(618a) Life Cycle Assessment of Ethanol in 2022

The Energy Independence and Security Act of 2007 (EISA) mandates specific renewable energy market penetration targets for the year 2022. For liquid transportation fuels, the 2022 EISA mandate is 36 billion gallons per year (bgy) of biofuel, of which 21 bgy must come from biomass feedstocks other than corn starch. Despite this legal mandate for renewable biofuels, many questions remain unanswered with regard to the potential environmental effects of such a large increase in the production and use of biofuels. The objective of this study is to use life cycle assessment to evaluate the global warming potential, water use, and net energy value associated with the EISA-mandated 36 bgy biofuels target, which is assumed in this study to be met by a combination of corn starch-based and cellulosic-based ethanol. The cellulosic feedstocks considered are corn stover, switchgrass, wheat straw, and forest residues. Projections are made for feedstock production and refinery configurations into 2022. Results for this study will be presented both on a per mile and a per megajoule basis.