Sebuah Kajian Pustaka: JEMMME (Journal of Energy, Mechanical, Material, and Manufacturing Engineering) Vol. 6, No. 1, 2021 ISSN 2541-6332 | e-ISSN 2548-4281 Journal homepage: http://ejournal.umm.ac.id/index.php/JEMMME Sudarman | A Feasibility Study on a Micro Hydro Power Plant at Coban Jahe… 41 A Feasibility Study on a Micro Hydro Power Plant at Coban Jahe Waterfall, Jabung, Malang Regency Sudarmana, Wahyu Guszolilb, Daryonoc, Muhammad Lukmand a,b,c,d Mechanical Engineering Dept, Engineering Faculty, University of Muhammadiyah Malang Jl.Raya Tlogomas No.246., Malang 65144 Telp.(0341)4624318 – 128 Fax. (0341) 460782 e-mail: sudarman@umm.ac.id Abstract Micro Hydro Power (MHP) Plant is a small-scale power plant under 100 kW. Generally, MHP is built in a place that the electricity network has not touched. Many waterfalls in Taji Village are only used as tourist attractions. One of them is Coban Jahe waterfall which has a water discharge of 0.60567 m3/s in the dry season. Waterfall in Coban Jahe was used and planned as Micro Hydro Power Plant, it was called as MHP. Potential electric power generated from the MHP Coban Jahe Waterfall is 14.0368 kW with an effective head of 3.4742 m. The results show from the financial analysis, the construction of MHP is quite feasible with NPV of Rp. 45,676,769, BCR of 1.0852, which means it is feasible to be continued, the Payback Period is 9 years which does not exceed the project life, and the IRR obtained is 10,0087% which the projects are feasible and profitable to build. Keywords: MHP; coban jahe; discharge; head; power; npv; bcr; payback period; irr 1. INTRODUCTION Water as a basic necessity of life is an important component for the quality of human life [1,2]. As an agricultural country, Indonesia has a fairly large water consumption power in the agricultural sector, especially in terms of irrigation [3]. In fact, Indonesia has a geographical location where some areas are hills and mountains [4,5], which sometimes become an obstacle in fulfilling the daily water supply. In comparison, the demand for electricity and fresh water is increasing due to the increase in population and comfort level of human beings. Micro hydropower is one of the best available solutions as it has economic, social, and environmental benefits and has a huge potential globally [6,7]. So this will make the demand for micro-hydro power generation [8]. From the background above, the construction of a Micro Hydro Power (MHP) Plant is one of the alternative energies that can be applied in Taji Village, Jabung District, Malang Regency, where there are many springs. The definition of micro-hydro or Microhydro Power Plant is a small-scale power plant that uses hydropower [9,10] as its driving force such as irrigation channels, rivers, or natural waterfalls by utilizing the waterfall height (head) and the amount of water discharge [11–13]. Micro-hydro-electric power is both an efficient and reliable form of a clean source of renewable energy. It can be an excellent method of harnessing renewable energy from small rivers and streams [14]. From the explanation above, it is necessary to have a deeper analysis both from technical analysis and financial analysis. 2. METHODS In conducting research, especially for technical and financial data collection, it is necessary to have a good and correct methodology because good methodology http://ejournal.umm.ac.id/index.php/JEMMME mailto:sudarman@umm.ac.id JEMMME (Journal of Energy, Mechanical, Material, and Manufacturing Engineering) Vol. 6, No. 1, 2021 doi: 10.22219/jemmme.v6i1.16433 Sudarman | A Feasibility Study on a Micro Hydro Power Plant at Coban Jahe… 42 produces good results. This Micro-hydro Power Plant Feasibility Study is made based on the flow chart as follows below in Figure 1: Figure 1. Feasibility Study Flowchart 3. RESULT AND DISCUSSION 3.1 Water Discharge The first step in carrying out technical analysis is by taking the discharge data from the Coban Jahe waterfall flow. This process requires a minimum of 3 people to take the water discharge. By counting the cross-Section Area (m2), Velocity of flow (m/s) and Water Discharge (m3/s). Then obtained the water discharge as follows in Table 1: Table 1. The average Water Discharge Location Cross section area (m2) Velocity of Flow (m/s) Water discharge (m3/s) 0 0 0 0 1 0,483 0,2908 0,1404 2 0,657 1,092 0,8666 3 0,441 0,1679 0,0865 Velocity of Flow mean 0,5169 m/s Water discharge mean 0,9318 m/s3 The calculation is carried out through the following equation [3]. 𝑄 = (𝐴1 π‘₯ 𝑉1) + (𝐴2 π‘₯ 𝑉2) + (𝐴3 π‘₯ 𝑉3) 𝑄 = (0,483 π‘₯ 0,2908) + (0,657 π‘₯ 1,092) + (0,441 π‘₯ 1,679) 𝑄 = 0,1404 + 0,7174 + 0,0740 START PROBLEM IDENTIFICATION TECHNICAL ANALYSIS FINANCIAL ANALYSIS FEASIBILITY PROPOSED NO JEMMME (Journal of Energy, Mechanical, Material, and Manufacturing Engineering) Vol. 6, No. 1, 2021 doi: 10.22219/jemmme.v6i1.16433 Sudarman | A Feasibility Study on a Micro Hydro Power Plant at Coban Jahe… 43 𝑄 = 0,9318 π‘š3/𝑠 𝑄 = 𝑐 π‘„π‘‘π‘œπ‘‘π‘Žπ‘™ With c = The water depth with free-flow, so the correction factor is 0.65, Qd = Total water discharge (m3/s) 𝑄𝑑 = 0,65 Γ— 0,9318 = 0,60567 π‘š3 𝑠 3.2 Weir and intake This weir is located at an elevation point of 690 m with a coordinate point of 7Β° 58ˊ10" S 112Β° 48ˊ10" E. The dam is planned to be 12 meters long, 3 meters high, and 9.2 meters wide, equipped with a spillway channel with a width of 5 m, a height of 2 m, and a length of 2 m, as shown in Figure 2. The dimension of intake is planned to be 0.8 m length, 0.4 m width, and 0.25 m distance from the free surface. The weir is planned to use a single side gate that is less than 2.5 m in width. And the design of gate with sliding gate. The retrieval capacity must be at least 120% of the dimension requirement to increase flexibility and to be able to meet higher needs over the life of the project. 𝑄𝑖𝑛 = 1,2 𝑄𝑑 𝑄𝑖𝑛 = 1,2 Γ— 0,60567 = 0,7268 π‘šπ‘  𝑠 Figure 2. The design of Dam/weir 3.3 Headrace In this study, the headrace with the trapezoidal open channel and length of approximately 50 meters width of 90 cm having a height of 75 cm and a channel base width of 70 cm, as shown in Figure 3. However, the water carrying channel must be able to hold water more than 10% higher in operation, the forebay water level does not drop from its usual height, and for guard height to avoid overtopping in case of excess discharge. The formula for the trapezoid-shaped channel is as follows [15]. 𝑄 = 𝑉. 𝐴 𝑉 = 1 𝑛 π‘₯ 𝑅 2 3 π‘₯ 𝑆 1 2 𝑅 = 𝐴 𝑃 With: Q = Water Discharge (m3/s) V = Velocity of Flow rate (m/s) R = hydraulic spokes (m) A = Cross section area (m2) P = Wet of circumference (m) s = slope of the channel base JEMMME (Journal of Energy, Mechanical, Material, and Manufacturing Engineering) Vol. 6, No. 1, 2021 doi: 10.22219/jemmme.v6i1.16433 Sudarman | A Feasibility Study on a Micro Hydro Power Plant at Coban Jahe… 44 n = coefficient of roughness (for slice 0.0017) h = water level (m), b = wide bottom channel (m) Table 2. Manning on the headrace Tunnel Explanation 'n Manning Land straight, new, uniform, ramps and clean 0,016-0,033 Winding, sloping and grassy 0,023-0,040 Poorly maintained and dirty 0,050-0,140 The ground is rocky, rough and irregular 0,035-0,045 Pair Gravelly 0,023-0,035 A pair of split stones 0,017-0,030 Concrete Smooth, good connection and flat 0,014-0018 Less smooth and connection is not flat 0,018-0,030 𝐴 = (𝐡 π‘₯ π‘š. β„Ž)β„Ž = (0,70 π‘₯ 0,75 π‘₯ 0,5)0,5 = 0,13125 π‘š2 𝑃 = 𝐡 + 2β„Ž (π‘š2 + 1)0,50,70 + 2 π‘₯ 0,5(0,752 + 1)0,5 = 1,9 π‘š 𝑅 = 0,13125 π‘š2 1,9 π‘š = 0,06907 π‘š Then, 𝑆 = √ 𝑛 𝑅2/3 = √ 0,0017 0,069072/3 = 0,0647 Then it can be obtained π‘Š = √0,5 π‘₯ 0,5 = 0,50 Figure 3. Design of the headrace 3.4 Forebay A calming tub or forebay is located before the approach pipeline, which has a steep slope and hits the turbine's blades. The design of this calming basin will be provided with complementary buildings such as overflow, sediment drainage facilities, filters, open- close (stop-log) gates, as shown in Figure 4. The formula for the heating bath size is as follows: [15] Calming tube/forebay area, 𝐴 = 𝐡𝐿 Penstock cross-section area: 𝐴 = πœ‹ 4 𝐷2 The velocity of flow at intake: 𝑉 = 𝑄 𝐴 Water depth above penstock: 𝑠 = 0,54 π‘₯ 𝑉π‘₯ 𝐷0,5 The depth of the water in the soaking tub: T = s + D + f The volume of the tranquilizer pool V = AT The width of the forebay, B = 3B = 3 Γ— 0.5 m = 1.5 m The length of the forebay, L = 2B = 2 Γ— 1.5 m = 3 m JEMMME (Journal of Energy, Mechanical, Material, and Manufacturing Engineering) Vol. 6, No. 1, 2021 doi: 10.22219/jemmme.v6i1.16433 Sudarman | A Feasibility Study on a Micro Hydro Power Plant at Coban Jahe… 45 The area of the forebay, 𝐴 = 𝐡𝐿 = 1,5 Γ— 3 = 4,5 π‘š2 The cross-sectional area of the penstock, 𝐴 = πœ‹ 4 𝐷2 = 0,785 Γ— 0,59382 = 0,2767π‘š2 The flow velocity when entering the pipe, 𝑉 = 𝑄 𝐴 = 0,5938 0,2767 = 2,146 π‘š 𝑠 The water depth above the penstock 𝑠 = 0,54 𝑉 𝐷0,5 = 0,54 Γ— 2,146 Γ— 0,59380,5 = 0,8929 π‘š The depth of the water as a tranquilizer pool 𝑇 = 𝑠 + 𝐷 + 𝑓 = 0,8929 + 0,5938 + 0,1 = 1,5867 π‘š The volume of the water as a tranquilizer pool 𝑉 = 𝐴𝑇 = 4,5 Γ— 1,5867 = 7,1401 π‘š3 β‰… 7,2 π‘š3 Figure 4. The design of Forebay 3.5 Penstock Penstock is planned using cold-rolled steel and to be joined by welds and flanges as joints. The penstock diameter can be rapidly calculated to ensure that the pipe is rapidly durable, safe, economical, and practical. The following equation can be used: 𝐷 = 2,69 π‘₯ ( 𝑛2 π‘₯ 𝑄2 π‘₯ 𝐿 𝐻 ) 0,1879 (Rizal Firmansyah, et. al, 2014) With: D = penstock diameter (m) n = penstock coefficient (for welded steel 0,012) Q = water discharge (0,60567 m/s3) L = penstock length (20 m) H = Head gross (4 m), then: 𝐷 = 2,69 π‘₯ ( 0,0122 π‘₯ 0,605672 π‘₯ 24 4 ) 0,1875 𝐷 = 2,69 π‘₯ ( 0,0122 π‘₯ 0.605672 π‘₯ 24 4 ) 0,1875 𝐷 = 0,5938 β‰… 0,6 meter Table 3. Materials Used in penstock Material Young Modulus of elasticity E(N/m3) E9 Coefficient of linear expansion a (m/m oc) E6 Ultimate tensile strength (N/m2) E6 n Welded Steel 206 12 400 0,012 Polyethylene 0,55 140 5 0,009 Polyvinyl Chloride (PVC) 2,75 54 13 0,009 Asbestos Cement n.a 8,1 n.a 0,011 Cast Iron 78,5 1 140 0,014 Ductile Iron 16,7 11 340 0,015 JEMMME (Journal of Energy, Mechanical, Material, and Manufacturing Engineering) Vol. 6, No. 1, 2021 doi: 10.22219/jemmme.v6i1.16433 Sudarman | A Feasibility Study on a Micro Hydro Power Plant at Coban Jahe… 46 Figure 5. Penstock The velocity of flow at the penstock The velocity of flow by the following equation: 𝑉 = 0,125√2π‘”β„Ž With V = velocity of flow in the penstock, g = acceleration due to gravity of 9.81 m / s3, h = gross head, then: V = 0,125 𝑉 = 0,125√2 π‘₯ 9,81 π‘š 𝑠3 π‘₯ 4 π‘š = 1,1073 π‘š 𝑠 Penstock Thickness The design of the pipe thickness Ξ΄ (mm), by the following equation: πœ• = 𝐷 3√ π‘›π‘π‘œ 2 𝐸 Where Po = 0.1 Mpa, and E = 200 Gpa, then: πœ• = 0,6093 3√ 4 π‘₯ 0,1 2 π‘₯ 200 = 0,06093 π‘š β‰… 6 π‘šπ‘š (The penstock thickness is quiet secure, according to guidelines with a minimum of 1.5 mm) 3.6 Power House The design planning for the powerhouse itself uses the SketchUp application as support. The dimensions of the powerhouse itself are 7 meters long, 5 meters wide, 5 meters high. 3.7 Net Head Net head is the difference between gross head and head loss in the pipe. Gross head is the vertical distance between the source water surface and the level of the tailrace for the reaction turbine and the nozzle exit for the impulse turbine. The head loss in the pipe system is in the form of head loss in the pipe and head loss for piping equipment such as connections, valves, branching, and diffusers and so on. Head losses major are calculated using the following calculation formula [16]. β„Žπ‘“ = 𝑓π‘₯ LVΒ² D.2g With JEMMME (Journal of Energy, Mechanical, Material, and Manufacturing Engineering) Vol. 6, No. 1, 2021 doi: 10.22219/jemmme.v6i1.16433 Sudarman | A Feasibility Study on a Micro Hydro Power Plant at Coban Jahe… 47 V = velocity of flow in the pipe (1.1073 m / s) f = friction efficiency = 0.065 (from moody diagram) g = acceleration of gravity 9.8 m / s2 L = pipe length (24 meters) D = inside diameter of pipe (0.5938m) Then it found, β„Žπ‘“ = 0,065 π‘₯ 24 π‘šπ‘’π‘‘π‘’π‘Ÿ π‘₯ 1,1073 m/s 0,5938 π‘₯ 2 π‘₯ 9,8 m/𝑠2 = 0,1484 π‘š Losses on joining, hs: β„Žπ‘  = π‘˜ 𝑣2 2 .𝑔 [15] Where k = coefficient 0,2 for an open valve β„Žπ‘  = 0,2 π‘₯ 1,1072 π‘š/𝑠 2 .9,8 π‘š/𝑠2 = 0,0124 Losses in the trash filter (Trashrack loss) βˆ†Hr βˆ†π»π‘Ÿ = πœ‘ ( 𝑠 𝑏 ) 4 3 𝑣2 2 𝑔 𝑠𝑖𝑛 𝛼 [15] Coefficient based on the shape of the mesh bar profile, form factor (2.4 for rectangles, and 1.8 for round bars), s = thickness of the mesh bars (m), b = distance between bars (m), Ξ± = slope against horizontal (75o), βˆ†π»π‘Ÿ = 2,4 π‘₯ ( 0,01 0,015 ) 4 3 π‘₯ 1,1072 π‘š 𝑠 2 π‘₯ 9,8 π‘š 𝑠2 π‘₯ 𝑠𝑖𝑛 75Β° = 0,303 π‘š 3.8 Water Turbine In general, the research results in the field show the potential for developing PLTMH with a head height of 6 - 60 m, which can be categorized as the low and medium head. The graphic in Figure 5 below can help with turbine selection. Figure 5. Turbine Selection In determining the type of turbine, first determine the specific speed using the following Kaplan Turbine speed equation: 𝑁 = 2283 𝐻0,486 JEMMME (Journal of Energy, Mechanical, Material, and Manufacturing Engineering) Vol. 6, No. 1, 2021 doi: 10.22219/jemmme.v6i1.16433 Sudarman | A Feasibility Study on a Micro Hydro Power Plant at Coban Jahe… 48 The speed of water entering the turbine impeller is𝑉 = π‘βˆš2π‘”β„Ž Where c = velocity coefficient (0,95 ≀ C ≀ 0,98), maka 𝑉 = 0,96√2 π‘₯ 9,81 π‘š 𝑠2 π‘₯ 3,4742 π‘š = 7,9258 π‘š/𝑠 Spesifik Turbine speed 𝑁𝑠 = 2283 3,4742 0.486 = 1246,38 Then it can be calculated the turbine speed Nt (rpm) with the following equation, 𝑁𝑑 = 𝑁𝑠 𝐻 5/4 βˆšπ‘ƒ 𝑁𝑑 = 1246,38 π‘₯ 3,47425/4 √16,5139 = 1454,76943 π‘Ÿπ‘π‘š β‰… 1455 π‘Ÿπ‘π‘š 3.9 Power Net fall height is 3.4742 and discharge is 0.60567 m3 / s, turbine efficiency Ι³t = 0.80, generator efficiency Ι³g = 0.85, then the electric power generated : 𝑃 = πœ‚π‘‘ π‘₯ 𝑔 π‘₯ 𝑄 π‘₯ 𝐻𝑒𝑓𝑓 [16] Water power 𝑃 = 0,8 Γ— 9,81 Γ— 0,60567 Γ— 3,4742 = 16,5139 π‘˜π‘Š Generator power 𝑃𝑔 = 𝑃 Γ— πœ‚π‘” = 16,5139 Γ— 0,85 = 14,0368 π‘˜π‘Š Based on the above analysis, it shows that the mean flow rate of Coban Jahe Waterfall is 0.60567 m3 / s with an effective flow rate of 3.4742 m and is estimated to produce electric power of 14.0368 kW. 3.10 Financial Analysis The economic analysis was carried out to evaluate the feasibility of building an MHP in Coban Jahe to determine the amount of financial benefits that were given. With energy sales costs of Rp. 1,100 per kWh with PLN sales benchmarks, and in this study, it is assumed that the project life is 10 years and taking into account the PF power factor of 70%, the income that will be obtained in one year is: πΈπ‘›π‘’π‘Ÿπ‘”π‘¦ π‘Œπ‘’π‘Žπ‘Ÿ = 𝑃𝑛𝑒𝑑 Γ— 8760 Γ— 𝑃𝐹 [16] πΈπ‘›π‘’π‘Ÿπ‘”π‘¦ π‘Œπ‘’π‘Žπ‘Ÿ = 14,0368 Γ— 8760 Γ— 70% = 86073,6576 π‘˜π‘Šβ„Ž 𝑅𝑒𝑣𝑒𝑛𝑒𝑒 = (𝑅𝑝. 1100/π‘˜π‘Šβ„Ž )π‘₯ 86073,6576 π‘˜π‘Šβ„Ž = 𝑅𝑝. 94.681.023, βˆ’ Table 4. Investment Costs Issued No Descriptions Total (Rp) 1 Preparation works 14.002.188 2 Building works - a Weir / Intake 52.176.415 b Forebay 21.936.632 c Spillway 1.340.313 d Headrace 13.403.128 e Penstock 111.746.103 f PowerHouse 52.408.438 3 Electrical-Mechanical Works 192.091.600 4 Tax 10% 45.910.482 Total 505.015.298 The construction of MHP Coban Jahe requires an investment cost of Rp 505,015,298 or Rp 35,977,951 per kW, the proceeds from the sale of electrical energy produced by the JEMMME (Journal of Energy, Mechanical, Material, and Manufacturing Engineering) Vol. 6, No. 1, 2021 doi: 10.22219/jemmme.v6i1.16433 Sudarman | A Feasibility Study on a Micro Hydro Power Plant at Coban Jahe… 49 MHP. Operational and maintenance costs are costs that must be prepared to carry out operational and maintenance activities. In this study, it is assumed that the operational and maintenance costs amount to 1% of the total project investment costs. 𝑂𝑀 = 1% x Rp505,015,298 𝑂𝑀 = Rp. 5,050,153 3.11 Net Present Value Net Present Value is an assessment of the project value by analyzing the cash flow obtained by comparing the revenue and issuance each year with the discount factor. The discount factor can be found using the interest rate. In this study it is assumed that the interest rate is 10%, so the discount factor is calculated in year 1. (Harto Jawadz, Prasetijo, and Purnomo 2019). In the first year the discount factor is 0.909. To find out the cash flow (Cf) in year 1, it is necessary to find the difference between revenue (Ci) and expenditure (Co) which was previously multiplied by the discount factor that was previously sought. 𝐢𝑓1 = 𝐢𝑖 βˆ’ πΆπ‘œ [16] 𝐢𝑓1 = (𝑅𝑝. 94.681.023π‘₯ 0,909) βˆ’ (Rp. 5.050.153 x 0,909) Cf1 = Rp. 86.065.050 The same calculation is carried out to find the discount factor in years 2 to 10 according to the planned age of the project. The results of the calculations that have been done are shown in the table below. Tabel 5. The calculation of NPV NPV Calculation NPV with Discount Factors 10% Years Discount Factors Cash in (Rp) Cash out (Rp) Cashflows (Rp) 0 1 0 505.015.298 505.015.298 1 0,909 86.065.050 4.590.589 81.474.461 2 0,826 78.206.525 4.171.426 74.035.099 3 0,751 71.105.449 3.792.665 67.312.784 4 0,683 64.667.139 3.449.254 61.217.884 5 0,621 58.796.916 3.136.145 55.660.771 6 0,564 53.400.097 2.848.286 50.551.811 7 0,513 48.571.365 2.590.728 45.980.637 8 0,467 44.216.038 2.358.421 41.857.616 9 0,424 40.144.754 2.141.265 38.003.489 10 0,386 36.546.875 1.949.359 34.597.516 Total - 581.720.208 536.043.438 45.676.769 From the results of these calculations it is known that the NPV value obtained is Rp. 45,676,769. This indicates that the NPV> 0 which means the project is feasible to continue. 3.12 Benefit Cost Ratio Benefit cost ratio is the ratio between the revenue obtained from the sale of electrical energy with the total costs that must be incurred during the life of the project. In this study, the benefit cost ratio obtained is 𝐡𝐢𝑅 = 𝑃𝑉[𝐡𝑒𝑛𝑒𝑓𝑖𝑑𝑠] 𝑃𝑉[πΆπ‘œπ‘ π‘‘] [16] JEMMME (Journal of Energy, Mechanical, Material, and Manufacturing Engineering) Vol. 6, No. 1, 2021 doi: 10.22219/jemmme.v6i1.16433 Sudarman | A Feasibility Study on a Micro Hydro Power Plant at Coban Jahe… 50 𝐡𝐢𝑅 = 𝑅𝑝. 581.720.208 𝑅𝑝. 536.043.438 = 1,0852 Based on these calculations, the benefit cost ratio obtained is more than 1 (BCR> 1), which is 1.0852. This shows that this project is worth continuing. 3.13 Payback Period The payback period shows the time it takes for the project to be able to return the investment value from the reduced revenue for operations and maintenance each year. In this study, the accumulated cash flow value was calculated to determine the year in which the accumulated cash flow value was positive. Tabel 6. The Calculation of Net Cashflow PBP Year Cash in (Rp) Cash Out (Rp) Net Cash flow (Rp) Cashflow (Rp) 0 0 505.015.298 505.015.298 0 1 86.065.050 509.605.887 423.540.837 81.474.461 2 164.271.576 513.777.314 349.505.738 155.509.560 3 235.377.024 517.569.979 282.192.955 222.822.344 4 300.044.163 521.019.233 220.975.070 284.040.228 5 358.841.079 524.155.378 165.314.300 339.700.999 6 412.241.176 527.003.664 114.762.489 390.252.810 7 460.812.541 529.594.393 68.781.852 436.233.446 8 505.028.579 531.952.814 26.924.236 478.091.063 9 545.173.333 534.094.079 11.079.253 516.094.552 10 581.720.208 536.043.438 45.676.769 550.692.068 Based on the results of the calculations in table 10, it is known that the last year the net cash flow was negative occurred in the 3rd year as (n). In calculating the payback period, it is necessary to know the investment costs as (a), the value of accumulative cash flow for the 3rd year as (b), and the accumulative cash flow for the 4th year as (c). The results of the cash flow calculation are used to calculate the payback for the following period: 𝑃𝑃 = 𝑛 + π‘Žβˆ’π‘ π‘βˆ’π‘ π‘₯ 1 π‘¦π‘’π‘Žπ‘Ÿ [16] 𝑃𝑃 = 8 + 𝑅𝑝. 505.015.298 βˆ’ 𝑅𝑝. 11.079.253 𝑅𝑝. 516.094.552 βˆ’ 𝑅𝑝. 11.079.253 π‘₯ 1 π‘¦π‘’π‘Žπ‘Ÿ 𝑃𝑃 = 8,978 year Based on the calculation results, the payback period or the payback period for investment can occur for 8.978 years or 9 years. 3.14 Internal Rate Return Internal rate of return is an indicator of the level of efficiency of an investment which shows how much the interest rate provided by the investment is compared to the interest rate from the bank. To be able to find the IRR value, it is necessary to look for a discount factor when the NPV is negative, which is greater than the interest rate on the NPV. In this study, an interest rate of 34% was used. πΉπ‘–π‘Ÿπ‘ π‘‘ π‘¦π‘’π‘Žπ‘Ÿ βˆ’ 1 = 1 (1+34%)1 = 0,746 [16] JEMMME (Journal of Energy, Mechanical, Material, and Manufacturing Engineering) Vol. 6, No. 1, 2021 doi: 10.22219/jemmme.v6i1.16433 Sudarman | A Feasibility Study on a Micro Hydro Power Plant at Coban Jahe… 51 In the first year the discount factor is known to be 0.746. To find out the cash flow in year 1, it is necessary to find the difference between revenue and expenditure which was previously multiplied by the discount factor that was previously sought. Cashflow year 1 = Receipt-Expenditure Cash flow year 1 = (Rp. 94,681,023-0,746) - (Rp. 5,050,153 x 0.746) = Rp. 70,632,043 Table 7. Calculation of NPV with interest rate 34% IRR Calculation NPV with Discount Factors 10% Years Discount Factors Revenue (Rp) Expenditure (Rp) Cashflows (Rp) 0 1 0 505.015.298 505.015.298 1 0,746 70.632.043 3.767.414 66.864.629 2 0,557 52.737.330 2.812.935 49.924.395 3 0,416 39.387.306 2.100.864 37.286.442 4 0,31 29.351.117 1.565.547 27.785.570 5 0,231 21.871.316 1.166.585 20.704.731 6 0,173 16.379.817 873.676 15.506.141 7 0,129 12.213.852 651.470 11.562.382 8 0,096 9.089.378 484.815 8.604.564 9 0,072 6.817.034 363.611 6.453.423 10 0,054 5.112.775 272.708 4.840.067 Total 263.591.969 519.074.924 255.482.955 From the calculation results in the table, it is known that the NPV obtained with a discount factor of 34% is RP-255,482,995 with The results are performed the following IRR calculations: 𝐼𝑅𝑅 = 10% + 𝑅𝑝.45.676.769 (𝑅𝑝.45.676.769βˆ’(βˆ’π‘…π‘.255.482.955) π‘₯ (34 βˆ’ 10)% [16] 𝐼𝑅𝑅 = 10% + 0,0364 π‘₯ 24% 𝐼𝑅𝑅 = 10,0087 % Based on the calculation, it is known that the IRR level in this project is 10.0087%, which means that this project is feasible and profitable. 4. CONCLUSION Technical Feasibility Based on the results of this study, the following conclusions were obtained: 1. Coban Jahe water flow has a potential flow of water with a reliable discharge of 0.60567 m3 / s and an effective head of 3.4742 m. 2. The hydropower potential can be utilized to plan the construction of an MHP with a capacity of 14.0368 kW. 3. The turbine used is a Kaplan turbine from a low head and the generator used is 15 kW. Economic Feasibility 1. The investment cost required for the construction of MHP Plant is Rp. 505,015,298 or RP 35,977,951 per kW. 2. The planning of this MHP Plant project is feasible to be continued with a project life of 10 years with economic analysis such as NPV of Rp. 45,676,769. This shows that the NPV> 0 means that the project is feasible to be continued. The Benefit Cost Ratio obtained is 1.0852 and is obtained more than 1 (BCR> 1). This shows that this project is worth continuing. Payback Period within 9 years. Based on the calculation results, and the IRR on this project is 10.0087%, which means this project is feasible and profitable. JEMMME (Journal of Energy, Mechanical, Material, and Manufacturing Engineering) Vol. 6, No. 1, 2021 doi: 10.22219/jemmme.v6i1.16433 Sudarman | A Feasibility Study on a Micro Hydro Power Plant at Coban Jahe… 52 REFERENCES 1. Chauhan A, Saini RP. A review on Integrated Renewable Energy System based power generation for stand-alone applications: Configurations, storage options, sizing methodologies and control. Renew Sustain Energy Rev. 2014 Oct;38:99–120. 2. Penche C. Guide on How to Develop a Small Hydropower Plant. Eur Small Hydropower Assoc. 2004;296. 3. Firmansyah I, Mahmudsyah S, Yuwono T. Studi Pembangunan Pembangkit Listrik Tenaga Mikro Hidro (PLTMH) Dompyong 50kW Di Desa Dompyong, Bendungan, Trenggalek Untuk Mewujudkan Desa Mandiri Energi (DME). Jur Tek Elektro FTI-ITS. 2008;1. 4. Harto Jawadz UR, Prasetijo H, Purnomo WH. Studi Potensi Pembangkit Listrik Tenaga Mikro Hidro (PLTMH) Di Aliran Sungai Desa Kejawar Banyumas. Din Rekayasa. 2019 Feb 1;15(1):11. 5. Marhendi T. Studi Potensi Pembangkit Listrik Tenaga Mikro Hidro Di Sungai Brukah (Kali Bening, Banjarnegara). Techno (Jurnal Fak Tek Univ Muhammadiyah Purwokerto). 2019 Apr 30;20(1):10. 6. Mantiri HE, Rumbayan M, Mangindaan GMC. Perencanaan Pembangkit Listrik Tenaga Listrik Minihidro Sungai Moayat Desa Kobo Kecil Kota Kotamobagu. J Tek Elektro dan Komput. 2018;7(3):227–38. 7. Prabowo Y, B S, Nazori N, Gata G. Studi Kelayakan Pembangkit Listrik Tenaga Mikrohidro (Pmlth) Pada Saluran Irigasi Gunung Bunder Pamijahan Bogor. J Ilm FIFO. 2018 Jun 10;10(1):41. 8. Patel SU, Pakale PN. Study on Power Generation By Using Cross Flow Water Turbine in Micro Hydro Power Plant. Int J Res Eng Technol. 2015;04(05):1–4. 9. Sallata MK, Nugroho HYSH, Wakka AK. THE UTILIZATION OF MICROHYDRO POWER TO ESTABLISH ENERGY SELF-SUFFICIENT VILLAGE. J Penelit Kehutan Wallacea. 2015 Apr 30;4(1):71. 10. Saputra AT, Weking AI, Artawijaya IW. Eksperimental Pengaruh Variasi Sudut Ulir Pada Turbin Ulir (Archimedean Screw) Pusat Pembangkit Listrik Tenaga Mikro Hidro Dengan Head Rendah. Maj Ilm Teknol Elektro [Internet]. 2019 May 6;18(1):83. Available from: https://ojs.unud.ac.id/index.php/JTE/article/view/45313 11. Dwiyanto V, Kusumastuti DI, Tugiono S. Analisis Pembangkit Listrik Tenaga Mikro Hidro (PLTMH) Studi Kasus: Sungai Air Anak (Hulu Sungai Way Besai). J Rekayasa Sipil dan Desain. 2016;4(3). 12. Sukamta S. Studi Analisis Pembangkit Listrik Tenaga Mikrohidro di Kedung Sipingit Desa Kayupuring Kecamatan Petungkriyono Kabupaten Pekalongan. Edu Elektr J. 2018;7(1). 13. Murni SS, Suryanto A. Analisis Efisiensi Daya Pembangkit Listrik Tenaga Mikrohidro Menggunakan HOMER (Studi Kasus PLTMH Parakandowo Kabupaten Pekalongan). J List Instrumentasi, dan Elektron Terap. 2020;1(2). 14. Nasir BA. Design of Micro-Hydro-Electric Power Station. Int J Eng Adv Technol. 2013;2(5):39–47. 15. Firmansyah R, Utomo T, Purnomo H. Perancangan Pembangkit Listrik Tenaga Mikrohidro Gunung Sawur Unit 3 Lumajang. J Mhs TEUB. 2014;2(7). 16. Harto Jawadz UR, Prasetijo H, Purnomo WH. Studi Potensi Pembangkit Listrik Tenaga Mikro Hidro (PLTMH) Di Aliran Sungai Desa Kejawar Banyumas. Din Rekayasa. 2019;