𝑉(𝑛)−𝑉(𝑛−1) (8)  if the operating voltage of the pv array is perturbed in a given direction and dp/dv>0, then the perturbation moves the array's operating point toward the mpp. the po algorithm would then continue to change the pv array voltage in the same direction.  if dp/dv⟨0 then the change in operating point moves the pv array away from the mpp, and the po algorithm reverses the direction of the perturbation [femia]. some limitations are encountered such as: oscillations around the mpp in steady state operation, slow response speed, and even tracking in wrong way when atmospheric condition instability [kim, liu, femia]. the duty cycle of the boost is changed and the process is repeated until the maximum power point has been reached. in actual experiments, the system oscillates around the mpp. to minimize the oscillations amplitude, we can reduce the perturbation step size. however, small step size slows down the convergence of the mppt. to solve this problem, we can use smaller perturbation size towards the mpp. 2. perturb and observe methods the incremental conductance (inccond) [femia], method is based on the fact that the slope (or the pv conductance g= di/dv ) of the pv array, in the power curve is zero at the mpp and it is positive (constant) on the left of the mpp. the slope becomes negative on the right of th mpp. these relations can be rewritten in terms of the array current and voltage as: 𝑑𝑃 𝑑𝑉 = 𝑑𝑉𝐼 𝑑𝑉 = 𝐼 𝑑𝑉 𝑑𝑉 +v 𝑑𝐼 𝑑𝑉 = 𝐼 + 𝑑𝐼 𝑑𝑉 to keep dp/dv = 0 we need: g=di/dv=-i/v; dp/dv = 0 at the mpp  if g = 𝑑𝐼 𝑑𝑉 > − 𝐼 𝑉 (this means that 𝑑𝑃 𝑑𝑉 > 0 ⁄ ), the operating point is on the left side of the mpp, v has to be raised.  if g = 𝑑𝐼 𝑑𝑉 < − 𝐼 𝑉 (dp/dv<0), the operating voltage is on the right side of the mpp then v has to be reduced. voltage is on the right side of the mpp then v has to be reduced. 3. hill climbing method in general the almost applications, use dc-dc converters and dc-ac inverters, as the power interface devices between pv modules and loads. the basic idea of the hc (hill climbing) method is the http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 65 resd © 2015 http://apc.aast.edu same as p&o method. it tests if p(n) is greater than p(n-1) or not, to reach mpp. the po method uses instead a test on dp/dv to determine whether the maximum power point has been found or not. however, the hc method uses a test condition on p(n)-p(n-1) and uses the duty cycle (d) of these switching mode power interface devices as the decision action parameter for the maximum power point tracking. the figure7 shows a flow diagram of the hill climbing algorithm. 4. the proposed vsas-mppt algorithms the desired objective to get is that the mpp reached when the maximum power is obtained (p(t)=pmax and dp/dt=0). the power is function of the voltage v, the current i and the time t, then the required maximum power point to track is really defined by the following objective function: 𝑑𝑃 𝑑𝑡 = 𝑑𝑉𝐼 𝑑𝑡 = 𝐼 𝑑𝑉 𝑑𝑡 + 𝑉 𝑑𝐼 𝑑𝑡 = 0 (8) let us consider the control in case of discrete time, then the fetched mppt may be defined by δp(k)=0, { ∆𝐼 = 𝐼𝑃𝑉(𝑘)− 𝐼𝑃𝑣(𝑘 − 1) ∆𝑉 = 𝑉𝑃𝑉(𝑘) − 𝑉𝑃𝑉(𝑘 − 1) ∆𝑃 = 𝑃𝑃𝑉(𝑘)− 𝑃𝑃𝑉(𝑘 − 1) 𝑃𝑃𝑉(𝑘) = 𝑉𝑃𝑉(𝑘).𝐼𝑃𝑉 ∆𝑃(𝑘) = 𝐼(𝑘).∆𝑉(𝑘) + 𝑉(𝑘).∆𝐼(𝑘) ∆𝑃(𝑘) = 𝐼(𝑘).𝑢1(𝑘)+ 𝑉(𝑘).𝑢2(𝑘) the two control variables are then u1(k)= ∆v(k) (the voltage variation) and u2(k)=∆i(k) (the current variation). 5. ruca: robust unified control algorithm for the proposed ruca algorithm, both control inputs can be used if we look for adjusting both variables (v and i), either at each control step or alternatively. it can be noticed that the previous algorithms can be considered as particular cases of this one, when simplifying the proposed control method. p max is a constant chosen greater than the maximum power in any weather condition pmax≥p(t) . let us then consider the lyapunov like function w(t) = ( 𝑃2𝑚𝑎𝑥 − p(t) 2 ) > 0 which is strictly positive everywhere ( ∀t, ∀i, ∀v ). the derivative of the proposed lyapunov function w(t)=( p^2〗_max-〖p(t)〗^2 )>0 , is �̇�(t) = −p(t) 𝑑𝑃(𝑡) 𝑑𝑡 = −p(t)(𝐼 𝑑𝑉 𝑑𝑡 + 𝑉 𝑑𝐼 𝑑𝑡 ) �̇�(t) = −𝐼2𝑉 𝑑𝑉 𝑑𝑡 − 𝑉2𝐼 𝑑𝐼 𝑑𝑡 ) t can be made negative by choosing the appropriate control laws u1(k)= ∆v(k)and u2(k)=∆i(k) to get a decreasing lyapunov function. the ruca uses two control inputs which can be done either simultaneously or alternatively or one of them can be frozen depending on the needed voltage or current. choosing u1(k)= kα∆p(k)sign(∆v(k)) u2(k)=k_2 α_2 ∆p(k)sign(∆i(k)) ensures that w (̇t)<0 and then the convergence of the ruca algorithm. this proves, theoretically also the convergence of the mepo algorithm which follows. we can use both inputs or only one of them either, in a first case u1(k)= kα∆p(k)sign(∆v(k)), or in the second case u2(k)=k_2 α_2 ∆p(k)sign(∆i(k)). in control context, the previously presented mppt controllers use only one control variable u1 or u2 and impose the second to be zero. the implementation of the proposed enhanced mppt controller ruca can be summarised as follows:  the reference voltage is set be equal to the double of the pv open circuit voltage.  measurement of the of input signals (pv voltage, http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 66 resd © 2015 http://apc.aast.edu pv current and load voltage).  estimate the pv power at the sample time k : ppv (k)= ipv(k).vpv(k)  calculate the pv current and pv power increments (see equation eq:optim). 6. mepo: modified enhanced po algorithm if we take as input u1(k) and put a constant current u2(k)=0 , which means that the voltage is perturbed and the current is fixed u2(k)= ∆i(k)=0 , we are in the same configuration as the po algorithm. we propose, as a modified enanced po algorithm which will be more robust, the reference voltage is given by vref=vk+ kα∆p(k)sign(∆v(k)) knowing that we impose ∆i(k)=0 , we get for the proposed mepo control algorithm we take u1(k)= kα∆p(k)sign(∆v(k)) and u2(k)= ∆i(k)=0 . the reference voltage vref(k) is calculated as below, where α is a gain weighting the perturbation variation step. note that δvref= αsign(∆p(k)∆v(k)) produces exactly the same result as the classical po algorithm with a much simpler implementation. this method gives an enhanced variable step size algorithm. the step size is adjusted in proportionally to the power variation produced in the previous step. the adaptive step adjustment gain k is used with ∆p(k), for weighting the variation (voltage perturbation) step. it is useful for oscillation avoidance, fast convergence and noise sensitivity reduction. we can also use only the control variable u2 (k)= ∆i(k) (and put u1(k)=0 ), the current is perturbed and the voltage is fixed ∆v(k)=0. c. comparative simulations and tests the simulation was performed under psim software as shown in figure 3. the physical model of a pv panel is used. the panel is considered to have 36 cells. a boost converter is built using a mosfet as a switch. the load is a 100 ω resistor. the algorithms are implemented in a c block and the duty cycle is calculated from vref using another c block. the actual, measured irradiation and panel temperature are read from a txt file as inpt to the simulation. 1. mppt alghorithms comparison in this study we compare four mppt algorithms under the same experimental conditions. the first algorithm called p&o stands for perturb and observe. the second algorithm called inccond stands for incremental conductance. the third algorithm called mepo stands for modified enhanced perturb and observe (from vsasmppt). and the fourth algorithm called rsmca (from vsas-mppt approach) stands for robust sliding mode control algorithm. note that ruca algorithm is simply combining use of the two vsas mppts alternatively. the comparison is made under changing values of irradiation and temperature. two cases are considered: first we update the irradiance and temperature each time without interpolation to create sudden variation in power output, second we interpolate the values of irradiance and temperature to create quasi-continuous irradiation and temperature. at the end we use real measured data for simulation. in this study we focus on the pwm commutation frequency of the mppt algorithm. 2. zero order hold interpolation analysis we perform many simulations with varying irradiance and temperature. the values are not interpolated causing sudden variation in power output. for high mppt algorithm frequencies (25hz, 50hz, 100hz) no difference in power output is noted between the four algorithms. after a change in environmental conditions that makes an increase in power output, mepo algorithm may present an oscillation because it is based on the value of dp and not on the sign of dp. at high irradiances, the rsmca algorithm present oscillation caused by the gain in calculation of vref.for low frequencies (5hz, 10hz, 12.5hz), the mepo and the rsmca algorithms excel the po and inccond algorithms. we can see in figure 2 that the po power and the inccond power are too far from the maximum power that can be generated from the panel. this is due to the fixed or small step size of the vref. we must recall that the mepo and the rsmca algorithms also converge rapidly to the maximum power after the start of the simulation. 3. first order interpolation analysis when interpolating data for irradiance and temperature (approaching real conditions), we can see that that the difference between po and inccond algorithms and mepo and rsmca algorithms are emphasized when we have high variation of environmental conditions and low algorithm frequency. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 67 resd © 2015 http://apc.aast.edu fig .4. shows the electric circuit diagram of the 4 mppt algorithms http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 68 resd © 2015 http://apc.aast.edu 4. real data analysis in this simulation we take real data measured for one day. we choose 20 minutes that present high fluctuations of irradiance ( 878w/m2 126w/m2 ) and temperature ( 26°c – 14°c ). the data is available each 5 min which mitigates the high variation in environmental conditions. this is why the algorithms results are almost identical even for low frequency. iii. conclusion in this paper, a new robust mppt algorithm is proposed to optimize the production of a photovoltaic (pv) chain. we developed a new technique to design the maximum power point tracking (vsas-mppt) based on variable structure automatic systems approach. this approach generalizes the sliding mode control to systems with commutations in a simplified technique, easy to implement. new and very efficient algorithms are proposed from vsas-mppt approach:  the mepo (modified enhanced perturb and observe)  the ruca algorithm (robust unified control algorithm).  the mpp is computed online using a very simple algorithm which uses two control inputs (one in current and one in voltage). the other algorithms like perturb and observe (po), hill climbing, incremental encoder (incond) and smc look as particular cases of the proposed algorithm called ruca (robust unified control algorithm).the proposed mppt has several advantages: simplicity, high convergence speed, and is independent on pv array characteristics. we study and compare execution efficiency for the proposed vsas-mppt algorithms to the other methods, including perturbation and observation (p&o). realistic simulations are presented to show ease of implementation of our new algorithms, and compare its efficiency and accuracy to other mppts. the obtained results prove that the mppt is tracked even under sudden change of irradiation level or temperature. in our comparative tests, a particular case (use only voltage input), called the modified and enhanced perturb and observe algorithm (mepo), is shown to be the most fast and efficient, despite using low frequency commutation and sudden fast temperature and irradiation changes. the proposed mppt has several advantages: simplicity, high convergence speed, oscillation free and is independent on pv array characteristics. in summary the best algorithms are those designed using the sasv-mppt approach and considering that the system can move from one characteristic to another. the proposed algorithms are the most efficient despite using low frequency commutation. they are the faster converging. the simulations was performed under psim software to use realistic physical models. fig .5. sudden variation of irradiation and t with frequency (100hz) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 69 resd © 2015 http://apc.aast.edu fig .6. variation of irradiation and temperature with low frequency (5hz) fig .7. interpolated variation of irradiation and t with low frequency (10hz) fig .8. real data interpolated with low 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[32] matlab simulink. creating graphical user interfaces. version 7.9 [online]. available : http://www.mathworks.com/access/ helpdesk/ help/ techdoc / creating_guis/ bqz79mu.html. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 http://dx.doi.org/10.21622/resd.2022.08.1.011 11 http://apc.aast.edu integrating renewable energy into nigeria’s energy supply mix nuhu caleb amulah department of mechanical engineering, faculty of engineering, university of maiduguri, p. m. b 1069, maiduguri, nigeria. amulahn@unimaid.edu.ng nigeria’s population is rapidly on the rise, and by 2050 nigeria would account for 4.2% of the total world population, becoming the third most populous country only behind china and india (united nations, department of economic and social affairs, population division, 2017). population increase coupled with increase in standard of living would lead to a high demand for energy. energy security is essential; the economic growth of a nation, as well as its progress and development largely depend on energy (oyedepo, 2012). making energy more affordable, accessible, and environmentally friendly has become a major global topic when discussing energy. for no less than a century, burning fossil fuels has spawned most of the energy required to drive cars, power businesses, and keep the lights on in homes (denchark, 2018). even today, oil, coal and gas provide for nearly 80% of the nigerian energy needs. this dominance is not without a price, as it is associated with environmental and climate challenges. people in nigeria need to change their energy consumption, and they need to change the way they produce their products and plastics; they need to move away from fossil fuels and they need to do it quickly (herder, 2019). an increased popularity in the use of renewable energy technology is perceived as one way of meeting these challenges. a shift towards the use of renewable energy has been a key point on the policy agenda in most countries around the world. more than a few governments have made this a milestone by setting ambitious targets for the implementation of such projects. the level to which these policies have been positive varies between countries (rolf, et al., 2007). despites its numerous advantages, the penetration of renewable energy is still faced with barriers such as market failure, market distortion, and technical, financial, economic as well as institutional barriers (painuly, 2001). abstract in this paper, simulat ion model for nigeria’s energ y system is developed using energ yplan simulat ion tool to st udy the str uct ure of the present energ y system and explore alternat ive fut ure scenarios based on renewable energ y sources. first, the 2017 reference scenario was developed and validated to reflect nigeria’s energ y supply and consumpt ion in 2017. two other fut ure scenarios were then developed; the 2030 remp scenario to show a pathway to achieving the renewable energ y master plan target of increasing the supply of renewable electricit y by 36% of the total electricit y generat ion by 2030; and the 2050 re scenario which seeks to increase the share of renewable energ y by >70% of the total electricit y generat ion and introduces the concept of electric vehicles and the use of biofuel in the transpor t sector. both the 2030 remp and the 2050 re scenarios employed the nat ional energ y master plan 7% reference g rowth scenario for all sectors using 2017 as the base year. the st udy shows that with the abundance of renewable energ y sources in nigeria, it is possible to develop an energ y system that is sorely dependent on renewable energ y. the 2030 remp shows that the shift from fossil fuel power plant to renewable energ y for electricit y generat ion results in an increase in the share of renewable energ y in electricit y product ion from 20.2% in 2017 to 37.88% in 2030 while the 2050 re shows that the share can go up to 71.20% if proper policies and infrastr uct ures are put in place. index terms: electricit y generat ion, energ yplan, energ y system, modelling, nigeria i. introduction received on, 25 march 2022 accepted on, 13 april 2022 published on, 16 may 2022 journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 http://dx.doi.org/10.21622/resd.2022.08.1.011 12 http://apc.aast.edu first, the foremost challenge is to expand the amount of renewable energy in the supply system, particularly the electricity supply (lund, 2007). nigeria renewable master plan (remp) provides a roadmap for increasing the usage of renewable energy in electricity supply. the master plan targets to increase the contributions to the electricity supply mix from renewable energy sources (solar, wind, hydro, and biomass) by 23% of total electricity generation in 2025 and 36% in 2030 (ecn, 2005). this study is set out to develop an energy system model for nigeria which integrates the use of renewable energy, particularly for electricity generation. firstly, a reference model based on the year 2017 is developed and validated for accuracy. two models for future scenarios i.e., the 2030 renewable energy master plan model (hereafter referred to as 2030 remp) and the 2050 renewable energy scenario (referred to as 2050 re), are then developed to highlight possible pathway to an efficient utilization of renewable energy sources in energy production. the energy scenarios are an “if-then” analysis and should not be considered as a prediction of what will happen in the future (teske, et al., 2016). a. nigeria energy situation nigeria is faced with energy crisis and this has been going on for the past five decades. the consequence of this is that many industrial and commercial activities are being affected negatively. there is a significant increase in the number of households, commercial ventures, and industries that consume electricity. this is due to the rapid increase in population and development in industrial and commercial activities. as a result, the demand for electricity has outstripped the supply capacity. the council for renewable energy of nigeria reports that power outages have caused a loss of about 126 billion naira annually (cren, 2009). nnanna and uzorh (2011) reported that firms spend about 25% to 40% of their initial investment on acquisition of facilities to enhance electricity supply. aside this negative economic impact, this situation also exposes people to carbon emissions due to the frequent use of generators in different households and business enterprises. according to the international energy agency (iea) estimates (iea, 2019), the total primary energy supply in nigeria in 2017 was 1827.50 twh, in which biofuel/waste had the highest share percentage (74.41%), followed by oil products (14.09%), natural gas (9.01%), crude oil (2.16%), hydro (0.30%) and coal (0.18%). the total final consumption in the same year was 1539.93 twh. the residential, commercial and public services sectors had the largest share at 80.38%, followed by transport (13.16%), industry (5.43%) and non-energy use (1.04%). the total electricity consumption of nigeria in 2017 was 25.77 twh. nigeria’s power generation capacity in 2017 was 12664 mw including 10522 mw from fossil fuels, 2110 mw from hydroelectricity, and 32 mw from solar, wind, biomass and waste. about 83% of fuel mix for power generation was natural gas. for a country with such a large population, the power generated is grossly inadequate. coupled with the population increase and increased economic activities, the power consumption is expected to radically amplify. the country is in an ominous state vis-à-vis the supply of energy. this translates into low economic growth and development. therefore, it is pertinent to delve to renewable energy which are in abundance to plan a new future path for nigeria. ii. methodology a. the energyplan simulation tool there is a great difficulty in selecting an appropriate energy tool for developing future scenarios of energy system, particularly as it pertains to nigeria. however, based on the review of 37 computer tools for analysing the integration of renewable energy into various energy systems (connolly, et al., 2010), the energyplan simulation tool was chosen for this study. there is no dearth of literature on the use of this simulation model for energy system modelling. the tool has been used to provide key insight and potentials for neo-carbon energy ecosystem (abdulganiyu, 2017); to develop an energy system model which integrates all the energy production, conversion and consumption sectors (ma, et al., 2014); to examine the role of energy storage in high renewable energy systems (lund & mathiesen, 2009), as well as to predict the optimization of the combination of various fluctuating renewable energy into the electricity system (lund, 2006). energyplan has also been used to effectively analyse energy systems with high share of renewable energy for several countries including ireland (connolly, et al., journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 http://dx.doi.org/10.21622/resd.2022.08.1.011 13 http://apc.aast.edu 2010), latvia (porubova, 2010), united kingdom (le & bhattacharyya, 2011), macedonia (ćosić, et al., 2012), denmark (kwon & østergaard, 2012), kenya and tanzania (abdulganiyu, 2017), etc. the energyplan model is an input/output simulation model that simulates the performance of a given energy system in hourly steps throughout a year. it was developed purposefully for energy planning strategies on the basis of technical and economic analyses with interest on the penetration of high renewable energy mix. the inputs into the model are demands, renewable energy sources, energy plant capacities, costs and a number of optional different simulation strategies emphasising import/export and excess electricity production. the outputs are energy balances and resulting annual productions, fuel consumption, import/ exports and total costs including income from the exchange of electricity (münster & lund, 2009; lund & thellufsen, 2021). a more detailed overview of the tool can be found in lund and thellufsen, (2021) and connolly (2015). b. the energy system analysis a reference model of nigeria’s energy system for the year 2017 was created. 2017 was chosen because it is the most recent year with the complete energy data for nigeria. the inputted data were based on iea energy balance sheet for nigeria (iea, 2019). the 2030 remp scenario is in accordance with the nigeria renewable energy master plan (ecn, 2005). the master plan targets an increase in contribution of renewable energy to electricity generation in nigeria by 36% in 2030. for other sectors, the reference scenario for the national energy master plan (ecn, 2014) wherein the real gdp grows by a mean of 7% per annum was used to predict energy demand using 2017 as the base year (the national energy master plan used 2009 as the base year). the industry will experience a growth rate of 24.01%, transport 6.46%, household 3.16% and others 6.01%. the electricity supply projection employed in this scenario is also adopted from ecn (2014) (7% growth scenario) and tabulated below. table i electricity supply projection for 2030 source: ecn (2014) lastly, the model for the 2050 re scenario was created. the scenario is aimed at increasing the percentage contribution of renewable energy to electricity supply by > 70%. the energy demand for other sectors was also predicted using the national energy master plan’s reference growth scenario. however, the scenario was modified through several steps of iteration to reduce the use of fossil by approximately 30% in the transport sector. this is replaced by the used of biofuel and electric vehicles. the following are the key assumptions made in the design of this scenario: 1. solar capacity was set at 70 gw, wind 25 gw and hydro 17759.4 mw 2. natural gas-powered plant capacity for the national energy master plan 7% growth for 2030 was maintained. however, it is assumed there will be construction of new biomass plants and the use of coal is assumed to have phaseout. 3. the transport sector is set to grow according the national energy master plan 7% growth scenario. it is assumed that the number of vehicles per 1000 people will increase from 60 in 2018 (national bureau of statistics/ federal road safety corps, 2018) to 200 in 2050. about 4 million of these vehicles will be electrically powered. 4. 20% of the fuel mix in the transport sector will be biofuel. this is set based on preliminary studies of some literatures (nnpc, 2007; abila, 2010; agba, et al., 2010; ohimain, 2013). journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 http://dx.doi.org/10.21622/resd.2022.08.1.011 14 http://apc.aast.edu the electricity demand for 2030 and 2050 was projected based on forecast of population growth (united nations, department of economic and social affairs, population division, 2017) and power demand estimates in literatures (olayande & rogo, 2008; world bank, 2013; ezennaya, et al., 2014; giz, 2015). table ii projected population and electricity demand for nigeria source: * united nat ions, desa, pop ulat ion div ision (2017) ** iea, 2019 a calculat ions based on * and power demand est imates from literat ures all the above data considerations were inputted into energyplan for technical simulation. østergaard (2009) gives some framework of optimization measures for energy system analyses of renewable energy integration. this study focuses on particularly on electricity generation. iii. results and discussion a. reference model verification and validation a comparison was made between the reference model created in energyplan, and the actual data of the nigeria’s energy system in 2017 obtained from iea (2019). this is necessary to ensure that energyplan can be used to generate accurate simulation result. the validation procedure employed by ma et al. (2014) and abdulganiyu (2017) was used in this study. first, the sources of electricity consumed were compared. as shown table iii, it can be observed that there is only a slight difference between the energy plan’s simulation result and the actual data from iea (2019). table iii comparison of electricity generation between energyplan model and actual data in 2017 (twh) *excluding 6.65 t wh which accounts for stat ist ical differences (0.45t wh), energ y ow n use (1.16 t wh) and losses (4.84 t wh) table iv compares total fuel consumption by source obtained from the energyplan model simulation result and the values in the nigeria energy balance (iea, 2019). journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 http://dx.doi.org/10.21622/resd.2022.08.1.011 15 http://apc.aast.edu table iv comparison of total fuel consumption in 2017 and the energyplan as can be seen on table iv, the energy plan data agrees to a large extent with the actual 2017 data. the only observable difference is natural gas consumption which differs by 4.84%. the verification of the reference model developed shows that energy plan can simulate nigeria’s energy system effectively and is therefore, employed to simulate the 2030 and 2050 future scenarios. b. the 2030 remp scenario this scenario takes into account the renewable energy master plan targets wherein renewable energy is to account for 36% of the total electricity generation capacity by 2030. the energy demand and supply for the other sectors (industry, transport, household and others) is projected according to the national energy master plan’s 7% growth scenario while using 2017 as the base year. the electricity supply is also projected based on the national energy master plan’s 7% growth scenario. these data were inputted into energyplan model, and the results are tabulated below. table v fuel mix in the 2030 remp scenario journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 http://dx.doi.org/10.21622/resd.2022.08.1.011 16 http://apc.aast.edu from table v, about 6.59% of the fuel consumption is for power generation. the main driver of growth in this scenario is industry (construction, manufacturing, mining, etc.) with annual growth rate of 24.01%. the transport, household and others (commercial and public services) will be having growth rates of 6.46%, 3.16% and 6.01%, respectively. as can be observed, aside biomass, oil still accounts for the highest share of fuel used in this scenario. table vi shows the simulation result for power production. the shift from fossil fuel power plant to renewable energy for electricity generation will result in an increase in the share of renewable energy in electricity production from 20.2% in 2017 (iea, 2019) to 37.88% in 2030. this is 1.88% more than the renewable energy master plan target for 2030 (ecn, 2005). in addition, 5.6% of the electricity production will be from nuclear power plant. this is in line with the national energy master plan projection for the year 2030 (ecn, 2014). table vi simulation result for power production 2030 remp scenario c. the 2050 re scenario this scenario is focused on achieving >70% contribution of renewable energy to power generation and the introduction of electric vehicles and biofuels in the transport sector. the scenario was designed considering the availability of renewable sources in nigeria (sambo, 2009), and renewable energy technologies assessment based on several critical sustainability indicators (evans, et al., 2009). the electricity production was from natural gas power plant, biomass power plant, solar, hydro and wind. coal-powered plant was assumed to have phaseout due to co2 content (95 kg/kj). the simulation result for the power production is shown in fig. 1. 71.20% of the total electricity production is from renewable energy sources (excluding biomass plants). fig. 2 shows energyplan electricity production for a month in 2050. fig. 1: simulat ion result for power product ion 2050 r e scenario fig. 2: energ yplan ele ct ricit y product ion outp ut in a t ypical month r es12–wind r es34 solar pv; pp+large hydropower plants + nat ural gas plant + biomass plant; storage– e le ct ricit y product ion from storage and vehicle to g rid t ranspor tat ion in the transport sector, it is assumed there would be four million battery electric vehicles (bevs) each having 50 kwh rechargeable battery packs, an equivalent of 200 gwh capacity in total. an estimated electricity demand of 24 twh was set for the bevs of which 75% would be for dump charge and the remaining 25% would be for smart charge. the maximum share of cars during peak demand was set at 20% and the share of cars that will be grid connected was set at 70%. table vii shows the fuel consumption in the transport sector for the year 2050. journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 http://dx.doi.org/10.21622/resd.2022.08.1.011 17 http://apc.aast.edu table vii fuel consumption in the transport sector 2050 re scenario it can be observed that fossil fuel still dominates the share of fuel mix used in transport sector in the 2050 re scenario. this is because vehicles stay on the road for up to 40 years in nigeria (maduekwe, et al., 2020) and there is still an increasing market for fossil fuel vehicles, so, therefore, replacing the already existing fossil fuel vehicles would be impractical. d. comparison of electricity production between the scenarios the annual electricity generation in each of the three scenarios is shown in fig. 3. there is a substantial shift in the generation capacities from fossil fuel power plant-dependent to renewable energy-dependent. in the 2017 reference scenario, the electricity production from condensing power is 20.19 twh, 5.56 twh from hydropower, and 0.02 twh from solar. renewable energy account to about 20% of the electricity generation in 2017. in the 2030 remp scenario, production from condensing power plant is 78.55 twh, 7.26 twh from nuclear power plant and 52.32 twh from renewable energy sources. renewable energy in this scenario accounts for 37.88% of the total power production. in the 2050 re scenario, renewable energy share in power generation is increased to 71.20%. fig. 3: e le ct ricit y generat ion by source in different scenarios iv. conclusion it is evident that nigeria’s energy demand would continue to increase due to the rapid growth in population and the economy. however, the supply which is still dominated by fossil fuel is not sufficient enough to meet such increasing demand. it is pertinent to introduce renewable energy sources which the country has in abundance into the supply mix. in this study, a reference scenario and two energy system scenarios for nigeria were technically designed and simulated. the 2017 reference scenario was designed to reflect nigeria’s energy supply and consumption in 2017; the 2030 remp scenario was designed to show a pathway to achieving the renewable energy master plan target of increasing the supply of renewable electricity by 36% of the total electricity generation by 2030. the 2050 re scenario seeks to increase the share of renewable energy by >70% of the total electricity generation; it also introduces the concept of electric vehicles and the use of biofuel in the transport sector. both the 2030 remp and the 2050 re scenarios employed the national energy master plan 7% reference growth scenario for all sectors using 2017 as the base year. the study shows that with the abundance renewable energy sources in the country, it is possible to develop an energy system whose supply is based on renewable energy. the 2030 remp shows the shift from fossil fuel power plant to renewable energy for electricity generation will result in an increase in the share of renewable energy in electricity production from 20.2% in 2017 to 37.88% in 2030 while the 2050 re shows that the share can go up to 71.20% if proper infrastructures and policies are put in place. journal of renewable energy and sustainable development (resd) volume 8, issue 1, june 2022 issn 2356-8569 http://dx.doi.org/10.21622/resd.2022.08.1.011 18 http://apc.aast.edu references [1] united nations, department of economic and social affairs, population division, “world population prospects: the 2017 revision, key findings and advance tables,” working paper no. esa/p/wp/248, 2017. 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[36] p. a. østergaard, “reviewing optimisation criteria for energy systems analyses of renewable energy integration.” energy, vol. 34, no. 9, pp. 1236-1245, september 2009. https:// doi.org/10.016/j.energy.2009.05.004 [37] a. s. sambo, “the place of renewable energy in the nigerian energy sector,” presented at the world future council workshop on renewable energy policies, addis ababa, ethiopia, 10th october, 2009 [38] a. evans, v. strezov and t. j. evans, “assessment of sustainability indicators for renewable energy technologies,” renewable and sustainable energy reviews, vol. 13, pp. 1082-1088, june 2009. https://doi.org/10.1016/j. rser.2008.03.008 [39] m. maduekwe, u. akpan and s. isihak, “road transport energy consumption and vehicular emissions in lagos, nigeria: an application of the leap model,” transportation research interdisciplinary perspectives, vol. 6, july 2020. http://dx.doi.org/10.1016/j.trip.2020.100172 journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 264 solitons and the new renewable energy approach mahmoud akdi 1, moulay brahim sedra 2 1 lhesir, f s k, ibn toufail university kenitra, morocco, e-mail address: makerase@gmail.com 2 lhesir, f s k, ibn toufail university kenitra, morocco, 2 ensah, mohammed first university, al hoceima, morocco e-mail address: sedramyb@gmail.com abstract this article aims at deepening research on the new renewable energy production from the dams reservoir. coupled to the solitary waves, the wind generated waves present an attractive natural phenomenon that deserves to be emphasized. the adomain numerical method is used to model the practical observation regarding the soliton propagation. the actual cases contained in this document provide an illustration of the given principals. keywords wind genrated waves; solitary waves; kd-v equation; adomian method; dams. i. context presentation as mentioned in [1], a new concept of renewable energy generation was presented. the main idea consists of operating the wind generated waves in order to produce an electrical energy. the researchers recall that, based on practical observation of several dams, four steps distinguishing this phenomenon can be identified: stagnated water: represents the surface of water in the state of stagnation. no movement is noted at this area. wind gusts: transition step in which the wind is blowing in gusts on the surface of water; wind generated wave: the surface of water is deformed. generation of waves due to action of wind on the water is assisted; wave propagation: the waves so generated are transported away from their creation zone. this distance is considered important compared to the length of the wind generated wave. all the above steps are presented schematically on fig. 1. solitary waves propagation wind generated wave wind gusts stagnant water fig .1. steps of the phenomenon observed. through [1], the researchers were able to establish the physical model governing the creation of the wind-generated waves. in the present document, the researchers will focus more precisely on the fourth step, which consists of wave propagation. the range of propagation of the above waves shows that they can’t be qualified as standard ones. as specified on the aforementioned figure, it comes of the solitary wave. actually, the solitary wave propagates in nonlinear and dispersive environment. it has localized energy in space and is extremely stable in the presence of disturbances. it moves without changing form or characteristics, and this explains the fact that it is relatively easy to observe in nature, such as in our case. hence, the weakly nonlinear kd-v type theories allow us to elucidate the essential features of these observations. they have the advantage of providing modeling of wave evolution with a reduced wave equation [2]. ii. solitary waves and the kd-v equation the researchers suggest defining the following, as represented in fig. 2: mailto:makerase@gmail.com journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 265  d: the average depth of the water relative to the free stagnant surface;  h: the amplitude of the deformation of the surface of water;  l: longitudinal scale representing a characteristic length of the deformation;  l: a characteristic width;  c: a characteristic speed;  h(x,y): presenting the water depth relative to the free stagnant surface;  v⃗⃗ (x,y,z, t) = [ vx vy vz ]: presenting the fluid velocity;  p(x,y,z, t): presenting pressure minus the hydrostatic pressure, devised by the density;  u(x,y, t): presenting the deformed water elevation relative to the free stagnant surface. free surface u (x ,y ,t ) h (x ,y ) free stagnant surface x z y bottom fig .2. convention of the characteristic variables of the water deformation. the fundamental equations (basic law of continuity and dynamics), constituting the navier stokes equations give: { ∂vx ∂x + ∂vy ∂y + ∂vz ∂z = 0 dv⃗⃗ dx + ∇p⃗⃗⃗⃗ = 0 , (1) with the following boundary conditions: { vz = du dt , p = gu vz + vx. ∂h ∂x + vy. ∂h ∂y = 0 (2) representing conditions respectively at the free surface and the tangent speed at the bottom and with p = pn ρ⁄ + gz, (pn being the total pressure). introducing the following dimensionless variables: x = λ.x′, y = l.y′, z = d.z′, t = λ.t′ c , u = h.u′, h = d.h′, vx = ch d . vx ′ , vy = chλ dl .vy ′ , vz = ch λ .vz ′, p = hgp′. where h is the amplitude, λ is a characteristic length, c is a characteristic velocity, d is the average depth of the water column and l is a characteristic length along the axis y. for the rest and to simplify editing equations, the researchers rewrite the system of navier-stokes equations using dimensionless variables without using « »́, namely: { ∂vx ∂x + γ ∂vy ∂y + ∂vz ∂z = 0 ∂vx ∂t + c0 2 ∂p ∂x + α(vx ∂vx ∂x + γvy ∂vx ∂y + vz ∂vx ∂z ) = 0 ∂vy ∂t + c0 2 ∂p ∂y + α(vx ∂vy ∂x + γvy ∂vy ∂y + vz ∂vy ∂z ) = 0 β ∂vx ∂t + c0 2 ∂p ∂z + αβ(vx ∂vz ∂x + γvy ∂vz ∂y + vz ∂vz ∂z ) = 0 ,(3) with the following boundary conditions: { vz = ∂u ∂t + α(vx ∂u ∂x + γvy ∂u ∂y ), p = u for z = αu vz + vx ∂h ∂x + γvy ∂h ∂y = 0 pour z = −h ; (4) and : α = h d , β = d2 λ2 , c0 2 = gd c2 , γ = λ2 l2 . as part of the previous approximation h ≪ d ≪ l, recovered in the second-order, the researchers deduce that β2 ≪ 1 and αβ ≪ 1. thus, they arrive at the boussinesq system: { ∂u ∂t + ∂ ∂x [(αu + h)vx̃] + γ ∂ ∂y [(αu + h)vỹ] = 0 ∂vx̃ ∂t + c0 2 ∂u ∂x + α(vx̃ ∂vx̃ ∂x + γvỹ ∂vx̃ ∂y ) + 1 3 βh ∂3u ∂t2 ∂x = 0 ∂vỹ ∂t + c0 2 ∂u ∂y + α(vx̃ ∂vỹ ∂x + γvỹ ∂vỹ ∂y ) + 1 3 βh ∂3u ∂t2 ∂y = 0 ; (5) journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 266 with : vx̃ = 1 h ∫ vx.dz, vỹ 0 −h = 1 h ∫ vy.dz . (6) 0 −h if the researchers focus on solutions ∂u ∂τ + ∂u ∂x =⊝ (α,β,γ), with τ = c0. t, for which they accept that solutions spread to the positive x, then they deduce the kd-v equation for a two-dimensional flow: ∂ ∂x ( ∂u ∂τ + ∂u ∂x + 3 2 αu ∂u ∂x + 1 6 β ∂3u ∂x3 ) + γ 2 ∂2u ∂y2 = 0. (7) in the one-dimensional case, either to γ = 0, the same equation becomes: ∂u ∂τ + (1 + 3 2 α)u ∂u ∂x + 1 6 β ∂3u ∂x3 = 0. (8) there exist many variants of the kd-v equation depending on the case study. in a configuration similar to ours, the above equation can take the following form [2]: ηt + (c0 + α1η + α2η 2)ηx + β1ηxxx = 0, (9) where η(x,t) refers to the wave amplitude related to the isopycnal vertical displacement. the coefficients α1, α2, and β1 are functions of the steady background stratification and shear through the linear eigenmode (vertical structure function) of interest. the linear phase speed c0 is the eigenvalue of the sturmlouiville problem for the eigenmode. the researchers can deduce from the preceding data that handling such equation to get analytic solution cannot be considered as an affordable issue. the situation can be more complicated when the boundary conditions change due to location and intrinsic site parameters. this is why the researchers present a numerical method in order to insure resolution of the above equation while complying with the efficiency required. iii. the adomian decomposition method applied to the kd-v equation consider the kd-v equation as follows: ∂u ∂t + 6u ∂u ∂x + ∂3u ∂x3 = 0, u(x,0) = f(x) (10) which can be rewritten as follows: ∂u ∂t = −ru − 6n(u), u(x,0) = f(x) (11) where r = ∂3 ∂x3⁄ represents the linear operator of the kd-v equation and n(u) = u∂u ∂x⁄ is the non-linear function. according to the adm, the solution is expressed by: u(x,t) = ∑un(x, t), (12) ∞ n=0 and the non-linear part: n(u) = ∑an ∞ n=0 , (13) with: an = 1 n! dn dλn [n(∑λiui ∞ i=0 )] λ=0 , (14) by integrating with respect to time and using the initial conditions the researchers have: u(x,t) = f(x) − ∫[lu t 0 + 6n(u)]ds. (15) so: journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 267 u(x,t) = f(x) − ∫[l(∑un(x,s) ∞ n=0 ) t 0 + 6∑an ∞ n=0 ]ds. (16) for the kdv equation, the adomian polynomials can be expressed as follows: an = ∑ui ∂un−i ∂x . (17) n i=0 this allows the researchers to deduce un(x,t), namely: { u0(x, t) = f(x) un+1(x,t) = −∫[run + an]ds, n ≥ 0 t 0 (18) with the following initials conditions: u(x,0) = 1 2 sech2 ( x 2 ). (19) the researchers proceed in the following to compute an(x, t) and un(x, t) for n ∈ ⟦0,10⟧ and try to determine the approximate solution ũn(x, t) using the following formula: ũn(x, t) = ∑ui(x, t) (20) n i=0 = f(x) − ∫[l(∑ui(x,s) n i=0 ) t 0 + 6∑ai n i=0 ]ds. (21) the numerical studies can be effectively elaborated by the use of this computational method. once created, the researchers can predict the evolution of the solitary waves with respect to the spatial and time variables. the following figure gives an idea about the numerical calculation obtained [3] and [4]. there exist other numerical methods that can also be used depending on their calculation effectiveness [5] and [6]. fig .3. numerical solution of the kd-v equation using the adm method. iv. intrinsic conditions favoring the exploitation of solitary waves the efficiency of the new renewable energy production approach is closely related to the implementation of site conditions. as presented in [7] several parameters are taken in consideration in the site selection. the researchers would like to mention those with critical issues as follows:  the wind speed constitutes one of the main parameters to take in consideration. the wind speed, the height of the wind generated waves, the swept area and the generated power all together evolve according to the same trend.  the second one is the wind direction. indeed, to get optimal conditions of the power extraction, one needs to have both: a regular and a dominant wind direction. journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 268  the third one is the area of the water surface. it allows increasing the recovery of energy during wave propagation.  another point is the availability of hydroelectricity plant in order to benefit from the direct injection of the generated electrical power in the network. another advantage of this new approach, in addition to those presented previously, lies in benefits due to the intrinsic features of the site implementation. in the following, the researchers will introduce two particular cases illustrating this fact. a. topography of the dam location the speed of the wind is further appreciated in the case of existence of a dominant wind direction. in this sense, the topography of the dam site can filter the wind direction so as to keep a dominant direction. thus there is consistency in the direction of the wind generated waves.the dam of ouirgane located in the atlas mountains, near of marrakech city (about 66 km), reflects this principle. as illustrated in fig. 4, the dam reservoir along the thalweg. fig .4. satellite image of ouirgane dam (31°11'23.3"n 8°05'16.5"w) with indication of the wind dominant direction. fig. 5 shows that the watersheds elevation constitutes a natural filter with respect to the wind direction: only the wind blowing in a direction parallel to the crest line of the mountains contributes to the creation of the wind generated waves. fig .5. elevation map at the ouirgane dam. (1) refer to the thalweg axis and (2) refer to crest lines of the mountains surrounding the dam reservoir. even if the wind direction distribution relating to this region is dispersed among several directions (cf. fig. 6), the naturel filter due to topographic feature isolates only the nne as a dominant wind direction. fig .6. annual wind direction distribution at marrakech-menara airport. the particular interest reached through this configuration is that the solitary waves once generated continue to propagate along the dam reservoir and do not break. thus the energy extricated 1 2 2 wind dominant direction journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 269 can be recovered a multitude times. b. dam wall orientation and solitary waves we detailed at the beginning of this document the different aspects of the solitary waves, in order to use their application in the new renewable energy concept. the propagation of these waves further away from their emplacement generation offer significant opportunities. this performance can be improved in the case where the dam wall has an orientation perpendicular to the solitary waves propagation as shown in fig. 7. z=0 dam wall propagation direction z=0 dam wall reflection direction solitary waves solitary waves outlet tunnel outlet tunnel fig .7. propagation and reflection of the solitary waves against the dam wall. for a phenomenon happening a single time, alias the wind generated waves, the swept area is duplicated. this means that the efficiency of any unitary conversion installation responding to this condition will double. the electrical production will occur in the first propagation step and also in the second one after dam wall reflection. allal al fassi dam (about 52 km from fes city) presented in fig. 8 gives an appropriate illustration concerning this case. effectively, as shown in the wind direction distribution in fig. 9, the dominant wind direction nw is perpendicular to the aforementioned dam wall. fig .8. satellite imagery of allal al fassi dam (33°55'53.0"n 4°40'37.9"w). fig .9. annual wind direction distribution at fes-saïss airport. v. conclusions in this paper the effect of the combination of the wind generated waves and the solitary waves was proven. once created under the particular conditions defined, the wind generated waves are transported away from their creation area via solitons. based on this, the swept area increases significantly and the propagation waves trajectory in dams reservoir becomes longer. journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 270 taking in consideration two particular cases, favorable topographical dam location and the well dam wall orientation, the above performance is further enhanced. references [1] m. akdi, m. b. sedra. (2015). new approach for renewable energy production from dams. international journal of sustainable and green energy. special issue: wind-generated waves, 2d integrable kdv hierarchies and solitons. [online]. 4(3-2), pp. 1-5. available: http://article.sciencepublishinggroup.com/pdf/10. 11648.j.ijrse.s.2015040302.11.pdf [2] karl r. helfrich, w. kendall melville. (2006). long nonlinear internal waves. the annual review of fluid mechanic. [online]. 38, pp. 395– 425. available: http://darchive.mbl.edu/bitstream/handle/1912/6 51/helfrich%20annurev.fluid.38.050304.pdf?seq uence=1 [3] m. akdi, m. b. sedra. (2013). numerical kdv equation by the adomian decomposition method. american journal of modern physics. [online]. 2(3), pp. 111-115. available: http://article.sciencepublishinggroup.com/pdf/10. 11648.j.ajmp.20130203.13.pdf [4] m. akdi, m. b. sedra. (2013). comments on the adomian decomposition methods applied to the kdv equation. applied and computational mathematics. [online]. 2(6), pp. 137-142. available: http://article.sciencepublishinggroup.com/pdf/10. 11648.j.acm.20130206.15.pdf [5] m. akdi, m. b. sedra. (2013). numerical simulation of kdv equation. advanced studies in theoretical physics. [online]. 7(9-12), pp. 407418. available: http://www.mhikari.com/astp/astp2013/astp9-122013/sedraastp9-12-2013.pdf [6] m. akdi. (2013). study of solitary waves: results of resolution by numerical methods of the korteweg-de vries equation and simulation of the fluid flow. phd thesis. [7] m. akdi, m. b. sedra. (2015). prospective study: choice of the potential sites intended for the new renewable energy approach. international journal of sustainable and green energy. special issue:wind-generated waves, 2d integrable kdv hierarchies and solitons. [online]. 4(3-2), pp. 6-9. available: http://article.sciencepublishinggroup.com/pdf/10. 11648.j.ijrse.s.2015040302.12.pdf http://article.sciencepublishinggroup.com/pdf/10.11648.j.acm.20130206.15.pdf http://article.sciencepublishinggroup.com/pdf/10.11648.j.acm.20130206.15.pdf journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 98 resd © 2015 http://apc.aast.edu numerical analysis of fluid flow and heat transfer for different fin designs and arrangements of ceramic platefin high temperature heat exchanger – part ii vijaisri nagarajana, yitung chena*, qiuwang wangb, ting mab a department of mechanical engineering, university of nevada, las vegas, nv 89154-4027, usa b key laboratory of thermo-fluid science and engineering, moe, xi’an jiaotong university, xi’an, shaanxi, 710049, china abstract in this study numerical analysis is carried out for four different types of fins for top and bottom fin arrangement. the obtained results are compared with each other and the design with best heat transfer and minimum pressure drop is selected. the working fluids used in the model are sulfur trioxide, sulfur dioxide, oxygen and water vapor. the operating pressure is 1.5 mpa and the operating temperature ranges from 973 k to 1223 k. from the results it was found that the ripsaw fin design with thickness of 0.00005 m gives a good heat transfer rate with minimum pressure drop. the inverted bolt fins also gives a good heat transfer rate but due to the fin arrangement and the flow disturbances caused by the arrangement the pressure drop is the highest compared to other fins. the pressure drop and the heat transfer obtained for the rectangular and triangular fins are similar to each other. friction factor, colburn jfactor and dimensionless numbers like nusselt number, schmidt number are calculated for all the models. the average nusselt number obtained for the ripsaw fin design with thickness of 0.00005 m for the top and bottom arrangement is 3.023. the friction factor for the ripsaw fins for the top and bottom arrangement is 0.589. keywords heat transfer enhancement factor, ceramic plate-fin (pfhe) heat exchanger, nusselt number, schmidt number, pressure drop. i. introduction compact heat exchangers (che) plays an important role in the field of aerospace, transportation, nuclear and other industries. the need for lightweight, space saving and economical heat exchangers have driven to the development of compact heat exchangers. surface area density of greater than 700 m2/m3 is achieved by incorporating fins, ribs tec. the book by hesselgreaves [1] describes different types of compact heat exchangers like plate-fin heat exchangers, spiral heat exchangers, printed circuit heat exchangers, tube fin heat exchangers etc. a plate-fin heat exchanger is a form of compact heat exchanger made of block of alternating layers of corrugated fins separated by parting sheets. surface interruption prevents the continuous growth of the thermal boundary layer by periodically interrupting it. thus the thicker thermal boundary layer which offers high thermal resistance to heat transfer are maintained thin and their resistance to heat transfer is reduced. in a plate-fin heat exchanger, fins are easily rearranged resulting in cross-flow, counter-flow, cross-counter-flow or parallel flow arrangements. from the research done by kayansayan [2] the effect of the performance of plate-fin and tube cross-flow heat exchangers due to the outer surface geometry was considered. in this study 10 geometrical configurations were tested and the reynolds number was varied from 2,000 to 30,000. the results showed that the heat transfer coefficient strongly depends on the finning factor ε and the value of ε increases with decrease in j-factor. ranganayakaulu & seetharamu [3] carried out an analysis of a cross-flow compact plate-fin heat exchanger for the combined effects of twodimensional longitudinal heat conduction through the exchanger wall, flow non-uniformity and temperature distribution was carried out using the finite element method. the exchanger effectiveness and thermal deterioration due to these effects were studied for various design and operating conditions. wen & li [4] proposed a study in order to enhance the uniformity of flow distribution. in their study an improved header configuration of plate-fin heat exchanger was proposed. the results showed that the fluid flow maldistribution was very severe in the direction of header length for the conventional header used in the http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 99 resd © 2015 http://apc.aast.edu industry due to poor header configuration. manglik & bergles [5] studied the heat transfer and pressure drop correlations for the rectangular offset strip-fin compact heat exchanger. the f and j parameters were also found for laminar, transition and turbulent flow regimes. steady state three-dimensional numerical model was used to study the heat transfer and pressure drop characteristics of an offset strip-fin heat exchanger by bhowmik & lee [6] three different performance criteria for heat exchangers were tested for different fluids and the appropriate performance criteria for pr = 7 and pr = 50 were found to be jf (thermal-hydraulic performance factor) and j/f1/3. research has been carried out by ma et al. [7] to find heat transfer and pressure drop performances of ribbed channels in the high temperature heat exchanger. from the results it was found that the nusselt number and the friction factor were unsuitable to compare heat transfer and pressure drop performances at different temperature conditions. schulte-fischedick et al. [8] proposed a ceramic high temperature plate-fin heat exchanger for externally fired combustion process. thermal performance and pressure drop in ceramic heat exchanger was evaluated using cfd simulations by monteiro et al. [9]. correlations for the colburn and the friction factors for the reynolds number ranging from 500 to 1500 were evaluated. simulations with conjugate heat transfer were conducted and the results show the influence of mass flow rate on pressure drop and effectiveness of the heat exchanger. ponyavin et al. [10] carried out a numerical analysis on the threedimensional computational model of the ceramic high-temperature heat exchanger to investigate fluid flow, heat transfer, and chemical reaction and stress analysis within the decomposer. a decomposition rate of 0.515% was achieved for so3 using this design. in this study numerical analysis of ceramic plate fin high temperature heat exchanger was carried out to investigate the fluid flow and heat transfer for different fin designs and fin arrangements. this study is an extension of the work done by nagarajan et al. [11]. in order to save computational space and time a single channel model of the heat exchanger is modeled and studied. the main operating parameters for the heat exchanger design models for the current study are taken from the research done by ponyavin et al. [10]. ii. geometry of the model and material properties in this study three-dimensional study of the fluid flow and heat transfer on four type of fins namely rectangular, triangular, inverted bolt fins and ripsaw fins for top and bottom arrangement is carried out. the computer aided geometry (cad) geometry for all the models are modeled in solid works [12] and simulations are carried out in ansys fluent 14.5. the geometry and dimensions for the current study is taken from the work done by ponyavin et al. [10] and from his study it was found that mass flow rate in all channels can be made almost uniform with a proper design of manifold channels. hence by applying that concept a single channel model is developed to reduce computational time and memory. singlebanking configuration is used where in the hot and the cold plates are stacked alternatively. the current study has hot fluid channel, cold fluid channel and two silicon carbide (sic) solid regions. helium fluid flows through the hot channel placed above the solid region and mixture of sulfur trioxide, sulfur dioxide, oxygen and water vapor flows through the cold fluid channel which is placed between the two solid regions. the flow is counter flow where the hot and the cold fluids enter the model from –x and +x directions and exit in the +x and –x directions, respectively. figure 1 shows the geometry and dimensions of the single channel of plate fin heat exchanger. fig .1. geometry and dimensions of the channel to enhance the thermal performance of the pfhe many fin designs are explored and studied. table 1 shows the dimensions of all the fins http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 100 resd © 2015 http://apc.aast.edu table 1. dimensions of various fins geometry definition rectangular fins height = 0.4 mm, length = 0.4 mm, width = 0.2 mm triangular fins height = 0.3 mm, breadth = 0.2 mm, length = 0.4 mm inverted bolt type fins diameter of top cylinder = 0.2 mm, diameter of bottom cylinder = 0.4 mm ripsaw fins larger height of the rectangle = 0.3 mm, smaller height of the rectangle = 0.15 mm, thickness = 0.05 m in order to avoid backflow and provide entrance zone for each channel no fins are placed near the inlet and the outlet region on the cold channel. a study was carried out by increasing the length of the inlet and outlet to 5, 10 and 15 times the hydraulic diameter. at 10 times the hydraulic diameter the flow becomes fully developed and hence the length of the inlet and outlet are taken to be 10 times the hydraulic diameter. the material properties, boundary and operating conditions are taken from the work done by nagarajan et al. [11]. iii. numerical method and algorithm the finite volume method is one of the most versatile discretization techniques used in cfd. the governing equations are solved in the cartesian coordinate system using a control volume finite difference method that is similar to the approach introduced by patankar [14]. ansys fluent [13] a commercial cfd program based on the finite volume method is among the most powerful packages of existing software used for solving fluid flow and heat transfer problems. the pressure-based segregated solution algorithm is used for the given problem. it can be simply described as the process of solving the governing equations in a sequential order as opposed to simultaneously as with a coupled solver. the geometry of the model is meshed in ansys workbench [13] mesh generator. hexahedral elements are used for meshing. the mesh is refined near the walls particularly for the cold flow channel with fins. the mesh refinement near the wall helps in calculating the fluid flow and heat transfer properties accurately. in order to check the mesh dependence on fluid flow and heat transfer properties, the grid independent study was done for both staggered and top and bottom arrangement. from the study, optimum nodes with difference in pressure drop and heat transfer of less than 5% is selected for further study. around 481,558 cells, 1,496,152 faces and 532,599 nodes are selected for further study for all the cases.the friction factor, the colburn factor and the prandtl number are calculated using the formula shown below: 𝑓 = ( ∆𝑃 𝐿 )∗𝐷ℎ (0.5∙𝜌∙𝑈2) (1) 𝑗 = 𝑁𝑢̅̅ ̅̅ 𝑅𝑒∙𝑃𝑟 1 3 (2) 𝑃𝑟 = 𝜇∙𝐶𝑝 𝐾 (3) the schmidt number which is the ratio of the viscous diffusion rate to the mass diffusion rate is calculated based on the average temperature of the reacting channel. the validation of the fluid flow and heat transfer for the rectangular and ripsaw fins was carried out in the previous study done by nagarajan et al. [11]. the friction factor was compared with the published result by manson [15] and the colburn factor was compared with the correlation published by wieting [16]. the obtained cfd result was in good agreement with the published result and the slight offset is due to the difference in the dimensions of the geometry. since the numerical results agree closely with the published results and follow the same trend, further research is carried out for the selected design. iv. results and discussions a. fins arranged on the top and the bottom solid in this study, the fins are arranged on both the top and the bottom solid regions to enhance the heat transfer. it is found that since the bottom solid region doesn’t have any heat input and the heat transfer is only from top solid region there is a little increase in heat transfer rate compared to the uniform arrangement. the pressure drop obtained is higher compared to the other two arrangements because there is an increase in heat transfer surface area and more flow disturbances produced by the fins. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 101 resd © 2015 http://apc.aast.edu 1. case 1 (single channel model with rectangular fins) in this study the rectangular fins are arranged on both the top and bottom solid regions. the heat transfer surface area of the rectangular fin arrangement is 2.47·10-5 m2. the pressure drop obtained for this model is 56.49 pa which is twice higher than the staggered arrangement. the friction and colburn jfactor is 1.778 and 0.016, respectively. due to the top and bottom arrangement there is strong flow disturbance which results in the increase of pressure drop. figure 2 shows the pressure and velocity contour for the single channel model with rectangular fins arranged on the top and the bottom solid regions. fig .2. pressure in pa and velocity in m/s contour for single channel model with rectangular fins arranged on the top and bottom solid regions the horseshoe vortex is formed at the beginning of the fins and it extends along the sides. recirculation is formed behind the fins in the wake region. the shear layer separates and form twin vortices where one vortex rotates in the clockwise direction and the other in the opposite direction, in figure 3, the recirculation can be seen clearly in the second and the fourth row of fins but not in the first and the third row. the y-plane is taken at a distance from threefourth of the top fin and from one-fourth of the bottom fin. hence more recirculation is found on the top fins. from the streamline along the z-plane recirculation can be found alternately along the top and the bottom fins. since the reynolds number is only 244 there is no secondary vortex formed. the recirculation region is located at 0.00108 m and the reattachment region of the shear layer is located at 0.00201 m. fig .3. velocity streamline for the single channel model with rectangular fins arranged on the top and bottom solid regions at y=0.0032 m and z=0.0053 m figure 4 shows the top and bottom arrangement of rectangular fins for pressure and velocity plots. the pressure decreases uniformly from inlet to p1 where the fins start. pressure is high at p1 and it starts decreasing and reaches minimum at p2. similarly the velocity increases as the fluid flow around the fins and becomes maximum at p2. recirculation zone is formed behind the top fin and adverse pressure gradient is formed. hence pressure increases at p3 and the velocity is minimum at p3. the bottom fin starts and the pressure is low at p4 where there is no obstacle and the velocity increases. the pressure decreases as the fluid travels to the rear of the fins. the process continues till the end of the fourth fin and the pressure and velocity becomes stable till it reaches the outlet. fig .4. pressure and velocity for single channel model with rectangular fins arranged on the top and bottom solid regions http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 102 resd © 2015 http://apc.aast.edu figure 5 shows the temperature and the local heat transfer coefficient for the rectangular fins. the temperature and the local heat transfer coefficient increases until it reaches p1. the local heat transfer coefficient decreases at p2, p3 which are placed away from the hot solid wall. the temperature becomes high at p4. the fins placed on the bottom solid are away from the heat source and hence the temperature and the local heat transfer coefficient at p5 and p6 are small. the heat flux is high at the upper solid wall and it decreases away from the hot wall. the temperature increases at p7 where the top fin start and again decreases at p8. away from the wall the temperature difference increases resulting in the decrease of the heat transfer coefficient. the process repeats till the end of the fins and the temperature and the local heat transfer coefficient increases till the fluid reaches the outlet. due to the increase in the heat transfer surface area, the obtained heat transfer rate is high compared to the uniform arrangement of rectangular fins. fig .5. temperature and local heat transfer coefficient of single channel model with rectangular fins arranged in the top and bottom solid regions 2. case 2 (single channel model with triangular fins) two rows with three triangular fins arranged in alternate manner along the top and bottom solid regions are studied. the heat transfer surface area of triangular fins is smaller than rectangular fins. the heat transfer surface area for the top and bottom fin arrangement is 2.342·10-5 m2. the pressure drop and the friction factor for this model are 34.04 pa and 1.073, respectively. the average nusselt number and the colburn j-factor is 3.099 and 0.016, respectively. the obtained heat transfer rate and the pressure drop is less than the rectangular fins. figure 6 shows the velocity streamline for the triangular fins along y and z-planes. the obtained streamlines are similar to the rectangular fins. recirculation zone is found in the wake region forming symmetrical twin vortices behind each fin. the recirculation region is located at 0.00123 m and the reattachment region is located at 0.00207 m. fig .6. velocity streamline for single channel model with triangular fins arranged on the top and bottom solid regions at y=0.0045 m and z=0.0059 m it can be seen that recirculation zone is formed behind the top and bottom fins alternately. since the reynolds number is low there is no formation of secondary vortex. though the bottom solid does not have any heat input the heat transfer rate of this model is more than the staggered triangular fin arrangement. the increase in heat transfer is due to the increase in heat transfer surface area. the pressure, velocity and local heat transfer coefficient plot for the triangular fins are similar to the rectangular fin model and hence not shown in this study. 3. case 3 (single channel model with inverted bolt type fins) the obtained heat transfer rate is higher than the triangular and rectangular fins. the heat transfer surface area is 2.438·10-5 m2 which is higher than all the fins. the only disadvantage of this fin type is the high pressure drop and the friction factor. due to the complex design and arrangement horseshoe vortices are formed which increases the pressure drop and the friction factor. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 103 resd © 2015 http://apc.aast.edu the obtained local heat transfer coefficient and the average nusselt number are 221 w/m2·k and 3.16, respectively. the pressure and velocity for the inverted bolt fin are similar to the rectangular and triangular fins. the velocity streamline plot for the inverted fin mounted on the top and the bottom solids is shown in figure 7. a strong horseshoe vortex is formed in front of the cylindrical fins and fluid flows around the cylinder to the rear side. the shear layers starts to separate and recirculation zone is formed in the rear side of the top fins for the top fins and in the rear side of the bottom fins for the bottom fins. the recirculation zone covers almost three-fourth of the space between the fins and the shear layers reattach to the wall after the wake region. again flow separation occurs and this results in periodic breaking of the boundary layer thus enhancing the heat transfer. the recirculation region is located at 0.00123 m and the reattachment region of the shear layer is located at 0.001978 m. fig .7. velocity streamline for the single channel model with inverted bolt fins arranged on the top and bottom solid regions at y=0.0036 m and z=0.0045 m figure 8 shows the velocity and local heat transfer coefficient. the velocity along the flow is uniform till it reaches the fins. the velocity is low at p1 and the pressure is high. the velocity increases at p2 as the fluid flow around the fins and it reaches a maximum at p3. the pressure is least at this point. recirculation takes place at the rear of the fins and the velocity is minimum at p4 and the pressure is maximum at p4. the fluid then flows through the bottom fins and the velocity is minimum at p5 and pressure is high at this point. the fluid velocity then reaches maximum at p6 and the pressure is minimum at p6. the process continues until it reaches the fourth row of the fins and it becomes stable after the end of the fins. the local heat transfer coefficient is high for the top fins which are in contact with the solid wall. the temperature and local heat transfer coefficient is low at p2, p3, p5, etc. which are away from the hot solid surface. after the fourth tow of the fin the temperature increases without much fluctuation till reaches the outlet. fig .8. velocity and local heat transfer coefficient for the single channel model with inverted bolt fins arranged on the top and bottom solid regions 4. case 4 (single channel model with ripsaw fin thickness of 0.00005 m) the last model studied in this research is the ripsaw fin thickness of 0.00005 m arranged on the top and bottom solid regions. the heat transfer surface area is 2.371·10-5 m2. this type of arrangement has no recirculation due to their shape. as a result of this the obtained pressure drop and the friction factor is also less. the obtained friction factor and the pressure drop is 0.589 and 18.73 pa, respectively. the obtained average heat transfer coefficient and the average nusselt number is 211.43 w/m2·k and 3.023, respectively. the streamline velocity plot shows that there is no recirculation the streamlines are parallel to the flow direction. the obtained velocity and local heat transfer coefficient is similar to the other fins explained above. figure 9 shows the velocity streamline along the y and z-planes. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 104 resd © 2015 http://apc.aast.edu fig .9. velocity streamline for single channel model with ripsaw fin of thickness 0.00005 m arranged on the top and bottom solid regions at y=0.0032 m and y=0.0046 m the pressure, temperature and local heat transfer coefficient plots are similar to the other fin types. the velocity is low and the pressure is high at the stagnation point and in the recirculation region. the temperature and the local heat transfer coefficient are high at places near the top solid wall and low at regions away from the hot solid wall. from the results it is found that there is not significant increase in heat transfer for the top and bottom fin arrangement. the reason is because the bottom solid has no heat input and the heat is transferred only from the top solid. in the top and bottom arrangement there are only 6 fins placed in the hot solid wall and 6 placed in the cold solid wall. hence the obtained heat transfer is less than the regular staggered arrangement of the fins. in real case, the channel arrangement is periodic and the hot helium fluid flows below the cold solid wall and heat transfer will be increased by having fins on both the solid walls. however in the current study the hot flow channel is present only above the reacting channel and hence the heat transfer obtained is less. the obtained average nusselt number and the colburn j factor is similar to the uniform fin arrangement. the friction factor is increased and the ripsaw fin with thickness of 0.00005 m is found to have the lowest friction factor. the effectiveness of the heat exchanger increases for the top and bottom arrangement. the pressure drop increases due to the presence of fins on both the top and bottom solids. in this arrangement recirculation and vortices are formed which increases the pressure drop and friction factor. the pressure drop is the highest for rectangular fins and least for the ripsaw fins. hence ripsaw fin with thickness of 0.00005 m is considered to be the best design because it gives good heat transfer with minimum pressure drop. the obtained effectiveness is around 52 to 54% for all the fin designs. the heat transfer surface area is less and hence the effectiveness of the heat exchanger is less. the length of the heat exchanger channel with staggered rectangular, triangular and ripsaw fin with thickness of 0.00005 m is increased from 0.0064648 m to 0.064648 m. the heat transfer area of the long staggered rectangular fins is 2.44·10-4 m2, triangular fins is 2.35·10-4 m2 and the ripsaws with thickness of 0.00005 m is 2.4354·10-4 m2. the obtained heat exchanger effectiveness for rectangular fin is 80.15%, triangular fin is 87.25% and ripsaw fins with thickness of 0.00005 m is 92.13%. v. conclusion the obtained average nusselt number is higher for inverted bolt fins which is 3.201 followed by triangular fins which is 3.099. the obtained pressure drop for the rectangular fins is higher compared to the triangular fins for similar heat transfer rate. for similar heat transfer rate the obtained pressure drop which is 18.73 pa is less for the ripsaw fins compared to the other fins. hence ripsaw fin with thickness of 0.00005 m is considered to be the best design with less pressure drop and reasonable heat transfer rate. the inverted bolt fins have the highest average nusselt number followed by the triangular fins. but the pressure drop for the rectangular fin which is 56.49 pa is almost twice that of the triangular fin which is 34.08 pa. eventhough the obtained average nusselt number for the ripsaw fin with 0.00005 m thickness which is (nu) ̅ = 3.026 is less compared to the other fins, the obtained pressure drop for the ripsaw fins is the least of all the four fins which is 18.73 pa. hence the ripsaw fin thickness of 0.00005 m is selected as the best design with good heat transfer rate of 0.475 w and minimum pressure drop of 18.73 pa. the effectiveness increased from 52% for 0.0064648 m to 82% for 0.064648 m. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 105 resd © 2015 http://apc.aast.edu references [1] hesselgreaves, j. e. (2001). compact heat exchangers selection, design and operation. oxford, uk: elsevier science ltd. [2] kayansayan, n. (1994). heat transfer characterization in plate-fin tube heat exchangers. international journal of refrigeration, 17, pp. 49-57. [3] ranganayakulu, c. & seetharamu. k.n. (1999). the combined effects of wall longitudinal heat conduction, inlet fluid flow non-uniformity and temperature non-uniformity in compact tubefin heat exchangers: a finite element method. international journal of heat and mass transfer, 42, pp. 263-73. [4] wen, j. & liu. (2004). study of flow distribution and its improvement on the header of plate-fin heat exchanger. cryogenics, 44(11), pp. 823831. [5] manglik, r. m. &. bergles, a. e. (1995). heat transfer and pressure drop correlations for the rectangular offset strip fin compact heat exchanger. experimental thermal and fluid science, 10, pp. 171-80. [6] bhowmik. h., &. lee.k. (2008). analysis of heat transfer and pressure drop characteristics in an offset strip fin heat exchanger. international communications in heat and mass transfer, 36(3), pp. 259-263. [7] ma, t., wang, q. w., zeng, m., chen, y., liu, y., & nagarajan, v. (2012). study on heat transfer and pressure drop performances of ribbed channel in the high temperature heat exchanger. applied energy, 99, pp. 393-401. [8] schulte-fischedick, j., dreibigacker, v., & tamme, r. (2007). an innovative ceramic high temperature plate-fin heat exchanger for efcc processes. applied thermal engineering, 27(8-9), pp. 1285-94. [9] monteiro, d. &. b., & batista, de mello, p.e. (2012). thermal performance and pressure drop in a ceramic heat exchanger evaluated using cfd simulations. energy, 45, pp. 489496. [10] ponyavin, v., chen, y., mohamed, t., trabia, m.b., hechanova, a.e., & wilson, m. (2012). design of a compact ceramic hightemperature heat exchanger and chemical decomposer for hydrogen production. heat transfer engineering, 33(10), pp. 853-70. [11] nagarajan, v., chen, y., wang, q., & ma, t. (2014). hydraulic and thermal performances of a novel configuration of high temperature ceramic plate-fin heat exchanger. applied energy, 113, pp. 589-602. [12] solidworks 2013., solidworks corp. [13] [ansys inc. (2011). ansys 14.5 user's guide. [14] patankar, s. (1980). numerical heat transfer and fluid flow. new york. [15] manson, s. v. (1950). correlations of heat transfer data and friction data for interrupted plate fins staggered in successive rows. washington dc: national advisory committee for aeronautics. [16] wieting, a. r. (1975). empirical correlations for heat transfer and flow friction characteristics of rectangular offset-fin-plate-fin heat exchanger. asme, int j. heat transfer, 97, pp. 480-490. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 72 resd © 2015 http://apc.aast.edu modelling of diesel generator sets that assist offgrid renewable energy microgrids j. salazar, f. tadeo, prada, c. dept. of system engineering and automatic control, dr. mergelina s/n, university of valladolid, 47005 valladolid, spain. abstract this paper focuses on modelling diesel generators for off-grid installations based on renewable energies. variations in environmental variables (for example, solar radiation and wind speed) make it necessary to include these auxiliary systems in off-grid renewable energy installations, in order to ensure minimal services when the produced renewable energy is not sufficient to fulfill the demand. this paper concentrates on modelling the dynamical behaviour of the diesel generator, in order to use the models and simulations for developing and testing advanced controllers for the overall off-grid system. a diesel generator is assumed to consist of a diesel motor connected to a synchronous generator through an electromagnetic clutch, with a flywheel to damp variations. each of the components is modelled using physical models, with the corresponding control systems also modelled: these control systems include the speed and the voltage regulation (in cascade regulation). keywords microgrids, off-grid, speed and voltage control, diesel generators, variable dead time, governors. i. introduction remote areas are not frequently connected to a reliable grid supply, so their usual method of electricity generation is the use of diesel generator sets in off-grid configurations. unfortunately, logistics, safety and environmental concerns impulse the use of electrical energy locally generated using renewable sources, mainly based on the conversion of solar and wind energy, as they are clean, silent and reliable, with low operation costs and small environmental impact. sunlight and the kinetic energy of the wind are free, inexhaustible, and involve only a small amount of residues or greenhouse gases emissions. despite these advantages, however, electric power production systems that use as primary sources exclusively solar and wind energy pose technical problems due to uncontrollable wind speed and radiation fluctuations [1,2,3]. as a consequence, the power supply continuity of an off-grid system should be backed-up by other reliable and non-fluctuant sources of primary energy, generally diesel generator sets. such systems, designed for the decentralized production of electric power using combined sources of primary energy, are called hybrid systems [4, 5]. a typical configuration is shown in figure 1, based on an off-grid system designed as part of the open gain project and installed in borj cedria (tunisia): see [6] for more details. the three-phase power supply system comprises photovoltaic panels, maybe a wind turbine, a battery bank for voltage regulation, and a small diesel generator. a central role in the operation of the system is provided by the control power electronics. the solar inverter changes the direct current electricity (dc) from a photovoltaic array into alternating current (ac), which is injected into the main ac bus of the system. the wind inverter converts the variable frequency voltage from wind generators into grid conforming ac voltage. the bidirectional battery inverter functions as inverter or rectifier charger mode. in the inverter mode, it converts direct current (dc) from the battery bank into alternating current (ac) which is injected into the main ac bus of the system. in rectifier charger mode, if the total power generated by the pv generator and the wind turbine exceeds the load needs, it will be used to charge the battery bank. in this system, there are two main operation modes [7]. the first is the island mode, in which the battery inverter defines the operating grid frequency and voltage (the diesel generator might be switched off). in the second operation mode, the diesel generator is the one that defines the frequency and voltage, so the battery inverter acts as a “grid parallel” unit, by synchronizing its output voltage to http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 73 resd © 2015 http://apc.aast.edu the grid voltage. in both cases, wind and solar inverters operate as “grid parallel” units, without any participation in the voltage or frequency regulation. fig .1. off-grid hybrid energy generation frequently carried out in these micro grids by small modifications of the grid frequency (for example, by the droop algorithm in [8, 9]). solar and wind inverters limit their output power based on this grid frequency. in island mode, this is automatically carried out by the battery inverter [10]. in genset mode, only specific diesel generators use the frequency for communications; standard diesel generators supply the voltage and frequency specified in the rating plate, without using a droop factor to operate in parallel with another energy source. thus, when standard generator sets are connected, the frequency is 50hz, so solar and wind inverter produce always the maximum available power. when the batteries are fully charged, the battery inverter temporarily increases significantly the grid frequency, to disconnect solar and wind sources from the local grid [11]. this paper focuses on modelling and simulation of the response of the diesel generator for start-up and load disturbances. models of other components of microgrids have been presented elsewhere (see [12] and references therein). the modelling concentrates on reproducing the dynamic response (especially at start-up). thus, the models are selected to be precise enough in the time scale of tens of seconds (given by the time dynamics of the loads), but quick enough so that the operation during many months can be evaluated in reasonable time using standard computers. the diesel generator is then assumed to consist of three main components: the diesel engine, the synchronous generator and the excitation system (see figure 2). thus, models of the diesel engine, the diesel engine governor, the synchronous generator, its excitation system, and the automatic voltage regulation (avr) module are now presented. synchronous generator fde diesel engine system sgt r tv excitation system fig .2. the overall block diagram of diesel generator ii. a model of diesel engine system although detailed models are available to simulate the complete dynamics of a diesel engine, that include thermodynamic aspects, as the focus here is in electricity production as auxiliary system, it is sufficient to use a much lower order model, so thermodynamic variables may be considered to be constant, but unknown. this approach has been adopted in other internal-combustion engine simulation studies, such as in [13]. the general structure of the diesel engine model is then shown in figure 3. it can be seen that it is assumed to consist of four main sub-models: the controller, the actuator, the engine and the flywheel. the model of each component is now briefly described. mechti k3 2 2 1 s k  s ek 11  hs2 1speed controller current driver actuator engine sgt  r  flywheel u d k ref r  fig .3. block diagram of a typical diesel engine system http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 74 resd © 2015 http://apc.aast.edu a. a controller model a “controller” consists of a standard pid speed controller (presented in detail in section 5), followed by a “current driver” module, represented by a scalar value k3, which depends on the operating point of the system, transforming the control signal into a current sent to the actuator. b. an actuator model the “actuator” block represents the governor (actuator) system of the diesel engine. a governor can be defined as a mechanical or electromechanical device for controlling the speed of an engine automatically by relating the intake of fuel. the input driving current () controls the fuel rack position, which in turn determines the amount of fuel () to be injected into the combustion chamber. the actuator is usually represented by a first order phase lag function, which is characterized by a gain  and a variable time constant (). here,  is the actuator constant, that is considered to be fixed,  is the actuator time constant, which is a complicated function of the temperature of the fuel. for simplicity, the variation of the parameters is ignored and  is assumed to be constant. c. a diesel engine model the “engine” block comprises the combustion system of the diesel engine. the injected fuel is ignited by the compressed hot air in the combustion chamber, causing the movement of the piston during the power strokes. this action drives the crankshaft, so the mechanical torque tmech is produced. for modelling, this engine combustion system is represented as an engine torque constant with a dead time element , which is the result of having several cylinders. for each individual cylinder, this has essentially two components. the “ignition delay” represents the time taken by the fuel-air mixture to reach combustion point at the particular operating temperature and pressure; it can be shown to have a hyperbolic variation with speed deviation. the “power stroke delay” represents the time that elapses from a load disturbance to the time at which a particular engine cylinder responds to the disturbance. this delay is random and depends on the crank angle value at which a load disturbance is imposed. its effect can be reduced by increasing the number of cylinders. since for a particular load disturbance, the time after which the cylinders responds goes down inversely with speed, it may be approximated by an inverse function of speed. the engine dead time () is a function of the speed deviation  (pu) through a nonlinear function. an adequate non-linear function to represent the dead time variation is (see figure 4): 2 2 r c r b r a 1      , (1) where a, b and c are parameters that are determined by curve fitting techniques to reproduce empirically determined curves, such as those in [14]. fig .4. typical variation of dead time with engine speed d. a flywheel model the “flywheel” block comprises the rotating system, so it comprises the dynamics of the engine inertia, the flywheel, the damping factor (kd) and the loaded alternator. the mechanical motion of equation is then: r ω d k sg t mech t dt r ωd h   2 (2) r dt d   0  (3) 1 rr  (4) where time t is in seconds, rotor angle  is in radians, rated generator speed 0 is in rad/s, r is the speed deviation (pu), r is the angular velocity of the rotor (pu),tsg is the generator torque (pu), h is the per unit inertia constant (s). 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 speed (pu) d e a d t im e ( s ) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 75 resd © 2015 http://apc.aast.edu iii. a synchronous generator model the equations of synchronous generator are obtained from park transformation, after a per unit representation and some simplifications. the most important simplification is that stator transients are neglected because it is much faster compared to the rotor ones. considering a salient pole synchronous generator, rotor consists of three windings. a field and a damping winding are considered on the direct axis in order to take into account the transient and subtransient behavior respectively in this axis. meanwhile, a damping winding is considering on the quadrature axis. the terminal voltage phasor is determined by, vt=vd + jvq, that can be evaluated from: qq ixd i s r d e d v  (5) dd ix q i s r q e q v  (6) where rs is the armature resistance, iq and id are the currents flowing in the stator winding, the x”d,q are the so-called subtransient d and q-axis reactances and e”d,q are given by [15]. qi s qo q x q x d e           1 (7)   dq i s do d x d x e s do q e       11 1 (8) where xd,q and x’d,q are the synchronous and transient reactances, the ’’d,qo are the open circuit subtransient time constants and e’q is given by qfd e s do d x d x d x d x d x d x d x d x e s do d x d x d x d xq e                                     1 (9) where efd is the exciter field voltage and ’do is the open circuit transient time constant. as it can be seen in figure 2, there is an additional feedback term from the generator to the diesel engine given by the electromagnetic torque that in flywheel mode can be evaluated from: q i d i q x d x q i q e d i d e sg t        (7) iv. an excitation system model the main function of an excitation system is to supply and automatically adjust the field current of the synchronous generator considering control and protective functions essential to the satisfactory performance of the system. the control functions include the control of voltage and the enhancement of system stability. the protective functions ensure that the capability limits of the synchronous machine, excitation system, and other equipment are not exceeded. the functional block diagram of a typical excitation control system is shown in figure 5. tv ~ selfexcited dc exciter synchronous generator voltage controller rv fde cv rv fv excitation system stabilizing ciruits f f st sk 1   t i c jx c r t v ~~  load compensator ti ~ rst1 1 c1v voltage transducer a a st k 1 maxrv minrv amplifiers fig .5. functional block diagram of a synchronous generator excitation control system [16]  excitation system stabilizing circuits: excitation systems comprised of elements with significant time delays have poor dynamic performance. hence, excitation system stabilizing circuits is used to improve the dynamic performance of the control excitation control system. a derivative feedback is the most commonly used form of compensation. the aim of the compensation is to minimize the phase shift introduced by the time delays over a selected frequency range.  load compensation: the compensator has adjustable resistance (rc) and inductive reactance (xc) that simulate the impedance http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 76 resd © 2015 http://apc.aast.edu between the generator terminals and the point at which the voltage is being effectively controlled. using this impedance and the measured armature current, a voltage drop is computed and added to or subtracted from the terminal voltage. the magnitude of the resulting compensated voltage (vc1), which is fed to the avr, is given by:   t i c jx c r t v c1 v ~~  (11) this is used to ensure proper sharing of reactive power between generators placed together at their terminals, sharing a common step-up transformer. the compensator functions as a reactive current compensator by creating an artificial coupling between the generators. without this provision, one of the generators would try to control the terminal voltage slightly higher than the other; hence, one generator would tend to supply all of the required reactive power while the other would absorb reactive power to the extent allowed. when load compensator is not used, rc and xc are set to zero.  voltage transducer: the time constant tr represents rectification and filtering of the synchronous machine terminal voltage. the voltage transducer output (vc) forms the principal control signal to the excitation system. if a load compensator is not used and vc is negligible, vc =vt.  amplifiers: amplifiers may be magnetic, rotating, or electronic type. magnetic and electronic amplifiers are characterized by a gain and may also include a time constant. a. a self-excited dc exciter the excitation systems of this category utilize dc generators as source of excitation power and provide current to the rotor of the synchronous machine through slip rings. the self-excited dc exciter is represented in block diagram form as shown in figure 6. all variables are in per unit.   dt de teesekv fd efdfdefder  (12) there are several mathematical expressions that may be used to approximate the effect of exciter saturation. a commonly used expression is the exponential function   fdex eb exfdfde eaees  (13) e st 1 e k   fdefd ese r v fde fig .6. block diagram of a selfexcited dc exciter v. a speed controller the speed controller is designed to keep constant the internal combustion engine speed by changing the quantity of fuel consumed by the motor. the direct result of this speed controller is a stable frequency for the voltage at the generator terminals. a constant frequency requires good precision and a short response time from the speed controller. detailed models of diesel engines are characterized by nonlinear, time-varying parameters including a nonlinear input dead-time variation that introduces an unknown delay () between the injection of fuel and the production of engine torque. the presence of this dead time together with some other system parameters gives rise to a serious control problem and significantly degrades the performance especially under varying loads. the dead time is an unknown time delay and is commonly considered as a complicated function of operating conditions and the engine speed [17,18]. conventional pid controllers are widely employed in diesel engine speed control, which gives acceptable performance. however, pid schemes might not be able to handle large variations in the engine dead time. here, several advanced control techniques for the speed control of the diesel engine systems have http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 77 resd © 2015 http://apc.aast.edu been reported in the literature, based on the methods of h∞ [19], adaptive control [20] and neural network [21]. vi. an automatic voltage regulator (avg) the automatic voltage regulator (avg) controls the exciter field to provide a constant terminal voltage. in the past, the generator response using an analog excitation system was a matter of adjusting potentiometers or adding or deleting capacitors and resistors in the control loops of the voltage regulator stability circuit. adjustment could be very time consuming because changes would often involve turning the excitation system on and off many times in order to make modifications. today, the digital excitation system provides the means to easily access the challenging parameters of the analog system. the most important point of digital controllers is the embedded microprocessors that perform various control functions for the excitation system. these control functions include the automatic voltage regulator, field current regulator, var/power factor control, and a host of excitation limiters to regulate and maintain the generator within safe operating limit of the machine [22]. conventional pid controllers are employed in digital avg. vii. a simulation example to show the typical responses of diesel generators, data from the open-gain prototype (see figure 7) have been used. this prototype included a diesel generator of 17/20kva continuous/emergency power (pramac gbw 22y), shown in figure 8. for this installation the parameters are given in tables 1 to 3. the main issue for off-grid renewable energy installations is the connection/disconnection transient, so some simulation results are presented for this situation in figures 8 to 10: the engine is assumed to be running at 80% of the nominal speed before connection to the grid, at t=0s. the responses presented in fig. 8 to 10 correspond to a worst case condition (cold oil), that gave an actuator time constant of 0.198 s and a droop of 5% (for comparison the hot oil time constant is 0.072 s. it can be seen that the simulations reproduce accurately the expected results. voltage is regulated to the desired output voltage in around 4 seconds, without significant oscillations in torques and speeds. the model was then integrated into the micro-grid library (see figure 11), developed in the ecosimpro© language (selected as it simplifies developing multidomain simulations thanks to the object oriented and non-causal approach). results using simulations of the complete installation are presented in [12]. diesel generator [20kva] photovoltaic modules [185 wp] safety subsystem wind subsystem backup subsystem renewable power supply system battery bank [30.24kwh] battery inverter wind inverter resistance protection box wind turbine [15kw] solar inverter solar subsystem rejected brine freshwater membranes reverse osmosis (ro) plant fig .7. renewable energy system proposed in the european project open gain fig .8. diesel generator pramac gbw 22 a complete set of parameter values and ranges is given in table 1 and table 2. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 78 resd © 2015 http://apc.aast.edu table 1. system parameters of a typical diesel engine [19] parameter value unit definition k1 1.15 pu engine torque constant k2 1 pu actuator torque k3 1 pu current driver torque 2 0.125 s actuator time constant a,c -0.085 ---- parameters for delay variation b 0.08 ----parameter for delay variation h 1 s inertia constant kd 0.1 pu damping factor table 2. system parameters of a synchronous generator model e1s13m f/4 provided by linz electric. parameter value unit definition dx 1.57 pu synchronous d-axis reactances dx  0.21 pu transient d-axis reactances dx  0.076 pu subtransient d-axis reactances qx 1.35 pu synchronous q-axis reactances 0dt 0.4 s transient d-axis open circuit time constant dt 0.053 s transient d-axis short circuit time constant 0dt  0.0064 s subtransient d-axis open circuit time constant g enj 0.083 kgm 2 moment of inertia of generator table 3. data for self-excited dc exciter parameter value definition a k 187 gain amplifiers a t 0.89 time constant amplifiers e t 1.15 time constant exciter e x a 0.014 parameter for exciter saturation function e x b 1.55 parameter for exciter saturation function f k 0.058 gain for stabilizing circuits f t 0.62 time constant for stabilizing circuits b t 0.06 voltage regulator c t 0.173 voltage regulator r t 0.05 time constant for voltage transducer r m a x v 1.7 amplifier limitation r m in v -1.7 amplifier limitation fig .9. terminal voltage response [v] fig .10. engine speed response [rad/s] fig .11. electromagnetic torque response [nm] fig .12. integration of the models into the ecosimpro microgrids library [12] http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 79 resd © 2015 http://apc.aast.edu viii. conclusion the paper discusses the modeling of diesel generators in order to integrate them in the simulation of off-grid renewable energy systems. as the objective is to develop models to test energy management systems and high-level control systems (such as those discussed in [23] and references therein), a model is developed as simple as possible, but with the precision required by this application. for this transfer-function based models have been developed with static nonlinear terms that take into account the possible variations in gains due to changes in the operating conditions. the final model consists of sub-models of the controllers, the diesel engine, the synchronous generator and the excitation system. it is expected to be capable of simulating a number of different events. some simple 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[12] salazar, j., tadeo, f., & de prada, c. (2014, august). a micro-grid library in a general simulation language. in ifac world congress, cape town, south africa (vol. 19, no. 1, pp. 3599-3604). [13] morris, r. l., hopkins, h. g. and borcherts, r. h. an identification approach to throttle torque modelling, soc. of automotive engrs., paper # 810448. [14] mina, t. i. a detailed study of the start and machinery, mcgraw hill. [15] krause, p. c. (1987) analysis of electric machinery, mcgraw hill. [16] kundur, p. power system stability and control, mcgraw-hill, inc. [17] haddad, s. and watson, n. (1984) principles and performance in diesel engineering, chichester [west sussex] : ellis horwood,. [18] choe ,y. w. and jung, b. g. (1994) an h∞ controller design for the speed control of large size and low speed diesel engine. proceedings of the sice annual conference, pp. 747-752. [19] kuang, b., wang, y,and tan, y. l. (2000) an http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 80 resd © 2015 http://apc.aast.edu h∞ controller design for diesel engine system. [20] roy,s., malik, o. p. and hope, g. s. (1991) a low order computer model for adaptive speed control of diesel driven power-plants, ieee transactions on energy conversion, pp. 16361642. [21] yacoub,y. (1999) mean value modeling and control of a diesel engine using neural networks, ph.d. dissertation, west virginia university. [22] richard, s. and kim, k. (march-april 2001) excitation control of the synchronous generator, ieee industry applications magazine, vol 7, no2, pp. 37-43. [23] salazar, j., tadeo, f., and valverde, l. (2013, november). predictive control of a renewable energy microgrid with operational cost optimization. in 39th annual conference of the ieee industrial electronics society, iecon 2013 (pp. 7950-7955). http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.001 1 http://apc.aast.edu i. introduction with the industrial revolution and the increase in energy consumption, concerns about the environment and global warming have been raised (mahmood, jaafar, and mustafa 2022). recent worldwide efforts to improve energy security and reduce climate change have necessitated a fundamental shift in the way solar energy is handled [2]. since photovoltaic (pv) phenomena were studied and solar cells were being made, countries have been using and relying on solar panels and modules for their electrical energy needs. the two prominent problems of pv are concerned with the environmental issues and energy that restricts the continuous development of economy and society. installation of the solar panel depends on sseveral uncontrollable factors, and dust deposition on the surface of the pv is an important reason to decrease the power. dust accumulation on the pv can scatter, reflect, and absorb the light, that will seriously drop the transmission of light and reduce the power (fan et al. 2021). furthermore, the variety of environmental factors decreased the efficiency of the pv by more than 30% (memiche et al. 2020). the chemical decomposition, density, and size of dust particles are the reason behind decreasing the power (mostefaoui et al. 2018) (said et al. 2018). the design of dust cleaning on the surface of solar cells is highly recommended to increase the pv output power (parrott et al. 2018). dust accumulation of (10 g/ m2) decreases the performance of the pv by 34% (chen et al. 2019), based on salimi et al. (2020). the adhesion of dust particles is proportionally related to the reduction of the output power of pv (kawamoto and guo 2018). there are growing appeals for cleaning steps that are more useful to raise the performance of a dusty panel (lorenz et al. 2019). also, the industrial activities lead to deposit of different kinds of dust particles on the pv, which drops the electrical efficiency from 29% to 64% based on the types of deposited dust (andrea, pogrebnaya, and kichonge 2019). the deposition of dust on the pv’s surface will increase directly with the density and the size of particles, but it changes inversely with the diaphaneity of the particles (xingcai and kun 2018). recently, theoretical developments have revealed that dust accumulation drops the pv’s power by 29, 31, and 50% (benghanem et al. 2018; mostefaoui et al. 2018; mussard and amara 2018). jaszczur (2018) stated that efficiency is reduced by 2.1% when 300mg of dust particles are deposited on each square meter. pv power is reduced directly with particles’ densities; meanwhile, it has been changed based on the tilt angle of the pv. the tilt angle of 0o to 45o reduces performance by 37.6% to 10.9%, respectively (hachicha, al-sawafta, and said 2019). a suggested way to weaken the adhesion of dust on the glass surface of the pv is to use hydrophobic coating when, for tilt angles of 30o and 60o, the power reduction is 44.4% and 11.2%, respectively (zhang et al. 2019). during dust storms, for angles of 00 to 450 tilt angle, the power efficiency of pv drops from 58.2% to 20.7% (khodakaramtafti and yaghoubi 2020) (hachicha et al. 2019). the dirty solar panel has power production of 10% lower than the clean one. the different dust samples have been tested and it was revealed that they have reduced the performance non-uniform dust distribution effect on photovoltaic panel performance saman s. jaafar1a, hiwa a. maarof1b, renas t. salh 1c, hoshang sahib1d, yousif h. azeez1e 1 physics department, college of science, university of halabja, halabja, krg-iraq asaman.jaafar@uoh.edu.iq, bhiwa.maroof@uoh.edu.iq, c renas.salh@uoh.edu.iq, dhoshang.sahib@uoh.edu.iq eyousif.husain@uoh.ed.iq abstract a novel experimental method for power efficienc y loss is presented in this paper. it is used to quant itat ively determine the impact of dust deposit ion on the pv power generat ion panel. to determine the select ion range of unknow n parameters in the experiment process, a photovoltaic panel with five collected dust samples (toner (c), soil, cement (cao, sio4), gypsum (ca2so4.2h2o), and sand (al2o3, sio4)) is designed. according to experimental results, the ex t inct ion coefficient for the five pollutants are recorded. event ually, the impact of dusts on the results is proved by repeat ing in t wo cont inuous days of same condit ions. the results show that the proposed process has a high effect on the reduct ion of output power (62% to 96%), decrease of irradiance (34% to 93%) and increase of output power due to increase of t ilt angle as a doubling of power except toner. the experimental and calculated results are in ag reement. the results show that non-uniform distribut ion of dust deposit pollutants on the photovoltaic panel significantly reduces the power output. index-words: dust deposit ion, dust accumulat ion, power reduct ion, solar pv performance, ex t inct ion coefficient. received on, 09 january 2023 accepted on, 06 february 2023 published on, 16 february 2023 journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.001 2 http://apc.aast.edu of the pv from 5% to 30% (chaichan and kazem 2020). the main adhesion forces between the dust particles and the pv surface are studied such as: capillary, van der waal, electrostatic and gravitational forces (isaifan et al. 2019). wang et al. (2018) showed that the coated pv with fluorine super-hydrophobic film has less effect than the silicon super-hydrophobic film. the rainy weather can be mentioned as an excellent natural cleaner of dust on the pv (panels 2020) (al-housani and bicer 2019). a common strategy used to study the influence of dust deposition on the solar panel surface is to take a period of sandstorm going to deposit more thickness of dust particles and it leads to reducing the transmission of light (mostefaoui et al. 2018). for decades, one of the most popular ideas for maintaining the highest performance in pv is the idea that the accumulated dust must be removed from its surface. the most detailed review of research has been done from 2012-2015, which shows the effects of dust accumulation on the pv in detail during the study of costa, diniz, and kazmerski (2018). in saudi arabia, to remove the pv from deposited dust, they used jet water with low pressure, and the performance of the solar cell farm increased by 27% (systems 2019). while the weak dust of density 0.644 g/m2 reduced the performance of the pv by 7.4% (chen et al. 2020). various research on dust accumulation show results on how the different types of deposited dust particles will cause the decrease of the efficiency of the solar cells (aljuhani et al. 2021; alnasser et al. 2020; chanchangi et al. 2020a, 2020b; dhaouadi et al. 2021; dida et al. 2020; drame et al. 2021; fan et al. 2021; ilse et al. 2023; javed et al. 2021; kazem et al. 2020; laarabi et al. 2021; liu et al. 2021; mustafa et al. 2020; ullah et al. 2020; zhang 2020). the rising temperature due to the high amount of solar radiation intensity caused a decrease in the pv cell’s efficiency (kazem and chaichan 2019). the layering of the dust particles is mostly related to the temperature of the pv (jaszczur 2019). the pv of higher surface temperatures has lower accumulated dust (gupta et al. 2019). the dust deposition on the pv’s surface caused an increase in its surface temperature based on the study of chaichan and kazem (2020). cleaning the different panels is shown by the temperaturecorrection performance ratio (guo et al. 2019). on the other hand, the cleaning process enhances the efficiency by 32.7% in a 1mwp pv farm (hammoud et al. 2019). based on the studies, the pv dust accumulation caused the thermal property settlement neither the electrical nor the optical (gupta et al. 2019). finally, concentrating on complexity of dust distribution density and reduction power of pv panels, the researchers designed an experimental set up and measured the (i-v) and (p-v) data to evaluate the degree of dust accumulation on pv that exists in the environment. firstly, the different types of dust samples are collected and each one is distributed on pv surface, the regular power production of pv panels is analysed, the basic equations form of dust density and power reduction rate is given, and dust density with irradiance is appointed. basically, the analysis of the obtained behaviour of each of the five sample pollutants, containing distribution, concentration, composition, and the effect of dust particles on light transmission under different mass density and tilt angle is carried out. to ensure the reliability of the experimental results, some principle equations are used to to show the wrong analysis method for dust concentration. the five-dust samples and their chemical decomposition are toner (c) (parthasarathy 2021), cement (cao, sio 4 ) (oliveira and moreira 1989), sand (al 2 o 3 , sio 4 ) (ibbeken and schleyer 1991), soil, and gypsum (ca 2 so 4 .2h 2 o 2 ) (bolukbasi, kurt, and palacio 2016). the basic contributions can be explored as follows: • different curve behaviour of dust particles and the reduction of power production at the same irradiance for obtaining the effect quantity of dust deposition are plotted. • to guarantee the experimental process results, different scenarios are applied like irradiance reduction with respect to the dust distributed density, and influencing the coefficient of tilt angle for each of the five collected dust samples. • the experimental and calculated results are in agreement. table i: nomenclature symbols meaning pv c cao, sio 4 al 2 o 3 , sio 4 ca 2 so 4 r sh rs i d φ i φ2 i φ3 k si ge t σ ext σ scat σ abs b ext b scat b abs 𝜌 φ 1 φ 2 φ 3 m i a η ir p max(dust yglass) p max(clearglass) x w i v photovoltaic carbon (chemical decomposition of printer toner) (chemical decomposition of cement) (chemical decomposition of sand) (chemical decomposition of gypsum) shunt resistance of solar cell series resistance of solar cell diode current irradiance light intensity current of clean pv light intensity current of dusty pv boltzmann’s constant chemical abbreviation symbol of silicon atom chemical abbreviation symbol of germanium atom temperature extinction cross-sections coefficient scattering cross-sections coefficient absorption cross-sections coefficient extinction coefficient scattering coefficient absorption coefficient mass density (g/cm2) irradiance intensity of sun irradiance intensity value after passing through plane glass irradiance intensity value after passing through plane glass and dusty glass mass of sample dust current area (m2) efficiency of pv infrared radiation maximum power of dusty glass maximum power of clear glass distance power unit (watt) current voltage journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.001 3 http://apc.aast.edu ii. methodology a. position of the problem as a basic reason that influences the output voltage (v) and output current (i) of pv, dust deposit on the solar panel can reduce the output power (i.v). the pv panel of internal circuit like figure 1 is shown and the main parameters of v and i which affect the solar cell’s actual power are described. fig.1. solar cell internal circuit where i _ φ 3 ), i φ2 are light current, i 0 = saturate current of diode, r s is series resistor, k boltzmann constant, t is temperature, n is constant (kazem et al. 2022). the influence of dust accumulation on reducing pv output power can affect the efficiency (η) and it can be described as: where p max is output power of pv cell that is usually determined by measuring the output voltage v and output current i. p in is input power of light to the pv which is (irradiance × area of pv) (ali et al. 2021). b. study area continuously, the experimental process is done in the halabja city-kurdistan region of iraq, as shown on 1st and 2nd october 2022. this city has an altitude angle and the azimuth angles are 35o and 5o (jaafar and maarof 2022). fig.2. location of halabja city on map (a) iraq map (b) halabja and sulaymaniyah provinces (halabja city (zakaria et al. 2013) naturally, this location and in general most of the iraqi provinces are under influence of dusty air in some months of year because of the existence of desert land in iraq and other neighbouring countries. more than this, due to industrial actives, the same types of the collected dust pollutant exist in the environment air. for that reason, these kinds of the pollutants are collected and experimentally analysed to determine their effect on decreasing the pv performance. now, to have more accurate analysis data on dust accumulation on surface of pv, the calculation of the output power is usually done for the case of dusty surface (p dusty ) and clean surface (p clean ). after that the researchers defined the power reduction rate, which is used to present the best achieved efficiency (ullah et al. 2020). thus where b ext is the extinction factor due to the dust particles, the p dusty is the output power of dusty panel and p clean is output power of clean pv panel. for having more detail and raising the level of accuracy the b ext can be calculated as dependent on and represent as: remark: for increasing the level of accuracy and test the next pollutants the previous one was totally removed from the surface of the pv. when the extinction coefficient of used plane glass b ext 0.028, it can be easy to measure the reduced irradiance for each dust samples with different mass density. the extinction coefficient can be determined from both scattered and absorption coefficient as (redmond,dial,and thompson 2010): where b scat , b abs is scattered and absorption coefficient, respectively. due to absorption ) coefficient of dust particle the intensity of light reduced, then lambert’s law stated as: where is the intensity reduced due to (dusty pv), initial intensity of light after pass through clean pv and x is the interaction distance between the light and the dust particles. c. experimental setup after establishing the basic theory of experimental process, five prepared dust particles on pv panels in different amount of masses are investigated. mainly, to detect the exact effectiveness coefficient b ext and the reduced actual power, a real design of experiment is designed. journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.001 4 http://apc.aast.edu d. experimental process dust accumulation on pv cell in the real environment, a single pv panel of 15w power generation for experiment setup is set up. the dust samples and experiment set up are given in figures 3 and 4. in the first part, a plane glass is used to put on the pv surface. the aim of that was just for measuring the irradiance after going through the plane glass and the accumulated dust on plane glass. after that an outdoor pv power generation system is established. three radiation levels are measured during the experiment, and the sun radiation range was from 925 to 1000 w/m2 and this rang was between 560 to 700 w/m2 for plane glass. in the second part, an electronic balance is used to calculate the dust mass density of the plane glass sheet. here, it was necessary to control the mass of deposited pollutants in the third part, so that dust density range is 0.2840 g/cm2 to 1.4198 g/cm2. in the third part, the dust distributing process is done manually. regarding to the non-uniform distribution of dust, it will have the same effect on the pv power same as the natural uniform deposition. after determining dust density and output power from the plotted curves, the effect model of dust accumulation and power efficiency is analyzed and obtained and the validity of the experiment is proved by the actual conditions. fig.3. different samples of dust particles (a) cao, sio4 (b) soil (c) ca 2 so 4 (d) al 2 o 3 , sio 4 (e) c each type of dust pollutants is subjected to two of its chemical decomposition. different dust masses are used for each sample, resulting in five levels of each sample. the density of each deposited dust is in a specific range. when the density is low, it has less influence on the power of pv panels. to keep going forward with the output power reduction, more dust pollutants are tested. the researchers appropriately increased the density of deposited dust sample. the accumulation steps are as follows: step 1. measure the light irradiance directly from the sun, then measure it again after going through plane glass and finally for the third time after depositing the dust on the glass surface the irradiance is measured behind dusty plane glass. step 2. lie the pv panel face up and put the plane glass on it and an area is specified by a marker in order not to deposit the dust out of pv panel area in case of high accuracy of dust influence on panel efficiency. step 3. by using voltmeter, ammeter, and a rheostat all v-i data are measured and the power is obtained for each couple i and v data. p-v curves are plotted as can be seen in fig. 6. step 4. for all type of dusts with specific mass density different tilt angle 0o to 45o and for c case extra angle of 60o are tested. step 3 is repeated for all tilt angle and the data are plotted. to reduce the error factor of the experiments process, the steps are repeated on two continuous days in same natural conditions. fig.4. a: soil and b: cao,sio2 c: c, d: ca 2 so 4 2h 2 o 2 deposited of pv surface fig.5. a: digital lux meter, b: electronics balance device iii. results and discussion in this part, the experimental outcome will be analyzed in detail. in subsection 5.1, the all parameters characteristics such as v-i curve, v-p curve, , , and different tilt angle of five dust pollutants are investigated. a. analysis impact of dust deposition on pv panels in order to acquire the power reduction factor, the experiment is set up to test and measure the energy performance of the pv panel, including output voltage, current, power, irradiance and tilt angle. fig. 6 shows the power output curves for all dust pollutants under unchanged radiation with a dust density of five levels. in addition, each sub-figure shows the evolution of the power efficiency of the same dust pollutant of different journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.001 5 http://apc.aast.edu mass (five concentrations of pollutant accumulation). experimental results show that the output power of the pv panels decreases in different degrees with the increase of mass density of each accumulation effect. at low density, the coverage area of toner on pv is more, which has high effect on power output. when the concentration of toner reaches 0.775 g/cm2, the output power drops to zero. when the soil concentration raised to the same value, the output power changes to 2.4 w and it is significantly lower than the power of clean pv. the output power is 2.86 w, when the maximum density is 1.4119 g/cm2 for al 2 o 3 , sio 4 . cao, sio 4 is one of the pollutants that have reduce the output power to 2.17 w of the same density as al 2 o 3 , sio 4 . it can be sensed that the output power of pv panels is highly sensitive to toner pollutant because of the its colour and adhesion. fig.6. v-p curves characterization a: soil, b: ca 2 so 4 .2h 2 o, c:,al 2 o 3 , sio 2 d: cao,sio 2 , e: c. from fig. 7, the plot (a): represents five different curves of the same mass density. when the density is 0.5679 g/ cm2, the power decline trend is 62.35%, 66.95%, 69.05%, 63.35% and 96.65% for soil, (al 2 o 3 , sio 4 ), (cao, sio 4 ), (ca 2 so 4 .2h 2 o) and (c), respectively. plot (b): among all pollutants, soil, (ca 2 so 4 .2h 2 o) and (al 2 o 3 , sio 4 ) rapidly changed with increasing the concentration. however, for (cao, sio 4 ), the output power extremely decreased from 0.28 g/cm2 to 0.56 g/cm2 and after that the change went slowly. for toner, output power rapidly goes to zero by concentration of 0.56 g/cm2. plot (c): soil, (al 2 o 3 , sio 4 ) and (cao, sio 4 ) by increasing the tilt angle, the effectiveness of their concentration will be reduced because the output power of each of the three increased. the output power increased highly after angle of 30o due to low adhesion. toner c has a small particle size and high adhesion, and the output power goes forward constantly. plot (d): toner pollutant highly reduced the irradiance, but other types of dust uniformly decreased the irradiance. the low concentration of pollutants has a little effect on irradiance, while high concentration of each influenced the irradiance significantly. journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.001 6 http://apc.aast.edu fig.7. curves of all pollutants a: p v curves, b: p – 𝜌 curves c: p – tilt angle curve fig.8. φ 3 –𝜌 curves with their fitting curves to find the value of bext .x journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.001 7 http://apc.aast.edu iv. conclusions the impact of five collected dust pollutants (toner (c), soil, cement (cao, sio 4 ), gypsum (ca 2 so 4 .2h 2 o), and sand (al 2 o 3 , sio 4 ) on the actual power of pv panels are determined in this study. fortunately, the effectiveness of extinction coefficient of various dust particles for different dust decomposition on the power of pv panels with various concertation is determined. the overall the results could be as: 1. dust deposition has a remarkable inhibitory influence on pv panels output power, and its efficiency debilitation depends on the kind of pollutant colour, composition, and more on the density of dusts. 2. joining the impact of concentration on the irradiance ratio of pv panels output power experimentally established. 3. the outcomes present that the calculated output power reduced (62% to 96%), irradiance (34% to 93%) decreased and increasing of output power due to increasing of tilt angle as redouble the power, but toner double down the power. 4. the extinction coefficient of all pollutants has been found and the toner has the highest extinction with (al 2 o 3 , sio 4 ). although the influence of different dusts is collected, their accumulation on the pv is considerably not uniformly, and there may be difference extinction coefficient various points on pv panel. in the future, the used model of uniform distribution condition of pollutant should be further developed to have a uniform experimental process for the recording of v-i and v-p graphs of pollutants. contribution saman jaafar carried out system building, data analysis, and interpretation experiments. hiwa abdlla maarof and renas t salh cooperated as a partner in data analysis. hoshang sahib did the plots and fitting of the data measures. yousif azeez cooperated as paraphrasing and rewrite the draft version. all authors have read and agreed to the published version of the manuscript. declarations ethical approval and consent to participate: not 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[52] s. zakaria, y. t. mustafa, d. a. mohammed, s. s. ali, n. al-ansari, and s. knutsson, “estimation of annual harvested runoff at sulaymaniyah governorate, kurdistan region of iraq,” nat sci (irvine), vol. 05, no. 12, 2013, doi: 10.4236/ ns.2013.512155. [53] l. zhi zhang, a. jian pan, r. rong cai, and h. lu, “indoor experiments of dust deposition reduction on solar cell covering glass by transparent super-hydrophobic coating with different tilt angles,” solar energy, vol. 188, 2019, doi: 10.1016/j.solener.2019.07.026. [54] x. li, t. liu, j. wang, l. xu, and z. zhang, “dust deposition can focus light at a limited distance on photovoltaic panels,” j quant spectrosc radiat transf, vol. 246, 2020, doi: 10.1016/j. jqsrt.2020.106921. journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.011 11 http://apc.aast.edu i. introduction in recent years, there has been an increasing interest in replacing conventional fossil fuels for electrical energy generation with renewable energy resources to reduce pollution in an attempt to achieve a green environment. with the transportation sector being a major source of carbon dioxide emissions, researchers are oriented towards electrifying the transportation section [1]. different electrical machines, including dc, synchronous, and induction machines could be used for propulsion [2], [3]. conventionally, the first-choice traction machine is the permanent magnet synchronous machine (pmsm) due to its high torque density, and wide constant torque/ speed range. however, escalated prices and restricted resources of rare-earth materials forced the market to look for a suitable, magnet-free alternative [4]. the switched reluctance machine (srm) is the dark horse in this race [5]. it has a simple, robust structure, with low cost. being a double-salient machine with concentrated winding on stator poles, and with neither windings nor permanent magnets on the rotor poles made its design and geometry simpler. despite the srm advantages, it suffers from two main drawbacks, namely, vibration and low power density when compared with other traction machines like the pmsm [6] [8]. recently, there have been decent attempts to improve the srm power density [9], [10]. improving the efficiency and the power density of the srm to compete with the pmsm was achieved [11] [13]. the srm has been studied extensively in recent decades [14]. a new srm trend explores a higher number of rotor poles than stator poles, as presented in [15]. the new motor concept (n s <n r ) (n s , n r are the number of stator and rotor poles, respectively) has lower mass and copper loss than the conventional srm (n s >n r ). due to the extra space available in the stator slot area, windings with a higher number of turns and thicker cross-sectional area can be deployed [16]. also, the rotor pole number increase minimizes torque ripple, which is vital for electric vehicle (ev) applications [17]. however, since the interpolar rotor airgaps are narrower in the new motor design, there is an increase in the unaligned inductance value when compared to that of the conventional srm. the increase of unaligned inductance reduces the energy conversion area, and hence the produced torque. in addition, the process of current build-up in the stator winding will be slower due to the decrease in the unaligned inductance value [18]. hence, to restore the speed of current build-up, a dc link voltage with higher magnitude is required. also, the salient rotor structure increases the windage loss, especially at high speeds. rotor ribs are proposed in [19], [20], to mitigate the srm windage loss. film magnetic material is inserted between rotor poles; hence, producing a cylindrical rotor shape. although the windage loss is significantly reduced, the torque density is reduced, and the torque ripple increased, in addition to the mechanical constraints imposed in fabricating the thin magnetic material. power density improvement due to rotor flux screens in an srm with a higher number of rotor poles than stator poles ali a. abdel-aziz1, khaled h. ahmed1, 2, ahmed m. massoud3 and barry w. williams1 1 departement of electronic and electrical engineering, university of strathclyde, glasgow, g1 1xq, uk 2department of electrical engineering, alexandria university, alexandria, 21544, egypt 3 department of electrical engineering, qatar university, doha, p.o. box 2713, qatar emails: ali.hassan-abdelaziz-ali@strath.ac.uk, khaled.ahmed@strath.ac.uk, ahmed.massoud@qu.edu.q, barry.williams@strath.ac.uk abstract this paper st udies the performance of screened switched reluctance motors (srms) with a number of rotor poles higher than the number of stator poles. flux (conduct ing) screens are electrically conduct ing, non-magnet ic materials like aluminum or copper. these screens fill the interpolar rotor air gaps decreasing the unaligned inductance, and thereby increasing the output torque. in addit ion, flux screens result in a c ylindrical rotor str uct ure which minimizes windage losses especially at high speeds. the paper invest igates the effect of the flux screens thickness and material on the srm performance including output torque, power and phase current. a modified flux t ube approach for est imat ing the unaligned inductance of screened srm is proposed. finite element analysis results for different screen cases confirm the effect iveness of conduct ing screens in improving the torque, hence power capabilit y, of switched reluctance motors. index-words: electric vehicles, finite element analysis, flux screens, power densit y, renewable energ y, switched reluctance motor, torque ripple. received on, 11 january 2023 accepted on, 03 may 2023 published on, 30 may 2023 http://dx.doi.org/10.21622/resd.2021.07.2.043 journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.011 12 http://apc.aast.edu segmented rotor srm (srsrm) with cylindrical rotor design was investigated [21]. however, it suffers from complexity in manufacturing and mechanical weaknesses [22]. in addition, the srsrm has a longer end winding, which deteriorates the electrical loading of the motor [23]. also, this motor is not suitable for applications requiring motors with short lamination stack length [24]. the concept of flux screens was proposed in [25]. interpolar rotor air gaps are filled with materials like copper or aluminium which are electrically conducting materials with non-magnetic properties. when the rotor rotates with any speed, voltage is induced in the conducting screens, resulting in the flow of eddy currents. a magnetic field is set up by the flow of eddy currents, which opposes the stator main magnetic field. the result is a decrease in the unaligned inductance value. in [25], the impact of utilizing rotor conducting screens on a three-phase 6/4 srm was investigated. the deployment of rotor conducting screens for three different srms was investigated in [26] – [28], where the screened machines produced higher torque levels than unscreened machines with equivalent volume. however, there was no attempt to investigate the srm performance when varying the thickness or the material of the conducting screen. also, the low number of rotor poles increases the torque ripple, which is undesirable for ev applications. in this paper, the utilization of rotor conducting screens for an srm with a higher number of rotor poles than stator poles (n r >n s ) is investigated. the increased rotor pole number reduces torque ripple. the deployment of rotor conducting screens reduces the unaligned inductance value, hence allowing faster current build-up resulting in higher power per unit volume. also, as with any srm, filling the spaces between rotor poles mitigates the windage loss, especially at higher rotor speed. a detailed procedure using the flux tube method for calculating the effective value of unaligned inductance for screened srms is presented. finally, the performance of screened srm with different screen thicknesses and materials is assessed. the paper is organized as follows. section ιι sheds light on the concept of utilizing rotor conducting screens for srms. a method, based on flux tube approach, is discussed in section iii to calculate the unaligned inductance value for screened srm. supporting 2d and 3d finite element analysis (fea) results are presented in section iv. ii. srm with rotor conducting screens the srm structure is simple having salient stator and rotor poles. only the stator poles have concentrated winding, where each two opposite poles are connected in series forming a phase. in the unaligned position, the flux linkage-current (λ-i) characteristics is linear as the core reluctance is much smaller than the air gap reluctance. on the other hand, when the srm is in the aligned position core reluctance cannot be ignored resulting non-linear (λ-i ) characteristics, as shown in figure 1. the conversion area oab, which is the increase in coenergy when the rotor moves from the unaligned to the aligned position, controls the developed torque. reducing the effective unaligned inductance increases the conversion area, hence increasing motor output torque. equation (1) defines the torque. (1) where θ is the rotor position and w f ' is the co-energy λ i λ λ 2 1 a bc d aligned position θ = θ 2 unaligned position θ = θ 1 o a* fig. 1. flux linkage-current (λ-i) characteristics of srm a new family of srms with a higher number of rotor poles than stator poles was presented as in literature. a threephase 6/10 srm and a four-phase 8/14 srm are examples of the new concept. the new srm can be operated using the traditional asymmetric half-bridge converter [29] and is characterized by reduced torque ripple since nr>ns, which results in an increased number of strokes per revolution whence increased phase overlap. figure 2 shows a three-phase 6/10 srm. where, d sh , d, d are the shaft diameter, rotor diameter, and outer stator diameter, respectively. h s , h r are the stator and rotor pole heights, respectively. b sy , b ry are the stator and rotor back iron, respectively.βs , βr are the stator and rotor pole arcs, respectively. l g is the air gap length, l is the stack length, and n is the number of turns per phase. β r sβ rh sh shd ryb bsy d d lg fig. 2. model of 6/10 srm http://dx.doi.org/10.21622/resd.2021.07.2.043 journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.011 13 http://apc.aast.edu for a high number of rotor poles, the available interpolar rotor spaces are narrower when compared with the traditional srm. thus, the unaligned inductance is high. copper or aluminum, which are electrically conducting but non-magnetic materials, are utilized to fill in the interpolar rotor air gaps as shown in figure 3. whence, this material is referred to as a conducting screen. when the rotor rotates with any speed, voltage is induced in the conducting screens, resulting in the flow of eddy currents. a magnetic field is set up by the flow of eddy currents, which opposes the stator main magnetic field. the result is a decrease in the unaligned inductance. iii. flux tube approach for unaligned inductance calculation of screened-srm the unaligned inductance effective value is of paramount importance to predict the srm performance [30]. fea is an intuitive choice for designing and testing electrical machines. nevertheless, in the early design stage any change in the srm geometry, turns number or conduction period, will dictate a new model to be built and simulated. which is a time-consuming process. hence, starting with a mathematical model is a wise choice which compromises both accuracy and time [31]. this section establishes the unaligned inductance calculation method of screened-srm using the flux-tube approach [32]. it is worth mentioning that, at the aligned position the screens do not alter the aligned inductance. five flux paths are used to describe the flux magnetic path at the unaligned position as illustrated in figure 3. figure 4 demonstrates the magnetic equivalent circuit for calculating the screened-srm unaligned inductance. where, r sp ,r g ,r rp , r sy and r ry are the reluctances of the stator pole, air gap, rotor pole, stator back iron, and rotor back iron, respectively. flux path reluctances are calculated based on the machine geometrical dimensions. in the unaligned position, core reluctance is insignificant when compared to air gap reluctance. hence, a linear flux linkage – current (λ i) characteristics curve is obtained. flux path 1 flux path 2 flux path 3 flux path 4 flux path 5 fig. 3. flux paths in unaligned position generally, reluctance could be expressed by [33], [34]. (2) where l is the flux magnetic-path length, a is the crosssectional area, and μ 0 and μ r are the permeability of air and core material relative permeability, respectively. the reluctances for the flux paths are derived in detail in the next subsections. 𝑹𝑹𝒔𝒔𝒔𝒔𝒔𝒔 𝑹𝑹𝒔𝒔𝒔𝒔𝟓𝟓 𝟒𝟒� + 𝟓𝟓 𝟖𝟖� 𝑵𝑵𝑵𝑵 + 𝝋𝝋𝟏𝟏 𝝋𝝋𝟐𝟐 𝝋𝝋𝒔𝒔 𝝋𝝋𝟒𝟒 𝝋𝝋𝟓𝟓 𝑹𝑹𝒈𝒈𝟓𝟓 𝟒𝟒� 𝑹𝑹𝒔𝒔𝒔𝒔𝟓𝟓 𝟒𝟒� 𝑹𝑹𝒔𝒔𝒔𝒔𝟒𝟒 𝟐𝟐� 𝑹𝑹𝒈𝒈𝟒𝟒 𝟒𝟒� 𝑹𝑹𝒔𝒔𝒔𝒔𝟒𝟒 𝟒𝟒� 𝑹𝑹𝒈𝒈𝒔𝒔 𝑹𝑹𝒓𝒓𝒔𝒔𝒔𝒔 𝑹𝑹𝒔𝒔𝒔𝒔𝒔𝒔 𝟐𝟐� 𝑹𝑹𝒓𝒓𝒔𝒔𝒔𝒔 𝟐𝟐� 𝑹𝑹𝒔𝒔𝒔𝒔𝟐𝟐 𝑹𝑹𝒈𝒈𝟐𝟐 𝑹𝑹𝒓𝒓𝒔𝒔𝟐𝟐 𝑹𝑹𝒔𝒔𝒔𝒔𝟐𝟐 𝟐𝟐� 𝑹𝑹𝒓𝒓𝒔𝒔𝟐𝟐 𝟐𝟐� 𝑵𝑵𝑵𝑵 𝟖𝟖� 𝑹𝑹𝒔𝒔𝒔𝒔𝟏𝟏 𝑹𝑹𝒈𝒈𝟏𝟏 𝑹𝑹𝒓𝒓𝒔𝒔𝟏𝟏 𝑹𝑹𝒔𝒔𝒔𝒔𝟏𝟏 𝟐𝟐� 𝑹𝑹𝒓𝒓𝒔𝒔𝟏𝟏 𝟐𝟐� + 𝑵𝑵𝑵𝑵 𝟒𝟒� fig 4. magnetic equivalent circuit a. flux paths 1, 2 and 3 the first three flux tubes are similar. hence, their analysis is combined in this subsection. figure 5 shows the first magnetic flux path where flux flows through the rotor back iron, the stator back iron, the rotor pole, the stator pole, and finally, the interpolar rotor air gap. five reluctances are used to describe the magnetic flux path. the magnetic-flux path length and cross-sectional area are calculated as follows: a b o c de θ θ θ 3 2 1 stator pole rotor pole conducting screen shaft flux path 1 fig. 5. flux path 1 http://dx.doi.org/10.21622/resd.2021.07.2.043 journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.011 14 http://apc.aast.edu 1. rotor back iron reluctance, r ry1 , r ry2 , r ry3 for rotor back iron, the average magnetic flux path length and the cross-sectional area are defined by (3) and (4), respectively. (3) (4) where, x =1, 2, 3 represents flux paths 1, 2 and 3, respectively. 2. stator back iron reluctance, r sy1 , r sy2 , r sy3 equations (5) and (6) define the average magnetic flux path length and the cross-sectional area for the stator back iron. (5) (6) 3. rotor pole reluctance, r rp1 , r rp2 , r rp3 for the first three flux paths, the flux travels through the entire rotor pole height. hence, the average magnetic flux path length is given by (7), where (8) defines the crosssectional area. (7) (8) 4. stator pole reluctance, r sp1 , r sp2 , r sp3 for path 1, the flux is assumed to leave the stator at the pole tip. for paths 2 and 3, the flux is assumed to leave the stator at ⅒ and ¾ of the stator pole height from the top, respectively. hence, the length of the flux path is defined by (9). the width of the flux path determines the area. for flux path 1, the area is assumed to have width ½ β s +¼ h s . for paths 2 and 3, the entire flux flows throughout the pole height at a width ½ h s and ⅛ h s , respectively. the area is then defined by (10). (9) (10) 5. air gap reluctance, r g1 , r g2 , r g3 the average magnetic flux path length for the air gap is the arc bc as illustrated in figure 5 and defined by (11) lgx=bc=½(eb+ec) θ2 rad (11) when calculating the cross-sectional area involving large air gaps, fringing cannot be neglected. hence, the area is considered to be the sum of the rotor area defined by (8) and the stator area given by (10). finally, the inductance for each flux path is calculated using: (12) b. flux path 4 flux path 4 is demonstrated in figure 6. θ 3 θ 4 o a b flux path 4 stator pole shaft c d e fθ 2 θ 1 fig. 6. flux path 4 in this magnetic flux path, the rotor is not involved as the flux lines cross from one stator pole to the adjacent through the air gap and then returns back through the stator back iron. hence, the three reluctances, r g4 , r sp4 , and r sy4 , could be calculated as follows: 1. air gap reluctance, r g4 the arc bc represents the average flux path length in the air gap as given by (13) lg4=bc=(ob)θ4 rad (13) the cross-sectional area is defined by: (14) 2. stator pole reluctance, r sp4 the flux is assumed to leave the stator pole at ¾ h s of the pole height from the top. therefore, the average magnetic flux path length and the cross-sectional area are defined by (15) and (16), respectively for the stator pole reluctance. http://dx.doi.org/10.21622/resd.2021.07.2.043 journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.011 15 http://apc.aast.edu (15) (16) 3. stator back iron reluctance, r sy4 the arc ef is the magnetic flux path length for the stator back iron reluctance, which is defined by lsy4=ef=(oe)θ3 rad (17) on the other hand, the cross-sectional area is expressed by: asy4= lbsy (18) the flux does not link the entire number of turns per phase, n. it only links ⅜ of the turns number. therefore, the fourth flux path inductance, l u4 is given by: (19) c. flux path 5 figure 7 illustrates flux path 5. flux path 5 stator pole c b fig. 7. flux path 5 the flux leaves the stator pole to enter the stator back iron, passing through the air gap. the flux path is assumed to represent the perimeter of a quarter circle with center at point a and radius of a quarter the stator pole height ¼ h s . the reluctances are calculated as follows: 1. air gap reluctance, r g5 the arc bc represents the length of the magnetic flux path and defined by (20). while, (21) defines the area. (20) (21) 2. stator pole reluctance, r sp5 for the stator pole reluctance, the flux path length is defined by (22), and the area is expressed by (23). lsp5=¼(hs+bsy) (22) (23) 3. stator back iron reluctance, r sy5 the mean flux path length and the cross-sectional area for the stator back iron reluctances are defined by (24) and (25), respectively. (24) asy5= lbsy (25) the flux links only ⅛ the turns per phase n. therefore, , which represents flux path 5 inductance is given by: (26) finally, the effective value of unaligned inductance for the screenedsrm is calculated by summing all the flux path inductances as expressed by (27). (27) iv. simulation results in this section, the performance of the screened-srm is investigated statically and dynamically using fea. the static test gives an insight on the effective value of unaligned inductance to validate the proposed mathematical approach. on the other hand, the dynamic test studies the effect of varying the thickness and material of the screen on the developed torque and the current build-up process. a three-phase, 6/10 srm with the specification in table 1 is used for analysis. the increased number of rotor poles allows for more space to accommodate the stator winding (since pole arcs of the new srm are narrower than the pole arcs of a conventional three-phase srm). according to the selected specification, the copper current density is less than 5a/mm2, thus special cooling is not required. for a fair comparison between unscreened and screened srms, the same firing angles are applied in both cases. table i. srm specification parameter value no. of phases m 3 stator/rotor poles 6/10 number of turns per pole n 60 phase winding resistance r 0.8ω dc link voltage 500v rated power 6kw base speed 1500rpm http://dx.doi.org/10.21622/resd.2021.07.2.043 journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.011 16 http://apc.aast.edu axial length 240mm shaft diameter 40mm rotor outer diameter 120mm rotor yoke thickness 30mm ratio of rotor pole arc to pole pitch 0.335 stator inner diameter 122mm stator outer diameter 200mm stator yoke thickness 25mm ratio of stator pole arc to pole pitch 0.21 a. static analysis the proposed mathematical approach for unaligned inductance calculation is validated by a 3d fea model. table ii shows good agreement between the proposed analytical method and the 3d fea model. table ii. unaligned inductance analytical 3d fea 4.66mh 5.05mh the inductance profile of the srm under test is plotted in figure 8 for both the screened and unscreened (original) srms. fig. 8. inductance profile results are obtained using 3d fea model. as expected, the flux screens have insignificant effect on the aligned inductance value. on the other hand, the unaligned inductance value decreased from 8.68mh in case of unscreened srm to reach 5.05mh for the screened srm. the 40% reduction in the effective unaligned inductance value will increase the conversion area (area oab in figure 1) resulting in more developed torque, hence increasing the torque/power density of the srm. b. dynamics analysis the dynamic performance of the screened-srm is presented in this sub-section using 2d fea where the process of current build-up along with the developed torque are demonstrated. conventional asymmetric halfbridge with two diodes and two switches per phase is used. the srm operates in a single-pulse mode; that is, the dc-link voltage is applied for the whole dwell period. then a negative voltage is applied at the end of the dwell period for rapid current commutation, as implied in figure 9. fig. 9. the voltage applied on phase a the dynamic performance at rated conditions is investigated, and figure 10 compares the results of unscreened and 6mm thick cu screened srms. figure 10a shows the phase current waveforms for the unscreened and screened srms. the reduction in the effective unaligned inductance alters the current response of the srm with conducting screens. utilizing the same dc-link voltage, the screened motor accelerates the current build-up. the rms phase current increases from 17.7a for the unscreened srm, to 21a for the screened case. figure 10b compares the torque profile in both cases. the screened motor is able to develop more torque as a result of a higher current and lower unaligned inductance. the average torque of the unscreened motor is 38.6nm. this value increases by 34% to 50.77nm for the screened srm, hence improving srm torque/volume. thus, the deployment of conducting screens improves the nm/a by 10%, which reflects on the motor power factor [5]. http://dx.doi.org/10.21622/resd.2021.07.2.043 journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.011 17 http://apc.aast.edu a b fig. 10. performance comparison of unscreened and screened srm: (a) phase current waveforms and (b) developed torque waveforms. figure 11 shows the torque/speed characteristics of the unscreened and screened srm. the screened srm offers superior torque over the entire speed range. fig. 11. torque/speed characteristics below the motor base speed, current chopping control (ccc) is used. in this control technique, the motor develops its rated torque, and the speed is controlled from zero up to base speed by controlling the phase currents. above base speed, the phase currents cannot be controlled (chopped) anymore, and the motor enters the single pulse mode. in this mode, the speed of the motor is controlled by adjusting the turn on and turn off angles. hence, this mode is referred to as advance angle control (aac). above the base speed, the motor cannot produce its rated torque. however, controlling the turn on/off angles allows the motor to operate at constant power. c. effect of screen material and thickness this subsection investigates the screened-srm performance when screens with different materials and thicknesses are utilized. figure 12 shows srm current and torque waveforms using two different screens. the first screen is 3.5mm thick copper, while the second screen is 10 mm thick aluminum (filling the whole interpolar rotor air gaps). a b fig. 12. performance of srm using different screen materials: (a) current waveforms and (b) torque waveforms the electrical conductivity of copper is 5.98×107 s/m with density 8960 kg/m3. the electrical conductivity of aluminum is 3.5×107 s/m with density 2600 kg/m3. the srm with a 3.5 mm copper screen is able to deliver the same output torque as the 10 mm aluminum screen. this establishes that electrical conductivity plays an important role in the behavior of the induced eddy current. figure 13 compares srm performance when different thickness copper screens are deployed, where increasing the screen thickness results in more developed torque. from this study, it is concluded that the thickness and material of the screen affect the srm performance. using a film screen with low conductivity results in higher resistance to the induced voltage, hence the eddy current is smaller. increased resistivity does result in a reduced eddy current decay time constant. http://dx.doi.org/10.21622/resd.2021.07.2.043 journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.011 18 http://apc.aast.edu a b fig. 13. performance of srm using different screen thicknesses: (a) current waveforms and (b) torque waveforms the deployment of rotor conducting screens does not alter motor physical volume (as opposed to material volume). hence, the increase in output power will directly reflect the increase in power density (kw/litre), as shown in figure 14a. the specific power (kw/kg) (which is an important factor in most applications) is compared for the unscreened and screened srms in figure 14b, showing an improvement in specific power when conducting screens are used. the penalty for reducing torque ripple and improved torque and power output is screen eddy losses, which reduce machine efficiency. a b fig. 14. performance comparison of unscreened and screened srms: (a) output power and (b) specific power vii. conclusion the paper investigated the effect of utilizing rotor conducting screens to enhance the torque capability of srm with a higher number of rotor poles than stator poles. the rotor pole increase reduces torque ripple. however, since the interpolar rotor gaps are narrower in the new motor design, the unaligned inductance is significantly higher when compared with conventional srm, thus reducing the conversion area. filling the rotor interpolar gaps with electrically conducting, nonmagnetic material reduces the effective unaligned inductance as a result of the opposing flux generated by eddy currents in the screens. a detailed derivation of the effective value of unaligned inductance for screened srm was presented and validated using fea. a 40% reduction in the unaligned inductance and a 34% increase in output torque was recorded using copper screens. also, a 10% increase in the nm/a, hence power factor improvement, was achieved. the effect of using conducting screens of different materials and thicknesses on srm performance was presented. the srm with copper screens is able to http://dx.doi.org/10.21622/resd.2021.07.2.043 journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.011 19 http://apc.aast.edu deliver more output torque. on the other hand, aluminum is lighter and cheaper. increasing screen thickness increases torque production. finally, screened srms provided better power density and specific power than unscreened srm. some interesting topics could further be investigated as: • the performance of srm with rotor conducting screens has been reported only for motoring mode. the research could be extended to cover the generating mode. • given the simple coil winding arrangement in the srm, and water cooling, advanced manufacturing techniques may offer higher copper density (slot fill factor) improvement possibilities, for example with square section conductors. references [1] z. wang, t. w. ching, s. huang, h. wang, and t. xu, “challenges faced by electric vehicle motors and their solutions,” ieee access, vol. 9, 2021, doi: 10.1109/access.2020.3045716. 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[19] j. dang, j. r. mayor, s. a. semidey, r. g. harley, t. g. habetler, and j. a. restrepo, “practical considerations for the design and construction of a high-speed srm with a flux-bridge rotor,” ieee trans ind appl, vol. 51, no. 6, 2015, doi: 10.1109/ tia.2015.2445813. [20] k. kiyota, t. kakishima, a. chiba, and m. a. rahman, “cylindrical rotor design for acoustic noise and windage loss reduction in switched reluctance motor for hev applications,” ieee trans ind appl, vol. 52, no. 1, 2016, doi: 10.1109/tia.2015.2466558. [21] x. sun, k. diao, g. lei, y. guo, and j. zhu, “study on segmented-rotor switched reluctance motors with different rotor pole numbers for bsg system of hybrid electric vehicles,” ieee trans veh technol, vol. 68, no. 6, pp. 5537–5547, jun. 2019, doi: 10.1109/tvt.2019.2913279. [22] z. xu, j. liu, m. j. kim, d. h. lee, and j. w. ahn, “characteristics analysis and comparison of conventional and segmental rotor type 12/8 switched reluctance motors,” in ieee transactions on industry applications, 2019. doi: 10.1109/ tia.2018.2859324. [23] b. c. mecrow, e. a. el-kharashi, j. w. finch, and a. g. jack, “preliminary performance evaluation of switched reluctance motors with segmental rotors,” ieee transactions on energy conversion, vol. 19, no. 4, 2004, doi: 10.1109/tec.2004.837290. [24] b. c. mecrow, j. w. finch, e. a. el-kharashi, and a. g. jack, “switched reluctance motors with segmental rotors,” iee proceedings electric power applications, vol. 149, no. 4, p. 245, 2002, doi: 10.1049/ip-epa:20020345. [25] a. j. hutton and t. j. e. miller, “use of flux screens in switched reluctance motors,” in iee conference publication, 1989. [26] y. g. dessouky, b. w. williams, and j. e. fletcher, “conducting screen utilisation in switched reluctance motors,” ieee transactions on energy conversion, vol. 14, no. 4, pp. 946–951, 1999, doi: 10.1109/60.815012. [27] r. hamdy, j. e. fletcher, b. w. williams, and s. j. finney, “high-speed performance improvements of a two-phase switched reluctance machine utilizing rotor-conducting screens,” ieee transactions on energy conversion, vol. 17, no. 4, 2002, doi: 10.1109/ tec.2002.805202. [28] m. m. mahmoud, j. e. fletcher, and b. w. williams, “evaluation of rotor conducting screens on the single-phase switched reluctance machine,” electric power components and systems, vol. 34, no. 2, 2006, doi: 10.1080/15325000500244674. [29] s. xu, l. tao, g. han, and c. liu, “a novel driven scheme regarding to current dynamics enhancement for switched reluctance motor system,” ieee transactions on transportation electrification, 2023, doi: 10.1109/tte.2023.3243176. [30] d. roy and m. sengupta, “an experimentally validated novel analytical approach for modeling of a saturated switched reluctance motor,” ieee trans magn, vol. 58, no. 12, 2022, doi: 10.1109/ tmag.2022.3210155. [31] g. watthewaduge and b. bilgin, “reluctance meshbased magnetic equivalent circuit modeling of switched reluctance motors for static and dynamic analysis,” ieee transactions on transportation electrification, vol. 8, no. 2, 2022, doi: 10.1109/ tte.2021.3132885. [32] n. k. sheth and k. r. rajagopal, “calculation of the flux-linkage characteristics of a switched reluctance motor by flux tube method,” ieee trans magn, vol. 41, no. 10, 2005, doi: 10.1109/tmag.2005.854865. [33] r. krishnan, switched reluctance motor drives: modeling, simulation, analysis, design, and applications. 2017. doi: 10.1201/9781420041644. [34] p. materu and r. krishnan, “analytical prediction of srm inductance profile and steady-state average torque,” in conference record ias annual meeting (ieee industry applications society), 1990. doi: 10.1109/ias.1990.152189. http://dx.doi.org/10.21622/resd.2021.07.2.043 journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 167 resd © 2015 http://apc.aast.edu a sustainability assessment framework for waterfront communities increasing the resilience of the abu qir waterfront community in alexandria sally el.deeb1, rania abelgalil1, alaa sarhan1 1architectural engineering and environmental design department, arab academy for science, technology & maritime transport, abuqir campus, alexandria, egypt. abstract it is predicted that the global phenomena of climate change will have far reaching effects and implications on different local urban systems. for incidence, global average sea levels are expected to rise between 7 and 36 cm by the 2050s, and between 9 and 69 cm by the 2080s. waterfront communities are the first to be affected by such impacts, putting them at high risk. planning strategies are needed to assist these communities and increase their adaptive and learning capacities in the face of diverse challenges to their urban sub-systems. the research investigates a number of sustainability frameworks and assessment rating systems for neighbourhoods and communities. it investigates the sustainable evaluation criteria carried out by three assessment rating systems. first is the leed (leadership in energy & environmental design, usa), the second is the breeam (building research establishment environmental assessment method, uk), and the third is the estidama pearl rating system (uae).examples of waterfront communities which applied the previous rating systems are analysed in order to determine the applicability and relevance of these systems to waterfront communities in particular. the research concludes with a proposed framework of indicators for waterfront communities. the similarities and differences between the three rating systems and featured indicators specific to waterfront planning applied in the analysed examples; yet absent in the three rating systems, have informed the selection of indicators in the proposed assessment framework. the proposed framework could be an effective tool for the planning and development of à waterfront community in the mena (the port region). in order to validate the framework, the set of environmental and physical indicators were applied on the case study of abu qir waterfront, alexandria, egypt. conclusions and recommendations are made that would enhance the resilience of this waterfront community and provide a comprehensive tool for its sustainable planning. keywords waterfront communities, sustainability, rating systems, assessment framework. i. introduction waterfront regeneration is becoming one of the most celebrated practices of urban renewal in contemporary cities of the north. at the same time, developing regions have suffered prolonged inattention which lead to a gap between both (giovinazzi & moretti, 2010). urban waterfronts throughout the world suffered a series of deteriorating conditions related to environmental, social and economic issues. some of these issues include changing land uses, large areas of derelict land, lack of services and affordable housing for communities, contaminated air, water and soil, lack of connectivity and inefficient transport. with increased awareness of impacts of climate change, cities are facing big challenges with environmental conditions accomanied by pressures that threaten urban systems to accommodate rapid growth and development. planning for long term growth and increasing the resilience of urban areas in such a manner that addresses the number of crucial economic, environmental and social conditions is an important quest, more particularly for developing countries with surging population. this paper addresses this quest through providing a framework of indicators to assess the environmental and physical aspects of water front communities. the paper is divided into six sections, following the introduction. the second section explores principles agreed upon for the sustainability of waterfronts. the third section analyses the three rating systems http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 168 resd © 2015 http://apc.aast.edu designed for urban communities. moreover, it organises the indicators of those systems according to common categories critically assessing the importance granted to each one. the fourth section explores some international examples and their use of the rating systems plus any appendages made. the fifth section applies a framework to the case study done the area designated at abu quir to uncover priority themes based on the inputs collected from the field survey together with the interviews conducted, in order to facilitate the sustainable planning of this waterfront community. lessons learnt are drawn in the sixth section with concluding remarks that can be made use of by other mena (the port region), any coastal areas. ii. principles of sustainable waterfronts in the context of the initiatives for the global conference on the urban future (urban 21) held in berlin in july 2000 (hall and pfeiffer, 2000) and in the course of the expo 2000 world exhibition (giovinazzi,2008), 10 principles for a sustainable development of urban waterfront areas were approved. these principles are shown in table 1: table 1. principles of sustainable waterfronts it is concluded from the set of principles of urban 21 shown above that it offers general international concepts of sustainability that can be applied on waterfronts, specifically by methods which respect nature and human needs to make a vital waterfront. but an assessment tool is needed as an evaluative mechanism to measure the rate of sustainability. the following section will show such attempts. however, it must be noted that the rating systems could apply to any urban area ; and not particularly waterfront communities. it should be critically assessed whether the rating systems will fully consider the abovementioned principles or not. if so, their applicability to waterfronts could be possible. further to this step, their application on some examples of waterfront communities are studied in section 4. iii. sustainability assessment rating systems sustainability has become an accepted meta narrative, almost certain to be integrated into any future scenario of development (campbell, 1996). a lot of institutions in different cities began to call for applying the principles of sustainable development (wced, 1987; iucn, 1991;bell & morse,2008). different approaches have been developed; these include assessment techniques, indicators, audits, footprint studies and ecological accounts (munda, 2001; rydin et al, 2003, tanguay et al. 2009), all viewed as approaches translating a concept that is presumed to be agreed in principle into something workable on the ground (owens and cowell, 2002). assessment rating systems are considered an important approach which has become popular worldwide and even obligatory in some places to classify who would barely fulfill the requirements of sustainability and who would exceed it. examples of these rating systems are the leed (american system), breeam (european system), casbee (japanese system), green star (australian system), and pearl (uae system). three rating systems will be analysed. leed and breeam were selected in this study as they are the most commonly known rating systems, and the pearl system as it is a rating system used in the middle east (united arab emirates) which is similar to the egyptian context. a. leed indicators leed stands for leadership in energy and environmental design which is a green building rating system, originally developed in 1998 by the u.s. green building council (usgbc) to provide a recognized standard for the construction industry for assessing the environmental sustainability of building designs. leed for neighborhood development was later developed in 2007 and updated in 2009(usgbc, principles of sustainable waterfronts: 1 secure the quality of water and the environment 2 waterfronts are part of the existing urban fabric 3 the historic identity gives character 4 mixed use is a priority 5 public access is a prerequisite 6 public participation is an element of sustainability 7 planning in public private partnerships speeds the process 8 waterfronts are long term projects 9 waterfronts profit from international networking 10 re-vitalization is an ongoing process http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 169 resd © 2015 http://apc.aast.edu 2009). b. breeam indicators breeam (building research establishment’s environmental assessment method) is an environmental assessment method which was first addressed in 1990 for buildings to set the standard for best practice in sustainable design. eventually, in 2002 breeam released and published a comprehensive framework for the early stage of development called, « a sustainability checklist for developments », a common framework for developers and local authorities breeam communities. (bre, 2009). c. pearl indicators the pearl rating system for estidama (which means sustainability in arabic) is the first government initiative released in the middle east region, by estidama program of the abu dhabi urban planning council in 2010. the program includes a standard rating system for buildings, villas, and other neighborhoods. its aim is to create more sustainable communities, cities and global enterprises, balancing between the four pillars of estidama: environmental, economic, cultural and social. estidama itself is also a part of abu dhabi’s 20-year plan, known as « a plan for abu dhabi 2030 » which attempts to redefine how a contemporary arab city should look like to encourage sustainable growth and progress. (abudhabi urban planning council, 2010) d. comparison between the categories of the 3 rating systems after analyzing the 3 previous rating systems, it is observed that there is a considerable overlap between the three systems and that they all include the same main categories shown in table 2. these are community layout, buildings, transportation, water, energy, materials, waste, environment, and innovation (though the categories have different names within each rating system). on the other hand, each system still has its own particularities and definitions under each category. the similarities between the 3 rating systems are examined and the criteria for sustainability to be followed are collated in a framework. five categories were reached. the framework ,including the five categories, is set to assess the sustainability and resilience of waterfronts, and thus they can be applied in the case study of abu qir area . table2.demonstrates the common indicators between pearl, breeam, and leed rating systems (after grouping categories under headings devised by the researcher) table 2. demonstrates the common indicators between pearl, breeam, and leed rating systems (after grouping categories under headings devised by the researcher) category leed indicator breeam indicator pearl indicator c o m m u n it y l a y o u t s m a rt l o c a ti o n & l in k a g e -smart location proximity to water & waste water infrastructure floodplain avoidance brownfields redevelopment high priority brownfields redevelopment site design of habitat /wetland conservation -housing and jobs proximity -school proximity conservation management of habitat or wetlands --open community compact development diversity of uses reduced parking footprint access to surrounding vicinity access to public spaces access to active spaces universal accessibility community outreach and involvement c o m m u n it y / p la c e s h a p in g inclusive communities community consultation information / ownership land use form of development open space inclusive design mix of use l iv a b le c o m m u n it ie s & in te g ra te d d e v e lo p m e n t -integrated development strategy sustainable building guidelines community-dedicated-infrastructure-basic commissioning life cycle costing plan 2030 urban systems assessment provision of amenities and facilities outdoor thermal comfort strategy neighborhood connectivity open space network accessible community facilities community walkability active urban environments travel plan safe and secure community -regionally responsive planning http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 170 resd © 2015 http://apc.aast.edu b u il d in g s g re e n c o n s tr u c ti o n & t e c h n o lo g y diversity of housing types affordable rental housing affordable for-sale housing -construction activity pollution prevention -leed certified green buildings energy efficiency in buildings reduced water use building reuse and adaptive reuse -reuse of historic buildings b u il d in g s -residential buildings (csh or ecohomes) -non-domestic buildings (breeam) l iv a b le c o m m u n it ie s minimum pearl rated buildings within communities -housing diversity t ra n s p o rt a ti o n n e ig h b o rh o o d p a tt e rn & d e s ig n -reduced automobile dependence -walkable streets -street network -transit facilities -transportation demand management t ra n s p o rt public transport cycling requirements car parking -traffic management l iv a b le c o m m u n i ti e s transit supportive practices e n v ir o n m e n ta l is s u e s e c o lo g y g re e n c o n s tr u c ti o n & t e c h n o lo g y imperiled species and ecological communities wetland and water body conservation agricultural land conservation minimize site disturbance through site design. minimize site disturbance during construction. contaminant reduction in brownfields remediation heat island reduction solar orientation e c o lo g y & r e s o u rc e s ecological survey biodiversity action plan native flora wildlife corridor pollution issues land remediation n a tu ra l s y s te m s -natural systems assessment -natural systems protection -natural systems design &management strategy -reuse of land -remediation of contaminated land -ecological enhancement -habitat creation and restoration -food systems -improved outdoor thermal comfort -construction environmental management w a te r g re e n c o n s tr u c ti o n & t e c h n o lo g y -stormwater management r e s o u rc e s water resources management -flood risk issues -water consumption management p re c io u s w a te r -community water strategy -building water guidelines -water monitoring and leak detection -community water use reduction: landscaping -community water use reduction: heat rejection -community water use reduction: water features -storm water management -water efficient buildings e n e rg y g re e n c o n s tr u c ti o n & t e c h n o lo g y on-site energy generation on-site renewable energy sources district heating & cooling -infrastructure energy efficiency c li m a te & e n e rg y -passive design principles -energy consumption management -infrastructure r e s o u rc e fu l e n e rg y -community energy strategy -building energy guidelines -energy monitoring and reporting -community strategies for passive cooling -urban heat reduction -efficient infrastructure: lighting -efficient infrastructure: district cooling -efficient infrastructure: -smart grid technology -renewable energy: onsite -renewable energy:offsite -energy efficientbuildings w a s te g re e n c o n s tr u c ti o n & t e c h n o lo g y -construction waste management -comprehensive waste management r e s o u rc e s -waste management (operation and construction) s te w a rd in g m a te ri a ls basic construction waste management basic operational waste management improved construction waste management improved operational waste management organic waste management 2 hazardous waste management m a te ri a ls g re e n c o n s tr u c ti o n & t e c h n o lo g y recycled content in infrastructure r e s o u rc e s -impact of materials s te w a rd in g m a te ri a ls -cca treated timber elimination -modular pavement & hardscape cover -regional materials -recycled materials -reused or certified timber in n o v a ti o n in n o v a ti o n -innovation and exemplary performance -leed accredited professional b u s in e s s -business investment -employment -business facilities -connectivity in n o v a ti n g p ra c ti c e -showcase of regional & cultural practices -innovating practice -sustainability awareness http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 171 resd © 2015 http://apc.aast.edu e. comparison between the weightings of each category in the 3 rating systems leed, breeam and pearl. table 3 shows the relative weights in each rating system according to five categories arrived at from the previous analysis. the weighting of each category is measured as a percentage of each system’s total credit points. table 3. shows the relative weights in each rating system to the following main categories categories leed breeam pearl community layout 43.5% 31% 13% buildings 16% 4% 10% transportation 11.5% 22% 1% e n v ir o n m e n ta l is s u e s water 8.5% 6.5% 24% energy 5.5% 10.5% 25% materials 1% 3% 7% waste 2% 3% 4.5% ecology 6.5% 15% 14% innovation 5.5% 5% 2% it is shown in the table above that each system gives a different weighting to each category, as each region focuses mainly on one category more than the other in terms of the issues-atstake and according to the policies or strategies of the region towards sustainability. leed’s main focus is on community layout reflecting the united states most common planning problems. breeam’s main focus is on community layout and transportation. pearl’s main focus is on environmental issues, specifically water and energy issues as the very hot weather and the scarce water resources are considered problems of main concern in the united arab emirates. similarly, a new rating system for neighbourhoods has to be made for the egyptian context as it is a different region with its own characteristics and own needs. moreover, waterfront neighbourhoods have specific issues reflected in the principles outlined in section 3. the following section will examine some examples of waterfront communities which applied the three above mentioned rating systems to deduce any aspects that had been added and how useful the indicators are. iv. analytical examples of waterfront communities applying sustainability rating systems three types of waterfront cities which apply the categories of the sustainability rating systems are studied and analyzed. the first example is the city of toronto, canada, which applied the guidelines of leed rating system on west don lands waterfront community. the second is media city, uk, which applied the guidelines of the breeam rating system on the waterfront area. the third is abu dhabi, uae, which applied the guidelines of the pearl rating system on mina zayed waterfront community. the framework previously discussed will be used to compare between these examples and their implementation to methods of sustainability. the case studies were selected by a simple methodology which is demonstrating the principles of sustainability. this concept is seen in the 3 examples but with different applicability due to their location, and this is the reason for analyzing examples in three different regions to learn how each region dealt with its surrounding environment to be sustainable. a. west don lands, toronto, canada (twdi, 2002) the toronto waterfront development has received the leed for neighborhood development gold certificate with a total of 61 points achieved. shown in table 4 is a summary of the application of toronto waterfront to the leed points of sustainable development. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 172 resd © 2015 http://apc.aast.edu table 4. summary of toronto’s application of leed b. media city, uk (bre global, 2006), (breeam communities, 2009) mediacity uk is the first scheme in the world to become a breeam approved sustainable community. the project achieved a score of 76%: potential final certificate excellent. table 5 below is a summary of the application of media city waterfront to the breeam points of sustainable development. table 5. summary of media city application of breeam common categories application (breeam achievement) community layout • mixed use compact development • decreased % of industrial sites & increased % of commercial & residential to 96% • radial planning centered towards waterfront • one huge open space on the waterfront buildings • 80% breeam certified buildings transportation • using canal in water transportation • increased % of multi modal transport • encouraging cycling through providing special lanes e n v ir o n m e n t water • water resources management • use of water from the canal to create a combined heat & power plant energy system (tri gen plant) energy • tri gen plant as a renewable source of energy materials • 80% of construction timber environmentally friendly waste • new waste management plan for waste collection and recycling • production of fuel from waste & using it in a power plant on site ecology • reduce air pollution by the tri gen plant & the increased use of public transport • major brownfield urban regeneration c. mina zayed community, abu dhabi, uae (abu dhabi urban planning council,2010) mina zayed is a new community mixed use project development on the waterfront of abu dhabi developed by aldar corporation. mina zayed’s ambition is to create an integrated and sustainable new waterfront community that affords a vibrant example for the future development of abu dhabi. table 6 below incorporates many practices for achieving estidama. common categories application (toronto leed achievement) community layout • smart mixed use neighborhood design • high % parks & opens spaces connected to the waterfront • 90% within ¼ mile to transit stops, 50% within ½ mile to services, 99% within ½ mile to schools buildings • 60 % leed certified buildings 20% affordable renting transportation • increased % multi modal transport, cycling, reduced car use e n v ir o n m e n t water • 15% reduction in water consumption due to enwave project • new storm water collection system energy • 27% reduction in energy use • 30% energy supplied renewable sources enwave deep water technology materials • using recycled materials in infrastructure waste • recycling 50% of construction waste waste diversion ecology • preservation of the habitat near the water body by natural parks • enwave technology reduces tones of co2 emissions http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 173 resd © 2015 http://apc.aast.edu table 6. summary of abu dhabi application of pearl common categories application (pearl achievement) community layout • mixed use compact development • 20% open spaces & parks on the waterfront • continuous shaded pedestrian routes that link the center to it’s waterfront. buildings • 99% pearl certified buildings • housing variety transportation • multiple transportation options and transit supportive practicesto reduce car use • street management between car lanes, rails & walking lanes e n v ir o n m e n t water • low water use landscape • utilize biological water treatment systems with least energy consumption energy • district cooling strategy • green roofs & compact development for shading & cooling materials  use of local materials, reuse and recycle materials waste • waste management plan • recycle a large % of the demolition of industrial site ecology • conserving the shoreline • re-introducing nature on a formerindustrial site • high % of parks reinforce the natural systems and help in habitat creation the analysis of the three previous examples and their implementation of the different rating systems prove that all the previous rating systems are concerned with the environmental factor of sustainability more than the social and economic factors (given that environmental, social and economic are the 3 pillars of sustainability(wced, 1987). another conclusion is that all the rating systems when dealing with a waterfront community include rating categories like waterfront (water body or wetland) conservation either from pollution or from habitat extinction which are environmental aspects, but there are no rating categories for integration with the waterfront ; the social and economic aspects (other 2 pillars of sustainability) for example, specifying the percentage of open spaces which must be on the waterfron or the type of land use on the waterfront, or the percentage of recreational facilities which must be on the waterfront as all these principles increase the social and physical interaction between people and the waterfront as well as the economic values pointed by the principles in section 2. although these indicators were not required in the rating systems, the examples succeeded in applying some of them to integrate with the waterfront, which means that integration with the waterfront is an important feature for sustainable planning and must be considered under any rating system when dealing with a waterfront. so, a set of new indicators concerning waterfront development, including environmental, social and economic aspects of sustainability along with the categories discussed before will be taken to form a rating system to be implemented on the case study of abu qir area. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 174 resd © 2015 http://apc.aast.edu a set of indicators « integration with the waterfront » fig .1. conclusion, addition of a new category « integration with the waterfront » & the indicators under it v. analytical review of alexandria’s waterfront (abu qir as a case study) abu qir area analysis includes a study of it’s physical, environmental and historical features. in the following subsections, the problems of the area are concluded and organized in terms of priority, under the five categories of the framework.this helps in determining what the biggest problem of the area is like, which must be considered first. afterwards, the other potential problems should be considered prior to the urban development of the area as well. the study is based on a document review of the future comprehensive planning for the development strategy of abu qir area, including site visits, observtions, interviews, together with consulting experts of urban planning, coastal planning and environmental design. a. abu qir review alexandria city is the second largest city in egypt, either in terms of population or economical growth. located on the mediterranean sea with a length of 93.5 km on the waterfront from abu qir bay on the east up to matrouh city on the west. abu qir (shown in fig.2) is one of the communities of montazah district in alexandria city with an area of 60 km2 from the total area of the montazah district which is 81 km2 (alexandria governorate, 1984). abu qir with a population range of 200,000 residents consists of 3 neighborhoods which are abu qir, toson, and mamoura elbalad. it represents one of the most important historical places in egypt (alexandria integration with the waterfront, a comparison principles of sustainable waterfronts: 1 secure the quality of water and the environment 2 waterfronts are part of the existing urban fabric 3 the historic identity gives character 4 mixed use is a priority 5 public access is a prerequisite 6 public participation is an element of sustainability 7 planning in public private partnerships speeds the process 8 waterfronts are long term projects 9 waterfronts profit from international networking 10 re-vitalization is an ongoing process toronto • reduce water consumption from the river • benefit from water by enwave water technology media city • planning order is almost radial (centered towards the waterfront) • huge open space on the waterfront mina zayed • preventing pollution of the water by removing former industrial land • 20% of the project’s total area is dedicated for open spaces, parks and green areas, most of these spaces are on the waterfront interconnected to each other by the green lanes common categories community layout buildings transportation e n v ir o n m e n t water energy materials waste ecology innovation integration with the waterfront degree of integration with the water body degree of benefiting from the water source sea level rise management using network of streets and parks % open spaces on the waterfront land use adjacent to or on the waterfront % recreational facilities on the waterfront linked facilities and open spaces on the waterfront + http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 175 resd © 2015 http://apc.aast.edu comprehensive plan 2017). fig .2. location of abu qir source: google maps, accessed june 2011 b. motives for replanning  it is a strategic location as it is considered an eastern gate to alexandria.  there are a lot of motives for development: a waterfront with many brownfields, unplanned open spaces, historical sites and sunken treasures (goddio, 2007; encyclopaedia of the orient, may 2011)  it has three important historical fortresses: elsabaa, tawfeekeya and el-raml fortresses, which could form an important historical tour in alexandria as they represent an important era in the history of egypt. unfortunately, they strongly need a great work of rehabilitation and renovation.  abu qir bay (lying on a dead sea area) is considered a fertile marine habitat when compared with other egyptian mediterranean coastal waters (asrt, 1984; hamouda & abdelsalam, 2010).  abu qir bay can be used for a variety of purposes: commercial and recreational fishing, shipping, recreational boating, yachting, swimming and diving to explore sunken monuments.  abu qir is famous for its warm temperature and warm seawater which facilitate the development of a lot of recreational beaches and touristic facilities on the waterfront which can enhance and promote the economic development of the area. c. site analysis: in the map below having a master plan for the city, we can observe from the land use, accessibility and building conditions analysis that martial sites occupy a large area of the waterfront which act as a barrier between central abu qir and the waterfront. as a result, scattered parts of groups of buildings are left in the center. another barrier is the train line which seperates west abu qir from east abu qir. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 176 resd © 2015 http://apc.aast.edu fig .3. map showing the master plan, street layout in abu qir source: the researcher d. problems of the site after analyzing the context of abu qir area as a whole, its natural, historical, economic and touristic features along with its land use, accessibility and building conditions, the following problems are concluded as follows.  problems related to community layout and integration with the waterfront abu qir area is not well connected to it’s waterfront due to the following : 1the absence of pedestrian accessible streets leading to the waterfront (either very narrow streets between slums which are the residential areas on the waterfront, or inaccessible streets inside military sites on the waterfront). 2inefficient street layouts which lead to the presence of only one main street as an entrance to abu qir and touson areas after mamoura neighborhood (gabr, 2009) 3 the absence of connected open spaces on the waterfront.stable till it reaches the outlet. residential martial sites green areas educational historical http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 177 resd © 2015 http://apc.aast.edu fig .4. presence of a lot of high illegal buildings on the waterfront 4 the absence of well developed attractive beaches or recreational facilities on the waterfront 5the absence of usable (opened) marines which can connect the area altogether if water transport is present. 6 the presence of military sites in separated zones on the waterfront which cut the way between abu qir downtown and the waterfront. fig .5. presence of martial sites in separated zones 7 the land use in abu qir area is either residential or industrial, plus the martial sites which occupy large areas in abu qir region (no mixed land use). 8 the presence of unplanned areas and scattered slums. 9 the presence of a lot of agricultural or space lands which separate abu qir urban zone from the rest of alexandria. 10the calculations of population density in abu qir community, made by alexandria governorate have proven that there is a continuous growth in population density in abu qir area without a balance in job opportunities, facilities, housing and infrastructure (alexandria comprehensive plan for 2017, 1997) fig .6. trafic problems in abu qir source : researcher  problems related to transportation 1 growth in population with insufficient public transportation leads to increasing reliance on private cars and buses 2 occurence of continuous traffic jam due to increasing number of cars. 3 occurence of traffic problems and accidents due to unplanned intersections and the absence of stop signs. 4 number of trains reaching abu qir train station is not big enough to meet the need targeted as it is the only means of transportation for most workers in abu qir area. moreover, trains and train lines are too old, dirty and don’t work with full power (gabr, 2009) 5 train lines occupy large space of the street width increasing traffic conjestion. they also form a barrier between west and east of abu qir as they are closed with a high wall barrier. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 178 resd © 2015 http://apc.aast.edu fig .7. the problems of transport in abu qir source : researcher  problems related to transportation 1illegal high buildings on the waterfront of abu qir (alexandria governorate, 1997) 2 the presence of slums and narrow streets, with deteriorated buildings scattered here and there makes it impossible to supply such places with efficient infrastructure needed (waste, water supply, electricity, gas, sewage grid, telephone lines …. etc) 3 the presence of illegal fast construction projects everywhere, streching out to the sea shore leads to the sloping down of buildings and in some cases collapsing. they also lead to the emergence of unplanned streets and narrow corridors. these illegal buildings never comply with the architectural character of theplace. fig .8. the problems of buildings in abu qir source: http://www.flickr.com/photos/david_vilder  problems related to waste 1 the presence of a lot of areas with no supply of drainage pipes leading to draining in wells. these wells cannot be reached by maintainace cars because the streets are very narrow, consequently a blockage of these wells occurs leading to sanitary problems. 2water pollution of abu qir bay due to untreated sewage and industrial waste discharged from different sources like eltabia pumping station. this station discharges polluted industrial waste from factories of food processing, canning, paper, fertilizers and textiles. the outlet of idku lake which contains drainage water from agriculture, usually containing pesticides, is another source of pollution. added to this is the rosetta mouth of the nile river which discharges fresh water carring agricultural waste from cultivated lands. (nasr, et al., 2003) 3 no waste collection which leads to accumulation of waste in front of buildings and houses. fig .9. the study area where the arrows indicate the sources of pollution along abu-qir bay source: the researcher fig .10. the problems of waste in abu qir source: http://www.flickr.com/photos/david_vilder http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 179 resd © 2015 http://apc.aast.edu  problems related to water 1 infrastructure problem related to sewage grid, leading to insufficient number of sewers that cause water blockage in the streets during rainy days of the year. (alexandria governorate comprehensive plan for 2017) 2 no water supply in many areas (particularly slums) which drives many citizens to practice unlawful activities to have water supply connections.  problems related to environment 1air pollution from different industrial factories in abu qir (kamel, 2002) 2water pollution in the eastern area of abu qir bay (dead sea) from ships and marine waste (gabr, 2009) 3the problem of climate change is being taken seriously by the egyptian authorities. the low lying land in the nile delta region is considered to be at risk due to the potential effects of any sea level rise resulting from global warming. in particular, the cities of alexandria, rosetta and port said, which are major industrial and economic centres, are expected to experience serious environmental impacts, if no action is taken (el-raey, 2009).therefore, as long as abu qir region represents a large area of the coast of alexandria, it is considered to be at a high risk of submerging.  problems related to energy 1the absence of any means of energy saving in buildings or in the community as a whole due to all the previous problems. 2 although abu qir area in particular (and alexandria in general) is one of the most sunny places in the world, still there is no benefit from the sun as a renewable source of energy. e. conclusion referring to the previous problems, the document review of the future comprehensive planning for development strategy of abu qir area, the site visits, the interviews, plus the consulting experts in urban and coastal planning as well as environmental design, it is concluded that most of the problems which are present in abu qir area are problems related to community planning and integration with the waterfront. moreover, the other problems of transportation, buildings and environment are all due to the unplanned community of abu qir, and can be solved if community planning and integration with the waterfront are maintained. as a result, community layout and integration with the waterfront should have the highest priority (as shown in fig.10) when considering a developmentproject. the problem of transportation, which is the second significant issue comes next. it should be solved instantly as abu qir area is full of workplaces and important facilities that have to be easily reached and made use of. next to transportaion is the problem of existing buildings. though it is not as important as transportation; still the field study and survey show that building conditions, heights and utilities constitute a major problem of concern. then comes the environmental category that forms higher levels of sustainability. this is explained by colouring priority table from red as the highest priority to violet as the lowest one. fig .11. defining priorities from problems of the case common categories community layout buildings transportation e n v ir o n m e n t water energy materials waste ecology integration with the waterfront common categories priority community layout integration with the waterfront transportation buildings e n v ir o n m e n t waste water energy materials ecology http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 180 resd © 2015 http://apc.aast.edu f. implementations of sustainability guidelines in development of abu qir abu qir community sustainable urban planning needs to consider all of the previous categories resulting from the problems discussed above, bearing in mind to follow the same priority order. rrenovation and rehabilitaion works should be environmentally, socially and economically sustainable. each indicator under those categories is chosen from one of the rating systems analyzed, the indicators chosen are only the indicators that concern the problems in abu qir area. in addition to the indicators specific for the waterfront (concluded in section 4), a checklist of recommended criteria should be set for the replanning of abu qir area. table 7. shows the checklist of criteria produced for sustainable replanning of abu qir vi. conclusion there is a need to develop a rating system specifically for the evaluation and upgrading of abu qir as a waterfront community. the rating system should consider the following:  priorities first (biggest problems are the first categor y indicator c o m m u n it y l a y o u t open community compact development diversity of uses street network access to public spaces universal accessibility community outreach & involvement in te g ra ti o n w it h t h e w a te rf ro n t degree of integration with the water body degree of benefiting from the water source open spaces on the waterfront land use adjacent to or on the waterfront recreational facilities on the waterfront linked facilities and open spaces on the waterfront t ra n s p o rt public transport reduced automobile dependence bicycle network transportation demand management transit facilities street network walkable streets reduced parking footprint traffic management b u il d in g s energy efficient buildings construction pollution prevention reuse of historic buildings building reuse & adaptive reuse housing & jobs proximity diversity of housing types affordable housing e n v ir o n m e n t w a s te waste management proximity to waste water infrastructure construction waste management w a te r water resources management water consumption management community water strategy wet land & water body conservation building water guidelines water monitoring & leak detection community water use reduction landscaping heat rejection water features storm water management water efficient buildings proximity to water infrastructure e n e rg y energy consumption management community energy strategy building energy guidelines energy monitoring & reporting community strategies for passive cooling urban heat reduction renewable energy onsite offsite energy efficient buildings infrastructure energy efficiency m a t e ri a l s local materials recycled materials e c o lo g y biodiversity conservation management of habitat & wetland natural systems protection reuse of land remediation of contaminated land habitat creation & restoration local food production minimize site disturbance through site design minimize site disturbance during construction heat island reduction solar orientation reduce air pollution http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 181 resd © 2015 http://apc.aast.edu to be solved).  creation of connections between waterfront and inner city districts.  benefit from the water source either physically or environmentally.  water as a means of transportation to reduce city traffic and improve the quality of the urban environment.  public accessibility to the waterfront by linking open spaces and recreational facilities to increase social and economic income.  utilization of unused land on the waterfront to serve the previous point.  revival of the waterfront with attractive uses, high-quality public spaces, and publicly oriented water-dependent uses, integrated with adjacent communities.  maintenance and improvement of the environmental quality of water bodies, land and air. vii. concluding remarks waterfront sustainable development is now an obligation for all waterfront cities. however, waterfront planning differs from one place to another according to the needs and problems of the region.that is why all rating system must have it’s own weighting sustainable strategies are the same worldwide, they all call for the same principles. on the other hand, different obligations, rules and regulations are applied to them according to the needs and problems of each region. the egyptian region (waterfront in particular) needs its own sustainability rating system. pursuing strategies to improve the sustainability of the city’s waterfront, the government should focus on increasing resilience to climate change and projected sea-level rise. economic interests must be balanced with environmental and social concerns. however, waterfront work is not just about economic development; yet it is not simply a design question or only about environmental issues. rather, it is a fusion of these elements and related disciplines like balance-people-recreation-public access-open space-safety-suitable and diverse living-mix of usesenvironmenttransport which are all principles of sustainability. references [1] abdel-shafy, h., & el-saharty, a. 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(2002). urban design report 1 . toronto: toronto waterfront revitalization corporation. [43] toronto waterfront revitalization corporation. (2005). east bayfront precinct plan. toronto: toronto waterfront revitalization corporation. [44] toronto waterfront revitalization corporation. (2005). east bayfront precinct plan., (pp. 11-20). toronto. [45] toronto, w. (2008). leed for neighbourhood development. toronto: credit valley conservation authority – strategic sustainability workshop. [46] usgbc, c. f. (2009). leed for neighborhood development. united states: u.s green building council. [47] vallega, a. (2001). urban waterfront facing integrated coastal management. ocean & coastal management, elsevier , volume 44, p.379–410. [48] waterfront toronto. (2009). mandatory green building requirements. toronto. [49] waterfront toronto. (march 2010). waterfront toronto environmental management plan for project-related activities. toronto. http://apc.aast.edu/ http://www.theworldincrisis.com/artman2/publish/climate/rising_sea_levels.shtml http://www.theworldincrisis.com/artman2/publish/climate/rising_sea_levels.shtml journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.021 21 http://apc.aast.edu drivers for, and barriers to solar energy use by manufacturing micro small and medium enterprises (msmes) in tanzania felichesmi s. lyakurwa mzumbe university, department of engineering management studies, po box 87, mzumbe, tanzania email: felichesmi.lyakurwa@mu.ac.tz abstract choice of solar energ y by manufact uring micro, small and medium enterprises (msme’s) has been associated with manufact uring sustainabilit y. in this st udy, the str uct ural equat ion modeling (sem) technique was employed to establish drivers for, and barriers to solar energ y use by manufact uring msme’s in selected districts in morogoro region. the sem results revealed social-economic, technological and environmental factors hindering deploy ment of solar energ y by manufact uring msme’s. also, the results indicated that there are several factors that hinder manufact uring msme’s use of solar energ y for different operat ions including the environmental concern (i.e., staff/ employers’ concern about air pollut ion resulted from energ y use, and staff/employers’ concern about climate change); solar energ y awareness (i.e., experience in previous use of solar energ y, and understanding of different t ypes of solar pv which can be used at industr y level), and solar energ y generat ion cost (i.e., the generat ion of solar energ y may cause addit ional cost, and solar energ y requires high init ial invest ment cost). hence, the results of this st udy can be used by energ y polic y making instr uments to make informed decisions for renewable energ y invest ment in the countr y’s manufact uring sector for manufact uring sustainabilit y. index-words: manufact uring sustainabilit y, renewable energ y, solar energ y, sem model received on, 04 april 2023 accepted on, 06 june 2023 published on, 20 june 2023 i. introduction to date, there is little doubt that fossil fuels are main energy source in the global energy mix despite the highest contribution to the carbon dioxide (co 2 ) concentrations in the atmosphere. in 2021, the global co 2 emissions from energy combustion and industrial processes reached 34.9 gtco 2, an increase of 4.8% from the co 2 in 2020 (deng & davis, 2022). hence, without appropriate technologies that reduce co 2 emissions, the global average atmospheric co 2 concentration, as well as ocean and surface temperatures, will continue to rise (chen et al., 2022). in the world, the magnitude of co 2 emissions varies from one sector to another whereby the industry has the highest contribution (32%), followed by building operations (28%), while transportation (23%), building materials (11%) and others contributing (6%) (ali & ahmad, 2020). eleftheriadis & anagnostopoulou (2015) documented a strong association between co 2 emissions and rise in global temperature, and climate change. for example, tollefson, (2021) documented that climate change impacts have increased the global surface temperature by around 1.1ºc compared to average in 1850-1900, a level that has not been witnessed in the past 125000 years ago whereby the ipcc’s best estimated remains at 3ºc. maximillian et al., (2019) and yang et al., (2022) revealed that rising of the global temperature caused by greenhouse gases (ghg) emission has caused significant damage to the human living environment like extinction of some species, droughts, ocean acidification and sea-level rise. this has affected significantly the livelihoods of people because earning from fishing is low, reduced number of jobs, thereby leaving the community food insecure. considering the negative social, economic and environmental effects of co 2 emissions, many governments in the world have invested heavily on designing efficient climate change policies including emission trading schemes, carbon trading and polluter pays principle. in spite of the short, and moderate term co 2 emissions reduction targets can be achieved with use of such economic pricing instruments, yet ambitious emission reduction goals can be difficult to achieve without pervasive diffusion of a low-carbon technologies (ren et al., 2021). usually, diffusion of renewable energy sources in the national energy mix provides a basis for achieving mass reductions in co 2 emissions in long term. for example, the european union (eu) has set a target of 20% co 2 emission reduction that will be achieved through consumption of more renewable energy sources (council, 2009). also, in 1990 the eu leaders committed about 80-95% reduction of co 2 emissions by 2050 such that it will not be materialized unless a magnitude of 95-100% of the country’s decarbonization of electricity sector is achieved (höhne et al., 2019). according to shahsavari & akbari, (2018) solar photovoltaic (pv) is the most appropriate technology for a source of renewable electricity in developing countries particularly in rural areas because solar pv reduces demand for fossil fuels, and related emissions such as co 2 , nitrogen oxides (no x ) and sulfur dioxide (so 2 ). moreover, it was projected that journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.021 22 http://apc.aast.edu utilization of solar pv by production systems will reduce about 69-100 million tons of co 2 , 126,000-184,000 tons of so 2 , and 68,000-99,000 tons of no x by 2030 such that these reductions will decrease human exposure to serious diseases including heart attacks, and asthma by 2030. in tanzania, many efforts have been made to reduce co 2 emissions, whereby reduction of co 2 emission from cement production was reduced with replacement of fossil fuel (i.e., coal) with sawmill residues. replacement of coal in cement production has reduced ghg emissions by 455-495 kg of co 2 eqmwh-1 which is equivalent to 83-91% decrease in ghg emissions (sjølie, 2012). also, in efforts to reduce co 2 emissions, the government of tanzania has invested a total of $112.4 million for renewable energy generation in the period of twelve years from 2007 to 2019 (lyakurwa, 2022). in the face of vast investment to ensure access, and use of renewable energy by different production sectors in the country, yet deployment of renewable energy for different applications is inadequate. lyakurwa & mkuna, (2018) and elasu et al., (2023) documented several factors hindering adoption of solar energy including consumer’s beliefs about renewable energy benefits, perception of self-effectiveness, political and institutional factors, environmental concern, renewable energy development and awareness, and financial abilities. according to hasan et al., (2022) and zulu et al., (2022), the uptake of renewable energy technologies is hindered by several factors mainly technology advancement, owner’s perception, incentive policy, customer’s behaviour and price of electricity that can be grouped into six groups mainly technical, economic, institutional policy, social, market and organizational. in regard to the manufacturing industries, renewable energy use for different processes is determined by different factors including socio-economic, technology, regulatory and environmental (seetharaman et al., 2019). based on the empirical evidence, access to clean, reliable and affordable energy for domestic and industrial uses is challenge to many developing countries of africa that contributed greatly to dependence on the non-renewable energy mainly fossil fuels for different domestic and industrial applications. fossil fuels are characterized with ever-increase in price, harmful effect on human health and quality of ecosystem like deterioration of aquatic lives, climate change and global warming effects. moreover, majority african countries including tanzania, are blessed with renewable energy sources such as solar energy which is readily available, clean, affordable and can be used for both domestic and industrial purposes (lyakurwa, 2022). despite the benefits of renewable energy (i.e., solar pv), the extent to which solar energy is used for different industrial applications is low. this has brought several probing questions that tries to uncover factors hindering use of solar energy for various industrial applications. hence this study was aimed to establish drivers for, and barriers to solar energy use by manufacturing msme’s for different industrial operations. a. theoretical framework this study was guided by the theory of constraints (toc) which has the objective of profit maximization through increased performance of a production system. saleh et al., (2019) revealed that profit maximization can be achieved via efficient utilization, and management of all input resources e.g., energy, manpower, machine and equipment, materials, and working methods, among others. hence, aggressive business organization places more focus on identified constrains because its elimination offers highest return towards effective and efficient resource utilization, and management. constraint refers to as the weakest link in process of a production system whereas its improvement can be achieved through five distinct stages namely constraint identification, analysis, elevation and subordinating everything to the constraint. application of toc is the most appropriate strategy to solve factors hindering achievement of the goals (e.g., productivity improvement & green manufacturing) by an industry through bottlenecks identification and work out to eliminate or eradicate them. hence, it brings benefit to industries with increased profit due to reduced production cost mainly by adoption of appropriate renewable energy technologies. in this regard, toc can be used to establish as to why manufacturing msme’s do not use solar energy for different industrial operations. the understanding will inform formulation of strategies and policies that will promote use of solar pv by manufacturing industries for sustainable industrial development. kynčlová et al., (2020) sustainable industrial development refers to the situation whereby governments formulate policy and strategies that require industries to operates in a way to meet the economic objectives together with social inclusiveness and minimizing natural resource use, and environmental impacts. usually this can be achieved with effective implementation of the united nations sustainable development goals (sdgs), preferably goal 7: affordable and clean energy, goal 9: industry, innovation and infrastructure, and goal 13: climate action. the toc therefore, is closely linked with barriers to solar energy use by manufacturing industries because they all aim at profit maximization and sustainable industrial development which can be achieved through a shift from using fossil fuels to renewable energy i.e., solar pv. also, implementation of this theory can be achieved through application of reliable, clean and affordable energy sources by manufacturing msme’s to ensure optimal use of resources leading to less environment impacts in course of production processes. it is the interest of this study to make use of the constraint’s theory to explore factors hindering manufacturing msme’s use of solar energy for manufacturing sustainability. journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.021 23 http://apc.aast.edu ii. data and methods b. study area this study was conducted in the four (4) districts in morogoro region namely morogoro municipal council, mvomero district, kilombero and kilosa district council. morogoro region is located at latitudes 6.8278°south of equator, and longitudes 37.6591° east of greenwich meridian. the region covers a total area of 70,624 sq. kms with a population of 2,218,492 (urt, 2013). the study was conducted in the selected districts because many households are livestock keepers and farmers whereas their produce requires value addition by manufacturing msme’s. according to lyakurwa (2022) manufacturing enterprises are classified into four (4) broad categories based on the number of employees, total investment and sales turnover (table 1). table i: classification of enterprises category employees capital investment in machinery (tzs) micro enterprise 1 – 4 5 million small enterprise 5 – 49 >5 to 200 million medium enterprise 50 – 99 >200 to 800 million large enterprise 100+ >800 million urt (2012) also, morogoro region has adequate number of renewable energy sources including solar pv, biomass, biogas, wind and hydro power, to mention few. despite the availability, the selected districts as other districts in tanzania experiences inadequate access to reliable, clean and affordable energy sources whereby majority manufacturing msme’s use non-renewable energy for different applications. the dependency on nonrenewable energy sources has contributed greatly to the regions’ failure to realize the tanzania national five-year development plan 2021/22 2025/26, national strategy for growth and reduction of poverty (nsgrp), the sgds, and the tanzania development vision 2025 (urt, 2000; urt, 2010; urt, 2021; sonter & kemp, 20212015). hence, developing barriers to solar energy use by manufacturing msme’s is critical towards achievement of the sdgs, nsgrp, tanzania vision 2025 and national five-year development plan of 2021/22 to 2025/26. c. research design, data sources, and collection process a cross sectional survey research design was employed to establish barriers to solar energy use by the manufacturing msmes in the selected four (4) districts in morogoro region. according to van der stede (2014), this design enables collection of large amounts of data at one location in time in the most economical way. the method was also supported by connelly (2016) which documented that, a cross sectional survey design is mostly appropriate when the study intends to answer questions of who, what type, where, how many and how much as revealed by this study. a well-structured questionnaire and interviews guide questions were used to collect primary data from the manufacturing msme’s located in morogoro municipal council, mvomero, kilombero and kilosa district councils. the multistage sampling technique was applied in the selection of representative manufacturing msme’s (i.e., a sample size (n) of 242 enterprises) in the selected districts. d. methods for data analysis the preliminary, descriptive and inferential statistical analysis methods were employed in the analysis of the collected data about workers perceptions about sustainable manufacturing practices as well as drivers for, and barriers to solar energy use by the manufacturing msme’s in the selected districts in morogoro region. preliminary analysis involved data quality check and testing the assumptions of exploratory factors analysis (efa) such that all missing values were checked. the normality of data was also checked to establish whether the collected data are good for the structural equation modeling (sem) through confirmatory factor analysis (cfa). thereafter, the descriptive and inferential analysis were carried out. the descriptive analysis was conducted to different data groups mainly gender, work experience, education level, number of employees, and capital invested in the business, among others. the descriptive analysis intended to provide an insight of some findings, which may not necessarily be in the focus of the study’s specific objectives. the inferential analysis i.e., efa and cfa were performed. the efa was conducted in each construct (i.e., environmental concern (ec), solar energy awareness (sea), self-effectiveness perception (sep), solar energy generation cost (segc), solar technology advancement (sta), perceived benefits of solar energy (pb), msme’s intention to use solar energy (msme’siuse), and risk/trust perception of solar energy (rtse)), and confirm variables in different groups of the factors hindering use of solar energy by manufacturing msme’s. the sem through cfa has been applied in modeling drivers for adoption of manufacturing technologies and renewable power generation (hariyani & mishra, 2023; jabeen et al., 2019), and barriers to sustainable construction and sweetened beverages consumption (durdyev et al., 2018; wang & chen, 2022). the confirmed factors were analyzed by using cfa so as to identify the relative importance of each towards deployment of solar energy by manufacturing enterprises. thereafter, the inferential analysis mainly correlation analysis was used to characterize the relationship between the variables i.e., factors influencing decision to use solar energy by manufacturing msme’s. iii. results and discussion e. respondents profile table ii presents the descriptive statistics of the respondent characteristics for drivers for, and barriers to solar energy use by manufacturing msme’s in tanzania. journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.021 24 http://apc.aast.edu table ii: respondent profile s/no. variable measure n % gender male 166 72 female 66 28 age 18-24 37 16 25-31 83 35 32-38 81 34 >39 35 15 work experience 1-5 91 42 6-10 78 36 11-15 19 9 16-20 19 9 >20 11 5 marital status married 86 49 single 91 51 workers education primary 13 6 secondary 112 50 degree 98 44 the results (table ii) indicate that out of 232 staff working in the manufacturing msme’s, 166(72%) were male and 66(28%) were female which implies that tasks performed by these industries are not masculine and a sign of gender balanced working environment. in regard to the workers age, 38(17%) have ages ranging 18-24 years, 83(35%) ages 25-31 years, 80(34%) ages 32-38 years, while 35(15%) aged more than 39 years old. the results imply that majority working staff are young, matured and energetic person that reflects empowerment of youths. the results for the working experience showed that majoring staff are new employees with working experience ranging 1-5 years, that is 91(42%), followed by a working experience of 6-10 years i.e., 78(36%), while the manufacturing msme’s have few staff with a working experience more than 20 years, that is 11(5.0). considering the workers education level, majority have secondary education, 112(50%), followed by degree holders, a total of 98(44%), and 13(6%) have a primary education. the results imply that the surveyed manufacturing msme’s have employed staff trained at different levels to work in different production sectors. f. drivers for, and barriers to solar energy use by manufacturing msme’s the cfa revealed seven (7) factors that drive manufacturing msmes’ deployment of solar energy in different operations. with the cfa, it was assumed that there would be a single dominant factor whereas a number of factors were specified whereas the covariance of the 7 factors are fully explained by the single latent variable plus the unique variance of each factor. in this case, the unique variance or error variance, is being estimated for each of the seven (7) observed indicator variables (figure 1). in the cfa, it was assumed that deployment of solar energy by a manufacturing msmes’ should explain all the variance among seven factors. at first place, weak results were obtained such that stronger results will be obtained by removal of the measurement error given the latent variables are subsequently used as independent or dependent variables in a sem. the cfa model was fitted by using a maximum likelihood estimation method whereby variance-covariance matrix of the estimators i.e., the standard errors were computed using an observed information matrix. usually, with the assumption of normality, this method is often the best option and is fairly robust even with same violation of normality since it uses a listwise deletion approach (lee et al., 2002). figure 1: cfa model for drivers to the solar energy use by msmes’ figure 1 is the path diagram for a sem model with observed exogeneous variables and a latent variable. the model can be represented with a mathematical notation by a general equation 1 as follows: yi=βi0+m+β1i xi+ … +bin xn+ϵi; given i=1,… ,n (1) where, (y,x 1 ,… ,x n )~iid with mean μ and covariance matrix σ; y is the dependent exogeneous variable (msmes intention to use solar energy); xs are the independent observed exogeneous variables; and m is the single latent variable i.e., deployment of solar energy to msmes. fitting the cfa model the comparative fit index (cfi) and tucker lewis index (tli) are both incremental fit indices values >0.95 whereby these indices indicate a very good fit (sahoo, 2019) structural equation modeling is a buzz word in the arena of research in management, social sciences, and other equivalent fields. although the theoretical base bears its significance in building the measurement and structural models, assessing different goodness-of-fit indices (gofi. shi et al., (2019)the tucker–lewis index (tli indicated that values from 0.90 or above are considered evidence of the acceptable model fit. also, the standardized room mean square residual (srmr) values up to 0.05 are considered journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.021 25 http://apc.aast.edu indicative of a close-fitting model whereas the values ranging between 0.05 up to 0.10 suggest acceptable fit. the sem model fitting results presented in table iii showed that, the cfi (0.348) and tli (0.088) values are lower than 0.90. thus, the cfi and tli indicates poor model fitting such that re-analysis was performed to generate standardized results. table iii: sem model fitting results fit statistic value description likelihood ration chi2ms(20) 235.501 model vs. saturated p>chi2 0.000 p>bs(28) 358.757 baseline vs. saturated p>chi2 0.000 population error rmsea 0.221 root mean square error of approximation 90% ci, lower bound 0.196 upper bound 0.247 pclose 0.000 probability rmsea<=0.05 information ccriteria aic 3950.776 akaike's information criteria bic 4032.332 bayesian information criteria baseline comparisonn cfi 0.348 comparative fit index tli 0.088 tucker-lewis index size of residuals srmr 0.166 standard root mean squared residual cd 1.000 coefficient of determinationn cfa model estimation and interpretation table iv indicates that there are 21 observations with missing values excluded in the model because the default estimation method i.e., maximum likelihood uses listwise deletion such that all observations which do not have a response for all factors are dropped off (chen et al., 2020)whereas the model of interest to the researcher is at the composite (scale score. all observed factors from environmental concern (ec) to self-effectiveness perception (sep) in the model are all endogenous variables i.e., these measurement variables depend on the latent variable i.e., the solar energy deployment (sedeployment). also, the maximum likelihood estimator maximizes the log-likelihood function such that with the listwise deletion method, only 221 observations were available with no missing values. the results present the “measurement” and a “variance”. the measurement gives estimates of unstandardized measurement coefficients i.e., factor loadings, their standard errors, and a z-test for each estimate along loadings. to identify the variance of the latent variable, (i.e., solar energy deployment), the software fixes the loading of the first indicator at 1.0 that is called, a reference indicator whereas all unstandardized estimates will change if there is a change in reference indicator. table iv: cfa model estimation and interpretation structural equation model estimation method = ml number of observations = 221 log likelihood = -1617.7867 (1) ec [se_deployment] = 1 measurement coef. std. err. z p>izi [95% conf. interval] ec se_deployment .1671627 .0772 2.17 0.030 .0158534 .318472 const. 4.902182 .2426813 20.20 0.000 4.426535 5.377829 sea se_deployment -.6727413 .0789552 -8.62 0.000 -.8257267 -.5197558 const. 2.911463 .1539569 18.91 0.000 2.609713 3.213213 segc se_deployment .3142185 0.0731089 4.30 0.000 .1709278 .4575093 const. 4.399605 .2198134 20.02 0.000 3.968779 4.830432 sta se_deployment -.7953117 .0839691 -9.47 0.000 -.9598881 -.6307354 const. 2.750931 01471264 18.70 0.000 2.462568 3.039293 pb se_deployment -.2359973 .0764013 -3.09 0.002 -.3857411 -.0862535 const. 4.10418 .2064804 19.88 0.000 3.699486 4.508874 rtse journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.021 26 http://apc.aast.edu structural equation model estimation method = ml number of observations = 221 log likelihood = -1617.7867 (1) ec [se_deployment] = 1 measurement coef. std. err. z p>izi [95% conf. interval] se_deployment -.2337238 .0867011 -3.01 0.003 -.3859403 -.0815072 const. 3.926254 .1984981 19.78 0.000 3.537205 4.315303 sep se_deployment .2292345 .0867011 2.64 0.008 .0593035 .3991654 const. 3.618576 .1847959 19.58 0.000 3.256383 3.980769 the cfa results revealed that, three factor loadings (i.e., msmeiuse (p value =0.030), rtse (p value =0.039) and sep (p value =0.001)) are statistically significant (all p value < 0.050). this is construed to mean that such the indicator variables (msme’s intention to use solar energy (msmeiuse), risk perception of solar energy (rtse), and self-effectiveness perception (sep)) are significantly related to their respective factors, and therefore the main drivers for the solar energy use by manufacturing msme’s in tanzania. the results are in-line with the study by schoeneberger et al., (2020) which explored drivers for deployment of solar pv by manufacturing industries in us whereby economic, environmental and technological factors were critical for solar pv deployment. g. barriers to solar energy use by manufacturing msme’s factor hindering manufacturing msmes’ use of solar energy for different activities are explained by eight (8) constructs i.e., environmental concern (ec), solar energy awareness (sea), solar energy generation cost (segc), solar technology advancement (sta), perceived benefits of solar energy (pb), msme’s intention to use solar energy (msme’siuse), risk/trust perception of solar energy (rtse)), and self-effectiveness perception (sep). the correlation results (table v) showed that factors hindering solar energy use by manufacturing msmes’ are environmental concern (positive correlation=0.2070), segc (positive correlation=0.0726) and sep (positive correlation=0.0816), while the factors such as sta (-0.1195), pb (-0.0123), msme’siuse (-0.067) and rtse (-0.0477) have negative correlation. table v: correlation analysis factors ec sea segc sta pb msmeiuse rtse factors 1 ec 0.2070 1 sea -0.0255 -0.0572 1 segc 0.0726 -0.0244 -0.1975 1 sta -0.1195 -0.1579 0.5321 0.29 1 pb -0.0123 0.079 0.1071 0.02 0.2074 1 msmeiuse -0.067 0.4052 0.3094 0.13 0.3091 0.118 1 rtse -0.0477 -0.0709 0.193 0.18 0.1742 0.4428 0.2007 1 sep 0.0816 0.2966 -0.2565 0.18 -0.112 0.0355 0.325 0.0855 cfa of factors hindering use of solar energy by manufacturing msmes’ the exploratory factor analysis (efa) was conducted in each construct by using the principal component factor method which involved several processes including data examination, factor analysis, rotation and prediction of values. the examined data are presented in table vi. table vi: data examination variable obs. unique mean min max label ec 233 18 3.682 1.60 5.00 environmental concern sea 236 18 2.374 1.00 5.00 solar energy awareness segc 241 13 2.585 1.00 4.00 solar energy generation cost sta 236 13 1.894 1.00 5.00 solar technology advancement pb 241 15 2.466 1.00 5.00 public benefits of solar energy msmeiuse 240 17 3.156 1.00 5.00 msme's intention to solar energy rtse 237 16 2.889 1.00 5.00 risk perception of solar energy sep 240 16 3.256 1.00 5.00 self-effectiveness perception journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.021 27 http://apc.aast.edu the examination results (table vi) revealed that there were eight constructs whereas their mean values range from 1.894 to 3.6815. the factor analysis revealed eight principle factors with eigen values, and proportions as indicated in table vii. table vii: factor analysis results factor analysis/correlation number of obs=221 methods: principal-component factors retained factors=3 rotation:(unrotated) number of params=21 factor eigenvalues differences proportion cumulative factor1 2.10884 0.37864 0.2636 0.2636 factor2 1.73019 0.34917 0.2163 0.4799 factor3 1.38103 0.55016 0.1726 0.6525 factor4 0.83087 0.11617 0.1039 0.7564 factor5 0.7147 0.18972 0.0893 0.8457 factor6 0.52497 0.15444 0.0656 0.9113 factor7 0.37054 0.03167 0.0463 0.9576 factor8 0.33887 0.0424 1 lr test: independent vs. saturated: chi2(28) = 353.08 prob>chi2=0.000 factor loadings (pattern matrix) and unique variances variables factor1 factor2 factor3 uniqueness ec 0.0705 0.6788 -0.4300 0.3494 sea 0.7418 -0.3022 -0.1044 0.3475 segc -0.333 0.3354 0.5737 0.4476 sta 0.775 -0.2775 -0.0822 0.3157 pb 0.4744 0.2283 0.5257 0.4465 msmeiuse 0.6122 0.5200 -0.3535 0.2299 rtse 0.4893 0.2419 0.6660 0.2585 sep -0.0538 0.7795 -0.0669 0.3850 the eigenvalues explain factors in terms of variability such that only three components i.e., ec, sea, segc were retained because their eigenvalues are greater than 1 (table vii). this indicates that the main factors hindering manufacturing msmes’ use of solar energy falls in the three constructs i.e., environmental concern (ec): staff/ employers’ concern about air pollution resulted from energy use, staff/employers’ concern about climate change, staff/employer concern about source of energy which do not deteriorate the quality of ecosystem – biodiversity, decline of animal species, staff/employer’s concern on water/land pollution caused by energy use by msme’s and staff/employer’s concern about waste reduction); solar energy awareness (sea): experience in previous use of solar energy, awareness of solar pv use and needs/benefits, understanding of different types of solar pv which can be used at industry, availability of technical solutions for solar pv and awareness of the benefits-costs of solar pv; and solar energy generation cost (segc): the generation of solar energy may cause additional cost, solar energy requires high initial investment cost, solar energy consumption needs a high set-up & installation cost, and solar pv systems requires high repair cost. these results are in-line with lowe & drummond, (2022) high rates of growth appear likely to continue. in this paper we use ‘top-down’ extrapolation of global trends and simple and transparent models to attempt to falsify the proposition that pv and wind have the potential to achieve dominance in global primary energy supply by 2050. we project future deployment of pv and wind using a logistic substitution model, and examine a series of potentially fundamental constraints that could inhibit continued growth. adopting conservative assumptions, we find no insuperable constraints across physical and raw materials requirements, manufacturing capacity, energy balance (eroei study about global wind and solar energy supply, which revealed that use of renewable energy for different industrial purposes is hindered by various social (e.g., health impacts of the energy use for different industrial purposes), economic (e.g., high investment cost), and environmental (e.g., emission of ghgs) factors. these barriers to solar energy use not only resulted into social, economic and environmental problems but also delayed the growth and development of the manufacturing sector in tanzania. for example, rocco et al., (2020)together with a low electrification rate, are a limitation to growth, this paper studies the implications on the country's sustainable development of expanding the electricity sector. the analysis is based on the joint use of the osemosys opensource power system optimization model and the leontief input-output model (based on the tanzanian social accounting matrix found that lack of infrastructure for hydro-electric generation is the main cause of low electrification rate and ultimately has limited the growth of manufacturing sector in the country. with the industrialization strategy in tanzania access to clean, affordable and reliable energy source is critical since it the only way manufacturing industries can improve its operational performance i.e., ensure quality products, reduced cost of production and idle time, increase productivity, and achieve production flexibility. these will ensure a competitive position of the manufacturing msme’s in the local and international markets due to low production cost and ability to set a competitive selling price as well as compliance to the global standards like assurance of environmental performance of manufactured after use e.g., eco-labelling. in addition, the proportions explain the contribution of each factor in the model whereby factor1 (i.e., environmental concern) contribute about 26.36% of the total variance, which is the strongest factor. also, uniqueness explains the percentage of variance for the factor that is not explained by the common factors. also, table vii revealed that all values are not greater than 0.6 which implies that these values are considered low. therefore, the higher the uniqueness, the more likely that it is more than just a measurement error. factor rotation maintains that factor 1 (i.e., the environmental concern) is the strongest factor with a proportion of 25% (table viii. journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.021 28 http://apc.aast.edu table viii: factor rotation factor analysis/correlation number of obs = 221 method: principal-component factors retained factors = 3 rotation: orthogonal varimax (kaiser off) number of params = 21 factor variances difference proportion cumulative factor1 1.9705 0.28614 0.2463 0.2463 factor2 1.68436 0.11915 0.2105 0.4569 factor3 1.56521 1957 0.6525 lr test: independent vs. saturated: chi2(28) = 353.08, prob>chi2=0.000 rotated factor loadings (pattern matrix) and unique variances variable factor1 factor2 factor3 uniqueness ec -0.0918 0.7921 -0.1214 0.3494 sea 0.7915 -0.02 0.1602 0.3475 segc -0.6041 -0.0579 0.4292 0.4476 sta 0.8024 -0.0004 0.2014 0.3157 pb 0.1433 0.0803 0.7256 0.4465 msmeiuse 0.4124 0.7615 0.142 0.2299 rtse 0.1064 0.0325 0.8539 0.2585 sep -0.3535 0.6825 0.1559 0.385 factor rotation matrix factor1 factor2 factor3 factor1 0.8513 0.2577 0.4571 factor2 -0.4215 0.8546 0.3033 factor3 -0.3125 -0.4509 0.8361 table ix presents the predicted values based on the varimax rotated loadings of the variables by a regression method. table ix principle component predicted values predict factor 1, factor 2, factor 3 (regression scoring assumed) scoring coefficients (method=regression; based on varimax rotated factors) variables factor1 factor2 factor3 ec 0.03963 0.48426 -0.12607 sea 0.3967 0.02452 0.04462 segc 0.34591 0.06233 0.33393 sta 0.39903 0.01556 0.06958 pb 0.01692 0.00092 0.46113 msmeiuse 0.20042 0.44704 0.00984 rtse 0.01211 0.03818 0.55167 sep 0.19649 0.4003 0.08449 the results (table x) revealed that the mean score regarding factors hindering manufacturing msmes’ use of solar energy to be 2.79, and a standard deviation of 0.38. also, the means score of the factors hindering solar energy deployment revealed a normal distribution curve (figure 2). table x: mean score of the factors hindering use of solar energy summarize: se_deployment, detail se_deployment percentiles smallest 1% 1.94375 1.541667 5% 2.270833 1.57619 10% 2.43125 1.94375 obs 242 25% 2.535417 1.972917 sum of wgt 242 50% 2.7125 mean 2.786757 largest std. dev 0.3818454 75% 3.04375 3.7125 90% 3.30625 3.7125 variance 0.1458059 95% 3.40000 3.7125 skewness 0.2019058 99% 3.71250 3.8750 kurtosis 3.365797 0 10 20 30 40 50 fr eq ue nc y 1.5 2 2.5 3 3.5 4 se_deployment figure 2: distribution of factors hindering solar energy iv. conclusion the main objective of this study was to determine drivers for, and barriers to solar energy use by manufacturing msme’s in the selected districts in morogoro region. as the first study to model drivers for, and barriers to solar energy use by manufacturing msme’s in tanzania, the main drivers for solar energy use were established by using the sem. the results revealed that drivers for manufacturing msme’s deployment of solar energy for different operations includes the environmental concern, solar energy awareness, energy generation cost, technological advancement, benefits of solar use, and risk perceptions. in this regard, manufacturing msme’s management have significant influence on deployment of solar energy for different industrial operations. for example, the extent to which top management and journal of renewable energy and sustainable development (resd) volume 9, issue 1, june 2023 issn 2356-8569 http://dx.doi.org/10.21622/resd.2023.09.1.021 29 http://apc.aast.edu leaders, are exposed to the cost and benefits of renewable energy, determines decisions made for solar energy use, and even approve education programme to the staff about renewable energy technologies. in addition, sem results indicates that there are three main factors that hinder deployment of solar energy by manufacturing msme’s including environmental concern, solar energy awareness, and solar energy generation cost. as far as solar energy generation cost is one of the factors hindering msme’s deployment of solar energy, effective policy could involve offering tax subsidy to renewable energy production facilities i.e., machines and equipment; together with enforcement of national environmental management act of tanzania and its regulations like the sub-section which states about “polluter pays principle” for industries to strictly use energy sources that are environmentally friendly. the sem results therefore, provides critical information to energy policymaking instruments in tanzania about drivers for and barriers to solar energy deployment by manufacturing msme’s and make informed decisions about renewable energy technologies to be considered for investment in tanzania. acknowledgements this study was supported by vlir-uos project 3, mzumbe university, tanzania. references [1] k. a. ali, m. i. ahmad, and y. yusup, “issues, impacts, and mitigations of carbon dioxide emissions in the building sector,” sustainabilit y (switzerland), vol. 12, no. 18, 2020, doi: 10.3390/su12187427. 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[28] s. l. zulu, m. chabala, and e. zulu, “perceptions and beliefs influencing intention to use solar energy solutions in zambian households,” built environment project and asset management, vol. 11, no. 5, 2021, doi: 10.1108/bepam-01-2021-0010. journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 113 resd © 2015 http://apc.aast.edu on the long-term behavior of wind-wave climatology over the west region of scotland, uk tarek m. el-geziry laboratory of physical oceanography, division of marine environment, national institute of oceanography and fisheries, alexandria, egypt tarekelgeziry@yahoo.com abstract using 38 years (january 1973-december 2010) of hourly wind records, the present paper aims at drawing the possible long-term trends of winds and ten surface wave parameters over the west region of scotland, using the quadratic regression approach. four dominant wind components were determined: the southern, the western, the south-western and the north-western. two opposite groups of oscillations were proven: one for the southern groups and one for the western groups. the examined wave parameters were: the wave frequency, the wave angular frequency, the peak angular frequency, the wave spectral density, the significant wave height, the peak period, both the peak and group velocities and lastly the wave energy and the wave power. results revealed that every examined parameter tended to have a cyclic behaviour except the wave spectral density, which appeared to be linearly decreasing. all wave frequencies were in an inverse correlation to the mean monthly wind speed. all other wave parameters appeared to be highly correlated to the mean monthly wind speed with correlation factors exceeding 0.95 except the wave power, which had a correlation factor of 0.89. in conclusion, the general behaviours of the dominant wind components over the west region of scotland, and of the different wave parameters tend to be cyclic. a longer time series, than that presently used, will be advantageous in order to strengthen this outcome with more robust investigation. this concluded cyclic behaviour may positively have impact on the engineering work within the wave energy resource off the western coasts of scotland. keywords scotland, anomaly, wind, wave, quadratic regression, cycles. i. introduction it is well-known that air masses intrusion or replacement over any area or basin is the primary mechanism connecting atmospheric and oceanic characteristics through the transfer of heat, moisture and momentum at the sea surface (elgeziry et al. 2013). ocean waves are produced by the movement of these air masses (winds) over the sea surface. the faster the wind, the longer the wind blows, and the bigger the area over which the wind blows, the bigger the generated waves. wave energy, i.e. energy of ocean surface waves, is created by the drag of winds over the sea (mollison 1994). the west region of scotland (fig. 1), extending along the atlantic ocean, tends to have one of the strongest and, meanwhile, steadiest wind system all over the world. the region is also believed to be one of the worldwide vital renewable energy resource with its surface wave characteristics. geographically, the west region of scotland covers the western half of both the central lowlands and southern uplands of scotland. this comprises kintyre, strathclyde, galloway and dumfries. the region also includes the isles of tiree, mull, arran and jura. factually, the examination of the long-term behaviour of wind at a given site is considered a clue to understand changes in both the wind system, as a key player in the generation of surface ocean waves, and the wave resource itself. according to the uk met office climate wind data (http://www.metoffice.gov.uk/), the prevailing wind directions over the west region of scotland lie between south and northwest for the majority of occasions, and the strongest winds nearly always blow from this range of directions. this is mainly attributed to the atlantic depressions, which pass by the united kingdom, and is considered the main cause of air mass movement over the region. results of wind analysis by corbel et al. (2007) revealed that http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 114 resd © 2015 http://apc.aast.edu the occurrence of strong south westerly winds at sites around the scottish coasts is closely linked to the behaviour of the north atlantic oscillation (nao). most of the long-term wind analysis research and studies focused on the use of winds as a renewable energy resource, i.e. wind power, e.g. youm et al. (2005); sinden (2007); lindsey (2011); olaofe and folly (2012); anastasiades and mcsharry (2013). the target has mainly been to specify conditions and characteristics of windy regions and to test the feasibility of wind farm construction according to density function, height variability, wind energy potential, turbine distribution…etc. the behaviour of waves is determined by the spectrum of the sea state, s (f, θ), which specifies how the wave energy is distributed in terms of frequency and direction (longuet-higgins 1957; mollison 1994). however, many models of the spectrum of wave measured at a certain point are widely-used regardless the wave direction. generally speaking, there are two main types of these wave spectra: the mono-parameter spectrum (e.g. pierson and moskowitz 1964) and the multi-parameter spectrum (e.g. bretschneider 1959; hasselmann et al. 1973; ochi-hubble 1976). the spectrum type is determined based on the required number of the input parameters. wind and wave properties in the shelf regions of the atlantic ocean, including the coasts of scotland have been previously studied (e.g. woolf and challenor 2002; wolf and woolf 2005; weisse and von storch 2010). trends and cycles for climatological parameters, hydrography and fish catch have been investigated for long-term data in different regions worldwide, e.g. maiyza 1984; fedrouich 1985; baumgartner et al. 1992; kawasaki 1994; levitus 1995; hylen 2002; klyashtorin and lyubushin 2007; sundby and drinkwater 2007; maiyza and kamel 2009; 2010; maiyza et al. 2011; said et al. 2012; el-geziry et al. 2013. moreover, from a the behavioural point of view, long-term variations in winds have been previously investigated in the south-eastern mediterranean sea region (el-geziry et al. 2013). all these studies proved the cyclic nature and strengthened the concept of oscillations of the examined parameters. the cycle of those oscillations have periods that may extend to centuries. to the author’s knowledge, the long-term trends of variations in the wind-wave climatology over the west region of scotland have not been previously examined from a behavioural trend point of view. the present paper aims at drawing the possible long-term trends of winds and ten surface wave parameters over the west region of scotland, using the quadratic regression approach. for those who work in the wave energy field, year-to -year and long term climatic variability are especially important for estimating the life time extremes that a structure will experience (mollison 1994). fig .1. map of the west region of scotland showing the location of tiree meteorological station (adapted from speedie et al., 2009) ii. data and method of analysis the selected data set of wind vectors (speed and direction) covers 38 years (january 1973 december 2010) based on hourly records over the period of investigation. this is obtained from tiree meteorological station (56° 30.00’ n; 6° 52.98’ w; fig. 1) placed at an elevation of 9 m above the mean sea level (msl) (http://gis.ncdc.noaa.gov/map/viewer/#app=cdo). this station, facing an open sea region, is used as a representative meteorological point for the whole western region of interest. the dominant wind directions over the period of investigation have been specified through the calculation of the percentage of wind occurrence frequency. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 115 resd © 2015 http://apc.aast.edu the mean monthly wind speed (mmws; mean for specific month every year) for the four most dominant wind components over the 38-year data set and the monthly mean speed (wm; mean for specific month of all years) for every month in the whole data set are calculated. the deviation from the monthly mean (δw) is computed on monthly basis in order to express the monthly wind anomaly (mwa), using the following equation: m wwsmmmwaw  (1) the general trend of the monthly variation in the mwa is examined, using the quadratic regression approach. the specific years of the lowest and highest calculated mwa are determined using the first derivative concept for the generated equations. the available wind data and the location of tiree meteorological station satisfy the assumptions of pierson and moskowitz (1964):  north atlantic data, specified on the sea state as a fully developed sea (fds)  deep water  unlimited fetch  unidirectional sea, and  no swell therefore, the pierson-moskowitz spectrum model has been applied in the present research. the spectral function of the spectrum takes the form: 4 2 5 )(               o egs (2) where, s (ω) is the wave spectral density function (m2s), α = 0.0081, ω is the wave angular frequency (rad/s), g is the acceleration of earth’s gravity (9.81 m/s2), β = 0.74 and ωo = g/u19.5 (rad/s). u19.5 is the wind speed (m/s) at a height of 19.5 m above the msl; u19.5 = 1.075 u10. u10 is the measured wind speed (m/s) at a height of 10 m above the msl. in the present work, u10 is the wind speed directly recorded by tiree meteorological station. the wave peak frequency (rad/s) and peak speed (m/s) of the pierson-moskowitz spectrum are, respectively, calculated by the equations: ωp = 0.877 (g/u19.5) = 0.877 ωo (3) cp = g/ωp (4) the significant wave height (m) calculated from the pierson-moskowitz spectrum is          g u h s 2 5.19 21.0 (5) and the wave peak period (s) is        g u t p p 5.1914.7 2   (6) in order to get the wave angular frequency to build-up the pierson-moskowitz spectrum for the present research, the satisfied fds condition enabled to derive both the corrected wind speed (ua; m/s) and the wave period (t; s) using the following equations (holmes 2001): 23.1 10 71.0 uu a  (7) t = 0.83 ua (8) the wave energy (e; j) (holthuijsen 2007) and the wave power (p; w/m2) (phillips 1977) are calculated using the two following equations, respectively: 2 8 1 s hge  (9) where e is the wave energy ρ is the ocean water density 1025 kg/m3 p = e cg (10) where,p is the wave power cg is the wave group velocity (m/s), calculated as the half peak wave celerity for the present deep water wave status.the general trends of the long-term variations of the different wave parameters off the western coasts of scotland have been produced using the quadratic regression approach. these parameters are the wave frequency, the wave angular frequency, the peak angular frequency, the wave spectral density, the significant wave height, the peak period, both the peak and group velocities and lastly the wave energy and the wave power. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 116 resd © 2015 http://apc.aast.edu iii. results 1. hourly wind-wave climatology the raw data set downloaded directly from the meteorological site consists of 397340 hourly observations. this exceeds the supposed record of observation, 333096 hours, for the 38 years of study. this data excess is mainly attributed to data repetition and to the extra 10, 20 and 50 minutes of records in some months. accordingly, the initial data set has been filtered and the final data set used for the present analysis has been set up to consist of 323866 hourly records of both wind speed and wind direction. this represents 97.23% of availability, with 9230 records (2.77%) missed. however, statistically speaking, these missed records do not affect the data quality to proceed for the proposed investigation. over the period of investigation, the hourly wind speed varied between calm (0 m/s) and 38.89 m/s with an average of 7.34 m/s over the period of investigation. moreover, 12 wind speed classes have been specified as shown in table (1) and their percentage of occurrence has been figured out in figure (2). while the dominant speed interval over the study period was >5:10 m/s, with an occurrence of 41.25%, the lowest speed interval was >35:40 m/s with 0.0006%. table 1. hourly wind speed classes wind speed classes (m/s) no. of observations 0 (calm) 3628 >0:5 107312 >5:10 137408 >10:15 63083 >15:20 11273 >20:25 1071 >25:30 83 >30:35 6 >35:40 2 missed data 9230 fig .2. the percentage of occurrence of different wind speed intervals the hourly statistics of the different wave parameters from january 1973 to december 2010 are shown in table (2). the pierson-moskowitz wave spectrum for the present hourly wind speed is shown in figure (3). figure (4) shows the hourly significant wave height and hourly wave peak period calculated from the pierson-moskowitz spectrum. fig .3. the fds pierson-moskowitz spectrum off the western coasts of scotland based on the hourly wind records table 2. hourly statistics of the different wave parameters minimum maximum mean u10, recorded wind speed, (m/s) 0 38.89 7.34 ua, corrected wind speed, (m/s) 0 64.0 8.5 t, wave period, (s) 0 53.1 7.1 f , wave frequency, (hz) 0.0187 0.280 0.250 ω, wave angular frequency, (rad/s) 0.1181 28.714 1.571 u19.5, wind speed at 19.5 m above msl, (m/s) 0 41.8 7.8 s (ω), wave spectral density, (m2s) 0 1.122 0.189 ωp, wave peak frequency, (rad/s) 0.2057 17.903 1.577 cp, wave peak speed, (m/s) 0 47.6 8.9 hs, significant wave height, (m) 0 37.4 1.7 tp, wave peak period, (s) 0 30.4 5.7 e, wave energy, (j) 0 1759948 7467.19 cg, wave group velcoity, (m/s) 0 23.7 4.4 p, wave power, (w/m2) 0 41941970 64319.28 0.0 10.0 20.0 30.0 40.0 0 (calm) >0:5 >5:10 >10:15 >15:20 >20:25 >25:30 >30:35 >35:40 misssed wind speed intervals (m/s) % o f o c c u r r e n c e http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 117 resd © 2015 http://apc.aast.edu fig .4. significant wave height and period at the peak of the spectrum of fds calculated from the pierson-moskowitz spectrum using equations (5 and 6) 2. dominant wind directions the dominant wind directions in the present study have been determined using the percentage of wind occurrence frequency for the main 16 wind directions. table (3) shows this percentage in a descending order. from this table, the four major dominant winds during the period of investigation were the southern (s), the western (w), the south-western (sw) and the north-western (nw) winds. this agrees with the general climatology of the wind direction prepared by the uk met office for the region of west of scotland. the calm wind (0 m/s) represented 1.09% of the recorded wind data, i.e. 3628 hourly records. a. mean monthly wind speed (mmws) the mean monthly wind speed (mmws) is one of the most important parameters in the wind profile of any given site. figure (5) shows the histogram of the mmws variations. in table (4), vmin, vmax and mmws are the mean monthly minimum wind speed, mean monthly maximum wind speed and the mean monthly wind speed, respectively. it can be seen that the highest vmax as well as the maximum mmws occur during the three months of the winter season: january, february and december. this reveals that these months might have the potential of recording the highest amount of exploited wave energy in the area of investigation. fig .5. histogram of the mean monthly wind speed (mmws) over the study period table 3. percentage of occurrence frequency of wind directions wind direction no. of hourly records % of occurrence frequency s 34742 10.43 w 33310 10.00 sw 31777 9.54 nw 28646 8.60 ssw 25715 7.72 se 24216 7.27 wsw 21784 6.54 sse 21784 6.54 nwn 17421 5.23 wnw 16655 5.00 ese 16055 4.82 e 10926 3.28 ne 10659 3.20 nne 9560 2.87 n 9327 2.80 een 7661 2.30 direction records 320238 96.14 calm wind (0 m/s) 3628 1.09 missed records 9230 2.77 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 january february march april may june july august september october november december months m e a n m o n th ly w in d s p e e d ( m /s ) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 118 resd © 2015 http://apc.aast.edu table 4. minimum, maximum and mean monthly wind speeds over the study period vmin (m/s) vmax (m/s) mmws ((m/s) january 6.24 12.36 9.29 february 5.59 12.07 8.69 march 5.93 10.57 8.24 april 4.17 8.62 6.86 may 4.11 8.62 6.17 june 4.15 7.75 5.86 july 4.29 7.39 5.63 august 3.93 7.20 5.63 september 5.44 8.77 6.92 october 5.59 10.19 7.96 november 6.33 10.54 8.43 december 5.97 11.58 8.48 over the period of investigation, the quadratic regression of the mmws has a parabolic form (fig. 6), which reflects an apparent cyclic trend in the changes of the mmws over the investigated area. a longer time series of recorded wind data will be advantageous to confirm with more clarification this cyclic behaviour, i.e. cycle length and points of cyclereverse. the quadratic regression model is represented by the equation: mmws = 4.04e-06 x2 – 0.0035 x + 7.8665 (11) the month of the minimum mmws occurrence is determined to be january 2009. the resultant parabola shows a general trend of decrease from january 1973 to january 2009 with a rate of 0.0017 ms-1/month (0.0204 ms-1/yr), followed by a very slow gradual increase up to the end of the investigated period with a rate of 0.00008 ms-1/month (0.00096 ms-1/yr). fig .6. quadratic regression model of the mmws over the study period b. the four major dominant wind components in the following discussion, the trend of variations of the four major main dominant components over the region of interest will be discussed. this will be presented according to the descending percentage of occurrence frequency (table 3). 1. the southern wind component (s) wind blowing from the south dominates the region of investigation. over 38 years of hourly records, the southern wind represented 10.43% of occurrence. the quadratic trend of the southern variations is mathematically expressed by: s-mwa = 1.6287e-06 x2 – 0.0006 x + 0.0132 (12) this results in a parabolic cyclic variation (fig. 7) with a minimum occurrence of the s-mwa in april 1988. a general decrease (0.0003 ms-1/month; 0.0036 ms-1/yr) occurred from january 1973 to april 1988 followed by a general increase (0.00044 ms-1/month; 0.00528 ms-1/yr) afterwards. the zero values of the s-mwa (points of intersection with the months’ axis) occurred in november 1974 and september 2001. fig .7. quadratic trend of variation in the s-mwa over the period of investigation 2. the western wind component (w) wind blowing from the west represented 10% of the recorded hourly data over the 38 years of investigation. in contrast to the south wind component, the quadratic regression model of the westerly mwa tends to produce a concave-down parabolic figure (fig. 8), the maximum of which occurred in may 1995. there is an increasing rate from january 1973 to may 1995 (0.0003 ms-1/month; 0.0036 ms-1/yr) followed by a slight decreasing rate of 2 4 6 8 10 12 14 ja n -7 3 ja n -7 5 ja n -7 7 ja n -7 9 ja n -8 1 ja n -8 3 ja n -8 5 ja n -8 7 ja n -8 9 ja n -9 1 ja n -9 3 ja n -9 5 ja n -9 7 ja n -9 9 ja n -0 1 ja n -0 3 ja n -0 5 ja n -0 7 ja n -0 9 months m e a n m o n th ly w in d s p e e d ( m /s ) -1.6 -1.2 -0.8 -0.4 0 0.4 0.8 1.2 1 51 101 151 201 251 301 351 401 451 months (1 = january 1973) s -m w a ( m /s ) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 119 resd © 2015 http://apc.aast.edu 0.0002 ms-1/month (-0.0024 ms-1/yr) from may 1995 to december 2010. the zero values of the w-mwa occurred in september 1982 and january 2008. the quadratic regression model of the w-mwa is mathematically represented by the following equation: w-mwa = -1.1136e-06 x2 + 0.0006 x – 0.0551 (13) fig .8. quadratic trend of variation in the w-mwa over the period of investigation 3. the south-west wind component (sw) the south-west wind component comes third in the frequent occurrence during the period of investigation, with 9.54%. the quadratic regression of the sw-mwa (fig. 9) reflects a parabolic form the minimum of which is out of the present data in hand: may 1969. the apparent segment from the resultant parabola of the sw-mwa is an increasing segment with a rate of 0.00022 ms-1/month, i.e. 0.00264 ms-1/yr (equation 14). the zero values of the sw-mwa occurred in september 1994 and january 1947. sw-mwa = 4.9024e-07 x2 + 2.5313e-05 x – 0.0399 (14) fig .9. quadratic trend of variation in the sw-mwa over the period of investigation 4. the north-west wind component (nw) this wind component is the fourth dominant wind component over the study period with an 8.6% occurrence. the quadratic examination of changes of this monthly wind anomaly component (fig. 10) reflects both an increasing rate and a decreasing rate over two successive time-interval segments. while the first is 0.011 ms-1/month (0.012 ms-1/yr) from january 1973 to july 1994, the second rate is 0.0017 ms-1/month (-0.0204 ms-1/yr) from july 1994 onwards. this apparent trend of the nw wind component followed that of the westerly component shown above. the zero values of the nw-mwa occurred in september 1975 and april 2000. the quadratic model equation which represents the nwmaw is: nw-mwa = -1.6602e-06 x2 + 0.0006 x – 0.018 (15) fig .10. quadratic trend of variation in the nw-mwa over the period of investigation 3. quadratic regression models of the different wave parameters in order to describe the wave climate off the western coasts of scotland, the long term changes in the ten mentioned wave parameters are considered. the minimum mean monthly s (ω) was 0.01 m2s and the maximum was 0.53 m2s, with an average of 0.12 m2s over the study period. the mean monthly f ranged from 0.08 hz to 0.32 hz with an average of 0.16 hz, and the mean monthly ω varied between 0.48 rad/s and 1.98 rad/s with an average of 0.98 rad/s over the study period. the mean monthly hs and tp calculated from the mean monthly piersonmoskowitz spectrum in the present study is shown in figure (11). the mean monthly hs ranged from 0.38 m to 3.78 m with an average of 1.40 m, and the tp -1.6 -1.2 -0.8 -0.4 0 0.4 0.8 1.2 1 51 101 151 201 251 301 351 401 451 months (1 = january 1973) w -m w a ( m /s ) -1.6 -1.2 -0.8 -0.4 0 0.4 0.8 1.2 1 51 101 151 201 251 301 351 401 451 months (1 = january 1973) s w -m w a ( m /s ) -1.2 -0.8 -0.4 0 0.4 0.8 1.2 1.6 1 51 101 151 201 251 301 351 401 451 months (1 = january 1973) n w -m w a ( m /s ) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 120 resd © 2015 http://apc.aast.edu varied between 3.07 s and 9.67 s with an average of 5.75 s, over the study period. fig .11. the mean monthly hs and tp of the mean monthly pierson-moskowitz spectrum over the study period the examination of the long term trends of variations of the different wave parameters reveals that the mean monthly f is in an inverse relationship to the mean monthly winds speed (mmws), with a correlation factor of -0.96. this is the same situation for both ω and ωp. the latter varied between 0.65 rad/s and 2.00 rad/s, with an average of 1.14 rad/s over the study period. the general trends of the three frequencies are shown in figures (12-14). the mean monthly f (mmf) is quadratically expressed by the equation: mmf = -1e-07 x2 + 1e-04 x + 0.1442 (16) this mathematically expresses a concave-down parabola, the increase rate of which is 0.018 hzyr-1, with a maximum occurrence in august 2014. the mean monthly ω (mmω) tends to have the same parabolic form but with a maximum occurrence in august 2000, i.e. preceding that of the mmf by 14 years. this is expressed by the following equation: mmω = -9e-07 x2 + 0.0006 x + 0.9062 (17) this implies an initial increasing rate in the mmω of 0.003 rads-1yr-1 from january 1973 to august 2000 followed by a decreasing rate of 0.001 rads-1yr-1 afterwards. the quadratic expression of variations in the mean monthly ωp (mm ωp) is: mmωp = -8e-07 x2 + 0.0006 x + 1.0707 (18) the mmωp increased from january 1973 to march 2003 followed by a gradual decrease afterwards, with rates of 0.004 rads-1yr-1and -0.02 rads-1yr-1, respectively. fig .12. the mean monthly hs and tp of the mean monthly pierson-moskowitz spectrum over the study period fig .13. quadratic trend of variation of the mmω over the period of investigation fig .14. quadratic trend of variation of the mmωp over the period of investigation over the period of investigation, the mean monthly wave spectral density, mms(ω), did not show any parabolic form or a cyclic behaviour. in contrast, a general decrease trend is more obvious for the mms(ω), with both the quadratic (blue solid line) and 0 2 4 6 8 10 12 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 mean monthly wind speed (m/s) m e a n m o n th ly w a v e p e a k p e r io d ( s) 0 0.5 1 1.5 2 2.5 3 3.5 4 m e a n m o n th ly s ig n if ic a n t w a v e h e ig h t (m ) tp hs 0.05 0.10 0.15 0.20 0.25 0.30 0.35 1 51 101 151 201 251 301 351 401 451 months (1 = january 1973) m e a n m o n th ly w a v e f r e q u e n c y ( h z ) 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 1 51 101 151 201 251 301 351 401 451 months (1= january 1973) m e a n m o n th ly w a v e a n g u la r f r e q u e n c y ( r a d /s ) 0.50 1.00 1.50 2.00 1 51 101 151 201 251 301 351 401 451 months (1 = january 1973) m e a n m o n th ly w a v e p e a k a n g u la r f r e q u e n c y ( r a d /s ) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 121 resd © 2015 http://apc.aast.edu linear (red dashed-line) regressions almost superimposable (fig. 15). while the first has a rate of 0.0018 m2syr-1 the second has a rate of -0.0012 m2syr-1. the correlation factor between the mms(ω) and the mmws is 0.98. the quadratic regression model of the mms(ω) is given by the following equation: mms(ω) = 1e-07x2 – 0.0002 x + 0.1515 (19) fig .15. the mean monthly trends of variation of the mms(ω) over the study period during the study period, the mean monthly hs (mmhs) was highly correlated to the mmws, with a correlation factor of 0.98. the long-term variations in the mmhs have a parabolic form (fig. 16), which reflects a cyclic behaviour for this wave parameter. the mmhs decreased from january 1973 to may 2008, followed by a gradual increase afterwards. this is mathematically expressed by the following equation: mmhs = 2e-06 x2 – 0.0017 x + 1.9563 (20) fig .16. quadratic trend of variation of the mmhs over the study period the general trend of the mean monthly tp (mmtp) tends to be cyclic (fig. 17) with a quadratic expression as: mmtp = 3e-06 x2 – 0.00298 x + 6.1694 (21) this reflects a large cycle with a minimum occurrence in may 2014, which is obviously out of the present data set and comes 6 years after the minimum occurrence of the mmhs. the mmtp is highly correlated to the mmws, with a factor of 0.998. fig .17. quadratic trend of variation of the mmtp over the study period both the mean monthly cp (mmcp) and cg (mmcg) are positively correlated to the mmws, with a factor of 0.998, and both tend to have a cyclic behaviour of variations. while the minimum occurrence of the mmcp occurred in january 2010 (fig. 18), one year after that of the mmws, the minimum mmcg occurred in january 2003 (fig. 19), six years before that of the mmws. the equation, which represents the variations of the mmcp is: mmcp = 5e-06 x2 – 0.00445x + 9.663 (22) the yearly rate of the mmcp decrease is 0.0265 ms1yr-1from january 1973 to january 2010, followed by a very slow rate of increase of 0.00066 ms-1yr-1 afterwards. the mmcp varied from 4.91 m/s to 15.15 m/s with an average of 9 m/s over the period of investigation. the quadratic equation, which represents the variations of the mmcg is: mmcg = 3e-06 x2 – 0.00217x + 4.8287 (23) this results in two segments of variations (fig. 19), the first of which has a rate of -0.012 ms-1yr-1 from january 1973 to january 2003, followed by an 0.00 0.10 0.20 0.30 0.40 0.50 0.60 1 51 101 151 201 251 301 351 401 451 months (1 = january 1973) m e a n m o n th ly w a v e s p e c tr a l d e n si ty ( m 2 s) 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 1 51 101 151 201 251 301 351 401 451 months (1 = january 1973) m e a n m o n th ly s ig n if ic a n t w a v e h e ig h t (m ) 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 1 51 101 151 201 251 301 351 401 451 months (1 = january 1973) m e a n m o n th ly w a v e p e a k p e r io d ( s) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 122 resd © 2015 http://apc.aast.edu increasing segment with a rate of 0.0042 ms-1yr-1. the mmcg ranged between 2.45 m/s and 7.58 m/s, with an average of 4.5 m/s over the study period. fig .18. quadratic trend of variation of the mmcp over the study period fig .19. quadratic trend of variation of the mmcg over the study period over the period of investigation, the quadratic regression of the mean monthly e (mme) has a wellobserved parabolic form (fig. 20), which reflects an apparent cyclic behaviour for the changes of the wave energy in the investigated area. the quadratic regression model is represented by the equation: mme = 0.0172 x2 – 14.11602 x + 9536.2 (24) the mme varied from 183.49 j to 17951.93 j with an average of 2953.63 j over the study period. the minimum mme occurred in february 2007. the resultant parabola shows a general trend of decrease from january 1973 to february 2007 with a yearly rate of -160.5 jyr-1. this is followed by an increase up to the end of the investigated period with a rate of 688.2 jyr-1. the mme is highly correlated to the mmws, with a correlation factor of 0.93. fig .20. quadratic trend of variation in the mme over the study period the mean monthly p (mmp) is positively correlated to the mmws. however, it appears to be the weakest wave parameter, among the investigated parameters, to be correlated to the mmws having a correlation factor of 0.89. from january 1973 to december 2010, the mmp appeared to have a cyclic trend of variations (fig. 21) with a minimum occurrence in may 2005. the two yearly rates of variations are -952.86 wm-2yr-1 from january 1973 to may 2005, and 163.44 wm-2yr-1 from may 2005 to the end of the study period. the mmp varied from 450 w/m2 to 135990.49 w/m2 with an average of 15809.21 w/m2 over the period of investigation. the representative equation of these variations is: mmp = 0.2049 x2 – 159.5203 x + 86890 (25) fig .21. quadratic trend of variation in the mmp over the study period iv. discussion and conclusion to the author’s knowledge, no work has dealt before with the changes in the long-term behaviour of windwave climatology over the west region of scotland. 4.00 7.00 10.00 13.00 16.00 1 51 101 151 201 251 301 351 401 451 months (1 = january 1973) m e a n m o n th ly w a v e p e a k v e lo c it y ( m /s ) 2 4 6 8 1 51 101 151 201 251 301 351 401 451 monthly (1 = january 1973) m e a n m o n th ly w a v e g r o u p v e lo c it y ( m /s ) 0 5000 10000 15000 20000 25000 30000 35000 40000 1 51 101 151 201 251 301 351 401 451 months (1 = january 1973) m e a n m o n th ly w a v e e n e r g y ( j ) 0 50000 100000 150000 200000 250000 300000 350000 400000 450000 1 51 101 151 201 251 301 351 401 451 months (1 = january 1973) m e a n m o n th ly w a v e p o w e r ( w /m 2 ) http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 123 resd © 2015 http://apc.aast.edu the present study can be considered as an initial fair trial to get closer to the general behaviour of the major wind components and ten main wave parameters over this region. the long-term variations of the wind-wave climatology have been examined using the quadratic regression model approach. according to the percentage of occurrence frequency during the period january 1973-december 2010, the dominant wind components came from the south (s), the west (w), the southwest (sw) and the northwest (nw). all have the atlantic ocean origin and result mainly from the atlantic depressions passing over the uk. this percentage computation agrees with the given information by the uk met office. all over the period of investigation, the hourly wind speed varied between calm wind (0 m/s) to a maximum of 38.89 m/s, with an hourly average speed of 7.34 m/s. twelve hourly wind-classes have been specified for the area of investigation with the dominant speed interval >5:10 m/s (occurrence of 41.259%), and the lowest speed interval was >35:40 m/s with 0.0006%. the quadratic regression model of the mean monthly wind speed (mmws) has a parabolic form, which reflects a cyclic behaviour of occurrence. from a quadratic point of view, the approach applied in this research to examine periodicity and cyclic behaviour, it can be deduced that the two major southern components have a common parabolic trend and the two major western components have another opposite common parabolic trend. both the s and the sw monthly winds anomalies have concave-up parabola with minimum mwa speed occurrence in april 1988 and may 1969, respectively. the later, minimum of the sw-mwa, is obviously out of the present in-hand set but meanwhile, reflects the possibility of existence of large cycles of occurrence for this wind component. both the w and the nw monthly wind anomaly speeds have concave-down parabola with maximum occurrence in may 1995 and july 1994, respectively. from the calculations of the zero values of the different wma parabolas, september has appeared a common month when the mwa half-cycle reverses its path, whether upward or downward, i.e. positively with an increasing rate or negatively with a decreasing rate. the pierson-moskowitz spectrum conditions have been satisfied to apply the model in order to represent the wave climatology of the area of investigation. the spectrum has been previously discussed and applied in many regions, which satisfy the conditions of pierson and moskowitz (1964), e.g. holmes (2001); alves and banner (2003); sorensen (2006). both significant wave height and wave peak period have been calculated form the piersonmoskowitz spectrum and the resultant relationships with the mmws and between the two parameters are in good agreement with the results of harrison and wallace (2005). all wave frequencies are in an inverse correlation to the mmws. all other wave parameters appear to be highly correlated to the mean monthly wind speed with correlation factors exceeding 0.95 except the wave power, which has a correlation factor of 0.89. in conclusion, the general behaviour of the dominant winds over the western region of scotland tended to be cyclic. two opposite cycles appeared to dominate: one for the southern components (s & sw) and one for the western components (w & nw). september was a month of cycle reverse for the mwa over the region. the general behaviour of the ten examined wave parameters over the western region of scotland also tended to be cyclic. a longer time series, than that presently used, will be advantageous in order to strengthen this outcome of this natural cyclic behaviour with more robust investigation. longer time series will also enable to determine the cycle period for each of the investigated parameters. this concluded cyclic behaviour may positively impact on the engineering work within the wave energy resource off the western coasts of scotland. references [1] [alves, j.h, banner, m.l (2003) a symptotic limits for fully developed wind waves. journal of physical oceanography 33: 1301-1323. [2] anastasiades, g. and mcsharry, p.e. (2013) extreme value analysis for estimating 50 year return wind speeds from reanalysis data. wind energy 17(8): pp.1231-1245. [3] baumgartner, t.r., soutar, a., and ferreirabartrina v (1992) reconstruction of the history of pacific sardine and northern pacific anchovy http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 124 resd © 2015 http://apc.aast.edu populations over the past two millennia from sediments of the santa barbara basin. calcofi reports 33: pp 24-40. [4] bretschneider, c.l. (1959) wave variability and wave spectra for wind-generated gravity waves u.s. army corps of engineers, beach erosion board, technical memorandum pp. 118: 192. 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(2010) climatological trend of sea surface salinity anomalies in the south eastern mediterranean sea. journal of king abdul-aziz university: marine science 21(2): 63-72. [21] maiyza, i.a. (1984) long -term variation of water temperature in the eastern part of the mediterranean sea, ph. d. thesis, moscow university. [22] maiyza, i.a, el-geziry, t.m, maiyza, h.i. and http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) june 2015 issn 2356-8569 125 resd © 2015 http://apc.aast.edu kamel, m.s (2011) climatological trend of air temperature anomalies in the south-eastern mediterranean sea. journal of king abdul-aziz university: marine science 22 (2): 55-65. [23] mollison, d. (1994) assessing the wave energy resource. in: statistics for environment 2. barnett and turkman eds. wiley press, pp 205220. [24] ochi, m.k. and hubble, e.n. (1976) six parameter wave spectra. in: coastal engineering, pp 301-328. [25] olaofe, z.o. and folly, k.a. (2012) statistical analysis of the wind resources at darling for energy production. international journal of renewable energy research 2 (2): pp 250-261. [26] phillips, o.m. (1977) the dynamics of the upper ocean (2nd ed.). cambridge university press. [27] pierson ,w.j. and moskowitz, l. (1964) a proposed spectral form for fully developed wind seas based on the similarity theory of a. a. kitaigorodskii. journal of geophysical research 69: pp 5181–5190. [28] said, m.a, el-geziry, t.m, radwan, a.a (2012) long-term trends of extreme climate events over alexandria region, egypt. international conference on “land-sea interactions in the coastal zone” jounieh lebanon, 06-08 november 2012: pp 286-293. [29] sinden, g. (2007) characteristics of the uk wind resource: long-term patterns and relationship to electricity demand. energy policy 35 (1): 112-127. [30] sorensen, r.m. (2006) wind-generated waves. in: “basic coastal engineering. springer”, pp: 157-194. [31] speedie, c.d, johnson, l.a. and witt, m.j (2009) basking shark hotspots on the west coast of scotland: key sites, “threats and implications for conservation of the species”. commissioned report 339: 58p. [32] sundby, s. and drinkwater, k. (2007) on the mechanisms behind salinity anomaly signal of the northern north atlanti. progress in oceanography 73: pp190–202. [33] youm, i., sarr, j., sall, m., ndiaye, a. and kane, m.m (2005) “analysis of wind data and wind energy potential along the northern coast of senegal”. la revue des energies renouvelables 8: pp 95 – 108. [34] woolf ,d.k, and challenor, p.g (2002) variability and predictability of the north atlantic wave climate. journal of geophysical research 107 (c10): doi: 10.1029/2001jc001124, p 14. [35] wolf, j. and woolf, d.k. (2005) waves and climate change in the sea of the hebrides. proceedings of the 15th international offshore and polar engineering conference, seoul, korea, june 19-24, 2005: pp 100-107. [36] weisse, r. and storch, v. h. (2010) marine climate and climate change. springer praxis, p 219. http://apc.aast.edu/ journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 243 implications of human induced changes on the distribution of important plant species in the northwestern coastal desert of egypt marwa waseem halmy 1*, paul e. gessler 2, selim z. heneidy 1 1 department of environmental sciences, faculty of science, alexandria university, alexandria, egypt, 2 department of forest, rangeland and fire sciences, p.o. box: 441133, university of idaho, moscow, id, 83844-1133, usa., *corresponding author, email: marwa.w.halmy@alexu.edu.eg address: department of environmental sciences, faculty of science, p.o. box: 21511, alexandria, egypt. abstract the application of species distribution modeling in deserts is a useful tool for mapping species and assessing the impact of human induced changes on individual species. such applications are still rare, and this may be attributed to the fact that much of the arid lands and deserts around the world are located in inaccessible areas. few studies have conducted spatially explicit modeling of plant species distribution in egypt. the random forests modeling approach was applied to climatic and land-surface parameters to predict the distribution of ten important plant species in an arid landscape in the northwestern coastal desert of egypt. the impact of changes in land use and climate on the distribution of the plant species was assessed. the results indicate that the changes in land use in the area have resulted in habitat loss for all the modeled species. projected future changes in land use reveal that all the modeled species will continue to suffer habitat loss. the projected impact of modeled climate scenarios (a1b, a2a and b2a) on the distribution of the modeled species by 2040 is varied. some of the species were projected to be adversely affected by the changes in climate, while other species are expected to benefit from these changes. the combined impact of the changes in land use and climate poses serious threats to most of the modeled species. the study found that all the species are expected to suffer loss in habitat, except gymnocarpos decanderus. the study highlighted the importance of assessing the impact of land use/climate change scenarios on other species of restricted distribution in the area and can help shape policy and mitigation measures directed towards biodiversity conservation in egypt. keywords climate change land use change random forests species conservation importance (sci) index species distribution models (sdms). i. introduction a. species distribution models (sdms) species distribution models (sdms) were founded in ecology and natural history based on gradient modeling and niche theory [1], [2], [3]. habitat or species distribution models (sdm) are defined as models that ‘statistically relate the geographical distribution of species or communities to their present environment’ [4]. species distribution models (sdm) are also known as: bioclimatic models; climate envelopes; ecological niche models (enms); habitat models; resource selection functions (rsfs); and range maps [2]. the premise of these models is that environmental factors control the distribution of species and consequently communities [1], [4], [5]. prediction of species distribution started early on by descriptive studies conducted by ecologists interested in understanding the relationship between patterns of species in relation to geographical settings and environmental gradients [2]. later the evolution in ecology and other related fields coupled by the emergence of numerical analysis and quantitative approaches has greatly influenced species distribution modeling. quantitative approaches of species distribution modeling developed as a result of convergence of two lines of research trends in ecology and geography. the first line started in ecology as field-based research that studied specieshabitat relationships. these studies later adopted quantitative approaches by applying statistical analysis techniques (e.g. linear multiple regression techniques), then the advanced regression journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 244 techniques (e.g. generalized liner models (glms) and boosted regression techniques) were developed to overcome limitations of the linear paradigm. the second line emerged in geography, and specifically in physical geography, through the advancement in geographic information systems and remote sensing techniques [2]. the integration of gis and remote sensing has allowed the development of methods for interpolation of global climate and modeling global surface elevation, in addition to provision of spectral data that were employed in species prediction models. the development of the field of species distribution modeling and mapping has been driven by the need to map vegetation patterns over large areas for resource management and conservation planning, and to predict the effects of environmental changes on vegetation distribution [1], [5]. a suite of statistical and machine-learning techniques has been developed for conducting sdms [6]. although many approaches are used for the species distribution modeling, no rules exist to provide guidelines on the best modeling approach to use [3]. it is also likely that some approaches may be better for prediction of one species over another. this is related to many factors that include: the nature of the data used (quantity & quality); the nature of the predicator variables used; the spatial scale used (resolution and the extent); and the relevance of the environmental predicators used to the ecological characteristics of the species being predicted [4], [7], [8], [9], [10]. b. applications of sdms for studying global changes the use and application of sdms for different purposes is growing rapidly [11], because sdms provide useful tools for understanding the gaps in knowledge of species distribution. more recently they have been used to assess potential impacts of changes in environmental and climatic conditions on the distribution of species [12], [4], [3], [13]. in most cases these studies deal with different land use/land cover and climatic scenarios. the study by sala and his colleagues [14] is one of the first studies that provided projection of changes in biodiversity at the global scale under different scenarios of climate and land use change by 2100. the study provided scenarios of change in the ten widely known terrestrial biomes plus the fresh water aquatic ecosystems. they based their scenarios on how the change in some drivers (for example; climate, vegetation, land use, and levels of carbon dioxide) will trigger changes in biodiversity. over the last three decades, numbers of general circulation models (gcm’s) have been developed. the data distribution center (ddc) of the ipcc distributes a number of datasets, derived from various general circulation models (gcms). these models are available on the web at: http://www.ipccdata.org/. due to the coarse resolution of these data, they are mostly used to assess the potential impact of change in climate at a broad scale. this coarse resolution does not suit applications aiming at assessing the climate change impact on agriculture and biodiversity at finer scales [15], [16]. therefore, many attempts have been made for downscaling and disaggregating gcm outputs (for example; [17], [16]). spatial disaggregation based on worldclim data [15] as baseline climate was applied to 24 different gcms used in the ipcc4th assessment report for different emission scenarios and for seven different 30-year running mean periods [16]. the data are freely available through the cgiar research program on climate change, agriculture and food security (ccafs) web: http://www.ccafs-climate.org/data/. the data have been used to assess the response of different species to the simulated changes in climate (for example, [18], [19], [20]). arid lands in general and deserts specifically, are poorly studied areas with regard to the assessment of their biodiversity and understanding the distribution of species in their vicinity [21]. this is likely related to the harsh nature of these areas and the inaccessibility of parts of the desert areas. the few studies that used species distribution modeling techniques in desert ecosystems were successful in providing tools for modeling the distribution patterns of species. yet sdm approaches have rarely been used for addressing the influence of environmental changes (climate, land use change or any other disturbances) on the distribution of species in arid lands. this may be because arid lands are some of the most poorly studied areas in the world. species distribution modeling techniques were used in the current study to project the impact of environmental changes on the distribution of ten important plant species in the northwestern coastal desert of egypt. this region has experienced rapid change in land use/land cover recently due to coastal development projects. species distribution modeling techniques and available environmental predictors (bioclimatic journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 245 and land-surface parameters) were used here to: 1) predict the potential distribution of ten important plant species; 2) study the effect of land use change on distribution of the modeled species; and 3) project the potential changes in distribution of the species under different climate/land use scenarios. ii. materials and methods a. study area the study area is part of the northwestern coastal desert of egypt. it extends for 40 km from el-hamam town to westward to el-alamein town and from the mediterranean coast southward to moghra oasis (figure 1), occupying an area of about 2800 km2 located between 30° 10' to 30° 55' and n 28° 55' to 29° 25' e. the area has a short rainy season, which occurs mostly during winter from november to april but may extend to may. little precipitation occurs during the rest of the year [22], [23]. the mean annual precipitation ranges from100 to 150 mm/year, thus the area considered arid (rainfall zones of 0-300 mm) [24]. the climatic records [25] indicate that the total monthly evapotranspiration in the coastal area exceeds the total annual precipitation. this reflects the arid conditions and the water deficiencies that prevail in the area. a north-south climatic gradient was noticed in this region, with an increase in environmental aridity and ‘thermal continentality’ towards the south [26]. the vegetation of the region is dominated by dwarf shrubs less than one meter [24]. the agricultural activities in the northern part have resulted in changes throughout the area that might have impacted species distributions. the omayed biosphere reserve (obr) a.k.a. elomayed protected area (opa) is located in the northern part of the study area (figure 1). the protected area is considered as one of the largest terrestrial protected area in egypt [27]. b. data collection field visits were conducted to survey the plant species in the area, where more than 800 plots were selected randomly in order to account for the major physiographic variation in the study area. plant species were recorded and identified according to “students' flora of egypt” by täckholm [28] and nomenclature of the species was updated following “flora of egypt” by boulos [28], [29], [30], [31], [32] and the latin names of the species were updated following the “flora of egypt: checklist” by boulos [33]. species distribution modeling could be developed based on the presence-only data or presence-absence data [35]. in the current study, both presence and absence data were employed in modeling. fig .1. location of the studied area: a) egyptian governorates’ administrative boundaries; b) the northwestern coastal desert showing location of the study area northeast of qattara depression; and c) the study area as shown through part of landsat thematic mapper 2011 image. the location of omayed biosphere reserve (obr) is highlighted, core zones in red, buffer zone in green and transition zone in blue (after [34]). c. predictors the accuracy and the predictive power of any habitat distribution model depend on the quality and the accuracy of the field data employed and the choice of the environmental variables used to build the model [40]. in the current study, a number of land-surface parameters and bioclimatic variables were used to build the plant species distribution models (table 1). ecological land-surface parameters derived from 29°20'e29°10'e29°0'e 30°50'n 30°40'n 30°30'n 30°20'n 0 5 10 15 202.5km ± obr core zone obr buffer zone obr transition zone b ) c ) journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 246 digital elevation models (dems) are considered important for mapping vegetation, especially if combined with other parameters including spectral indices derived from satellite imagery [41]. a digital elevation data srtm v4.1 (jarvis et al. 2008) were used for the derivation of land-surface parameters. the land-surface parameters employed in the study (table 1) included slope; a terrain roughness index (tri) that provides an quantification of the level of undulation and the complexity of the surface [42]; topographic wetness index (twi) [43]; and a slope length and steepness (ls) factor. all the land-surface parameters were derived using the automated system geoscientific analyses version 2.0.7 [44]. climatic conditions are recognized as the most important environmental variables responsible for the patterns of species distribution at broad scales [45]. however, the availability of climatic data layers of appropriate resolution has been rare for researchers intending to do species distribution mapping, especially in understudied areas [3]. recently, interpolated global climatic data layers that represent the previous and current climatic conditions were made available to the public (for example; worldclim [15] and climond [46]). ‘worldclim’ is available with global coverage at a spatial resolution of 1 km2 and can be downloaded from http://www.worldclim.org. the worldclim data include monthly mean total precipitation and mean, minimum, and maximum temperature in addition to nineteen other bioclimatic variables. the current study used thirty environmental variables (table 1) representing important factors for plant survival; including bioclimatic variables, topographic variables and light controlling factors. the incorporation of light controlling factors in modeling plant distribution was recommended, particularly in studies that involve assessment of the impact of climate change on plant distribution [47]. solar insolation indices were derived from the digital elevation data and included in the analysis. the distance to the coast was also included as a factor in modeling plant species distribution to account for maritime influences due to proximity to the mediterranean sea. all the layers representing the variables employed in the analysis were re-sampled to match the spatial resolution of the dem used. d. modeling approach the data used in the current study were collected systematically using field surveys through which the presence/ absence observations were recorded for each species. generalized linear models (glms) or ensembles of regression trees such as random forests (rf) or boosted regression trees, (brt) are recommended in cases where presence/absence data are available [3], [48], [6]. the current study applied the machine learning ensemble method random forests (rf) to predict the distribution of the selected species using climatological and topographical factors. the collected presence/absence data were divided randomly to two sets; 70% for calibrating the models and 30% for testing and evaluating the models. all the analyses were conducted within the framework of the open source statistical computing environment of r 2.13.1 [49]. the ‘randomforest’ package [50] was used for carrying out the random forests analyses. random forests analysis (rf) has been used in some studies for modeling species and predicting changes in species distribution under different climate scenarios [51], [52], [10], [53], [54]. it is one of the ‘ensemble modeling’ techniques that have recently been used successfully in ecological modeling [3]. it is composed of an ensemble of [55] classification and regression trees (cart) [56]. the rf approach has the advantage of being a nonparametric approach that can produce a highly accurate classification results and can process a larger number of independent variables [57]. it has been recommended for being robust to outliers and noise [57], [58], [59], [56], [60], [61]. in rf model, an ensemble of classification and regression tree (cart) models is created by training each model on a bootstrap sample of the original training data set. the output from each cart model is then subjected to a voting process whereby the most common vote is selected for producing the final results of a classification and the average of all the tree results is obtained in the case of performing regression. the size of the random forests model (i.e. the number of trees) and the number of variables to be used for splitting nodes at each tree in the random forests model need to be specified by the analyst depending on the study. the selection of these parameters is based on the combination that minimizes the out-of-bag error (oob). out-of-bag error estimation is used as an assessment of the accuracy of the model. it is estimated by keeping out (out-ofbag) one third of each bootstrap replica generated from the original training data and using it to test the tree models. the use of oob error for evaluating the performance of the rf models is considered a robust journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 247 unbiased method [57]. the optimum combination of the number of trees in the rf model and the number of variables to be used for splitting nodes was determined based on trials, which revealed that models with a size of 750 trees and four splitting variables at each node attained the lowest error rates. a general model for predicting each species was fit using all the variables, whereby an assessment of the importance of each variable in fitting the model was estimated. the percentage of increase in mean square error (mse) was caused when a variable that is randomly permuted and introduced to the model was used as basis for selection of variables to create a reduced model for each species. table 1. variables used in building the models of species distribution in the study area. variable abbreviation source annual mean temperature bio1 baseline climate data [15] available from: http: //www.worldclim.org predicted climate data [16] available from: http: //www.ccafs-climate.org/data/ mean diurnal range (mean of monthly (max temp min temp)) bio2 isothermality (mean diurnal range/temperature annual range) (*100) bio3 temperature seasonality (standard deviation *100) bio4 max temperature of warmest month bio5 min temperature of coldest month bio6 temperature annual range (max of warmest month-min of coldest month) bio7 mean temperature of wettest quarter bio8 mean temperature of driest quarter bio9 mean temperature of warmest quarter bio10 mean temperature of coldest quarter bio11 annual precipitation bio12 precipitation of wettest month bio13 precipitation seasonality (coefficient of variation) bio15 precipitation of wettest quarter bio16 precipitation of coldest quarter bio19 aspect aspect derived from srtm dem [18] available from: http: //srtm.csi.cgiar.org across-slope plan curvature plcurv curvature [62] curv diffusion insolation diffinsol direct insolation dirinsol downslope profile curvature prcurv direct/diffusion insolation ratio difftodir elevation elev ls factor ls proximity to sea proxtosea slope [62] slope terrain roughness index according to [63] tri topographic wetness index (twi) [43] twi total insolation totinsol e. models evaluation the accuracy and credibility of habitat distribution models should be considered in the context of the intended applications [4]. accuracy assessment and uncertainty about the data used in developing these models should be reflected in and accounted for by any further analysis that might use the products of these models [64]. an account of the most commonly used measures for accuracy assessment of the species distribution models can be found in [3], [11]. the most commonly used threshold-dependent measure for assessing accuracy of habitat distribution models is the kappa statistic; however kappa has been criticized for producing a biased accuracy assessment. allouche and colleagues [65] described the bias encountered when using kappa statistic [66] and suggested using the true skill statistic (tss) [67] as an alternative method for assessing the accuracy of habitat distribution models. in the current study, both cohen’s kappa and the tss are used as threshold-dependent measures in assessing the accuracy of the produced models along with the overall accuracy, sensitivity (the proportion of the correctly predicted presence observations), and specificity (the proportion of the correctly predicted http://www.worldclim.org/ http://www.ccafs-climate.org/data/ http://www.cgiar-csi.org/data/srtm_90m_digital_elevation_database_v4_1/uot;http:/srtm.csi.cgiar.org journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 248 absence observations). the threshold-independent area under the receiver operating curve (auroc) [68] was also used to assess the accuracy of the models. 𝑘𝑎𝑝𝑝𝑎 = ( 𝑎 + 𝑏 𝑛 ) − (𝑎 + 𝑏)(𝑎 + 𝑐) + (𝑐 + 𝑑)(𝑑 + 𝑏) 𝑛2 1 − (𝑎 + 𝑏)(𝑎 + 𝑐) + (𝑐 + 𝑑)(𝑑 + 𝑏) 𝑛2 𝑇𝑆𝑆 = (( 𝑎 𝑎 + 𝑐 ) + ( 𝑑 𝑏 + 𝑑 )) − 1 where a, number of test presence records which were correctly predicted by the model; b, number of test absence records which the model predicted as presence; c, number of test presence records which the model predicted as absence; d, number of test absence records that were correctly predicted by the model; n, the total number of the test records. f. studying the combined impact of land use and climate change species distribution modeling is used frequently to predict the potential changes in species distribution under different change scenarios [48], [47]. prediction of the potential shift in plant distribution under different climate change scenarios is considered as one of the important applications of the species distribution models [69], [47]. most of the studies that project the impact of climate change on species distributions have been applied on global or regional scales (for example; study by sala and colleagues [14], and study by skov and svenning [70]). however, there is a need for applying the same principles at the landscape level which will be of great help to conservation efforts at this scale [71]. the information provided by such tools is considered crucial for decision making related to land management and conservation planning [72], [4]. most of the studies that have predicted the potential change in plant species under climate change scenarios have focused on temperate regions (for example; [45], [73], [71]). the current study provides an assessment of the potential impact of climate change on the distribution of ten plant species in a desert ecosystem. mapping the distribution of all the species recorded in the study area is a lofty goal that cannot be achieved in one single study due to the insufficiency of the occurrence records and additional logistical challenges. to overcome this problem, the current study sought to focus on predicting the distribution of ‘important’ species with sufficient occurrence records. important species were defined as those serving crucial functions and providing important services in any ecosystem. this could include, for example, sand stabilizing and nitrogen-fixing plants. many of the species recorded in the coastal area are considered ‘multipurpose’ species providing multi-use for local inhabitants [36], [37]. the current study focused on ten important species based on their importance values as indicated by the species conservation importance (sci) [38] and the number of occurrence records for each species. the value of the index includes information related to the conservation status, commonness, biological type, and utilitarian value of each species. the value of the sci are in the range from 0.2 to 1,with values approaching 1 indicating species with high importance value and those approaching 0.2 indicating species with a low importance value [38], [39]. the species with sci value of 0.55 or more and sufficient number of occurrence records (> 100) were modeled. land use/land cover maps representing different dates (1988, 2011 and projected 2023) were used to assess the impact of land use change on the distribution of the ten modeled plant species [34]. each of these lulc maps represents a different stage of human influence on the landscape, with an increase in human impact with time. the maps were reclassified into two categories only to create digital boolean layers. natural areas category represent all the areas that have not been transformed by human activities and the man-made category that includes all the artificially created areas (for example urban, roads, orchards and croplands). the natural areas were assigned values of one, while those considered man-made were assigned values of zero. the boolean layers representing each date were multiplied by the layers that represent the potential distribution of each of the modeled ten species. thus the reduction or the expansion in the area occupied by each species under each land use scenario was estimated. for projecting the potential distribution of the ten species of interest under different climatic scenarios, predicted climate changes according to the csiro mk 2.0 &mk3.0 gcms [74] were employed. these models are used to represent the predicted climate over the period 2010-2040 under different emission scenarios; journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 249 a2a and b2a are high greenhouse emission scenarios, while a1b is a medium emission scenario. the data were retrieved from the cgiar research program on climate change, agriculture and food security (ccafs) web: http://www.ccafsclimate.org/data/. the projected distribution of the plant species in the study area according to the used climate scenarios were compared to their potential distribution under the baseline climate. twelve scenarios were developed for each species (table 2) to estimate the change in species habitats under the combined impacts of changes in land use and climate. the increases and the decreases in the habitat area for each species under the different scenarios were estimated. table 2. scenarios of climate and land use change used in the study. the annual mean temperature and the annual precipitation predicted for the period 2010–2040 by each climate change scenario are compared to the baseline climate that represents an average for the period 1950-2000 [15] climate change scenarios land use change scenario no land use natural landscape (1) current land use scenario (2011) (2) simulated future scenario (2023) (3) a) average climate (1950-2000) baseline climate/natural baseline climate/2011 baseline climate/2023 b) a1b (+1.03 ºc & -12.23 mm) a1b/ natural a1b/2011 a1b/2023 c) a2a (+1.14 ºc & +3.11 mm) a2a/ natural a2a/2011 a2a/2023 d) b2a (+1.28 ºc & -6.34 mm) b2a/ natural b2a/2011 b2a/2023 iii. results& discussion a. species distribution a total of 244 species were recorded in the study area, out of which 57% are perennials, 38% are annuals and the remaining are biennials or short lived perennials. species recorded in the study area belong to fifty taxonomic families. compositae (asteraceae), gramineae, leguminosae (fabaceae) and chenopodiaceae are contributing the most to the flora of the region; this is in accordance with the study by shaltout [75].the use of sii facilitated the selection of the species based on their importance. the distribution of 10 out of the 244 species recorded in the study area was modeled (table 3). eight models out of the ten attained an area under the curve (auc) value over 0.7, which indicates that these models are of moderate performance [76]. astragalus spinosus and stipagrostis obtuse models attained auc values exceeding 0.65, which indicates that the models are better than random. based on kappa values, astragalus spinosus, echinops spinosus, and stipagrostis obtuse models are considered of poor performance as they had kappa values less than 0.4 (table 3). the models of seven species out of the ten performed fairly well as indicated by all the used measures of accuracy assessment. both models of haloxylon salicornicum and noaea mucronata exhibited good performance with kappa and tss exceeding 0.5, auc above 0.8, and overall accuracy above 81%. the accuracy and the predictive power of any species distribution model depends on the quality and the accuracy of the field data employed and the choice of the environmental variables to be used in the model [40]. taking into account the limitation of the resolution of the environmental data employed in the study, particularly the climatic variables used for predicting the distribution of species in the study area, the results obtained are considered acceptable. the availability of high resolution environmental predictors is important for modeling the distribution of species at landscape scales [77], [47]. such high resolution environmental data is difficult to obtain for the poorly studied areas. the deficiency in geographic databases (topographic and climatic databases) representing areas in developing countries and underdeveloped areas was and is still one of the major problems that faces researchers. the pattern of species distribution is often related to a number of environmental variables. predictive models of species distribution could include variables selected based on a theoretical basis following conceptual model [78]. the conceptual framework for modeling journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 250 plant species suggested by franklin [1] was revisited by austin and van [47]. they emphasized including environmental predictors that are considered direct factors influencing plant growth and distribution. this included light, temperature, nutrients, water, carbon dioxide and biotic interaction. although it is important to include the variables that correlate to the species distribution and also show meaningful biological relationships [78]; some studies fail to include some factors of importance. austin and van [47] highlighted the need for inclusion of light as a predictor in models predicting distribution of plant species, which has been overlooked by many studies. they argued that light as a predictor has an important influence on distribution of plant species. in the current study, light was included in modeling species of the study area expressed as total insolation, direct insolation, diffusion insolation, and direct/diffusion insolation ratios. each of these factors was found to be important for modeling plant species in the study area. diffusion insolation was found to be important for predicting all the species except for echinops spinosus, for which direct insolation was found important (table 4). austin and van [47] maintained that the difference in light regime between north and south-facing aspects can result in differences in temperature equal to that resulting from a shift of 200 km in latitude. table 3. the modeled important plant species selected out of the 244 species recorded in the study area; abbreviations used; estimated species importance index (sii) values; number of occurrences recorded in the study area; and the measures used to assess the accuracy of the random forests models predicting their distribution. accuracy assessment measures presented are: sensitivity; specificity; true skill statistic (tss); cohen’s kappa statistic; the overall accuracy; and the area under the curve (auc) statistic of the receiver operating characteristic (roc). species abbreviation sii number of occurrences sensitivity specificity tss kappa accuracy auc anabasis articulata (forssk.) moq. ana_art 0.72 454 0.92 0.509 0.429 0.447 73.790 0.790 asphodelus aestivus brot. asp_aes 0.64 119 0.533 0.882 0.415 0.405 81.855 0.828 astragalus spinosus (forssk.) muschl. ast_spi 0.64 137 0.442 0.784 0.226 0.191 72.470 0.664 deverra tortuosa (desf.) dc. dev_tor 0.76 212 0.589 0.828 0.417 0.417 75.709 0.764 echinops spinosus l. ech_spi 0.64 103 0.489 0.847 0.335 0.314 78.138 0.703 gymnocarpos decanderus forssk. gym_dec 0.64 250 0.835 0.62 0.455 0.401 69.355 0.744 haloxylon salicornicum (moq.) bunge ex boiss. hal_sal 0.6 184 0.709 0.845 0.554 0.507 81.452 0.840 noaea mucronata (forssk.) asch. and schweinf. noa_muc 0.56 211 0.73 0.849 0.579 0.547 81.855 0.872 stipagrostis obtuse (delile) nees sti_obt 0.56 208 0.651 0.697 0.348 0.296 68.548 0.671 thymelaea hirsuta (l.) endl. thy_hir 0.76 300 0.784 0.682 0.466 0.444 72.177 0.789 journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 251 table 4. variables selected for the predictive models for each species based on the percentage increase in mse when a given variable was randomly permuted and introduced into the model. see table 1 for variable abbreviations and table 3 for species binomial abbreviations. variable ana_art asp_aes ast_spi dev_tor ech_spi gym_dec hal_sal noa_muc sti_obt thy_hir bio2 + + + + + + + + + bio3 + + + + bio4 + + + + + + + + + + bio12 + + + + + + + + bio13 + + + bio15 + bio16 + + + + + + + + + + bio19 + + + elv + + + + + + + + + ls + + slope + + + tri + + twi + + + + + + + proxtosea + + + + + + + + + + diffinsol + + + + + + + + + dirinsol + + + + difftodir + + in the current study, generally seventeen out of the original thirty environmental variables contributed to the modeling of the species in the study area. of the climatic variables, the mean of temperature diurnal range, temperature seasonality, annual precipitation and precipitation of the wettest quarter were the common climatic factors in controlling the distribution of most the modeled species (table 4). climatic variables representing annual cycle (for example annual mean temperature and annual precipitation) seem to control the general vegetation cover over the broad scale. bornkamm and kehl [24] divided the western desert into five zones characterized by different vegetation cover and plant communities based on the mean annual rainfall. the study area falls within zone i and zone ii of this classification. the vegetation cover of zone i (semi-desert with mean annual rainfall > 20 mm) is composed of dwarf shrubs dominated by thymelaea hirsuta. zones ii and iii are full-desert (with mean annual rainfall 10-20 mm) with communities dominated by asphodelus microcarpus and plantago albicans. climatic factors that represent seasonality (e.g. mean of temperature diurnal range, temperature seasonality and precipitation of the wettest quarter) are more important for the distribution of the species at local scales as is suggested by the results of the current study. the results indicate that the land-surface parameters are of influence on the distribution of species. topographic factors such as elevation, diffusion insolation, direct insolation, and topographic wetness index were found to be important in predicting most of the modeled species (table 4). hammouda [79] in a study focusing on the omayed area (part of the study area) found that species distribution and plant community composition are influenced by topography, the nature and origin of the parent material, in addition to the land use and degree of human intervention. land-surface parameters controlling moisture availability were found to be of importance for species distribution by some studies that focused on assessing the quantitative relationships between environmental variables and vegetation in the northwestern desert (for example; [80], [81], [82], [83]). ayyad and ammar [81] found that abundance and the distribution of the perennials are more affected by factors controlling moisture availability through run-off; such as slope and curvature. ayyad and ammar [84] also, found factors controlling moisture availability (for example; slope inclination, topographic position, nature of surface, soil depth and soil texture) which are the most important in controlling vegetation composition in the area. ayyad and el-ghareeb [83] found that the micro-variations in the soil were attributed to variations in topography and journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 252 the nature of parent materials on the distribution of species in the area. the results of the current study also showed that the proximity to sea is one of the common important factors for predicting all the modeled species. communities of the coastal dunes dominated by echinops spinosus and thymelea hirsuta and those of the inland ridges dominated by gymnocarpos decanderus and deverra tortuosa are stated to be the most diverse in the area [85]. however, these communities are stated to be threatened due to the establishment of summer resorts on the coastal dunes and the establishment of the irrigation network on the non-saline depressions [86]. b. effect of climate and land use changes on species distribution 1. effect of land use change species distribution models are increasingly used for prediction of the potential distribution of the species in response to disturbance or changes resulting from human intervention. predictive habitat distribution models are used as important tools for assessing the impact of land use change and other forms of human interference on different species. habitat distribution models have proven to be useful for modeling both commonly distributed species [87] as well as rare species [12], [54]. some studies used models with auc values > 0.6 for projecting the impact of climate change on plant distribution [71]. however, the intention here was to be more conservative and use only the models that showed reasonable performance according to all the accuracy assessment measures to assess the impact of both land use and climate change. as a result, only seven species were mapped to assess the impact of change in land use on their distribution (figure 2). assessment was done by comparing the area occupied by each species under no land use change in the area (theoretically natural landscape) to that in the years 1988 and 2011. the results show that all species face reduction in their habitats (figure 3). the results also show that all the species are at risk for increased reduction of their habitats under the projected land use change by the year 2023. noaea mucronata attained the maximum loss in habitat area in 1988 (7.47% of the potential area; figure 3), this increased five folds by 2011 (37.74%) and six folds by 2023 (44.79%). the major loss for this species occurs between the years 1988 and 2011. this trend is noticed for all the modeled species. halmy and colleagues [34], [38] assessed the change in the landscape between the years 1988 and 2011 and found that the landscape has experienced changes by which many natural areas were transformed to new uses. the study concluded that the landscape is trending towards being more artificial. this explains the dramatic increase in loss of areas occupied by each species between the years 1988 and 2011. the projected loss in the species’ area between the years 2011 and 2023 was shown to be lower than that between 1988 and 2011. noaea mucronata, asphodelus aestivus, and deverra tortuosa (figure 3) are most affected by the changes in land use in the period 1988-2011 and will continue to be at risk of habitat loss by the year 2023. the distribution of these three species is concentrated in the northern part of the landscape. this part of the landscape has been the most modified by human activities, and will continue to face more modifications pressures in the future. the urban sprawl, agricultural activities and other activities occurring in the area have resulted in habitat loss. these recent changes in the region place the plant species and their habitats under threat. in the late 1980s, establishment of summer resorts on the coastal dunes started to reshape the landscape of the area. quarrying activities increased as a result of the establishment of these resorts. mining and cutting of the limestone ridges in the area provide building materials necessary for the establishment of the resorts. this may have contributed to the fragmentation, destruction and loss of habitats. species inhabiting the coastal dunes and the non-saline depression habitats are stated to be threatened due to the establishment of summer resorts on the coastal dunes and the establishment of the irrigation network on the non-saline depression [86]. factors such as habitat size reduction or habitat fragmentation represent the most serious causes of species loss. however, arrangement and connectivity of habitat patches are also of great importance. habitat fragmentation makes it difficult for wildlife to maintain stable populations [88], [89]. the current study did not assess the fragmentation in the habitat of each species or estimated the degree of connectivity among patches. this will be part of future work planned to include more species with restricted distribution in the area. journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 253 fig .2. some of the species modelled; (a) anabasis articulata, (b) asphodelus aestivus, (c) astragalus spinosus, (d) deverra tortuosa, (e) gymnocarpos decanderus, (f) haloxylon salicornicum, (g) noaea mucronata, and (h) thymelaea hirsuta. (a) (a) (c) (d) (e) (f) (g) (h) journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 254 fig .3. change in habitat area due to change in land use in 1988, 2011, and the projected change by 2023. the loss is expressed as percentage of the potential habitat area for each species under the baseline climate and no land use. see table 3 for species binomial abbreviations. 2. effect of climate change many studies have focused on projecting the impact of climate change on the distribution of plant species [45], [90], [14], [73], [91], [92], [71]. most of these studies have been applied on global or regional scale. the current study attempts to assess the potential impact that climate change might have on the distribution of some plant species at the landscape scale within a desert ecosystem. under the csiro gcm models, the different emission scenarios used in the current study are predicted to lead to changes in the temperature and precipitation of the area (table 2 & figure 4). the study area is expected to experience an increase in annual mean temperature under the three applied scenarios, with b2a expected to result in the highest increase in temperature. not all the scenarios predict reduction in the annual mean precipitation of the area. the area is expected to experience increase in the annual mean precipitation by 3.11mm compared to the average over the period 1950-2000 under the a2a scenario. climate has an influence on species distribution at broad scale [45], [93].the results show that at the landscape level and the change in climate under the different emission scenarios have resulted in changes in the modeled species distribution. although the differences among the climate scenarios developed by the different models up to 2050 are stated to be minor [94], [95], the current results show that the expected impact of each of the used climate scenarios on the modeled species is different (figure 4). noaea mucronata, asphodelus aestivus, and anabasis articulataare are expected to be at risk of loss of habitat under all the employed scenarios. the high emission scenarios b2a and a2a cause higher impact on these species compared to the low emission scenario (a1b). for example, under b2a noaea mucronata, asphodelus aestivus, and anabasis articulata are expected to lose about 96%, 58% and 17% of their potential area respectively, while under a1b each are expected to lose 85%, 29%, and 13% of their potential area respectively (figure 5). scenario a1b, on the contrary, is expected to cause more loss in area for asphodelus aestivus and deverra tortuosa (29% and 7%, respectively) compared to the a2a scenario (23% and 2%, respectively). for gymnocarpos decanderus, and haloxylon salicornicum the a1b scenario is expected to cause loss in the area of their habitat (1.2% and 2.2%, respectively), while these species are expected to gain habitat under the other two high emission scenarios (20.5 and 5.8% under a2a scenario, respectively). under the a1b scenario, there will be an expected reduction in the annual precipitation and precipitation of the wettest quarter compared to the average observed for the period 1950-2000 (figure 4). on the contrary, under the a2a and b2a scenarios, the area is expected to experience increase in both annual precipitation and precipitation journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 255 of wettest quarter compared to the average observed for the period 1950-2000. these factors were found to be important for the occurrence of asphodelus aestivus, deverra tortuosa, gymnocarpos decanderus, and haloxylon salicornicum (table 4). thymelaea hirsute seems to favor the change in climate under the three different scenarios. the species is expected to gain habitat under these scenarios. the decrease in temperature seasonality and the increase in annual precipitation, precipitation of wettest month, precipitation of wettest quarter, and precipitation of coldest quarter under a2a and b2a compared to the average for the period 1950-2000 may explain this expected gain in habitat for thymelaea hirsute under these scenarios. noea mucronata is expected to be the most affected of the modeled species by the change in climate under the employed scenarios. noea mucronata seems to be sensitive to the increase in temperature seasonality that is expected to increase under the three scenarios. fig .4 mean of the climatic variables contributed in modeling plant species in the study area. the mean is calculated over the whole study area for each scenario (a1b, a2a & b2a) and for the baseline climate that represents the mean for the period 19502000. journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 256 fig .5. gain/loss in habitat area under three climate change scenarios combined with different land use scenarios: a) no land use; b) current land use; and c) projected land use scenario by the year 2023. gain/loss is expressed as percentage of the potential habitat area for each species under the baseline climate and no land use. see table 3 for species binomial abbreviations. 3. land use and climate change combined effect the results show that while the change in land use in the study area resulted in loss of the area of the potential habitat for all species, the change in the climate under the employed scenarios may result in gain in area for some species. the expected loss in the area of noaea mucronata, asphodelus aestivus, and anabasis articulata (96%, 58%, and 17%, respectively) under the high emission climate change scenario b2a is higher than the expected loss under the projected change in land use by the year 2023 (44%, 32%, and 15%, respectively). under the scenarios of combined change in climate and land use either under the current land use or that projected by 2023, all the species are expected to suffer loss in area (figure 5). an exception to that is gymnocarpos decanderus, which is expected to gain area under the combined scenario of a2a emission and each of the current land use scenarios and the projected land use by 2023. however, this increase is less than 5% of the potential area suitable for the species under a2a/2011 scenario and less than 1% under a2a/2023 scenario. the results reveal the serious fate that plant species might face under scenarios of climate and land use change. immediate actions are needed to ensure that species as asphodelus aestivus (figure 6) and noaea mucronata (figure 7) are not declining in other places across the northwestern coast. the current study modeled the distribution of the species in part of the phytogeographical region and the status of these species needs to be known over the whole phytogeographical region. more future studies to assess the status of the species in the area, especially those of restricted distribution, are still needed. based on the findings of these results, measures should be taken to maintain these species in the flora of the region. iv. conclusions the application of random forests to the employed climatic and land-surface parameter data proved to be successful in predicting the distribution of the plant species in the arid land landscape. the performance of the species distribution models in the current study could be attributed to the resolution of the environmental predictors used. at the landscape level the use of finer scale environmental predictors, especially climatic factors, may increase the prediction power of distribution models. the inclusion of environmental predictors that represent light proved to be of importance for the prediction of some of the modeled species in the study area. the study found that the expected impact of the a1b, a2aand b2a scenarios on the distribution of the modeled species is variable. in arid lands some species might be adversely affected by the change in climate under certain scenarios, while others might benefit from these changes. land use change poses more risk on most of the species modeled compared to climate change. the impact of land use is not differential while that of climate change is. change in land use in the area resulted in habitat loss for all the modeled species. land use change impact could be faster and more substantial in reducing the size of journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 257 plant species habitat. if the current trend in land use change continues, all species will continue to suffer habitat loss. the combined impact of land use and climate change pose serious threats to most of the species modeled. under combined scenarios of change in land use as projected by 2023 and change in climate, all the species are expected to suffer loss in habitat, except gymnocarpos decanderus.the results show that some species such as noaea mucronata and asphodelus aestivus may suffer serious threats in the area under the combined land use climate change scenarios. so, actions are needed to ensure that these species are not threatened across the northwestern coast and in egypt. this also, highlights the importance of assessing the impact of land use/climate change scenarios on other species of restricted distribution in the area.the application of species distribution modeling in desert and arid lands can provide a useful tool for mapping species and assessing the impact of human induced changes on different species. such applications are still rare, and this may be attributed to the fact that most of the arid lands and deserts are located in inaccessible or lightly populated areas. most of these areas are also located in less developed areas where the systematic surveys of the natural resources are not conducted on a regular basis. the lack of environmental predictors of appropriate landscape resolution to be used for modeling species in such areas is another factor to be considered. the current study will promote more studies that map plant species distribution and assess the risk to important species as a result of human interference. future studies are needed to assess the magnitude of fragmentation in each species habitat and to estimate the degree of connectivity among patches. fig .6 potential distribution of asphodelus aestivus under different land use and climate scenarios.1, 2 and 3 represent the natural landscape, current land use and future land use by 2023, respectively; and a, b, c and d represent the average climate (1950-2000), a1b, a2a and b2a climatic scenarios, respectively. climate scenarios la n d u se s ce n a ri o s journal of renewable energy and sustainable development (resd) volume 1, issue 2, december 2015 issn 2356-8569 258 fig .7 potential distribution of noaea mucronata under different land use and climate scenarios.1, 2 and 3 represent the natural landscape, current 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