Technoeconomic analysis of biorefinery based on multistep kinetics and integration of geothermal energy

In this work, a technoeconomic study is conducted to assess the feasibility of integrating geothermal energy into a biorefinery for biofuel production. The biorefinery is based on a thermochemical conversion platform that converts 2,000 metric tons of corn stover per day into biofuels via gasification. Geothermal heat is utilized in the biorefinery to generate process steam for gasification and steam-methane reforming. A process simulation model is developed to simulate the operation of the proposed biorefinery, and corresponding economic analysis tools are utilized to predict the product value. Process steam at 150 ºC with a flow rate of approximately 16 kg/s is assumed to be generated by utilizing the heat from geothermal resources producing a geothermal liquid at 180 °C and a total flowrate of 105 kg/s. In addition to the use for gasification and steam-methane reforming, additional geothermal capacity at 100 kg/sec from multiple wells is used for electricity production via Organic Rankine Cycle to add to the profitability of the biorefinery. The total capital investment, operating costs, and total product values are calculated considering an operating duration of 20 years for the plant and the data are reported based on the 2012 cost year. Simulation results show that the price of the fuel obtained from the present biorefinery utilizing geothermal energy ranges from $5.18 to$5.50 per gallon gasoline equivalent, which is comparable to $5.14 using the purchased steam. One important incentive for using geothermal energy in the present scenario is the reduction of greenhouse gas emissions resulting from the combustion of fossil fuels used to generate the purchased steam. Geothermal energy is an important renewable energy resource, and this study provides a unique way of integrating geothermal energy into a biorefinery to produce biofuels in an environmentally friendly manner. In the other part of the study, the simulation of biomass gasification is carried out using multistep kinetics under various oxygen-enriched air and steam conditions. The oxygen percentage is increased from 21% to 45% (by volume). Five different kinds of biomass feedstocks including pine wood, maple-oak mixture (50/50 by weight), seed corn, corn stover, and switchgrass are used in this study. The bed temperature is maintained at 800 oC. Different conditions such as flowrates of biomass and different oxygen-enriched air and steam ratios are used to simulate different cases. The simulation results for different species are in good agreement with the experimental data.. From the results, it is evident that the proposed gasification kinetics model can predict the syngas compositions. The model is able to capture the effects of biomass feedstock and oxygen and steam concentrations. The model is able to predict the concentrations of H2, CO, CO2, H2O, CH4, N2 in the syngas; nonetheless, more rigorous simulation has to be carried out to model NOx, NH3, and other higher alkane and alkenes such as C2H4, C2H2, C2H6 etc

Technoeconomic Analysis of Biofuel Production and Biorefinery Operation Utilizing Geothermal Energy

A technoeconomic study is conducted to assess the feasibility of integrating geothermal energy into a biorefinery for biofuel production. The biorefinery is based on a thermochemical platform that converts low-value lignocellulosic biomass into biofuels via gasification and fuel reforming. Geothermal energy is utilized in the refinery to generate process steam for gasification and steam-methane reforming in addition to providing excess electricity via the organic Rankine cycle. A process simulation model is developed to simulate the operation of the proposed biorefinery, and corresponding economic analysis tools are utilized to predict the product value. The biorefinery uses 2000 metric tons of corn stover per day, and the products include gasoline, diesel fuel, hydrogen, and electricity. Implementation of geothermal energy into the proposed biorefinery is analyzed through two studies. In the first study, process steam at 150 °C with a flow rate of approximately 16 kg/s is assumed to be generated through a heat exchanger process by utilizing the heat from geothermal resources, producing a geothermal liquid at 180 °C and a total flow rate of 105 kg/s which is used to provide steam for gasification and steam-methane reforming within the biorefinery. In the second study, additional geothermal capacity of 204 kg/s is assumed to be available and is separated into two phases (liquid and steam) via a flash column. The steam produced is utilized in the same manner as the initial study while the geothermal liquid is used for electricity production via the organic Rankine cycle to add to the profitability of the biorefinery. This analysis considers that the technology is feasible in the near future with a high scope of technology development and the end products are compatible with the present fuel infrastructure. The total capital investment, operating costs, and total product values are calculated considering an operating duration of 20 years for the plant, and the data are reported based on the 2012 cost year. Simulation results show that the price of the fuel obtained from the present biorefinery utilizing geothermal energy ranges from $5.17 to$5.48 per gallon gasoline equivalent, which is comparable to $5.14 using the purchased steam. One important incentive for using geothermal energy in the present scenario is the reduction of greenhouse gas emissions resulting from the combustion of fossil fuels used to generate the purchased steam. Geothermal energy is an important renewable energy resource, and this study provides a unique way of integrating geothermal energy into a biorefinery to produce biofuels in an environmentally friendly manner

Techno-economic and Sensitivity Analysis of Microalgae-based Biorefinery

University of Minnesota Ph.D. dissertation. December 2019. Major: Bioproducts/Biosystems Science Engineering and Management. Advisor: Shri Ramaswamy. 1 computer file (PDF); viii, 184 pages.Microalgae possess tremendous potential to meet the ever-increasing demand for food, feed, energy and fuels in a sustainable manner. However, to be commercially viable, the entire supply chain of microalgae production including harvesting and conversion needs to be thoroughly investigated and better understood. To this end, a comprehensive theoretical approach was used in the present study involving first-principles based detailed modeling, simulation and analysis. Mathematical models were developed to quantify microalgae productivity potential and the associated feed stock costs in commercial scale biorefineries. In addition, detailed process modeling of the conversion of algae to multiple value-added products and the associated technical and economic feasibility and environmental assessment were conducted for the different geospatial locations. Using a first principles-based approach, algae growth and productivity were modeled considering an open raceway pond reactor and a flat panel photobioreactor to understand the implications of reactor geometry on microalgae growth and harvesting. Economic analysis was also conducted to determine algae production costs in the two different reactor systems, and across several geographic locations, thereby offering direct comparisons to facilitate selection of the most productive algae reactor system and the location. Then process models were developed for the conversion of microalgae to natural astaxanthin and eicosapentanoic acid (EPA) and docosahexanoic acid (DHA). These process models were used to assess the cost of production of the above products using different bioreactor systems and at various geospatial locations. In addition to value-added products, utilization of the residual algae biomass was also included in the overall techno-economic analysis to understand the economic competitiveness of microalgae-derived natural products and algal biorefinery in a fossil fuel-dominated market. The results obtained here suggest that microalgae productivity potential as well as production costs are heavily influenced by geographic location. Predicted yields and corresponding costs for astaxanthin and EPA and DHA suggest that the production of these high-value products may be more successful in locations characterized by favorable environmental profiles that are more conducive to algae growth. While the costs of production in algal biorefineries were found to be higher than those of their petroleum-based counterparts, with further research and development the commercial production of microalgae-based natural products is highly promising for future industrial applications

Technoeconomic analysis of biorefinery based on multistep kinetics and integration of geothermal energy

In this work, a technoeconomic study is conducted to assess the feasibility of integrating geothermal energy into a biorefinery for biofuel production. The biorefinery is based on a thermochemical conversion platform that converts 2,000 metric tons of corn stover per day into biofuels via gasification. Geothermal heat is utilized in the biorefinery to generate process steam for gasification and steam-methane reforming. A process simulation model is developed to simulate the operation of the proposed biorefinery, and corresponding economic analysis tools are utilized to predict the product value. Process steam at 150 ºC with a flow rate of approximately 16 kg/s is assumed to be generated by utilizing the heat from geothermal resources producing a geothermal liquid at 180 °C and a total flowrate of 105 kg/s. In addition to the use for gasification and steam-methane reforming, additional geothermal capacity at 100 kg/sec from multiple wells is used for electricity production via Organic Rankine Cycle to add to the profitability of the biorefinery. The total capital investment, operating costs, and total product values are calculated considering an operating duration of 20 years for the plant and the data are reported based on the 2012 cost year. Simulation results show that the price of the fuel obtained from the present biorefinery utilizing geothermal energy ranges from $5.18 to$5.50 per gallon gasoline equivalent, which is comparable to $5.14 using the purchased steam. One important incentive for using geothermal energy in the present scenario is the reduction of greenhouse gas emissions resulting from the combustion of fossil fuels used to generate the purchased steam. Geothermal energy is an important renewable energy resource, and this study provides a unique way of integrating geothermal energy into a biorefinery to produce biofuels in an environmentally friendly manner. In the other part of the study, the simulation of biomass gasification is carried out using multistep kinetics under various oxygen-enriched air and steam conditions. The oxygen percentage is increased from 21% to 45% (by volume). Five different kinds of biomass feedstocks including pine wood, maple-oak mixture (50/50 by weight), seed corn, corn stover, and switchgrass are used in this study. The bed temperature is maintained at 800 oC. Different conditions such as flowrates of biomass and different oxygen-enriched air and steam ratios are used to simulate different cases. The simulation results for different species are in good agreement with the experimental data.. From the results, it is evident that the proposed gasification kinetics model can predict the syngas compositions. The model is able to capture the effects of biomass feedstock and oxygen and steam concentrations. The model is able to predict the concentrations of H2, CO, CO2, H2O, CH4, N2 in the syngas; nonetheless, more rigorous simulation has to be carried out to model NOx, NH3, and other higher alkane and alkenes such as C2H4, C2H2, C2H6 etc.</p

Technoeconomic Analysis of Biofuel Production and Biorefinery Operation Utilizing Geothermal Energy

A technoeconomic study is conducted to assess the feasibility of integrating geothermal energy into a biorefinery for biofuel production. The biorefinery is based on a thermochemical platform that converts low-value lignocellulosic biomass into biofuels via gasification and fuel reforming. Geothermal energy is utilized in the refinery to generate process steam for gasification and steam-methane reforming in addition to providing excess electricity via the organic Rankine cycle. A process simulation model is developed to simulate the operation of the proposed biorefinery, and corresponding economic analysis tools are utilized to predict the product value. The biorefinery uses 2000 metric tons of corn stover per day, and the products include gasoline, diesel fuel, hydrogen, and electricity. Implementation of geothermal energy into the proposed biorefinery is analyzed through two studies. In the first study, process steam at 150 °C with a flow rate of approximately 16 kg/s is assumed to be generated through a heat exchanger process by utilizing the heat from geothermal resources, producing a geothermal liquid at 180 °C and a total flow rate of 105 kg/s which is used to provide steam for gasification and steam-methane reforming within the biorefinery. In the second study, additional geothermal capacity of 204 kg/s is assumed to be available and is separated into two phases (liquid and steam) via a flash column. The steam produced is utilized in the same manner as the initial study while the geothermal liquid is used for electricity production via the organic Rankine cycle to add to the profitability of the biorefinery. This analysis considers that the technology is feasible in the near future with a high scope of technology development and the end products are compatible with the present fuel infrastructure. The total capital investment, operating costs, and total product values are calculated considering an operating duration of 20 years for the plant, and the data are reported based on the 2012 cost year. Simulation results show that the price of the fuel obtained from the present biorefinery utilizing geothermal energy ranges from $5.17 to$5.48 per gallon gasoline equivalent, which is comparable to $5.14 using the purchased steam. One important incentive for using geothermal energy in the present scenario is the reduction of greenhouse gas emissions resulting from the combustion of fossil fuels used to generate the purchased steam. Geothermal energy is an important renewable energy resource, and this study provides a unique way of integrating geothermal energy into a biorefinery to produce biofuels in an environmentally friendly manner.Reprinted with permission from Energy Fuels, 2013, 27 (3), pp 1381–1390. Copyright 2013 American Chemical Society.</p