On May 29, 2014, the Environmental Working Group (EWG) released a report entitled "Ethanol's Broken Promise: Using Less Corn Ethanol Reduces Greenhouse Gas Emissions." A copy of the report is available online.

The report concludes that "[t]he Environmental Protection Agency's pending proposal to cut the amount of corn ethanol that must be blended into gasoline in 2014 by 1.39 billion gallons would lower U.S. greenhouse gas emissions by the equivalent of 3 million tons of carbon dioxide (CO2e) – as much as taking 580,000 cars off the road for a year." The report finds that the corn ethanol volume requirements in the Renewable Fuel Standard (RFS) have led to increased greenhouse gas emissions as more uncultivated land is cleared to grow biofuels feedstocks.

Key biofuels trade groups have made public statements challenging the report's findings. For instance, the Renewable Fuels Association (RFA) issued a press release disputing the flawed EWG report. In the release, RFA President Bob Dinneen states that "[t]he Department of Energy's GREET model clearly shows that corn ethanol reduces GHG emissions by 34 percent compared to gasoline, including hypothetical land use change emissions. Additionally, a Life Cycle Associates study found that corn ethanol reduces GHG emissions by 37-40 percent when compared to tight oil from fracking and tar sands." RFA's press release is available online.

The report comes at a time when EPA is expected to release its final 2014 RFS rule soon, perhaps in June. The biofuels industry generally has urged EPA to revisit the proposed reductions to the advanced and corn ethanol 2014 RFS volumes, while RFS opponents, including generally the oil and gas and livestock industries, have been supportive of EPA's proposed 2014 RFS reductions.