DOI: 10.3303/CET25120011
Paper Received: 23 May 2025; Revised: 4 September 2025; Accepted: 8 October 2025
Please cite this article as: Tapia J.F.D., Abrasia A.M., Dalisay J.A., Halili J.A., Miguel A.F., Mangali K.M., Lopez C.J., Foo D.C.Y., Tan R.R.,
2025, Techno-economic Analysis of Sustainable Aviation Fuel Production from Corn Stover in the Philippines, Chemical Engineering
Transactions, 120, 61-66 DOI:10.3303/CET25120011
CHEMICAL ENGINEERING TRANSACTIONS
VOL. 120, 2025
A publication of
The Italian Association
of Chemical Engineering
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Copyright © 2025, AIDIC Servizi S.r.l.
ISBN 979-12-81206-21-2; ISSN 2283-9216
Techno-economic Analysis of Sustainable Aviation Fuel
Production from Corn Stover in the Philippines
John Frederick D. Tapiaa, Alexandra Mirfi Abrasiaa, Jahsiel Ann Dalisaya, Julia
Aliana Halilia, Alexandra Francesca Miguela, Kylie Marie Mangalia, Christine Joselle
Lopeza, Dominic C. Y. Foob, Raymond R. Tana
aDepartment of Chemical Engineering, De La Salle University, 2401 Taft Avenue, Malate, Manila, Philippines, 0922
bDepartment Chemical and Environmental Engineering, University of Nottingham Malaysia, Semenyih, Malaysia
john.frederick.tapia@dlsu.edu.ph
The growing demand for sustainable aviation fuel (SAF) has driven innovation in alternative fuel technologies,
with synthetic paraffinic kerosene (SPK) emerging as a viable candidate as it offers a reduction in environmental
footprint compared to conventional fossil fuels. In this study, the feasibility of biomass-derived SPK was
explored, utilizing corn stover as the process feedstock. The designed process integrates key thermochemical
processes such as gasification, Fischer-Tropsch (FT) synthesis, and hydrocracking, to convert corn stover into
SPK. The process was simulated in commercial software Aspen Plus V12, where its material and energy flows
were analyzed. Moreover, the Anderson-Schulz Flory distribution model was used to determine the FT product
distribution. The simulation results show a 75 % molar conversion of carbon monoxide and a biomass-to-SPK
conversion of 6 % was achieved. The sustainability of the developed process was assessed through its carbon
dioxide (CO₂) emissions, with syngas cleaning reducing emissions by 30.70 %, resulting in a carbon footprint
of 0.58 kg CO₂/kg syngas. The remaining CO₂ in the FT fuel underwent flashing and adsorption, enabling 63.27
% recovery for reuse in steam and power plants. Subsequently, the total capital investment, including working
and fixed capitals, were estimated. The FT-SPK pathway was proven to be costly due to the energy-intensive
processes. However, a positive ROI and a payback period within 5 y were achieved. The product selling prices
were also ascertained alongside a breakeven analysis to ensure that the manufacturing operation remains
economically viable.
1. Introduction
The growing demand for sustainable aviation fuel (SAF) has driven innovation in the production of alternative
fuel technologies. Synthetic paraffinic kerosene (SPK), a drop-in type of SAF, is a promising candidate as it
offers a reduction in environmental footprint compared to conventional fossil fuels. Corn stover, an abundant
agricultural waste, presents an excellent renewable feedstock for SPK production, while simultaneously
supporting agricultural waste management and sustainable fuel development. Ail and Dasappa (2016) explored
switchgrass, residual wood straw, and woody biomass, while Lopez et al. (2024) focused on forest waste, and
municipal solid waste as possible feedstock. In contrast, this study focuses on corn stover due to its regional
availability and waste potential in the Philippines. Mohsin et al. (2017) identify the supply cost as a major barrier
to SAF adoption, as production costs typically exceed those of gasoline and diesel. However, this study
demonstrates an economically viable process of producing SPK from corn stover. Several studies have also
used corn biomass for bio-aviation fuel using lignin conversion (Shi et al., 2024) and hydrothermal conversion
of corn stalk (Wang et al., 2024). Improvements of the upgrading of pyrolysis oil have been made through
characterization of catalysts for hydrotreating (Suh et al., 2024). However, the economic and environmental
advantages of thermochemical processes such as gasification and Fischer-Tropsch (FT) synthesis have yet to
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be studied. These processes are key stages that facilitate the conversion of corn stover to SPK. It provides
sustainable and cost-efficient SAF production.
2. Process Design
The production process for corn stover-based SPK is analyzed through the following steps: (1) determination of
appropriate plant capacity with Philippines as the main market, (2) simulation of the process in Aspen Plus, (3)
analysis of environmental impacts through accounting of carbon footprint and (4) analysis of economic benefits
through various indicators.
2.1 Feedstock Profile and Plant Capacity Determination
The jet fuel demand in the Philippines is projected to increase from 640,000 t in 2023 to 1,095,000 t in 2033
based on the jet fuel consumption data of the Philippines from 2013 to 2022 (Department of Energy, 2024). The
annual plant capacity to remain market competitive in the Philippines is 20,300 t of SPK, requiring 317,000 t of
corn stover. The required corn stover for this production is justified by the selection of Cagayan Valley in the
Luzon region as the plant location, as it is the leading area for corn production in the Philippines. The average
corn stover production in Luzon is determined to be 1,726,000 t (Philippine Statistics Authority, 2024).
Considering market constraints such as allocations to other industries and losses from harvesting, the available
corn stover is around 690,000 t annually.
The proximate analysis and elemental composition of corn stover as raw material for the process is shown in
Table 1. The high volatile matter content contributes to the fraction of biomass expected to decompose into light
organic compounds in the form of syngas, a precursor for various bioenergy synthesis applications. As the
model relies on these specific composition values, which are inherently variable, this constitutes a limitation in
representing real-world process conditions.
Table 1: Proximate analysis and elemental composition of corn stover (Munu et al., 2021)
Properties wt % Composition wt %
Volatile Matter 66.20 Carbon 34.91
Moisture Content 12.50 Hydrogen 6.22
Fixed Carbon 15.70 Nitrogen 0.56
Ash 5.60 Sulfur 1.06
Oxygen 57.25
2.2 Steady State Process Simulation
The designed process was modelled in Aspen Plus V12 (www.aspentech.com) to assess the mass and energy
flows within the system. The parameters used for the simulation are shown in Table 2, while the simulation
flowsheet shown in Figure 1. During gasification, processes such as drying, pyrolysis, oxidation, and reduction
occur within the chamber, modelling a downdraft gasifier. In the drying process, the amount of moisture removed
was determined based on its fraction in the proximate analysis. Tar formation is modelled based on the study
by Marcantonio et al. (2020). A decomposer block is added before pyrolysis to break down the non-conventional
biomass component into conventional components. Gibbs-free energy minimization is assumed for production
formation in the pyrolysis block. Formation of H2S and NH3 as impurities are also simulated. The Power Law
model was employed for the kinetic rate equations in the oxidation and reduction processes, which are adopted
from the study of Njuguna et al. (2023). For syngas cleaning, the key process is cryogenic distillation. The
Radfrac block was utilized to model the process using the parameters in the study of Li et al. (2022). Meanwhile,
the bottoms flow rate varied until a removal rate of 98.2 % was achieved. The Fischer-Tropsch (FT) reactor was
modeled using the Anderson-Schulz Flory (ASF) distribution to facilitate the calculation of the carbon monoxide
conversion and estimate the FT product distribution. In this block, the chain-growth probability constant is 0.91
with the carbon monoxide conversion initially set to 80 %. Then, a series of distillation columns is used to recover
and refine the SPK product. The FT liquid undergoes fractional distillation to separate the light fuel from heavy
fuel. The light FT fuel is further distilled to separate C1-C10 gas from the SPK. FT gas is sent in a pressure swing
adsorber (Sep) to recover the hydrogen from the FT gas, to be used for the hydrocracker. The hydrocracking
reactor was simulated as a kinetic reactor following Langmuir-Hinshelwood-Hougen-Watson (LHHW) rate law.
Only mono-methyl alkanes of carbon chains ≥ C19 are cracked to primarily yield products within the SPK carbon
range.
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Table 2: Simulation settings in Aspen Plus
Process Block Settings
Drying RStoic 100 °C, 1 bar, Fractional Conversion: 0.125
Decomposition RYield 700 °C, 4 bar, Component Yields: Ash, C, H2, N2, S, O2
Pyrolysis RGibbs 700 °C, 4 bar, Calculation Option: Phase and Chemical
Equilibrium, Products: C, H2, CO2, CO, CH4, N2, S, H2O, O2
Tar Formation RStoic 700 °C, 4 bar, Fractional Conversion: 1.00
NH3 and H2S Formation RStoic 700 °C, 4 bar, Fractional Conversion: 1.00 (S); 1.00 (N2)
Reduction RPlug 700 °C, 4 bar
Oxidation RPlug 700 °C, 4 bar
Flash Separation Flash2 0 °C, 32.3 bar
Cryogenic Distillation Radfrac No. of Stages: 44, Reflux Ratio: 2.4, Feed Stage: above 20th
Top-stage Pressure: 32.2 bar, 44th-stage Pressure: 32.3 bar
Fischer-Tropsch RStoic 220 °C, 25 bar
FT Fuel Flash Separation Flash3 1 bar, 0 kW
Pressure Swing Adsorption Sep H2 recovery: 0.85 %
FT Light-Heavy Fuel
Distillation
Radfrac Reflux Ratio: 1.2, Condenser Pressure: 1.3 bar
Reboiler Pressure: 1.5 bar
Light Key Component: C14H30, Recovery: 0.90
Heavy Key Component: C15H32, Recovery: 0.01
FT Gas-SPK Distillation Radfrac Reflux Ratio: 1.2, Condenser Pressure: 1.2 bar
Reboiler Pressure: 1.3 bar
Light Key Component: C9H20, Recovery: 0.95
Heavy Key Component: C10H22, Recovery: 0.05
FT Diesel-Wax Distillation Radfrac Reflux Ratio: 1.2, Condenser Pressure: 1.3 bar
Reboiler Pressure: 1.5 bar
Light Key Component: C18H38, Recovery: 0.90
Heavy Key Component: C19H40, Recovery: 0.10
Hydrocracking RPlug Constant at Specified Reactor Temperature: 425 °C
Reactor Length: 6 m, Reactor Diameter: 2 m
Catalyst Loading: 6 kg, Bed Voidage: 0.40
Figure 1: Process simulation flowsheet of SPK production
2.3 Environmental and Economic Analysis
Key metrics for profitability such as total capital investment (TCI), profitability, payback period, and breakeven
point were determined. The TCI, which comprises the fixed capital investment (FCI) and working capital (WC),
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was established based on the equipment cost. The purchased equipment cost, estimated via cost indexing,
assumes that the major equipment (cryogenic distillation column, FT reactor, FT fuel distillation column,
hydrocracking reactor, and SPK storage tank) comprises 60 % of the total equipment. As a rule of thumb, the
local delivery fee is taken as 10 % of the equipment cost. The costs were estimated using ratio factors (Lang)
to convert the delivered equipment cost into fixed capital investment as shown in Table 3. The CO2 emissions
are also determined based on conversion of the carbon content of the biomass in several stages, such as
gasification and reverse water-gas shift reactions, calculated from the mass flow data in the simulation.
Table 3: Total capital investment estimation via Lang method
Ratio Factor
Direct Costs
Delivered equipment 10 % of the purchased equipment cost
Purchased equipment installation 39 % of the delivered equipment cost
Instrumentation and controls 26 % of the delivered equipment cost
Piping 31 % of the delivered equipment cost
Electrical systems 10 % of the delivered equipment cost
Buildings 29 % of the delivered equipment cost
Yard improvements 12 % of the delivered equipment cost
Service facilities 55 % of the delivered equipment cost
Indirect Costs
Engineering and supervision 32 % of the delivered equipment cost
Construction expenses 34 % of the delivered equipment cost
Other Expenses (Legal, Contractor’s fee, Contigency) 60 % of the delivered equipment cost
Fixed Capital Investment Sum of direct and indirect costs
Working Capital 75 % of the delivered equipment cost
Total Capital Investment Sum of FCI and WC
3. Results and Discussion
3.1 Material Flows
Presented in Table 4 is a summary of the mass flow across each section, from pre-treatment to purification.
Results show that a total of 674,943 kg/d of syngas was generated after the pre-treatment stage. Upon
subjecting the cleaned syngas to the reverse water-gas shift reactor, the molar ratio of hydrogen to carbon
monoxide was reduced from 3.26 to 2.00, which is ideal for FT reactions using cobalt-based catalysts. For the
FT synthesis, a carbon monoxide conversion of 75 % was achieved, resulting in the production of 125,855.90
kg/d paraffins. The produced FT fuel undergoes a series of purification processes, leading to daily SPK
production of 67,728 kg. Additionally, this process yields 19,247 kg/d of green diesel as a valuable by-product.
Table 4: Summary of material flows (all flowrates given in kg/d)
Components Gasification Syngas
Cleaning
FT
Reaction
Separation Hydrocracking
Syngas 3,297,840.00 674,943.04 549,087.14 0.00 708.91
SPK (C11-C14) 0.00 0.00 21,876.61 20,586.56 41,488.45
Diesel (C15-C18) 0.00 0.00 19,792.47 51.84 476.11
3.2 Economic Study
The construction of the plant requires a TCI of 27.55 M USD, comprising 4.11 M USD for WC and 23.44 M USD
for FCI. The breakeven volume is determined as the minimum production capacity needed. Upon analysis, an
annual breakeven volume corresponding to 17.32 ML SPK and 10.17 ML green diesel are needed by the plant
after 3 y when the plant operates at full capacity. Figure 2 shows the breakeven analysis for the production
plant. The selling prices of both SPK and green diesel were strategically set to ensure profitability and full cost
recovery while remaining competitive in the market. The selling prices are projected at 4.46 USD/L for SPK and
4.09 USD/L for green diesel when the plant operates at full capacity. The price range for SPK is from 1.7 USD/L
to 5.02 USD/L based on the analysis in Azarova et al. (2024) which shows that the price set is on the higher
end. Consequently, the proposed facility demonstrates strong economic viability, with a payback period of 5 y
and a total net profit of 27.81 M USD this year—exceeding the TCI of 27.55 M USD. Additionally, the return on
investment (ROI) is calculated at 426.17 %, indicating that the SPK production plant not only recovers its initial
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capital but generates substantial returns. This high ROI reflects the project's ability to cover all associated costs
while delivering significant profits, making it an attractive prospect for investors.
Figure 2: Breakeven volume and sales forecast for the proposed production facility
The strong financial performance underscores the plant’s potential for rapid capital recovery and long-term
profitability. Furthermore, this positive economic outlook is particularly compelling given the rising global demand
for SAF, driven by stricter environmental regulations and decarbonization commitments. The profitability of SPK
production, therefore, aligns well with both current market trends and broader sustainability objectives—
positioning the project as a competitive and forward-looking investment in the renewable energy sector.
3.3 CO2 Emissions
The designed process utilized corn stover with 34.91 % carbon. This is significantly less compared to
conventional petroleum sources, whose typical carbon content ranges from 82 % to 85 % by weight (Gordon,
2012). Note that the carbon content of the corn stover comes from the plant metabolism of CO2 in the
atmosphere while the carbon content from fossil fuel source comes from underground reservoir. Presented in
Figure 2 is the CO2 reduction analysis based on the converted and emitted CO2 across each stage.
Figure 3: CO2 mass flow and reduction across each stage
During the gasification stage, the entire carbon content of the biomass is converted into raw syngas, of which
66.64 % is transformed into CO₂. Subsequently, impurities are eliminated during syngas cleaning to attain purity
requirements for FT synthesis. This process leads to the release of 30.70 % of CO2 from the syngas stream,
corresponding to a carbon footprint value of 0.58 kg CO2/kg syngas produced. In comparison, Dion et al. (2013)
reported a carbon footprint of 0.64 kg CO2/kg syngas for the biomass gasification using wood pellets. The
relatively lower carbon footprint may be attributed to the lower carbon content of corn stover compared to wood
pellets as well as the effectiveness of the syngas cleaning process in the present study. During the reverse
water-gas shift reaction, no emissions were observed, as CO2 was consumed to adjust the ratio between
hydrogen and carbon monoxide. The produced FT fuel undergoes cooling and flash separation, during which
0.13 % CO2 is converted into its liquid form. The effect of this small amount of liquid CO2 on the atmosphere
may be considered less significant compared to that of the gaseous form. The larger fraction of CO2, which
exists as gas, is fed to a pressure swing adsorption (PSA) reactor along with the other components in the syngas
stream. The amount of CO2 produced in the PSA unit can then be further captured after the combustible
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components such as CO and H2 are burned for plant utilities. Overall, the net conversion of carbon in the
biomass to CO2 is only 17 %, implying the delayed carbon emissions of 83 % at the end of the production
process, through conversion of carbon in the biomass to fuels and CO. Net carbon emission also from production
yields.
4. Conclusions and future work
In the designed syngas-to-SPK production process, a daily output of 67,728 kg SPK and 19,247 kg diesel was
achieved. The process integrates an effective removal of CO2 during syngas pretreatment, leading to a carbon
footprint of 0.58 kg CO2/kg syngas produced. In addition, it was determined that a capital investment of 27.55
M USD is needed to construct the plant. Distributing the product at the current market price would take over 5 y
to recover the amount of money invested. Hence, selling prices of 4.46 USD/L SPK and 4.09 USD/L green
diesel were imposed, to ensure generation of profit in 2028. At these selling points, a payback period of 5 y is
achievable with a positive ROI. Generally, the FT pathway for producing SPK is the most expensive due to its
inherent energy-intensive processes. It can also be anticipated that partnerships with relevant groups like the
Department of Energy (DOE) and airline companies would also help reduce the costs of the project. With all
these established, the project is deemed feasible, sustainable, and profitable in the long run. Future work
includes process intensification and heat integration to improve the process, and a life-cycle analysis and
optimization to consider indirect emissions of the plant, and cost optimization to set a better price for SPK.
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