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Renewable Energy Vision
Expert analysis on the most pressing issues facing the renewable energy sector in the U.S and abroad from ACORE staff, members and supporters.

When You Start with a Faulty Assumption, You End Up with a Faulty Conclusion: The Problem with an Anti-Cellulosic Ethanol Study

Published on 24 Apr 2014  |   Written by    |  

This weekend, the Associated Press published its coverage of the results of a recent University of Nebraska study that wrongly concluded that cellulosic ethanol from corn residue (like stover) could result in 7% more greenhouse gas emissions than gasoline in the short term. The study was conducted under conditions that are entirely inapplicable to modern cellulosic ethanol production, rendering its findings meaningless. Renewable fuel experts and agricultural scientists alike have slammed the study’s methodology and the EPA also distanced itself from its findings - with good reason.

The study was conducted under highly unrealistic conditions. It took place on a single, experimental field at the University of Nebraska where 75% - 100% of the corn residue (stalks, stover, and other leftovers from the harvest) was removed from the land for ethanol production over 9 years. As any farmer can tell you, this is absurd. In reality, no farmer removes nearly that much corn residue from their fields because that will render the land unsuitable for crop growth soon after.

Secretary of Agriculture Tom Vilsack echoed this criticism of the report at a recent forum. “The study started with an assumption about the way corn stover would be removed from the land. The problem with the assumption is no farmer in the country would actually take that much crop residue,” he said. “When you start with a faulty assumption, you end up with a faulty conclusion.”

According to advanced biofuel producer POET, the average corn residue removal from farmland for cellulosic ethanol is around 25% - much lower than the level assumed by the study. This is important, because when more residue is left on the land, more carbon is sequestered in the soil and consumed by next year’s crops, and thus does not contribute to climate change. Of course, this also demonstrates that the Nebraska study’s findings are essentially meaningless.

Other studies on the lifecycle greenhouse gas emissions of cellulosic ethanol have tested techniques in line with common agricultural practice and have shown significant reductions in greenhouse gas emissions as a result. For instance, the Environmental Protection Agency’s lifecycle assessment of cellulosic ethanol assumed 50% and 35% stover removal, depending on the type of farmland. The EPA still found at least a 60% reduction in greenhouse gas emissions from cellulosic ethanol compared to gasoline. Likewise, researchers affiliated with the Argonne National Laboratory examined the lifecycle greenhouse gas emissions of various biofuels types and found that cellulosic ethanol from corn stover resulted in a 90-103% reduction in greenhouse gasses compared to gasoline.

The Argonne study was undertaken by regulatory agencies to properly assess GHG emissions from current and predicted practices of removing small amounts of crop residues, as opposed to the University of Nebraska study, which was a common research grant whose findings improperly assessed GHG emissions based on nonexistent practices and was not designed to guide government policy.

Are we really being asked to believe that fossil fuel-based gasoline is better for the environment than organically-sourced biofuels, based on a single study that flies in the face of all other research? Well, yes. I suppose we are – at least in instances where farmers are willingly destroying their land. Thankfully, that sort of overconsumption is currently not a reality, nor will it ever be, given the damage it would do to farmland. This hasn’t stopped certain organizations, like the American Petroleum Institute, from over-hyping the results of the study to suit their needs. But the facts show that cellulosic biofuels remain an essential tool for reducing the 30% or more of all greenhouse gas emissions contributed by the transportation sector, and ultimately combatting climate change.

Jeramy Shays

Jeramy Shays is ACORE's Director of Transportation

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