USDA: Corn Ethanol Emissions 43% Lower Than Gasoline

Study validates biofuels as good for the environment, lung health.

In the case against Big Oil, biofuels just received another win.

Emissions from the production of corn-based ethanol are even lower than expected, according to a recent report from the U.S. Department of Agriculture (USDA). According to the report, biofuels provide significant reduction in greenhouse gas emissions associated with cornbased ethanol in the U.S.

USDA sets that number at 43 percent, when measured on an energy-equivalent basis with gasoline over a 10-year period (2005 - 2015).

And if current trends in corn yields, process fuel switching and trucking fuel efficiencies continue, the forecasters anticipate corn ethanol’s carbon profile to be nearly 50 percent lower than gasoline by 2022.

This study directly refutes reports that instead claim biofuels increase carbon dioxide emissions. The USDA report offers a chance for industry supporters to renew their efforts in rallying against such claims and to uphold the greenhouse gas benefits of corn ethanol.

“It’s encouraging to see an important respected organization say, this is happening. In Washington, we’re endlessly debating the environmental benefits of ethanol.... Having this study is critical in the debate,” says Jessie Stolark, policy associate with the Environmental and Energy Study Institute (EESI), a Washington-based think tank. Environmental policy experts say the study’s findings are on trend with reports from the Department of Energy (DOE) and other groups doing similar work.

“The USDA study is good because it’s further validating what the models are telling us,” Stolark says.

Stolark cited a 2012 study from the DOE’s Argonne National Laboratory, which estimates 19 to 48 percent reductions from lifecycle greenhouse gas emissions from corn ethanol, depending on the source of energy used during ethanol production.

While other studies of greenhouse gas benefits considered forecasts of future ethanol production systems and expected impacts on the farm sector, this study looked at performance of industry and farm sectors over the past decade to determine corn-based ethanol’s greenhouse gas profile.

“Biofuels and corn ethanol can provide significant reductions in global greenhouse gas,” says Steffen Mueller, PhD, Principal Economist at the Energy Resources Center at the University of Illinois at Chicago. “Biofuels can really be a solution to climate change. [This study] shows how much more efficient biofuels have become. It shows how vibrant the industry is. It’s the leading industry in terms of energy improvement and efficiencies.”

Beyond showing the environmental benefits of ethanol production, the USDA study also speaks to the growing efficiencies of production.

Conservation practices such as reduced tillage, cover crops and improved nitrogen management, along with more efficient corn production, are driving improvements. At ethanol biorefinery plants, ethanol production technologies – such as the use of combined heat and power and using landfill gas for energy – have helped reduce greenhouse gas emissions.


This study is also a reminder that consumers’ choice at the pump makes a difference in air quality.

“Transportation is a key factor in increasing greenhouse gas emissions. This study shows that the type of fuel we use is important. … It’s good for the environment to make a choice and pick the right fuel. It’s good for the environment and ultimately good for lung health,” says Angela Tin, Vice President of Environmental Health for the American Lung Association of the Upper Midwest.

The long-term campaign for the American Lung Association of the Upper Midwest is to make the “Clean Air Choice.”

“Unless you make a choice, you’re not going to make the environment any better. These are individual choices people can make. We choose to recycle. We choose to conserve water. We can make a proactive choice in the fuels we use,” Tin says.

USDA estimates that additional conservation and efficiency measures could further improve ethanol’s lifecycle greenhouse gas emissions. The report looked at the benefits of improving the efficiency of ethanol plants and adopting additional conservation practices on corn-producing farms.

In that framework, the greenhouse gas benefits of corn ethanol are further articulated – about a 76 percent reduction.

“That is an incredible reduction from what is currently your standard fuel,” Mueller says. “… It’s close to a carbon-neutral fuel.”

But is that reduction obtainable? Mueller remains hopeful, considering the industry’s progress over the past ten years especially. “It’s a goal that we can meet. It’s a realistic goal, but we have to work at achieving it.”



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