Studies draw different conclusions on fuel’s climate impact

Source: Marc Heller, E&E News reporter • Posted: Wednesday, April 3, 2019

Supporters and critics of corn-based ethanol may each find talking points in a pair of environmental studies released today.

The Department of Agriculture touted its own study that pointed to greenhouse gas benefits of ethanol, while a study published in the journal Nature said fertilizer-related emissions from cornfields are dangerous to people’s health.

Studies related to ethanol’s environmental impact have become ammunition in the long-standing debate over the federal renewable fuel standard, which mandates the blending of ethanol into gasoline. Agriculture Secretary Sonny Perdue referenced the issue in a statement praising his department’s findings.

USDA’s study found that corn-based ethanol could reduce greenhouse gas emissions by more than the 21% compared with gasoline that EPA projected in a 2010 analysis.

Emissions could be 39% lower with corn ethanol and 43% lower with ethanol produced in natural gas-fired refineries, USDA found. And with further technological improvements, the reductions could reach between 47% and 70%, the department said.

“These new findings provide further evidence that biofuels from America’s heartland reduce greenhouse gases even more than we thought, and that our farmers and ethanol plants continue to become more efficient and effective,” Perdue said.

He cited the administration’s moves toward expanding availability of E15 fuel, which is 15% ethanol, to the summer driving season, beginning in June.

“Expanding the sale of E15 year-round will provide consumers with more choices when they fill up at the pump, including environmentally friendly fuel with decreased emissions,” Perdue said. “I appreciate EPA Administrator Andrew Wheeler moving expeditiously to finalize the E15 rule before the start of summer driving season.”

The other study, led by researchers at the University of Minnesota in St. Paul, said air pollution tied to corn production — mainly from the ammonia used in fertilizer — causes as many as 4,300 premature deaths annually in the United States. Estimated monetary damages may total between $14 billion and $64 billion, according to the study, published yesterday in Nature.

The lead researcher on that study, Jason Hill, said the effects vary from region to region and are more pronounced on the Eastern Seaboard, where population density is higher and farmers tend to use more cow manure, which releases ammonia.

The Minnesota researchers said they also found greenhouse gas contributions from corn could cause between $1.5 billion and $7.5 billion in damages.

Negative effects from corn could be lessened by changing the fertilizer type and application method, improving nitrogen use efficiency, switching to crops requiring less fertilizer, and shifting production to different areas, the researchers said.