Comprehensive techno-economic analysis across a wide set of technologies and products provides in... more Comprehensive techno-economic analysis across a wide set of technologies and products provides insight into the economic feasibility of electron-mediated CO2 reduction.
A novel, highly efficient deacetylation and disk refining (DDR) process to liberate fermentable s... more A novel, highly efficient deacetylation and disk refining (DDR) process to liberate fermentable sugars from biomass was recently developed at the National Renewable Energy Laboratory (NREL). The DDR process consists of a mild, dilute alkaline deacetylation step followed by low-energy-consumption disk refining. The DDR corn stover substrates achieved high process sugar conversion yields, at low to modest enzyme loadings, and also produced high sugar concentration syrups at high initial insoluble solid loadings. The sugar syrups derived from corn stover are highly fermentable due to low concentrations of fermentation inhibitors. The objective of this work is to evaluate the economic feasibility of the DDR process through a techno-economic analysis (TEA). A large array of experiments designed using a response surface methodology was carried out to investigate the two major cost-driven operational parameters of the novel DDR process: refining energy and enzyme loadings. The boundary con...
Global demand for methanol as both a chemical precursor and a fuel additive is rising. At the sam... more Global demand for methanol as both a chemical precursor and a fuel additive is rising. At the same time, numerous renewable methanol production pathways are under development which, if commercialized, could present significant environmental benefits over traditional methanol synthesis pathways. There is a need to harmonize the analyses of renewable pathways using a consistent techno-economic approach to evaluate the potential for commercialization of various pathways. This analysis considers economic and environmental factors critical to market acceptance of three renewable pathways versus a commercial baseline. We suggest that biomass gasification to methanol represents a near-term viable pathway with high technology readiness level and commercially competitive market price. However, longterm solutions should consider CO2 electrolysis pathways which offer further improvements in sustainability metrics to support global decarbonization efforts.
As the demand for utilizing environment-friendly and sustainable energy sources is increasing, th... more As the demand for utilizing environment-friendly and sustainable energy sources is increasing, the adoption of waste-to-energy technologies has started gaining attention. Producing biogas via anaerobic digestion (AD) is promising and well-established; however, this process in many circumstances is unable to be cost competitive with natural gas. In this research, we provide a technical assessment of current process challenges and compare the cost of biogas production via the AD process from the literature, Aspen Plus process modeling, and CapdetWorks software. We also provide insights on critical factors affecting the AD process and recommendations on optimizing the process. We utilize four types of wet wastes, including wastewater sludge, food waste, swine manure, and fat, oil, and grease, to provide a quantitative assessment of theoretical energy yields of biogas production and its economic potential at different plant scales. Our results show that the cost of biogas production fro...
Renewable electricity can be leveraged to produce fuels and chemicals from CO2, offering sustaina... more Renewable electricity can be leveraged to produce fuels and chemicals from CO2, offering sustainable routes to reduce the carbon intensity of our energy and products-driven economy.
With the increased availability of low-cost natural gas, co-conversion of natural gas and biomass... more With the increased availability of low-cost natural gas, co-conversion of natural gas and biomass-to-liquid fuels has gained interest due to the potential to improve liquid fuel yields while lowering greenhouse gas emissions.
Biomass-derived jet fuel is an alternative jet fuel (AJF) showing promise of reducing the depende... more Biomass-derived jet fuel is an alternative jet fuel (AJF) showing promise of reducing the dependence on fossil fuel and greenhouse gas emissions. Hydroprocessed esters and fatty acids (HEFA) concept is also known as one of the pathways for producing bio jet fuel. HEFA fuel was approved by the American Society for Testing and Materials in 2011, and can be blended up to 50% with conventional jet fuel. Since then, several HEFA economic and life-cycle assessments have been published in literature. However, there have been limited analyses on feedstock availability, composition, and their impact on hydrocarbon yield (particularly jet blendstock yield) and overall process economics. This study examines over 20 oil feedstocks, their geographic distribution and production levels, oil yield, prices, and chemical composition. The results of our compositional analysis indicate that most oils contain mainly C and C fatty acids except pennycress, yellow grease, and mustard, which contain higher ...
ABSTRACT Introduction Biofuels production worldwide is continuing to grow at a very rapid pace. E... more ABSTRACT Introduction Biofuels production worldwide is continuing to grow at a very rapid pace. Energy policy in the form of a renewable fuel standard (EISA 2007)1 has helped to maintain strong markets for bioethanol and biodiesel as first generation biofuels. However, recent market price fluctuations for feedstocks have been quite dramatic. Average corn prices during this time have also ranged from $2 per bushel to $4.20 per bushel (USDA 2008)2 with spot prices rising over $8 per bushel. Butanol is considered a second generation biofuel that is better for the existing infrastructure. It has a higher heating value than ethanol and it is compatible with gasoline at high concentrations without engine modification. It is also more hydrophobic than ethanol and can be shipped via existing pipelines and distributed through the existing petroleum infrastructure. It becomes increasingly important to understand butanol production economics as a potential biofuel. Production cost data for non-existing or non-commercial biofuels processes is less readily available and comes largely from detailed techno-economic models and evaluations. Therefore, detailed techno-economics models and evaluations are applied to several current and future biofuel processes in the paper. This work presents detailed comparative analysis on the production economics of butanol via biological conversion using corn. Our objectives include demonstrating the impact of key parameters on the overall process economics (e.g. plant capacity, raw material pricing, yield, etc), and comparing how next-generation technologies and fuels will differ from today's technologies. Methods Developing process economics of this sort requires experimental data, modeling toolsets, vendor equipment information, and engineering expertise. The first step is to develop a conceptual process design from information on the products, feeds, and proposed chemical and physical processing steps (Douglas 1989)3. The effective use of conceptual design methods in the early stages of process design can have a large impact on overall process design and development. Material and energy balance and flowrate information for a given process design are then generated using process simulation software packages. For these particular applications, Aspen Plus (Aspen Plus 2006)4 was used. This software contains physical property and thermodynamic data for a large number of chemical compounds. The material and energy balance data generated by these models are used to size and cost process equipment, which are fed into spreadsheets built for capital and operating cost estimation. Results and Discussion Fermentation of sugar-containing substrates to acetone, butanol, and ethanol (ABE) is well known. With the onset of rising petroleum prices and new biotechnology, biological butanol production may become the more cost effective technology once again. In the long run, the butanol production via biomass may be more economical than petrochemical industry as a transportation fuel with much larger scale than in the past. Process description. While several designs and process variations have been explored in literature, very little modeling has been done using rigorous physical property models. Simple assumptions of how components are expected to fractionate and separate, for example, can often be proven wrong through such an approach. After analyzing several conceptual designs, NREL developed its own conceptual design for ABE production. The USDA corn dry mill ethanol model was used as a basis for modeling. The ethanol fermentation and downstream recovery was replaced with a butanol fermentation using Clostridium. A complex sequence of distillation steps was then added to separate and purify the acetone, butanol, and ethanol components from the water. Non-random two-liquid (NRTL) modeling package was used to more accurately predict the liquid/liquid interactions that would take place in a system such as this. As with corn ethanol, the byproduct from this process is animal feed. While DDGS from yeast-based production is common, bacterial-based DDGS would have to undergo animal feeding trials. H2 is also produced from Clostridial strains of this sort. This is collected and purified using commercial pressure-swing adsorption (PSA) technology. In this fashion, 5 total products are produced: ethanol, hydrogen, DDGS, acetone, and butanol. Corn is milled first then sent to liquefaction. After liquefaction, microorganism is added to ferment the glucose to acetone, butanol and ethanol mixture. Total residence time in the fermentors is 72 hours. The gas stream from the fermentors goes through a PSA unit to recover hydrogen, which is sold as co-product. The whole beer is degassed and sent to distillation systems. About 85% water is removed from the dehydration column then recycled back to liquefaction. Downstream distillation columns further separate acetone, ethanol and n-butanol from residual water,…
To reduce the environmental impacts of the aviation sector as air traffic grows steadily, the avi... more To reduce the environmental impacts of the aviation sector as air traffic grows steadily, the aviation industry has paid increasing attention to bio-based alternative jet fuels (AJFs), which may provide lower life-cycle petroleum consumption and greenhouse gas (GHG) emissions than petroleum jet fuel. This study presents well-to-wake (WTWa) results for four emerging AJFs: ethanol-to-jet (ETJ) from corn and corn stover, and sugar-to-jet (STJ) from corn stover via both biological and catalytic conversion. For the ETJ pathways, two plant designs were examined: integrated (processing corn or corn stover as feedstock) and distributed (processing ethanol as feedstock). Also, three H2 options for STJ via catalytic conversion are investigated: external H2 from natural gas (NG) steam methane reforming (SMR), in situ H2, and H2 from biomass gasification. Results demonstrate that the feedstock is a key factor in the WTWa GHG emissions of ETJ: corn- and corn stover-based ETJ are estimated to pro...
Introduction Biofuels production worldwide is continuing to grow at a very rapid pace. Energy pol... more Introduction Biofuels production worldwide is continuing to grow at a very rapid pace. Energy policy in the form of a renewable fuel standard (EISA 2007)1 has helped to maintain strong markets for bioethanol and biodiesel as first generation biofuels. However, recent market price fluctuations for feedstocks have been quite dramatic. Average corn prices during this time have also ranged from $2 per bushel to $4.20 per bushel (USDA 2008)2 with spot prices rising over $8 per bushel. Butanol is considered a second generation biofuel that is better for the existing infrastructure. It has a higher heating value than ethanol and it is compatible with gasoline at high concentrations without engine modification. It is also more hydrophobic than ethanol and can be shipped via existing pipelines and distributed through the existing petroleum infrastructure. It becomes increasingly important to understand butanol production economics as a potential biofuel. Production cost data for non-existing...
Comprehensive techno-economic analysis across a wide set of technologies and products provides in... more Comprehensive techno-economic analysis across a wide set of technologies and products provides insight into the economic feasibility of electron-mediated CO2 reduction.
A novel, highly efficient deacetylation and disk refining (DDR) process to liberate fermentable s... more A novel, highly efficient deacetylation and disk refining (DDR) process to liberate fermentable sugars from biomass was recently developed at the National Renewable Energy Laboratory (NREL). The DDR process consists of a mild, dilute alkaline deacetylation step followed by low-energy-consumption disk refining. The DDR corn stover substrates achieved high process sugar conversion yields, at low to modest enzyme loadings, and also produced high sugar concentration syrups at high initial insoluble solid loadings. The sugar syrups derived from corn stover are highly fermentable due to low concentrations of fermentation inhibitors. The objective of this work is to evaluate the economic feasibility of the DDR process through a techno-economic analysis (TEA). A large array of experiments designed using a response surface methodology was carried out to investigate the two major cost-driven operational parameters of the novel DDR process: refining energy and enzyme loadings. The boundary con...
Global demand for methanol as both a chemical precursor and a fuel additive is rising. At the sam... more Global demand for methanol as both a chemical precursor and a fuel additive is rising. At the same time, numerous renewable methanol production pathways are under development which, if commercialized, could present significant environmental benefits over traditional methanol synthesis pathways. There is a need to harmonize the analyses of renewable pathways using a consistent techno-economic approach to evaluate the potential for commercialization of various pathways. This analysis considers economic and environmental factors critical to market acceptance of three renewable pathways versus a commercial baseline. We suggest that biomass gasification to methanol represents a near-term viable pathway with high technology readiness level and commercially competitive market price. However, longterm solutions should consider CO2 electrolysis pathways which offer further improvements in sustainability metrics to support global decarbonization efforts.
As the demand for utilizing environment-friendly and sustainable energy sources is increasing, th... more As the demand for utilizing environment-friendly and sustainable energy sources is increasing, the adoption of waste-to-energy technologies has started gaining attention. Producing biogas via anaerobic digestion (AD) is promising and well-established; however, this process in many circumstances is unable to be cost competitive with natural gas. In this research, we provide a technical assessment of current process challenges and compare the cost of biogas production via the AD process from the literature, Aspen Plus process modeling, and CapdetWorks software. We also provide insights on critical factors affecting the AD process and recommendations on optimizing the process. We utilize four types of wet wastes, including wastewater sludge, food waste, swine manure, and fat, oil, and grease, to provide a quantitative assessment of theoretical energy yields of biogas production and its economic potential at different plant scales. Our results show that the cost of biogas production fro...
Renewable electricity can be leveraged to produce fuels and chemicals from CO2, offering sustaina... more Renewable electricity can be leveraged to produce fuels and chemicals from CO2, offering sustainable routes to reduce the carbon intensity of our energy and products-driven economy.
With the increased availability of low-cost natural gas, co-conversion of natural gas and biomass... more With the increased availability of low-cost natural gas, co-conversion of natural gas and biomass-to-liquid fuels has gained interest due to the potential to improve liquid fuel yields while lowering greenhouse gas emissions.
Biomass-derived jet fuel is an alternative jet fuel (AJF) showing promise of reducing the depende... more Biomass-derived jet fuel is an alternative jet fuel (AJF) showing promise of reducing the dependence on fossil fuel and greenhouse gas emissions. Hydroprocessed esters and fatty acids (HEFA) concept is also known as one of the pathways for producing bio jet fuel. HEFA fuel was approved by the American Society for Testing and Materials in 2011, and can be blended up to 50% with conventional jet fuel. Since then, several HEFA economic and life-cycle assessments have been published in literature. However, there have been limited analyses on feedstock availability, composition, and their impact on hydrocarbon yield (particularly jet blendstock yield) and overall process economics. This study examines over 20 oil feedstocks, their geographic distribution and production levels, oil yield, prices, and chemical composition. The results of our compositional analysis indicate that most oils contain mainly C and C fatty acids except pennycress, yellow grease, and mustard, which contain higher ...
ABSTRACT Introduction Biofuels production worldwide is continuing to grow at a very rapid pace. E... more ABSTRACT Introduction Biofuels production worldwide is continuing to grow at a very rapid pace. Energy policy in the form of a renewable fuel standard (EISA 2007)1 has helped to maintain strong markets for bioethanol and biodiesel as first generation biofuels. However, recent market price fluctuations for feedstocks have been quite dramatic. Average corn prices during this time have also ranged from $2 per bushel to $4.20 per bushel (USDA 2008)2 with spot prices rising over $8 per bushel. Butanol is considered a second generation biofuel that is better for the existing infrastructure. It has a higher heating value than ethanol and it is compatible with gasoline at high concentrations without engine modification. It is also more hydrophobic than ethanol and can be shipped via existing pipelines and distributed through the existing petroleum infrastructure. It becomes increasingly important to understand butanol production economics as a potential biofuel. Production cost data for non-existing or non-commercial biofuels processes is less readily available and comes largely from detailed techno-economic models and evaluations. Therefore, detailed techno-economics models and evaluations are applied to several current and future biofuel processes in the paper. This work presents detailed comparative analysis on the production economics of butanol via biological conversion using corn. Our objectives include demonstrating the impact of key parameters on the overall process economics (e.g. plant capacity, raw material pricing, yield, etc), and comparing how next-generation technologies and fuels will differ from today's technologies. Methods Developing process economics of this sort requires experimental data, modeling toolsets, vendor equipment information, and engineering expertise. The first step is to develop a conceptual process design from information on the products, feeds, and proposed chemical and physical processing steps (Douglas 1989)3. The effective use of conceptual design methods in the early stages of process design can have a large impact on overall process design and development. Material and energy balance and flowrate information for a given process design are then generated using process simulation software packages. For these particular applications, Aspen Plus (Aspen Plus 2006)4 was used. This software contains physical property and thermodynamic data for a large number of chemical compounds. The material and energy balance data generated by these models are used to size and cost process equipment, which are fed into spreadsheets built for capital and operating cost estimation. Results and Discussion Fermentation of sugar-containing substrates to acetone, butanol, and ethanol (ABE) is well known. With the onset of rising petroleum prices and new biotechnology, biological butanol production may become the more cost effective technology once again. In the long run, the butanol production via biomass may be more economical than petrochemical industry as a transportation fuel with much larger scale than in the past. Process description. While several designs and process variations have been explored in literature, very little modeling has been done using rigorous physical property models. Simple assumptions of how components are expected to fractionate and separate, for example, can often be proven wrong through such an approach. After analyzing several conceptual designs, NREL developed its own conceptual design for ABE production. The USDA corn dry mill ethanol model was used as a basis for modeling. The ethanol fermentation and downstream recovery was replaced with a butanol fermentation using Clostridium. A complex sequence of distillation steps was then added to separate and purify the acetone, butanol, and ethanol components from the water. Non-random two-liquid (NRTL) modeling package was used to more accurately predict the liquid/liquid interactions that would take place in a system such as this. As with corn ethanol, the byproduct from this process is animal feed. While DDGS from yeast-based production is common, bacterial-based DDGS would have to undergo animal feeding trials. H2 is also produced from Clostridial strains of this sort. This is collected and purified using commercial pressure-swing adsorption (PSA) technology. In this fashion, 5 total products are produced: ethanol, hydrogen, DDGS, acetone, and butanol. Corn is milled first then sent to liquefaction. After liquefaction, microorganism is added to ferment the glucose to acetone, butanol and ethanol mixture. Total residence time in the fermentors is 72 hours. The gas stream from the fermentors goes through a PSA unit to recover hydrogen, which is sold as co-product. The whole beer is degassed and sent to distillation systems. About 85% water is removed from the dehydration column then recycled back to liquefaction. Downstream distillation columns further separate acetone, ethanol and n-butanol from residual water,…
To reduce the environmental impacts of the aviation sector as air traffic grows steadily, the avi... more To reduce the environmental impacts of the aviation sector as air traffic grows steadily, the aviation industry has paid increasing attention to bio-based alternative jet fuels (AJFs), which may provide lower life-cycle petroleum consumption and greenhouse gas (GHG) emissions than petroleum jet fuel. This study presents well-to-wake (WTWa) results for four emerging AJFs: ethanol-to-jet (ETJ) from corn and corn stover, and sugar-to-jet (STJ) from corn stover via both biological and catalytic conversion. For the ETJ pathways, two plant designs were examined: integrated (processing corn or corn stover as feedstock) and distributed (processing ethanol as feedstock). Also, three H2 options for STJ via catalytic conversion are investigated: external H2 from natural gas (NG) steam methane reforming (SMR), in situ H2, and H2 from biomass gasification. Results demonstrate that the feedstock is a key factor in the WTWa GHG emissions of ETJ: corn- and corn stover-based ETJ are estimated to pro...
Introduction Biofuels production worldwide is continuing to grow at a very rapid pace. Energy pol... more Introduction Biofuels production worldwide is continuing to grow at a very rapid pace. Energy policy in the form of a renewable fuel standard (EISA 2007)1 has helped to maintain strong markets for bioethanol and biodiesel as first generation biofuels. However, recent market price fluctuations for feedstocks have been quite dramatic. Average corn prices during this time have also ranged from $2 per bushel to $4.20 per bushel (USDA 2008)2 with spot prices rising over $8 per bushel. Butanol is considered a second generation biofuel that is better for the existing infrastructure. It has a higher heating value than ethanol and it is compatible with gasoline at high concentrations without engine modification. It is also more hydrophobic than ethanol and can be shipped via existing pipelines and distributed through the existing petroleum infrastructure. It becomes increasingly important to understand butanol production economics as a potential biofuel. Production cost data for non-existing...
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