Biofuel from Corn Generates More Greenhouse Gases than Gasoline

Apr 21, 2014 12:35 PM EDT

Biofuels made from corn crop residue can generate more greenhouse gases than gasoline, and are worse for global warming in the short term, according to a study published Sunday in the journal Nature Climate Change.

Corn stover - stalks, leaves and cobs that remain after harvest - appear to emit more carbon dioxide than current federal standards allow.

A $500,000 study paid for by the federal government concludes that biofuels made with leftovers of harvested corn crops release 7 percent more greenhouse gases initially when compared with conventional gasoline. Though they are more eco-friendly in the long run, the study says they don't qualify as renewable fuel based on standards set in the 2007 Energy Independence and Security Act.

The findings deal a heavy blow to cellulosic biofuels, which have received over $1 billion in federal support, and include ethanol made from corn.

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The research, led by assistant professor Adam Liska, is the first to estimate the effect of residue removal on 128 million acres across 12 Corn Belt states. When corn stover is removed and used to make biofuel, instead of being left to naturally replenish the soil with carbon, it produces an additional 50 to 70 grams of carbon dioxide per megajoule of biofuel energy. That is 62 grams above the 60 percent reduction in greenhouse gas emissions mandated by the government.

"I knew this research would be contentious," Liska of the University of Nebraska-Lincoln told The Associated Press. "I'm amazed it has not come out more solidly until now."

And removing less of these stalks, leaves and cobs doesn't do the trick.

"If less residue is removed, there is less decrease in soil carbon, but it results in a smaller biofuel energy yield," Liska said in a news release.

Crop residue is not just present for show, either, as farmers well know. It protects against erosion and preserves soil quality.

Researchers suggest alternatives such as planting cover crops to fix more carbon in the soil, turning to alternative feedstocks, such as perennial grasses or wood residue, or exporting electricity from biofuel production facilities to offset emissions from coal-fueled power plants.

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