Carbon Intensity of Marginal Petroleum and Corn Ethanol Fuels

This study shows the trend in GHG emissions from the aggregate mix of petroleum gasoline and corn ethanol in the U.S. and California. GHG emissions based on a weighted average of crude oil resource by production type are higher than those originally estimated for baseline values under the RFS2 and the LCFS and they continue to grow with a decline in conventional crude oil and growth in high CI petroleum options. Meanwhile, GHG emissions from corn based ethanol continue to decline over time . Several factors contribute to this reduction in emissions . Notably, estimates of land use conversion have declined with recently published studies from Purdue University and Argonne National Laboratory . Energy efficiency and fuel switching as well as an expansion of co-products reduce the CI of corn ethanol . The GHG savings from CRF offset the land use conversion ( LUC ) from corn ethanol. Other feed options such as corn oil also displace products with high LUC emissions. The production of cellulosic ethanol from stover will further reduce the average CI of ethanol from the corn crop.