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Life Cycle Assessment of Ethanol produced from Lignocellulosic Biomass: Techno-economic and Environmental Evaluation

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Title: Life Cycle Assessment of Ethanol produced from Lignocellulosic Biomass: Techno-economic and Environmental Evaluation
Author: Roy, Poritosh
Department: School of Engineering
Program: Engineering
Advisor: Dutta, Animesh
Abstract: The life cycle (LC) of ethanol derived from lignocellulosic biomass (hereafter referred to biomass: wheat straw, sawdust & miscanthus) by both enzymatic hydrolysis and thermochemical [gasification-biosynthesis pathway; torrefied/non-torrefied, with/without chemical looping gasification (CLG)] conversion processes has been evaluated, considering various scenarios. A follow-up study has also been conducted to identify the potential locations for ethanol industries in Ontario. Life cycle assessment (LCA) methodologies have been used to evaluate the LC of ethanol to determine if environmentally preferable and economically viable ethanol can be produced in Ontario, Canada. A novel continuous stirred tank bioreactor has also been developed (consisting of an innovative gas supply and an effluent extraction process) for syngas fermentation into ethanol. The net energy consumption, GHG emissions and production cost of ethanol were found to be dependent on ethanol yield, feedstock cost, processing plant capacity and assumptions. This study revealed that environmental benefit can be gained from biomasses, the economic viability and biomass logistics of agri- and forest residues remain doubtful, unless a nominal subsidy (for example FiT) is provided. The CLG process seems to be useful to reduce net energy consumption and GHG emissions for both torrefied and non-torrefied miscanthus. Consequently, miscanthus has emerged as a promising feedstock for ethanol industries (both enzymatic hydrolysis and biosynthesis) even if it is grown on marginal land in Ontario, avoids any sort of competition with food crops for higher quality land, avoids the food vs fuel debate, and improves farm income and the rural economy. Eastern Ontario has emerged as the best option for miscanthus based ethanol industry. This study also revealed that syngas can be fermented with Clostridium Ljungdahlii into ethanol by using the developed bioreactor. It is worthy to note that careful consideration has to be placed on the land use changes, soil quality and their rebound effects if biomass, especially agri-residues are to be put to use in the ethanol industry. The information generated in this study has emerged to be novel and may help the stakeholders in their decision making processes, help meeting the ethanol demand, and achieving GHG emissions target of Canada.
Date: 2014-08
Rights: Attribution-NoDerivs 2.5 Canada

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