New research suggests using corn crop residue to create ethanol could produce more greenhouse than gasoline and reduce soil carbon.
The study calls into question whether corn residue can be effectively used to "ramp up ethanol production and reduce greenhouse gas emissions," a University of Nebraska-Lincoln news release reported.
Corn stover ("the stalks, leaves and cobs in cornfields after harvest")has been widely considered a source for ethanol production. The process of making this conversion has not yet been commercialized, but a number of companies are working on "specialized biorefineries" that convert corn fibers into fuel.
Researchers used a supercomputer to study the effect of residue removal on "128 million acres across 12 Corn Belt states," the news release reported.
The team determined this corn residue generated between 50 and 70 grams of "carbon dioxide per megajoule of biofuel energy produced." Over a five year period total annual emissions would reach an average of 100 grams of carbon dioxide per megajoule; this is seven percent greater than gasoline emissions and 62 grams above the 60 percent reduction in greenhouse gas emissions mandated by the 2007 Energy Independence and Security Act.
The amount of stover that was removed did not influence its harmful environmental effects.
"If less residue is removed, there is less decrease in soil carbon, but it results in a smaller biofuel energy yield," assistant professor Adam Liska said in the news release.
In order to combat this issue the researchers suggest planting cover crops to help fix soil carbon. Taking other measures such as exporting electricity to help reduce the process' carbon footprint in other ways.
"If this research is accurate, and nearly all evidence suggests so, then it should be known sooner rather than later, as it will be shown by others to be true regardless," Liska said. "Many others have come close recently to accurately quantifying this emission."
