University of Nebraska-Lincoln says GHG of stover ethanol worse than gasoline

In Nebraska, using corn crop residue to make ethanol and other biofuels reduces soil carbon and can generate more greenhouse gases than gasoline, according to a study published in the journal Nature Climate Change. The findings by a University of Nebraska-Lincoln team of researchers cast doubt on whether corn residue can be used to meet federal mandates to ramp up ethanol production and reduce greenhouse gas emissions.

The researchers, led by assistant professor Adam Liska, used a supercomputer model at UNL’s Holland Computing Center to estimate the effect of residue removal on 128 million acres across 12 Corn Belt states. The team found that removing crop residue from cornfields generates an additional 50 to 70 grams of carbon dioxide per megajoule of biofuel energy produced. Total annual production emissions, averaged over five years, would equal about 100 grams of carbon dioxide per megajoule – which is 7 percent greater than gasoline emissions and 62 grams above the 60 percent reduction in greenhouse gas emissions as required by the 2007 Energy Independence and Security Act. Importantly, they found the rate of carbon emissions is constant whether a small amount of stover is removed or nearly all of it is stripped, the study found.