A Project of The Annenberg Public Policy Center

Ethanol: Higher Emissions or Lower?


In dueling TV ads, foes of the federal ethanol mandate claim that it “doubles greenhouse gas emissions,” while the ethanol lobby says that “the oil industry is lying” and the mandate will lead to lower emissions.

In fact, the scientific jury is still out on whether requirements to blend ethanol with gasoline lead to the lower carbon emissions that Congress intended when it made those requirements law. A 2011 report by the National Research Council, which is part of the U.S. National Academies, found that it may do just the opposite, and the matter is under official review by the Environmental Protection Agency’s internal watchdog.

Furthermore, the ethanol lobby misleads viewers by suggesting that only “big oil” is opposed to the mandate. Several environmental groups oppose it as well. So does a wide coalition that includes restaurant owners concerned about upward pressure on food prices and boat manufacturers upset at the problems that ethanol can cause in marine engines.

Two ads have been running heavily in the Washington, D.C., market and in some other markets in advance of a Nov. 30 deadline for the EPA to finalize requirements for the total volume of ethanol to be put into gasoline, and for other renewable fuels.

An ad by the anti-ethanol group “Smarter Fuel Future” says: “Mandating corn for ethanol doubles greenhouse gas emissions compared to gasoline, over 30 years.”

That indeed was the finding of one study, published in Science magazine in 2008, by a team headed by Timothy Searchinger, a Princeton University research scholar. Projecting worldwide effects of converting large amounts of U.S. farmland to producing corn for fuel rather than for food, the study said that “we found that corn-based ethanol, instead of producing a 20% savings [the reduction required by law], nearly doubles greenhouse emissions over 30 years and increases greenhouse gases for 167 years.”

And a 2009 study led by Robert Jackson, who at the time was the Nicholas Professor of Global Environmental Change at Duke University’s Nicholas School of the Environment, concluded that plowing up untilled land to grow more corn for ethanol fuel is “an inefficient and expensive greenhouse gas mitigation policy.” The authors added, “[O]ur analysis shows that carbon releases from the soil after planting corn for ethanol may in some cases completely offset carbon gains attributed to biofuel generation for at least 50 years.”

But those studies conflict with government-sponsored research that concludes that the ethanol mandate will reduce greenhouse gas emissions as the law requires. For example, a 2012 study headed by Michael Wang of the Argonne National Laboratory for the U.S. Department of Energy projected that the corn-based ethanol found at practically all U.S. fuel pumps would cut carbon emissions by around 34 percent in 2015 (Table 7), even when considering changes in land use.

SciCHECKinsertAll such “life cycle” studies attempt to estimate all the carbon emissions created by producing and burning ethanol, including carbon released from soil by plowing and from fuel burned in planting, harvesting and refining.

But the studies don’t agree, and each side cites the science that supports its position.

The ethanol lobby’s “Fuels America” coalition cites the Wang study in its ad. But it misleads by saying in a graphic that ethanol produces “34-88% lower carbon than gasoline today.” That’s not true of the ethanol in use today. The 88 percent figure is what the Wang study concluded would be accomplished by ethanol made from switchgrass, which holds greater promise of greenhouse gas reduction than corn-based ethanol, but isn’t yet being produced in large quantities.

So far, practically all ethanol in U.S. gasoline comes from corn. The U.S. Energy Information Administration reports that only 20,000 gallons of ethanol was produced from non-food, “cellulosic” sources in 2012. The first U.S. plant designed to produce cellulosic ethanol in commercial quantities opened for startup operations in 2014.

A Fog of Uncertainty

The conflicting projections and estimates have left scientists and independent experts in a fog of uncertainty about whether mandating corn-based ethanol leads to higher or lower carbon emissions.

An independent panel of academic scientists for the National Research Council of the National Academy of Sciences — reviewing the conflicting work of Searchinger, Wang and several others — concluded in a 2011 report that “corn-grain ethanol might not have lower [greenhouse gas emission] values than petroleum-based gasoline.” It cited “plausible scenarios in which GHG [greenhouse gas] emissions from corn-grain ethanol are much higher than those of petroleum-based fuels,” and questioned the method by which EPA determined that ethanol would produce 21 percent less emissions.

National Research Council: [A]ccording 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.

Similarly, the nonpartisan Congressional Budget Office issued a report on the subject in June 2014, finding “only limited potential” for reducing greenhouse gas emissions through use of corn-based ethanol in the future:

CBO: Estimates of those emissions are uncertain, and researchers’ predictions vary considerably. However, available evidence suggests that replacing gasoline with corn ethanol has only limited potential for reducing emissions (and some studies indicate that it could increase emissions).

In the midst of such uncertainty, on Oct. 15 the EPA’s Office of Inspector General announced it would conduct an independent inquiry into whether the agency properly updated its own life cycle analysis in light of the 2011 National Academy of Sciences study.

It’s Not Just ‘Big Oil’

The ethanol lobby’s ad shows President Obama with a devil on one shoulder and a figure with a halo on the other, saying he must choose to listen to his “own experts” or to “the oil industry,” which it says “is lying about biofuels.” That’s a common deceptive technique known as the “false dilemma.” In fact, environmental groups oppose the ethanol mandate, too.

The current anti-ethanol ad is sponsored by a wide coalition. The “Smarter Fuel Future” group does include the American Fuel and Petrochemical Manufacturers among its many members. But others include: the National Council of Chain Restaurants (which says “diverting corn to fuel unfairly drives up food prices for chain restaurants and their customers”); the National Marine Manufacturers Association (which says requiring a 15 percent ethanol blend in gasoline could damage boat engines); as well as poultry producers; cattlemen and dairy farmers concerned about higher feed prices; motorcyclists; and makers of chain saws, lawn mowers and other outdoor power equipment.

And — as mentioned in the anti-ethanol ad — even former Vice President Al Gore has called the federal requirement for adding corn-based ethanol to gasoline “a mistake.” In a 2010 address in Athens, Greece, Gore said he had come to conclude that burning ethanol had helped increase food prices, and that he had erred in backing the requirement as a presidential candidate in 2000.

Gore, November 2010: One of the reasons I made that mistake is that I paid particular attention to the farmers in my home state of Tennessee, and I had a certain fondness for the farmers in the state of Iowa because I was about to run for president.

And who lobbies for ethanol? The pro-ethanol “Fuels America” group includes grain farmers (who profit from higher demand for corn), Monsanto (which sells hybrid seed corn), and distillers of ethanol including Archer Daniels Midland and DuPont (which just opened a cellulosic ethanol plant in Iowa).

Editor’s Note: SciCheck is made possible by a grant from the Stanton Foundation.