A comprehensive new study (with appendix) conducted by Life Cycle Associates found that the carbon footprint of corn ethanol continues to shrink, while the carbon impacts associated with crude oil production continue to worsen as more marginal sources are introduced to the fuel supply. According to the report, “As the average carbon intensity of petroleum is gradually increasing, the carbon intensity of corn ethanol is declining. Corn ethanol producers are motivated by economics to reduce the energy inputs and improve product yields.”
The study, commissioned by the Renewable Fuels Association (RFA), found that average corn ethanol reduced greenhouse gas (GHG) emissions by 32% compared to average petroleum in 2012. Importantly, this estimate includes prospective emissions from indirect land use change (ILUC) for corn ethanol. When compared to marginal petroleum sources like tight oil from fracking and oil sands, average corn ethanol reduces GHG emissions by 37-40%.
As more unconventional crude oil sources enter the U.S. oil supply, and as corn ethanol production processes become even more efficient, the carbon impacts of ethanol and crude oil will continue to diverge. By 2022, average corn ethanol reduces GHG emissions by 43-60% compared to petroleum, the study found.