USDA Report: Corn Ethanol and Gasoline

January 23, 2017

Originally published in the Des Moines Register, Jan. 12, 2017
By Donnelle Eller, Des Moines Register

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Gasoline Pumps

Photo courtesy of the Des Moines Register.

Corn ethanol releases 43 percent fewer greenhouse gases than gasoline, making the renewable fuel greener than the federal government initially estimated, a study released Thursday by the U.S. Department of Agriculture shows. 

Corn ethanol carbon emissions could drop to about half of gasoline's by 2022 with improvements in corn yields and shifting fuel used during production, the report said. And added conservation practices would make corn ethanol 76 percent greener than gasoline over the next six years.

The federal government had previously estimated corn ethanol has 21 percent fewer greenhouse gas emissions than gasoline. Carbon dioxide and other greenhouse gases get trapped in the atmosphere and contribute to climate change and global warming.

"This report provides evidence that corn ethanol can be a GHG-friendly alternative to fossil fuels, while boosting farm economies," said Agriculture Secretary Tom Vilsack, Iowa's former governor.

The new estimate is significant because some scientists have long questioned whether ethanol is as environmentally friendly as supporters claim. Scientists interviewed Thursday questioned the accuracy of the new estimate.

The report found greater greenhouse benefits from corn ethanol than earlier studies because it factored in improvements in ethanol production, "from the corn field to the ethanol refinery," the Agriculture Department said.


Iowa is the nation's largest corn and biodiesel producer, both of which set records last year. And the state led the nation in corn production last year at 2.74 billion bushels and was second only to Illinois in soybean production with 571.7 million bushels, a USDA crop production report showed Thursday.

The USDA's ethanol report showed the nation's ethanol production increased significantly between 2005 and 2015 — from 3.9 billion gallons to 14.8 billion gallons per year.


Jason Hill, a University of Minnesota associate professor, said the study fails to take into account the "fuel market rebound effect — mainly when you introduce more fuel into the market, prices drop and people tend to consume more."

"For ethanol to even break even as a climate-reducing strategy, it has to have a carbon footprint that's at least 50 percent better than gasoline to even break even," said Hill, who teaches in the bioproducts and biosystems engineering department.

He also criticized the report for failing to address land-use changes in the Midwest and worldwide that resulted from "increased demand for corn production. That carbon has been released to the atmosphere and will continue to be released to the atmosphere as the land is cultivated," Hill said.

Sabrina Fang, a spokeswoman for the American Petroleum Institute, said the group is reviewing the study but added that part of the ethanol production gains are made through "increased use of natural gas."

Carl Jardon, an Iowa Corn Growers Association board director, said farmers — and ethanol producers — will only become better at reducing their carbon footprint.

Better seed genetics, for example, mean farmers make fewer trips across their fields.

"We're getting more yield with fewer inputs all the time," said Jardon, who farms in Fremont County in southwest Iowa.

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