The People of America's Oil and Natural Gas Indusry

Facts, Credible Research Undercut E15 Claims

Mark Green

Mark Green
Posted September 12, 2014

One of the oft-repeated claims of ethanol producers is that higher-ethanol blend fuels like E15 are better for air quality than the E10 gasoline that’s the staple of the U.S. fuel supply. Short response: No. And while we’ve addressed the ethanol/air quality claim recently here and here, spurious assertions often have more lives than Lulu, my daughter’s cat. So let’s look at the facts and credible research again.

We’ll underscore “facts and credible research,” because an advocacy group is promoting a study on ethanol, air quality and potential cancer risks that isn’t an original study at all. Rather, it’s an overly simplistic exercise in data aggregation that ignores the confounding effects of different test procedures, laboratories and fuel properties. In other words, it’s a crummy analysis that would send real scientists running in the other way. Let’s debunk further:

Cancer – Cherry-picked data is based on interpolated or hypothetical emissions from just seven flex-fuel vehicles, which are not the typical vehicles most Americans drive. Statistically, scientifically – it’s simply faulty to use this as a basis to assert an E15 benefit for the entire U.S. vehicular fleet.

Air quality – The aggregation shows no statistically significant reduction in ozone precursors, and the volume of other test data, including EPA’s, show nitrogen oxides increasing with higher ethanol content. More detail:

  • In 2011 the National Academy of Sciences – using EPA data and Argonne Lab modeling on greenhouse gases, regulated emissions and energy use in transportation – concluded that corn ethanol increases greenhouse gas emissions. From the report’s discussion of the ethanol-mandating Renewable Fuel Standard (referred to here as RFS2):

… according to EPA’s own estimates, corn-grain ethanol produced in 2011, which is almost exclusively made in biorefineries using natural gas as a heat source, is a higher emitter of GHG than gasoline. … The discrepancy between how RFS2 is implemented (under the assumption of 21-percent reduction of GHG emissions by corn-grain ethanol compared to gasoline) and EPA’s own analysis suggests that RFS2 might not achieve the intended GHG reductions. According to EPA’s results … atmospheric GHG concentrations will be higher in the presence of RFS2 due to the cumulative GHG effect of corn-grain ethanol produced over 2008-2022 than in the absence of RFS2, in which case gasoline would be used.

  • The Environmental Working Group’s 2014 report, “Ethanol’s Broken Promise,” argues that federal corn ethanol mandates under the RFS have raised food prices, strained agricultural markets, increased competition for arable land and promoted conversion of uncultivated land to grow crops.  EWG said its research found that more than 8 million acres of grassland and wetlands were converted for corn alone and that these changes resulted in annual emissions of 85 million to 236 million metric tons of greenhouse gases:

A few recent studies still claim that corn ethanol produces fewer emissions than gasoline, but a careful look reveals that their methods don’t properly account for land use change. Studies that do factor in land use change show that using food crops to produce biofuels – once considered a promising climate change mitigation strategy – is worse for the climate than gasoline.

  • A 2013 white paper by the Clean Air Task Force found significantly higher emissions from corn ethanol compared to gasoline:

If EPA had analyzed corn ethanol produced during 2010-2015 … the Agency would have found that corn ethanol’s net emissions over 30 years are approximately 28% higher than the emissions that would result from the use of gasoline over the same period.

  • In 2011 congressional testimony Ingrid C. Burke, director of the University of Wyoming’s Haub School and Ruckelshaus Institute of Environment and Natural Resources, said that claimed savings in greenhouse gas emissions from corn-based ethanol were “uncertain”:

If the expanded biofuel feedstock production involves removing perennial vegetation on a piece of land and replacing it with an annual commodity crop, then the land-use change would incur a one-time greenhouse-gas emission from biomass and soil that could be large enough to offset greenhouse-gas benefits gained by displacing petroleum-based fuels with biofuels over subsequent years. Furthermore, such land conversion may disrupt any future potential for storing carbon in biomass and soil.

Burke adds:

Production and use of ethanol results in higher concentrations of such pollutants affecting air quality as volatile organic compounds, nitrous oxides, particulate matter, and ammonia than gasoline on a national average. On the whole, estimates of emissions of pollutants affecting air quality from using corn-grain or cellulosic ethanol and gasoline in vehicles (including tailpipe emissions and evaporative emissions from vehicles and filling station) are comparable. However, the pollutant amounts emitted during the fuel-production phase (including feedstock production and transportation) are typically higher for corn-grain or cellulosic ethanol than for petroleum-based fuels.

  • A 2014 study by Northwestern University researchers found that in the region of Sao Paulo, Brazil, ozone levels fell 20 percent during 2010 and 2011 as vehicles shifted from using ethanol to gasoline. Acknowledging that the location-specific meteorological and geographic factors affecting ozone formation in Sao Paulo might not be identical in other places, it’s still a significant result. Study co-author Alberto Salvo:

“Individuals often don’t realize it, but in the aggregate, you can have a real impact on the environment. In São Paulo, there were more than a million cars switching from ethanol to gasoline in the same season, and we found that ozone levels went down. We didn’t expect this, but it is a precise result.”

Bottom line: Repeatedly claiming that E15 has more environmental and/or health benefits than conventional gasoline doesn’t make the claim any less false – not given the weight of the facts and credible research arguing otherwise.


Mark Green joined API after a career in newspaper journalism, including 16 years as national editorial writer for The Oklahoman in the paper’s Washington bureau. Mark also was a reporter, copy editor and sports editor. He earned his journalism degree from the University of Oklahoma and master’s in journalism and public affairs from American University. He and his wife Pamela live in Occoquan, Va., where they enjoy their four grandchildren.