Experts, economists criticize recent EWG ethanol report

By Erin Voegele | June 17, 2014

Experts from Argonne National Laboratory, the University of Illinois at Chicago’s Energy Resource Center, Purdue University College of Agriculture and the North Carolina University Department of Agricultural and Resource Economics have published an extensive response to a recent report issued by the Environmental Working Group that claims the lifecycle emissions of corn ethanol are actually greater than those of gasoline. That report, titled “Ethanol’s Broken Promise,” concluded that lowering the ethanol mandate under the renewable fuel standard (RFS) would reduce greenhouse gas emissions by 3 million tons of CO2 equivalent in 2014.

In their response Michael Wang, Jennifer Dunn  and Zhangcai Qin of Argonne National Laboratory; Steffen Mueller of the Energy Resource Center; Wally Tyner of Purdue; and Barry Goodwin of North Carolina State pointed out several problems with the EWG’s analysis.

In its report, the EWG argued that a significant amount of land was converted to corn farming from 2008 to 2012. However, the Wang, Dunn, Qin, Mueller, Tyner and Goodwin note that the land areas SWG estimated were converted are high when compared to earlier detailed studies and modeling results. They group also applied comparatively high emissions factors when compared to reports and studies that take into account important variations in initial and final lands states. “Most importantly, the emission factor EWG applied to wetland-to-corn agriculture transitions reflects emissions from conversion of peat- and carbon-rich tropical wetlands rather than from conversion of temperate wetlands found in the United States. Conversion of U.S. temperate wetlands should be less carbon-intensive,” wrote the experts.

The EWG also used U.S. EPA’s land use change (LUC) greenhouse gas (GHG) emissions results for ethanol for year 2012 to calculate high life-cycle GHG emission for corn ethanol. “EPA’s intent for including corn ethanol LUC GHG emissions results for 2012 and 2017, however, seems to have been mostly for sensitivity analyses because these emissions were not discussed in the RFS final rule or its Regulatory Impact Analysis (RIA). Further, 2012 emissions were not calculated for all biofuel pathways included in RFS. In their report, EWG picked the EPA 2012 GHG emissions for corn ethanol and applied them to the EPA-proposed reduced volume for corn ethanol in to make the erroneous conclusion that the proposal resulted in 3 million tonnes of CO2 reduction in 2014,” the experts wrote in their response.

In their response, the experts also criticized the EWG’s modeling use. While the EWG stated that Argonne National Laboratory’s GREET model uses unrealistic assumptions in estimating LUC associated with increased corn ethanol production, the exports noted that EWG actually confused GREET parameters with those in the economic GTAP model. “The particular parameter EWG discussed, the yield-price elasticity, in the GTAP model is supported by a recent analysis,” the experts wrote. 

A full copy of the response is available on the Renewable Fuels Association website. The RFA has also issued a response to the report. 



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