Minimum Ethanol Selling Price Research Articles

Sustainability Assessment of 2G Bioethanol Production from Residual Lignocellulosic Biomass

The development of sustainable biofuels can help to reduce the reliance on fossil fuels and mitigate the impact of climate change. This study analyzes bioethanol production from agro-forestry residual biomass, namely eucalyptus residues and corn stover. The study includes process simulation using Aspen Plus software, followed by economic analysis and life cycle assessment (LCA) with the help of SimaPro software and by applying the environmental footprint (EF) 3.0 method. The economic analysis on the biorefinery’s economic viability, equipment, and production costs reveals a positive decision for bioethanol production from eucalyptus residues due to logistical and transportation costs. The minimum ethanol selling price (MESP) obtained was 2.19 €/L and 2.45 €/L for eucalyptus residues and corn stover, respectively. From the LCA with a functional unit of 1 MJ of ethanol, bioethanol production from eucalyptus residues results in a single score impact of 37.86 µPt, whereas for corn stover, it is 33.47 µPt. In the climate change impact category, the eucalyptus residues scenario has an impact of 0.264 kg CO2 eq/MJ ethanol while corn stover leads to 0.254 kg CO2 eq/MJ ethanol. In-situ enzyme production, heat integration, and the use of renewable energy sources were also analyzed. Combining in situ enzyme production with renewable energy sources lowers CO2 equivalent emissions by 89% for both feedstocks, in comparison to the base-case scenario.

Influence of feedstock selection on cellulosic ethanol production based on densified biomass with calcium hydroxide and regular steam pretreatment

Feedstock selection is a key factor affecting the process of cellulosic ethanol production. Densifying lignocellulosic biomass with chemicals (calcium hydroxide) followed by regular steam autoclave (DLCA(ch)) is an emerging and efficient pretreatment technology. In this study, different crop straws were selected as feedstock in a DLCA(ch) based process for cellulosic ethanol production, and their experimental and economic performances were evaluated. Both single crop straws and mixed crop straws were used and compared as feedstock for DLCA(ch) based biorefinery. Among single crop straws of corn stover, rice straw and wheat straw, wheat straw had the highest ethanol yield and the lowest feedstock cost, with a minimum ethanol selling price of 2.03 $/gal ethanol considering a 10 % internal rate of return and a 2000 tons crop straw per day biorefinery scale. When mixed crop straws were used as the feedstock, both feedstock cost and ethanol production cost were further reduced, and the minimum ethanol selling price was reduced to 2.02 $/gal ethanol. In addition, the use of mixed crop straws has great potential for large scale DLCA(ch) based process for cellulosic ethanol production.

Potential solution to the sustainable ethanol production from industrial tail gas: An integrated life cycle and techno-economic analysis

Utilising industrial tail gas for ethanol production is a viable pathway to significantly mitigate CO2 emissions whilst simultaneously producing value-added fuels and chemicals, which has received great attention in recent years. While some technologies have been commercial deployed, new technological concepts continue to emerge in order to improve the life cycle and techno-economic performance. In this investigation, a novel ethanol production technology integrating tail gas-based ethanol (TG-ethanol) with electro-catalytic CO2 reduction (ECR), called TGEE technology, was first proposed to address the energy and carbon efficiency issues associated with the state-of-the-art TG-ethanol technologies. The process was modularly modelled for to accommodate different ECR integration scenarios for three typical industrial tail gas streams (steel, iron alloy and calcium carbide). In addition, life cycle & techno-economic analysis based on Monte Carlo simulation were employed to evaluate the environmental and economic performance of the TGEE process. Results show that ethanol capacity can be increased by 1.3–2.9 times with carbon efficiency up to 36–82%. Life cycle carbon footprints of TGEE-ethanol were estimated to be 1.77–3.93 t CO2eq/t ethanol, with a carbon reduction potential of 32–63% higher than the TG-ethanol. Minimum ethanol selling price is estimated to be 428–962 $/t ethanol, which is lower than the current ethanol market price (900–1080 $/t). Overall, the comprehensive analysis suggests that the TGEE process emerges as a more economically and environmentally benign next-generation technology for ethanol production from industrial tail gas.

Life cycle assessment and techno-economic analysis of wood-based biorefineries for cellulosic ethanol production

Poplar is widely used in the paper industry and accompanied by abundant branches waste, which is potential feedstock for bioethanol production. Acid-chlorite pretreatment can selectively remove lignin, thereby significantly increasing enzymatic efficiency. Moreover, lignin residues valorization via gasification-syngas fermentation can achieve higher fuel yield. Herein, environmental and economic aspects were conducted to assess technological routes, which guides further process optimization. Life cycle assessment results show that wood-based biorefineries especially coupling scenarios have significant advantages in reducing global warming potential in contrast to fossil-based automotive fuels. Normalization results indicate that acidification potential surpasses other indicators as the primary impact category. In terms of economic feasibility, coupling scenarios present better investment prospects. Bioethanol yield is the most critical factor affecting market competitiveness. Minimum ethanol selling price below ethanol international market price is promising with higher-levels technology. Further work should be focused on technological breakthrough, consumable reduction or replacement.

A strategy for commercialization of macroalga biorefineries

The transportation sector significantly contributes to global warming due to the extensive use of fossil fuels. Biofuels have the potential to eliminate inherent problems associated with the combustion of fossil fuels. However, large-scale deployment of biorefineries is limited because of high capital and operating costs as well as the low market value of biofuels that make such plants economically unfavorable. Additionally, using sustainable feedstock (algae, cyanobacteria, etc.), i.e., with no social, environmental, or technological challenges, is another major bottleneck for biorefineries. Considering these challenges, this study presents a strategy for the commercialization of macroalga-derived bioethanol via a circular economy-based integrated biorefinery concept. A standalone (conventional) process was designed for bioethanol production at 50.0 million gallons (189.3 million liters) per year capacity in Aspen Plus V12.2. Economic and environmental indicators were assessed through discounted cash flow and cradle-to-grave (SimaPro V9.4.0.7) analyses, respectively. Once the potential targets are identified, a novel integrated process was designed for biofuel and biochemical production, which is not only economically favorable in the current market but also has a better life cycle profile compared to that of a standalone process. The results showed that the integrated design has a minimum ethanol selling price of USD 0.35/L and a global warming potential of 0.35 kg CO2 eq/L of ethanol, which is 45% and 82.7% lower than that of the standalone design. Sensitivity analysis showed that the Bio-SA selling price, total capital investment, and seaweed price are the most critical economic parameters for the economic feasibility of the process.

A techno-economic assessment of bioethanol production from switchgrass through biomass gasification and syngas fermentation

The consumption of fossil fuels, which are not economically and environmentally sustainable, can be reduced by producing biofuels, such as bioethanol. This study presents a reproducible model of the ethanol production process developed with Aspen Plus® software. The work's goal is to enhance the amount of ethanol produced per tonne of biomass and, therefore, the carbon yield of the process. The main steps of the process are the gasification of the pretreated switchgrass, the cleaning of the syngas obtained, the fermentation of the syngas to ethanol and its purification. The parameters relating to gasification were set to produce syngas with an optimal composition for the fermenter. A discounted cash flow analysis was used to determine the minimum ethanol selling price for different plant scales and H2 prices. By enriching the syngas with green H2 and adopting an optimal bioreactor, a remarkable ethanol yield of 1015.04 L/t of switchgrass can be obtained. Considering a plant size of 750,000 t/y of switchgrass, the minimum ethanol selling price is 1.07 $/L for the base scenario and is further lowered to 0.77 $/L for the 2050 H2 scenario. The potential savings of building more plants were also assessed thanks to the learning effects.

Cost and Life Cycle Emissions of Ethanol Produced with an Oxyfuel Boiler and Carbon Capture and Storage.

Decarbonization of transportation fuels represents one of the most vexing challenges for climate change mitigation. Biofuels derived from corn starch have offered modest life cycle greenhouse gas (GHG) emissions reductions over fossil fuels. Here we show that capture and storage of CO2 emissions from corn ethanol fermentation achieves ∼58% reduction in the GHG intensity (CI) of ethanol at a levelized cost of 52 $/tCO2e abated. The integration of an oxyfuel boiler enables further CO2 capture at modest cost. This system yields a 75% reduction in CI to 15 gCO2e/MJ at a minimum ethanol selling price (MESP) of $2.24/gallon ($0.59/L), a $0.31/gallon ($0.08/L) increase relative to the baseline no intervention case. The levelized cost of carbon abatement is 84 $/tCO2e. Sensitivity analysis reveals that carbon-neutral or even carbon-negative ethanol can be achieved when oxyfuel carbon capture is stacked with low-CI alternatives to grid power and fossil natural gas. Conservatively, fermentation and oxyfuel CCS can reduce the CI of conventional ethanol by a net 44-50 gCO2/MJ. Full implementation of interventions explored in the sensitivity analysis would reduce CI by net 79-85 gCO2/MJ. Integrated oxyfuel and fermentation CCS is shown to be cost-effective under existing U.S. policy, offering near-term abatement opportunities.

Implications of Biorefinery Policy Incentives and Location-Specific Economic Parameters for the Financial Viability of Biofuels.

Cellulosic biofuels are part of a portfolio of solutions to address climate change; however, their production remains expensive and federal policy interventions (e.g., Renewable Fuel Standard) have not spurred broad construction of cellulosic biorefineries. A range of state-level interventions have also been enacted, but their implications for the financial viability of biorefineries are not well understood. To address this gap, this study evaluated the efficacy of 20 state-level tax incentives from 14 states and their interactions with other location-specific economic parameters (e.g., state income tax rates, electricity prices). To characterize implications of location-specific policies and parameters on biorefinery cash flows, we developed a new BioSTEAM Location-Specific Evaluation (BLocS) module for the open-source software BioSTEAM. Leveraging BLocS and BioSTEAM, we characterized the minimum ethanol selling price (MESP) for a cellulosic biorefinery (using corn stover as feedstock) and two conventional biorefineries (using corn or sugarcane as feedstock) for comparison. Among state-specific scenarios, nonincentivized MESPs for the corn stover biorefinery ranged from 0.74 $·L-1 (4.20 $·gallon gasoline equivalent [gge]-1) [0.69-0.79 $·L-1; 3.91-4.48 $·gge-1; Oklahoma] to 1.02 $·L-1 (5.78 $·gge-1) [0.95-1.09 $·L-1; 5.39-6.18 $·gge-1; New York], while the tax incentive-induced MESP reduction ranged from negligible (Virginia) to 5.78% [5.43-6.20%; Iowa]. Ultimately, this work can inform the design of policy incentives for biorefineries under specific deployment contexts.

A new insight into integrated first and second-generation bioethanol production from sugarcane

Bioethanol has been proven as an alternative clean fuel for road vehicles, with the conversion of lignocellulosic waste biomasses into ethanol through economically and environmentally viable production processes becoming increasingly important. In this study, the economic feasibility of seven process configurations for integrated molasses (1 G) and lignocelluloses (2 G) bioethanol production, in combined first- and second-generation (1G2G) facilities annexed to a typical South African sugar mill, were examined. Simulations for various first generation (1 G-only), second-generation (2 G-only) and integrated 1G2G biorefinery scenarios were developed and rigorous techno-economic and sensitivity analyses were conducted. The results determined that production of 1 G-only ethanol from C-molasses obtained a better minimum ethanol selling price (MESP) of 0.68/ $/l, compared to A-molasses (1.05 $/l) due to the significantly higher price of A-molasses (314 $/t) relative to C-molasses (192 $/t). The integration of 1 G and 2 G sugars for 1G2G ethanol production showed significant economic benefits (up to 50% improvement), compared to 2 G-only ethanol production, thereby lowering the cost of lignocelluloses conversion. The 1G2G scenario that produced the most favourable MESP of 1.23 $/litre involved the supplementation of the whole slurry of pre-treated lignocelluloses (2 G) with A-molasses (1 G) for co-fermentation of sugars by Separate Hydrolysis and Co-fermentation (SHcF). Despite technical differences between scenarios 1G2G1, 1G2G3 and 1G2G7, no significant differences could be observed in terms of MESPs (1.25, 1.23 and 1.26 $/l, respectively), which were the lowest value among all integrated scenarios. The main drivers of the outstanding economic performance were (1) the ability of the selected fermenting microorganism to function at sufficiently high substrate concentrations without inhibition or glucose suppression, (2) economies-of-scale benefits, (3) the high yield of sugar utilization and (4) the choice of optimum process condition for co-fermentation of C5 and C6 sugars.

Multifunctional landscapes for dedicated bioenergy crops lead to low-carbon market-competitive biofuels

Switchgrass is a promising feedstock for cellulosic biorefineries, due to its ability to maintain comparatively high biomass yields across a wide range of soil and climatic conditions. However, there is an incomplete understanding of the economic and environmental tradeoffs associated with cultivating switchgrass on low-productivity land for conversion to biofuels. This study surveys prior literature and demonstrates a new integrated assessment framework, including agroecosystem, ecosystem services valuation, technoeconomic, and life-cycle assessment models, to quantify and contextualize the economic and environmental impacts of switchgrass cultivation on marginal land with downstream conversion to biofuels. Monetizing and incorporating the value of ecosystem services, such as improved water quality benefits from nitrate and sediment reductions, climate change mitigation benefits from CO2 emission reduction, and recreational and pollination benefits from increased biodiversity, the modeled multifunctional landscape reduces the ethanol production cost by 33.3–58.9 cents/l-gasoline-equivalent ($1.3–2.2/gge). Planting switchgrass in low productivity land improves soil health, resulting in the carbon footprint reduction credit of 12.8–20.2 gCO2e/MJ. For an improved switchgrass-to-ethanol conversion pathway with the maximum benefits from ecosystem services, the minimum ethanol selling price and carbon footprint of ethanol, respectively, could reach to 31 cents/l-gasoline-equivalent (47% reduction relative to average gasoline price) and 3 gCO2e/MJ (97% reduction relative to gasoline). This low carbon renewable ethanol leads to substantial State and/or Federal policy incentives (∼$1/l-gasoline-equivalent) providing a large benefit to biorefinery operators, farmers, and the public as a whole.

Production of ethanol from corn straw based on chemical looping gasification: Economic analysis

Biomass chemical looping gasification is a promising technique allowing high quality syngas production with low energy penalty and low tar generation. In this study, a new ethanol production process from corn straw based on chemical looping gasification is developed and simulated. According to the results of prediction, the energy efficiency as well as techno-economic performance for the ethanol from corn straw system are researched to give useful information for the investment as well as development of the system. The results demonstrate that the proposed system has an energy efficiency of 49.32%, fixed capital investment of 1.61×108 $ and minimum ethanol selling price of 0.81 $/kg. More importantly, the equipment investment of the chemical looping gasification is 0.71% of the total equipment investment and beneficial to reduce the investment. Finally, the minimum ethanol selling price is compared with other ethanol production processes.

Techno-economic assessment of poly-generation pathways of bioethanol and lignin-based products

In this study, two fermentation-pyrolysis pathways for cellulosic ethanol production were established to improve the economy of cellulosic ethanol plants by lignin-rich residue pyrolysis. Techno-economic assessment (TEA) was conducted for both novel pathways compared with conventional fermentation-combustion pathway based on biomass Arundo donax. Pathway simulation showed that compared with the fermentation-combustion pathway, fermentation-pyrolysis pathway produced extra bio-char and hydrocarbon fuels except 256,000 m3 of ethanol each year. Economic analysis showed that the Minimum Ethanol Selling Price (MESP) of fermentation-combustion pathway was 1.623$/gal. The MESP of fermentation-pyrolysis A pathway and fermentation-pyrolysis B pathway was 1.673$/gal and 1.494$/gal respectively. The MESP of fermentation-pyrolysis B pathway indicated a potential process of lignin pyrolysis applied in cellulosic ethanol plants in the future. Sensitivity analysis indicated that price change of A. donax and plant scale both have a great impact on the MESP.

DLCA (ch) pretreatment brings economic benefits to both biomass logistics and biomass conversion for low cost cellulosic ethanol production

Densifying lignocellulosic biomass with chemicals (calcium hydroxide) (DLC(ch)) followed by regular steam autoclave treatment (DLCA(ch)) is a novel pretreatment method, which unlocks highly fermentable sugars and showed great potential. This study investigated the economics of DLCA(ch) based biorefinery for cellulosic ethanol production and studied the effects of solid loading, enzyme dosage, enzyme price and biorefinery scale on the economics. Compared with dilute acid pretreatment based biorefinery, DLCA(ch) based biorefinery showed much lower feedstock logistics cost, and the savings in feedstock logistics almost offset the DLC(ch) pretreatment cost. DLCA(ch) based biorefinery exhibited higher ethanol yield and lower pretreatment costs. When the biorefinery scale was 2000 Mg rice straw per day, the total capital investment and minimum ethanol selling price of DLCA(ch) based biorefinery were 17.9% and 30.0% lower, respectively, compared to dilute acid pretreatment based biorefinery. This work demonstrated the great potential of DLCA(ch) pretreatment for the commercial production of cellulosic ethanol.

Net Energy Analysis and Techno-Economic Assessment of Co-Production of Bioethanol and Biogas from Cellulosic Biomass

Co-production is a process based on the biorefinery concept that maximizes the benefit of biomass by reusing residue from the production of one product to produce others. In this regard, biogas is one of the most researched second products for the production of ethanol from cellulosic biomass. However, operating this scheme requires additional investment in biogas processing equipment. This review compiles data from research studies on the co-production of bioethanol and biogas from lignocellulosic biomass to determine which is more worthwhile: leaving the residue or investing more to benefit from the second product. According to previous research, ethanol stillage can be converted to biogas via anaerobic digestion, increasing energy output by 2–3 fold. Techno-economic studies demonstrated that the co-production process reduces the minimum ethanol selling price to a level close to the market price of ethanol, implying the possibility of industrializing cellulosic ethanol production through this scheme.

Multi-Objective Sustainability Optimization of Biomass Residues to Ethanol via Gasification and Syngas Fermentation: Trade-Offs between Profitability, Energy Efficiency, and Carbon Emissions

This work presents a strategy for optimizing the production process of ethanol via integrated gasification and syngas fermentation, a conversion platform of growing interest for its contribution to carbon recycling. The objective functions (minimum ethanol selling price (MESP), energy efficiency, and carbon footprint) were evaluated for the combinations of different input variables in models of biomass gasification, energy production from syngas, fermentation, and ethanol distillation, and a multi-objective genetic algorithm was employed for the optimization of the integrated process. Two types of waste feedstocks were considered, wood residues and sugarcane bagasse, with the former leading to lower MESP and a carbon footprint of 0.93 USD/L and 3 g CO2eq/MJ compared to 1.00 USD/L and 10 g CO2eq/MJ for sugarcane bagasse. The energy efficiency was found to be 32% in both cases. An uncertainty analysis was conducted to determine critical decision variables, which were found to be the gasification zone temperature, the split fraction of the unreformed syngas sent to the combustion chamber, the dilution rate, and the gas residence time in the bioreactor. Apart from the abovementioned objectives, other aspects such as water footprint, ethanol yield, and energy self-sufficiency were also discussed.

Techno-economic analysis of bioethanol preparation process via deep eutectic solvent pretreatment

This study conducted a techno-economic analysis of the biorefining process via deep eutectic solvent pretreatment. Rice straw was the feedstock to prepare main product bioethanol, and by-product lignin. The economic analysis model with sensitivity analysis based on Aspen Plus was applied to evaluate the commercial potential and the impact of critical parameters on the minimum ethanol selling price (MESP). Acidic DES showed better results in biomass refining. MESP based on choline chloride/urea pretreatment process was 3049.9 $/ton, while the choline chloride/lactic acid pretreatment was 2128.1 $/ton. The bioethanol yield was 0.21 t/t via choline chloride/lactic acid pretreatment process, which was higher than choline chloride/urea. In choline chloride/lactic acid pretreatment, sensitivity analysis showed that due to the enzymatic hydrolysis of cellulose conversion rate, acetone price, and lactic acid price, MESP was fluctuated by 23.4 %, 6.25 %, and 5.31 %, respectively. Combined heat and power part could reduce MESP. High solid loading pretreatment had a positive impact on cost reduction.

Techno‐economics of one‐stage and two‐stage furfural production integrated with ethanol co‐production from sugarcane lignocelluloses

AbstractLignocellulosic biomass processing to produce platform chemicals and biofuels is a promising alternative utilization of non‐renewable resources. This study investigated the techno‐economics of two‐stage and one‐stage furfural production integrated with ethanol co‐production from sugarcane bagasse and harvest residues. The effect of process conditions on profitability was reflected by the minimum ethanol selling price (MESP) at a fixed furfural‐selling price. Aspen Plus V8.8 was used to simulate the integrated two‐stage furfural and ethanol co‐production biorefineries using low (scenario 1), medium (scenario 2) and high (scenario 3) severity steam‐explosion pretreatment. The two‐stage furfural biorefineries integrated with ethanol co‐production were compared with the most profitable one‐stage furfural biorefinery integrated with ethanol co‐production. The required MESP in scenario 2 (0.73 US$ L–1) was decreased by 36% compared with the one‐stage furfural‐ethanol biorefinery (1.14 US$ L–1). Scenarios 1 and 3 were disadvantaged by lower ethanol yields (150 versus 214 kg t–1 of feed) and higher capital investments (322–340) compared with scenario 2 (310 million US$). The one‐stage furfural production had higher heating demands (2034 versus 741–1124 kW t–1 feed) and reduced ethanol yields (90 versus 150–214 kg t–1 of feed) compared with integrated two‐stage furfural and ethanol coproduction biorefineries. Optimization of process conditions, improving energy efficiency, and maximizing productivity within these energy self‐sufficient facilities were critical to minimizing the MESPs, regardless of associated increases in capital and operational costs. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

Economic determinants on the implementation of a Eucalyptus wood biorefinery producing biofuels, energy and high added-value compounds

The economic impact of different potentially scalable process improvements was here assessed for the first time in the specific context of a Eucalyptus wood biorefinery producing biofuels, high-value chemicals and energy. The base case scenario referring to bioethanol as the only product was clearly unviable, which mostly resulted from the high cost of cellulases and heat transfer utilities and the moderate final ethanol titers. By supplementing cheese whey to eucalyptus wood hydrolysis, ethanol production increased 51% leading to a notable improvement on the NPV, from −14.4 to −3.4 M$. Similarly, when an additional section was included for the recovery of XOS present in the autohydrolysis liquor, the operating costs raised 36% but annual revenues increased around 5 M$, resulting in a very solid NPV of 18.9 M$. Internally burning the final stillage led to savings of 98% on low-pressure steam consumption and an additional electricity revenue, both contributing to a more economic scenario. One final scenario consisted on the simultaneous integration of all process variations, referring to a complex facility producing not only ethanol but also XOS and energy. This integrated process provided the best economic output, which was translated on a noticeable reduction of the minimum ethanol selling price from 4.88 $/gal (Base case) to 0.76 $/gal, and thus confirming the critical role of adopting biorefinery schemes for an economic utilization of lignocellulosic materials.

Systematic cost evaluations of biological and thermochemical processes for ethanol production from biomass residues and industrial off-gases

Bioethanol, as a sustainable fuel or as a precursor for high-value chemicals, may be produced through a variety process technologies, depending on the feedstock available. Thus, these processes are comprehensively evaluated to identify the most cost-effective process for a given feedstock, as well as cost reduction measures. Process designs for first (1G), second (2G) and third (3G) generation ethanol production were simulated in Aspen Plus® for technical evaluations, followed by economic modelling to determine the minimum ethanol selling price (MESP). 1G-ethanol from A-molasses at sugar mills was most cost-effective (MESP = 0.52US$/l). While the 1G-2G option (using sugarcane lignocelluloses) produced 98% more ethanol (MESP = 0.62US$/l), costs of enzymes were inhibitive. For 2G-ethanol using invasive alien plants, hydrolysis-fermentation had the lower MESP (0.72 US$/l) compared to gasification-fermentation because the latter had comparatively high capital costs (i.e.215vs135 million US$). Energy self-sufficiency for 3G ethanol from off-gas decreased the ethanol yield (178 to 114 l/tonne) and increased the MESPs (0.61 to 0.87 US$/l) compared to the buy-in of the required electricity. Similarly, for the gasification-fermentation scenario, a MESP of 1.58US$/l was required to obtain energy self-sufficiency. Energy self-sufficiency therefore increases process costs, but simultaneously abates the potential use of fossil fuels. Thus, it is worth pursing renewable electricity to meet process energy needs to improve ethanol yields and lower production costs. Furthermore, fermentation processes should be tailored to tolerate lower water quality requirements.

Life cycle assessment of ethanol produced in a biorefinery from liquid hot water pretreated switchgrass

Life cycle assessments of fuel bioethanol produced in Uruguay from liquid hot water pretreated switchgrass were performed for two scenarios: the production of ethanol and electricity and a biorefinery producing ethanol, electricity, furfural, acetic, and formic acid.Experimental data and material and energy balances derived from the simulations were used to analyze the global warming potential of fuel bioethanol. Greenhouse gas (GHG) emissions in both scenarios were lower than the reference emissions for fossil fuel. The biorefinery scenario had a better performance in terms of environmental impacts, and the biofuel produced met GHG reduction requirements. Switchgrass composition, enzyme dosage, fermentation and hydrolysis efficiency, and solids content had a significant effect on environmental performance, with enzyme use being the most significant factor. A multi-objective optimization was used to find the values of solid content and enzyme dose that minimize GHG emissions and the minimum ethanol selling price (MESP). An enzyme dosage of 37 mgprotein/gglucan and solids content of 21% w/w were the optimal conditions for bioethanol production with an associated GHG value of 2 ± 5 g CO2 eq./MJethanol and a MESP of $0.84/L.