C.R. Locker, S. Torkamani, I. Laurenzi, V. Jin, M. Schmer, D.L. Karlen
ExxonMobile Research and Engineering Co.,
Keywords: greenhouse gas, biofuels
Summary:The U.S. EPA has proposed corn (Zea mays L.) stover as a “renewable” biofuel feedstock because literature estimates of life cycle greenhouse gas (GHG) emissions associated with corn stover biofuels have been lower than conventional transportation fuels. However, there is a wide range in those estimates due to differences in modeling approaches and estimated GHG emissions associated with various crop production practices. In this study, we utilized publically-available data from the USDA-ARS Resilient Economic Agricultural Practices (REAP) research program to estimate GHG emissions for corn stover production in the Midwestern U.S. This enabled us to evaluate the modeling strategies for agricultural emissions utilized in other LCAs. We also explicitly addressed the agricultural carbon balance, and report a robust system expansion method to compute GHG emissions associated with cultivation and harvesting of both corn grain and stover. The methods presented here are generally applicable to LCAs for biofuels or biochemicals that are synthesized from agricultural residues.