Lincoln, Nebraska – Recent improvements in production efficiency have resulted in a 51 per cent improvement in greenhouse gas emissions (GHG) from corn ethanol as compared to gasoline, according to research by the University of Nebraska-Lincoln. This represents as much as three times the reduction reported in earlier research, thanks to more efficient processing.
The research, outlined in the Journal of Industrial Ecology, evaluated dry-mill ethanol plants that use natural gas. Such plants account for nearly 90 per cent of current production capacity. Previous studies, which found ethanol to have a much smaller advantage over gasoline in GHG emissions, relied on estimates based on corn and ethanol production methods used seven years ago.
“Critics claim that corn ethanol has only a small net energy yield and little potential for direct reductions in GHG emissions compared to use of gasoline,” said Ken Cassman, an agronomist at the university and member of the research team. “This is the first peer-reviewed study to document that these claims are not correct.”
Newer and more efficient plants now represent about 60 per cent of total ethanol production and will account for 75 per cent by the end of 2009, Cassman said. These newer biorefineries have improved technologies, and many are located near cattle feeding or dairy operations, which allows efficient use of distillers grain, a byproduct of ethanol production sold as cattle feed. Without the need for long-distance shipping, the distillers grain does not have to be dried, which requires up to 30 per cent of the total energy used in the ethanol plant.
Also contributing to corn ethanol’s GHG performance are improvements in how the crop is grown, including improved crop and soil management, and better hybrids that help achieve a steady increase in corn yields without a corresponding increase in fertilizer or energy inputs. As a result, the ethanol industry is currently producing a fuel that is 48 to 59 per cent lower in direct-effect lifecycle GHG emissions than gasoline. Cassman said that for every unit of energy needed to make ethanol, 1.5 to 1.8 units of energy are produced as vehicle fuel.