A new study, released last week by the U.S. Department of Agriculture (USDA), found that increased efficiencies for both ethanol plants and farmers growing corn make corn-based ethanol significantly better at reducing greenhouse gas (GHG) emissions compared with gasoline.

The report, which assessed the gains in ethanol-making and corn production, found that GHG emissions associated with corn-based ethanol are about 43 percent lower than those linked to gasoline when measured on an energy equivalent basis.

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

American success story

The new study was also ap­­plauded by farm and ethanol groups, which said it reaffirms the importance of ethanol and the Renewable Fuel Standard.

"Ethanol and the Renewable Fuel Standard are a true Amer­ican success story," said Wesley Spurlock, a farmer from Strat­ford, Texas, who is president of the National Corn Growers Association. "The USDA has reaffirmed what we already know: Ethanol does more than just save consumers money at the gas pump. It’s also better for the environment."

Efficiency gains

The new USDA study found that advances in ethanol production technologies, such as the use of combined heat and power, using landfill gas for energy and co-producing biodiesel, helped re­­duce GHG emissions at ethanol refinery plants. By 2022, given current trends, the GHG profile of corn-based ethanol is expected to be almost 50 percent lower than gasoline primarily due to improvements in corn yields, process fuel switching and transportation efficiency, the study showed.

The USDA report also examines a range of factors that could enhance the GHG benefits of corn ethanol production and provides estimates of how those factors change ethanol’s lifecycle GHG emissions. For example, the report examined the benefits of improving the efficiency of ethanol refinery plants and adoption of additional conservation practices on farms.

In a scenario where these improvements and practices are universally adopted, the GHG benefits of corn ethanol are even more pronounced over gasoline, about a 76 percent reduction.

The new report’s authors found several reasons behind the greater GHG benefits from corn ethanol than a number of earlier studies.

Previous estimates anticipated that growing corn to produce ethanol would result in "indirect land use change" — in other words, land would be converted from grasslands and forests to commodity production as a result of increased demand for corn used in ethanol production.

But based on new data and research, there is compelling evidence that while land-use changes have occurred, the actual patterns of changes and innovation within the farm sector have resulted in these indirect emissions being much lower than previously projected.

Recent studies of international agricultural land-use trends show that the primary land-use change response of the world’s farmers from 2004 to 2012 has been to use available land resources more efficiently rather than to expand the amount of land used for farming.