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Amit Kumar - One of the best experts on this subject based on the ideXlab platform.
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Evaluating Energy and greenhouse gas emission footprints of thermal Energy storage systems for concentrated solar power applications
Journal of Energy Storage, 2019Co-Authors: Spandan Thaker, Abayomi Olufemi Oni, Eskinder Demisse Gemechu, Amit KumarAbstract:Abstract Greenhouse gas emissions from the power geneRation sector contribute significantly to climate change. The use of thermal Energy storage systems can reduce the sector's impact depending on factors such as plant Energy performance and environmental friendliness. In this study, an Excel-based model was developed to evaluate the greenhouse gas emissions and Net Energy Ratio for thermal Energy storage technologies used in concentrated solar power applications. Five thermal Energy storage systems were considered: two-tank indirect sensible heat storage, two-tank direct sensible heat storage, one-tank direct sensible heat storage, latent heat storage, and thermochemical storage. To capture the uncertainties in the results for each type of storage, a Monte Carlo simulation was performed by varying key opeRational and model parameters. With uncertainty taken into consideRation, it was determined that the mean greenhouse gas emission values for two-tank direct sensible heat storage and one-tank direct sensible heat storage are 15 gCO2-eq/kWh and 11 gCO2-eq/kWh, respectively. The two systems offer higher Energy performances and lower emissions than the other storage systems and thus the potential to be implemented commercially for concentrated solar power applications.
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Comparative Energy and techno-economic analyses of two different configuRations for hydrothermal carbonization of yard waste
Bioresource Technology Reports, 2019Co-Authors: Maryam Akbari, Adetoyese Olajire Oyedun, Amit KumarAbstract:Abstract Hydrothermal carbonization (HTC) includes conversion of wet biomass to hydrochar, a coal-like product, eliminating the need for biomass pre-drying. There has been limited focus on the techno-economic assessment of the HTC process in the literature. In this study, techno-economic models were developed to assess the economics of bio-coal production from yard waste for two different HTC plant configuRations. In configuRation A, heat is recovered by steam using several flash separators while in configuRation B special heat exchangers are used. Process models were developed for the two configuRations and then further used to estimate bio-coal production costs. The bio-coal cost and the Net Energy Ratio (NER, or Ratio of Energy output to the Energy input in the system) indicate that configuRation A is preferable in terms of Energy (NER of 5.2 versus 1.4 for configuRation B) but less desired economically because it costs 3.3 $/GJ more than configuRation B.
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Comparative Net Energy Ratio analysis of pellet produced from steam pretreated biomass from agricultural residues and Energy crops
Biomass and Bioenergy, 2016Co-Authors: Hassan Shahrukh, Amit Kumar, Adetoyese Olajire Oyedun, Bahman Ghiasi, Linoj Kumar, Shahab SokhansanjAbstract:Abstract A process model was developed to determine the Net Energy Ratio (NER) for the production of pellets from steam pretreated agricultural residue (wheat straw) and Energy crops (i.e., switchgrass in this case). The NER is a Ratio of the Net Energy output to the total Net Energy input from non-renewable Energy sources into a system. Scenarios were developed to measure the effects of temperature and level of steam pretreatment on the NER of steam pretreated wheat straw and switchgrass pellets. The NERs for the base case at 6 kg h −1 are 1.76 and 1.37 for steam-pretreated wheat straw and switchgrass-based pellets, respectively. The reason behind the difference is that more Energy is required to dry switchgrass pellets than wheat straw pellets. The sensitivity analysis for the model shows that the optimum temperature for steam pretreatment is 160 °C with 50% pretreatment (i.e. 50 % steam treated material is blended with the raw biomass and then pelletised). The uncertainty results for NER for steam pretreated wheat straw and switch grass pellets are 1.62 ± 0.10 and 1.42 ± 0.11, respectively.
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Energy balance and greenhouse gas emissions from the production and sequestRation of charcoal from agricultural residues
Renewable Energy, 2016Co-Authors: Jignesh Thakkar, Amit Kumar, Sonia Ghatora, Christina E. CanterAbstract:Abstract Agricultural residues (wheat/barley/oat straw) can be used to produce charcoal, which can then be either landfilled off-site or spread on the agricultural field as a means for sequestering carbon. One centralized and five portable charcoal production technologies were explored in this paper. The centralized system produced 747.95 kg-CO 2 eq/tonne-straw and sequestered 0.204 t-C/t-straw. The portable systems sequestered carbon at 0.141–0.217 t-C/t-straw. The Net Energy Ratio (NER) of the portable systems was higher than the centralized one at 10.29–16.26 compared to 6.04. For the centralized system, the carbon sequestRation and the cumulative Energy demand were most sensitive to the charcoal yield. Converting straw residues into charcoal can reduce GHG emissions by 80% after approximately 8.5 years relative to the baseline of in-field decomposition, showing these systems are effective carbon sequestRation methods.
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Net Energy Ratio for the production of steam pretreated biomass-based pellets
Biomass and Bioenergy, 2015Co-Authors: Hassan Shahrukh, Amit Kumar, Adetoyese Olajire Oyedun, Bahman Ghiasi, Linoj Kumar, Shahab SokhansanjAbstract:Abstract A process model was developed to determine the Net Energy Ratio (NER) for both regular and steam-pretreated pellet production from ligno-cellulosic biomass. NER is a Ratio of the Net Energy output to the total Net Energy input from non-renewable Energy source into the system. Scenarios were developed to measure the effect of temperature and level of steam pretreatment on the NER of both production processes. The NER for the base case at 6 kg h −1 is 1.29 and 5.0 for steam-pretreated and regular pellet production respectively. However, at the large scale NER would improve. The major factor for NER is Energy for steam and drying unit. The sensitivity analysis for the model shows that the optimum temperature for steam pretreatment is 200 °C with 50% pretreatment (Steam pretreating 50% feed stock, while the rest is undergoing regular pelletization). Uncertainty result for steam pretreated and regular pellet is 1.35 ± 0.09 and 4.52 ± 0.34 respectively.
Timothy A Volk - One of the best experts on this subject based on the ideXlab platform.
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renewable Energy from willow biomass crops life cycle Energy environmental and economic performance
Critical Reviews in Plant Sciences, 2005Co-Authors: Gregory A Keoleian, Timothy A VolkAbstract:Short-rotation woody crops (SRWC) along with other woody biomass feedstocks will play a significant role in a more secure and sustainable Energy future for the United States and around the world. In temperate regions, shrub willows are being developed as a SRWC because of their potential for high biomass production in short time periods, ease of vegetative propagation, broad geNetic base, and ability to resprout after multiple harvests. Understanding and working with willow's biology is important for the agricultural and economic success of the system. The Energy, environmental, and economic performance of willow biomass production and conversion to electricity is evaluated using life cycle modeling methods. The Net Energy Ratio (electricity generated/life cycle fossil fuel consumed) for willow ranges from 10 to 13 for direct firing and gasification processes. Reductions of 70 to 98 percent (compared to U.S. grid generated electricity) in greenhouse gas emissions as well as NOx, SO2, and particulate emiss...
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life cycle Energy and environmental benefits of generating electricity from willow biomass
Renewable Energy, 2004Co-Authors: Martin Heller, Gregory A Keoleian, Margaret K Mann, Timothy A VolkAbstract:Biomass is a key renewable Energy source expected to play an important role in US electricity production under stricter emission regulations and renewable portfolio standards. Willow Energy crops are being developed in the northeast US as a fuel source for increasing biomass Energy and bioproduct demands. A life cycle inventory is presented that characterizes the full cradle-to-grave Energy and environmental performance of willow biomass-to-electricity. A willow biomass production model is developed using demonstRation-scale field experience from New York. Scenarios are presented that mimic anticipated cofiring opeRations, including supplemental use of wood residues, at an existing coal-fired generating facility. At a cofiring rate of 10% biomass, the system Net Energy Ratio (electricity delivered divided by total fossil fuel consumed) increases by 8.9% and Net global warming potential decreases by 7–10%. Net SO2 emissions are reduced by 9.5% and a significant reduction in NOx emissions is expected. In addition, we estimate system performance of using willow biomass in dedicated biomass gasification and direct-fired generating facilities and demonstrate that the pollution avoided (relative to the current electricity grid) is comparable to other renewables such as PV and wind.
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life cycle assessment of a willow bioEnergy cropping system
Biomass & Bioenergy, 2003Co-Authors: Martin Heller, Gregory A Keoleian, Timothy A VolkAbstract:Abstract The environmental performance of willow biomass crop production systems in New York (NY) is analyzed using life cycle assessment (LCA) methodology. The base-case, which represents current practices in NY, produces 55 units of biomass Energy per unit of fossil Energy consumed over the biomass crop's 23-year lifetime. Inorganic nitrogen fertilizer inputs have a strong influence on overall system performance, accounting for 37% of the non-renewable fossil Energy input into the system. Net Energy Ratio varies from 58 to below 40 as a function of fertilizer application rate, but application rate also has implications on the system nutrient balance. Substituting inorganic N fertilizer with sewage sludge biosolids increases the Net Energy Ratio of the willow biomass crop production system by more than 40%. While CO2 emitted in combusting dedicated biomass is balanced by CO2 adsorbed in the growing biomass, production processes contribute to the system's Net global warming potential. Taking into account direct and indirect fuel use, N2O emissions from applied fertilizer and leaf litter, and carbon sequestRation in below ground biomass and soil carbon, the Net greenhouse gas emissions total 0.68 g CO 2 eq . MJ biomass produced −1 . Site specific parameters such as soil carbon sequestRation could easily offset these emissions resulting in a Net reduction of greenhouse gases. Assuming reasonable biomass transportation distance and Energy conversion efficiencies, this study implies that generating electricity from willow biomass crops could produce 11 units of electricity per unit of fossil Energy consumed. Results form the LCA support the assertion that willow biomass crops are sustainable from an Energy balance perspective and contribute additional environmental benefits.
Jason C Quinn - One of the best experts on this subject based on the ideXlab platform.
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techno economic and life cycle assessment of an attached growth algal biorefinery
Bioresource Technology, 2016Co-Authors: Jay Barlow, Ronald C Sims, Jason C QuinnAbstract:Abstract This study examined the sustainability of generating renewable diesel via hydrothermal liquefaction (HTL) of biomass from a rotating algal biofilm reactor. Pilot-scale growth studies and laboratory-scale HTL experiments were used to validate an engineering system model. The engineering system model served as the foundation to evaluate the economic feasibility and environmental impact of the system at full scale. Techno-economic results indicate that biomass feedstock costs dominated the minimum fuel selling price (MFSP), with a base case of $104.31 per gallon. Life-cycle assessment results show a base-case global warming potential (GWP) of 80 g CO2-e MJ−1 and Net Energy Ratio (NER) of 1.65 based on a well-to-product system boundary. Optimization of the system reduces MFSP, GWP and NER to $11.90 Gal−1, −44 g CO2-e MJ−1, and 0.33, respectively. The systems-level impacts of integrating algae cultivation with wastewater treatment were found to significantly reduce environmental impact. Sensitivity analysis showed that algal productivity most significantly affected fuel selling price, emphasizing the importance of optimizing biomass productivity.
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techno economic feasibility and life cycle assessment of dairy effluent to renewable diesel via hydrothermal liquefaction
Bioresource Technology, 2015Co-Authors: Hailey Summers, Rhesa N Ledbetter, Alex T Mccurdy, Michael R Morgan, Umakanta Jena, Kent S Hoekman, Lance C. Seefeldt, Jason C QuinnAbstract:Abstract The economic feasibility and environmental impact is investigated for the conversion of agricultural waste, delactosed whey permeate, through yeast fermentation to a renewable diesel via hydrothermal liquefaction. Process feasibility was demonstrated at laboratory-scale with data leveraged to validate systems models used to perform industrial-scale economic and environmental impact analyses. Results show a minimum fuel selling price of $4.78 per gallon of renewable diesel, a Net Energy Ratio of 0.81, and greenhouse gas emissions of 30.0 g-CO2-eq MJ−1. High production costs and greenhouse gas emissions can be attributed to opeRational temperatures and duRations of both fermentation and hydrothermal liquefaction. However, high lipid yields of the yeast counter these opeRational demands, resulting in a favorable Net Energy Ratio. Results are presented on the optimization of the process based on economy of scale and a sensitivity analysis highlights improvements in conversion efficiency, yeast biomass productivity and hydrotreating efficiency can dramatically improve commercial feasibility.
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Two-step process for production of biodiesel blends from oleaginous yeast and microalgae
Fuel, 2014Co-Authors: Alex T Mccurdy, Andrew J. Higham, Michael R Morgan, Jason C Quinn, Lance C. SeefeldtAbstract:Abstract Biodiesel produced from oleaginous microorganisms shows promise in displacing use of petroleum diesel fuel, however, low biodiesel yields and rigorous processing have thwarted large-scale commercialization. Here, we report a simple and efficient two-step process for generating biodiesel blends from microbial biomass, which eliminates the need for solvent extractions, distillations, or additional purifications. In the present work, diesel fuel was utilized to extract biodiesel produced from direct transesterification of the yeast, Cryptococcus curvatus , and microalgae, Scenedesmus dimorphus , thus generating a blend of microbial biodiesel and diesel fuel. Up to 93% and 83% of the produced biodiesel is extracted from both yeast and microalgae, respectively, whereas the majority of pigments are excluded. A B20 blend produced from yeast meets key ASTM fuel requirements including flash point, viscosity, sulfur, oxidation stability, and acid number. IntegRation of experimental data into system models reveals a 25% reduction in the Net Energy Ratio (NER) with the process presented here compared to traditional solvent extraction.
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Improving energetics of triacylglyceride extraction from wet oleaginous microbes
Bioresource technology, 2014Co-Authors: Robert M. Willis, Alex T Mccurdy, Jason C Quinn, Mariah K. Ogborn, Bradley D. Wahlen, Leonard F. Pease, Lance C. SeefeldtAbstract:Abstract Oleaginous microbes can upgrade carbon to lipids, which can be used as a feedstock to produce renewable replacements for petroleum-based compounds. Efficient extraction of lipids from oleaginous microbes typically involves dewatering and drying of the biomass. Problematically, drying often requires an amount of Energy approaching that available from the cells. Here, we report an approach for the high efficiency extraction of triacylglycerides (TAG) from wet oleaginous microbes, bypassing the drying process. Solvent candidates for extraction of wet oleaginous biomass were identified using ASPEN’s databases to determine an activity based selectivity coefficient. Optimal extraction conditions were determined which resulted in >91% extraction of TAG from yeast, bacteria, and microalgae. Experimental data was integrated into system models to evaluate the energetics of the processes compared to traditional extraction methods. The Net Energy Ratio (NER) of a traditional dry solvent extraction is 0.84, whereas the approach presented here has a NER of 0.34 for yeast.
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Net Energy and greenhouse gas emission evaluation of biodiesel derived from microalgae
Environmental Science & Technology, 2010Co-Authors: Liaw Batan, Jason C Quinn, Bryan Willson, Thomas H BradleyAbstract:Biofuels derived from microalgae have the potential to replace petroleum fuel and first-geneRation biofuel, but the efficacy with which sustainability goals can be achieved is dependent on the lifecycle impacts of the microalgae-to-biofuel process. This study proposes a detailed, industrial-scale engineering model for the species Nannochloropsis using a photobioreactor architecture. This process level model is integrated with a lifecycle Energy and greenhouse gas emission analysis compatible with the methods and boundaries of the Argonne National Laboratory GREET model, thereby ensuring comparability to preexisting fuel-cycle assessments. Results are used to evaluate the Net Energy Ratio (NER) and Net greenhouse gas emissions (GHGs) of microalgae biodiesel in comparison to petroleum diesel and soybean-based biodiesel with a boundary equivalent to “well-to-pump”. The resulting NER of the microalgae biodiesel process is 0.93 MJ of Energy consumed per MJ of Energy produced. In terms of Net GHGs, microalgae-b...
Gregory A Keoleian - One of the best experts on this subject based on the ideXlab platform.
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growing algae for biodiesel on direct sunlight or sugars a comparative life cycle assessment
ACS Sustainable Chemistry & Engineering, 2015Co-Authors: Nolan D Orfield, Gregory A Keoleian, Robert B Levine, Shelie A Miller, Phillip E SavageAbstract:Growing heterotrophic algae in reactors with sugar as the Energy and carbon source rather than sunlight and carbon dioxide is an approach being commercialized today. However, the full environmental impacts of this fuel pathway have not been explored. The objective of this analysis was to compare the life cycle impacts of algal biodiesel produced heterotrophically to a phototrophic pathway featuring algae grown in ponds. A third, hybrid approach utilizing algae capable of both phototrophy and heterotrophy was also explored. Sugar beet and sugarcane were examined as feedstocks for the heterotrophic process. The results indicate that a reduction in the global warming potential (GWP) and an improvement in the Net Energy Ratio (NER) for algal biodiesel could be possible for the heterotrophic and hybrid pathways relative to the phototrophic, but only if reactor cultivation can be performed efficiently and with sugarcane as the feedstock. For example, the NER varies from 0.6 to 1.6 for the heterotrophic pathway,...
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life cycle design of an algal biorefinery featuring hydrothermal liquefaction effect of reaction conditions and an alternative pathway including microbial regrowth
ACS Sustainable Chemistry & Engineering, 2014Co-Authors: Nolan D Orfield, Phillip E Savage, Andrew Fang, Peter J Valdez, Michael C Nelson, Xiaoxia Nina Lin, Gregory A KeoleianAbstract:Algae are an appealing source for bioEnergy due to their high yields relative to terrestrial Energy crops. The high cost of production, however, has prohibited commercialization. Hydrothermal liquefaction is a technology that converts more of the algae into oil than alternative technologies, thereby reducing the amount of expensive pond infrastructure and Energy required for cultivation. We incorporate recent experimental results into an analysis that models the economic and life cycle performance of an algal biorefinery across a range of reaction conditions. Two strategies are explored: one pathway with gasification of the aqueous waste products for onsite Energy recovery and another pathway featuring cultivation of Escherichia coli on the aqueous products and recycling of the biomass back through the reactor for boosted oil yields. We found that the maximum Net Energy Ratio of 1.9 and minimum global warming potential of 1.0 kg CO2e L-oil–1 occurred with gasification, along with the minimum reaction temp...
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renewable Energy from willow biomass crops life cycle Energy environmental and economic performance
Critical Reviews in Plant Sciences, 2005Co-Authors: Gregory A Keoleian, Timothy A VolkAbstract:Short-rotation woody crops (SRWC) along with other woody biomass feedstocks will play a significant role in a more secure and sustainable Energy future for the United States and around the world. In temperate regions, shrub willows are being developed as a SRWC because of their potential for high biomass production in short time periods, ease of vegetative propagation, broad geNetic base, and ability to resprout after multiple harvests. Understanding and working with willow's biology is important for the agricultural and economic success of the system. The Energy, environmental, and economic performance of willow biomass production and conversion to electricity is evaluated using life cycle modeling methods. The Net Energy Ratio (electricity generated/life cycle fossil fuel consumed) for willow ranges from 10 to 13 for direct firing and gasification processes. Reductions of 70 to 98 percent (compared to U.S. grid generated electricity) in greenhouse gas emissions as well as NOx, SO2, and particulate emiss...
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life cycle Energy and environmental benefits of generating electricity from willow biomass
Renewable Energy, 2004Co-Authors: Martin Heller, Gregory A Keoleian, Margaret K Mann, Timothy A VolkAbstract:Biomass is a key renewable Energy source expected to play an important role in US electricity production under stricter emission regulations and renewable portfolio standards. Willow Energy crops are being developed in the northeast US as a fuel source for increasing biomass Energy and bioproduct demands. A life cycle inventory is presented that characterizes the full cradle-to-grave Energy and environmental performance of willow biomass-to-electricity. A willow biomass production model is developed using demonstRation-scale field experience from New York. Scenarios are presented that mimic anticipated cofiring opeRations, including supplemental use of wood residues, at an existing coal-fired generating facility. At a cofiring rate of 10% biomass, the system Net Energy Ratio (electricity delivered divided by total fossil fuel consumed) increases by 8.9% and Net global warming potential decreases by 7–10%. Net SO2 emissions are reduced by 9.5% and a significant reduction in NOx emissions is expected. In addition, we estimate system performance of using willow biomass in dedicated biomass gasification and direct-fired generating facilities and demonstrate that the pollution avoided (relative to the current electricity grid) is comparable to other renewables such as PV and wind.
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life cycle assessment of a willow bioEnergy cropping system
Biomass & Bioenergy, 2003Co-Authors: Martin Heller, Gregory A Keoleian, Timothy A VolkAbstract:Abstract The environmental performance of willow biomass crop production systems in New York (NY) is analyzed using life cycle assessment (LCA) methodology. The base-case, which represents current practices in NY, produces 55 units of biomass Energy per unit of fossil Energy consumed over the biomass crop's 23-year lifetime. Inorganic nitrogen fertilizer inputs have a strong influence on overall system performance, accounting for 37% of the non-renewable fossil Energy input into the system. Net Energy Ratio varies from 58 to below 40 as a function of fertilizer application rate, but application rate also has implications on the system nutrient balance. Substituting inorganic N fertilizer with sewage sludge biosolids increases the Net Energy Ratio of the willow biomass crop production system by more than 40%. While CO2 emitted in combusting dedicated biomass is balanced by CO2 adsorbed in the growing biomass, production processes contribute to the system's Net global warming potential. Taking into account direct and indirect fuel use, N2O emissions from applied fertilizer and leaf litter, and carbon sequestRation in below ground biomass and soil carbon, the Net greenhouse gas emissions total 0.68 g CO 2 eq . MJ biomass produced −1 . Site specific parameters such as soil carbon sequestRation could easily offset these emissions resulting in a Net reduction of greenhouse gases. Assuming reasonable biomass transportation distance and Energy conversion efficiencies, this study implies that generating electricity from willow biomass crops could produce 11 units of electricity per unit of fossil Energy consumed. Results form the LCA support the assertion that willow biomass crops are sustainable from an Energy balance perspective and contribute additional environmental benefits.
Mingxin Wang - One of the best experts on this subject based on the ideXlab platform.
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Environmental sustainability of bioethanol produced from sweet sorghum stem on saline-alkali land.
Bioresource technology, 2015Co-Authors: Mingxin Wang, Xinxing Pan, Xia Xunfeng, Lijun WangAbstract:Life cycle assessment was conducted to evaluate the Energy efficiency and environmental impacts of a bioethanol production system that uses sweet sorghum stem on saline-alkali land as feedstock. The system comprises a plant cultivation unit, a feedstock transport unit, and a bioethanol conversion unit, with 1000L of bioethanol as a functional unit. The Net Energy Ratio is 3.84, and the Net Energy gain is 17.21MJ/L. Agrochemical production consumes 76.58% of the life cycle fossil Energy. The category with the most significant impact on the environment is eutrophication, followed by acidification, fresh water aquatic ecotoxicity, human toxicity, and global warming. Allocation method, waste recycling approach, and soil salinity significantly influence the results. Using vinasse to produce pellet fuel for steam geneRation significantly improves Energy efficiency and decreases negative environmental impacts. Promoting reasonable management practices to alleviate saline stress and increasing agrochemical utilization efficiency can further improve environmental sustainability.
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Energy efficiency and environmental performance of bioethanol production from sweet sorghum stem based on life cycle analysis.
Bioresource technology, 2014Co-Authors: Mingxin Wang, Yahui Chen, Xunfeng Xia, Jianguo LiuAbstract:Life cycle analysis method was used to evaluate the Energy efficiency and environmental performance of bioethanol production from sweet sorghum stem in China. The scope covers three units, including plant cultivation, feedstock transport, and bioethanol conversion. Results show that the Net Energy Ratio was 1.56 and the Net Energy gain was 8.37 MJ/L. Human toxicity was identified as the most significant negative environmental impact, followed by eutrophication and acidification. Steam geneRation in the bioethanol conversion unit contributed 82.28% and 48.26% to total human toxicity and acidification potential, respectively. Fertilizers loss from farmland represented 67.23% of total eutrophication potential. The results were significantly affected by the inventory allocation methods, vinasse reusing approaches, and feedstock yields. Reusing vinasse as fuel for steam geneRation and better cultivation practice to control fertilizer loss could significantly contribute to enhance the Energy efficiency and environmental performance of bioethanol production from sweet sorghum stem.
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Life-cycle Energy efficiency and environmental impacts of bioethanol production from sweet potato.
Bioresource technology, 2013Co-Authors: Mingxin Wang, Xunfeng Xia, Yu Shi, Qun ChenAbstract:Life-cycle assessment (LCA) was used to evaluate the Energy efficiency and environmental impacts of sweet potato-based bioethanol production. The scope covered all stages in the life cycle of bioethanol production, including the cultivation and treatment, transport, as well as bioethanol conversion of sweet potato. Results show that the Net Energy Ratio of sweet potato-based bioethanol is 1.48 and the Net Energy gain is 6.55 MJ/L. Eutrophication is identified as the most significant environmental impact category, followed by acidification, global warming, human toxicity, and photochemical oxidation. Sensitivity analysis reveals that steam consumption during bioethanol conversion exerts the most effect on the results, followed by sweet potato yields and fertilizers input. It is suggested that substituting coal with cleaner Energy for steam geneRation in bioethanol conversion stage and promotion of better management practices in sweet potato cultivation stage could lead to a significant improvement of Energy and environmental performance.