New Studies Show Ethanol GHG Benefits

Cindy Zimmerman

Two new studies released this week provide further evidence that grain-based ethanol is significantly reducing greenhouse gas emissions and call into question the reliability of recent “land use change” analyses based on flawed satellite imagery-based methodologies, according to the Renewable Fuels Association (RFA).

The first new study, conducted by the Laboratory for Applied Spatial Analysis at Southern Illinois University Edwardsville (SIUE-LASA), exposes fundamental flaws in satellite imagery-based research regarding land use change that was quoted in the EPA’s Second Triennial Report, released in 2018. SIUE-LASA’s review of the data sets and methodologies that were used in the prior research revealed some remarkable errors.

In one example, a body of water was misclassified as deciduous forest and grass pasture, underscoring why the research based on this data should not be used for regulatory decision-making.

The second new study, a worldwide meta-analysis funded in part by the Department of Energy and USDA, determined that corn residue (“stover”) retained on fields—which is the common practice—results in the sequestration of approximately 0.41 metric ton of carbon per hectare per year in the soil. This implies not only that the carbon intensity of corn-based ethanol is significantly below current estimates by EPA, the California Air Resources Board, and others, but also that leaving more residue on the field can have a larger carbon benefit than significant removal and conversion of the residue into ethanol.

Based on this research, properly accounting for the soil carbon sequestration benefits of corn production would reduce the existing lifecycle “carbon intensity score” of corn ethanol by some 20-25 percent, meaning most dry mill corn ethanol produced today would result in a 50-65 percent GHG savings compared to gasoline.

“As the Environmental Protection Agency considers the GHG impacts of expanded ethanol consumption under the Renewable Fuel Standard, we urge them to strongly consider the latest science and data regarding ethanol’s tremendous carbon benefits,” said RFA President and CEO Geoff Cooper. “At the same time, we implore EPA to exercise great caution and prudence when considering the results of flawed land use change studies reliant on data from satellites that, frankly, can’t tell the difference between a pasture and a parking lot.”

View the SIUE report
View the DOE study

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