Biofuels from Corn Residue May Negatively Impact Climate: Increase in Carbon Emissions

It turns out that corn may not make the best biofuel. A new study reveals that using corn crop residue to make ethanol and other biofuels reduces soil carbon and can generate more greenhouse gases than gasoline.

Cellulosic ethanol production uses the stalks, leaves and cobs from corn in its creation. The U.S. Department of Energy has actually provided more than $1 billion in federal funds in order to support research to create cellulosic biofuels. While the process has yet to be commercialized, several private companies are developing biorefineries that are capable of converting tough corn fibers into fuel.

In order to examine what impact this biofuel would have on the environment, the scientists used models to estimate the effect of residue removal on 128 million acres across 12 Corn Belt states. They found that removing crop residue from cornfields generates an addition 50 to 70 grams of carbon dioxide per megajoule of biofuel energy produced. In fact, total annual production emissions, averaged over five years, would equal about 100 grams of carbon per megajoule; that's about 7 percent greater than gasoline emissions.

"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," said Adam Liska, one of the researchers, in a news release. "Many others have come close recently to accurately quantifying this emission."

So how do you get around this issue? To mitigate increased carbon dioxide emissions and reduced soil carbon, the scientists suggest planting cover crops. In addition, cellulosic ethanol producers could turn to alternative feed stocks such as perennial grasses or wood residue.

The findings reveal the importance of known all of the facts when it comes to biofuels. If carbon emissions aren't decreased through these methods, then it's crucial to know what ways can reduce emissions.

The findings are published in the journal Nature Climate Change.