Biological Systems Engineering


Date of this Version



Presented at CRC Life Cycle Assessment Workshop, Chicago, Oct. 20-21, 2009. Copyright 2009 Virgil R. Bremer, Adam J. Liska, Terry J. Klopfenstein, Galen E. Erickson, Haishun S. Yang, Daniel T. Walters, and Kenneth G. Cassman.



• Co-product GHG emissions credit varied by >2-fold, from 11.5 to 28.3 gCO2e per MJ of ethanol produced

• Co-product GHG emissions credit depend on
-types of co-products produced
-proportion fed to beef cattle vs. diary or swine
-location of corn production; the CP credit is highest in regions where GHG kg-1grain are highest

• Depending on CP production types and feeding livestock classes, corn-ethanol net life cycle GHG intensity is 44-56 gCO2e per MJ

• Midwest corn-ethanol reduces GHG emissions compared to gasoline by 47% on average, with co-products offsetting 23% of positive emissions