Study Finds Biofuels Worse for Climate than Gasoline

Most gasoline sold in the U.S. contains some ethanol, and the findings, published in Climatic Change, were controversial.  They rejected years of work by other scientists who have relied on a more traditional approach to judging climate impacts from bioenergy — an approach called life-cycle analysis.

Following the hottest month on record globally, and with temperatures nearly 2°F warmer and tides more half a foot higher than they were in the 1800s, the implications of biofuels causing more harm to the climate than good would be sweeping.

The research was financially supported by the American Petroleum Institute, which represents fossil fuel industry companies and has sued the federal government over its biofuel rules.

“I’m bluntly telling the life-cycle analysis community, ‘Your method is inappropriate,’” said professor John DeCicco, who led the work.  “I evaluated to what extent have we increased the rate at which the carbon dioxide is being removed from the atmosphere?”

Lifecycle analyses assume that all carbon pollution from biofuels is eventually absorbed by growing crops. DeCicco’s analysis found that energy crops were responsible for additional plant growth that absorbed just 37 percent of biofuel pollution from 2005 to 2013, leaving most of it in the atmosphere, where it traps heat.

“The question, ‘How does the overall greenhouse gas emission impact of corn ethanol compare to that of gasoline?’ does not have a scientific answer,” DeCicco said.  “What I can say definitively is that, whatever the magnitude of the emissions impact is, it is unambiguously worse than petroleum gasoline.”

The findings were criticized by scientists whose work is directly challenged by them.

Argonne National Laboratory scientist Michael Wang, who has led lifecycle analyses that found climate benefits from different biofuels, called the research “highly questionable” for a range of technical reasons, including its focus on growth by American crops instead of the global network of farms.

Driven by federal and Californian policies that promote biofuels to slow global warming, the use of ethanol, biodiesel and similar products more than trebled nationwide during the years studied, providing 6 percent of Americans’ fuel by 2013.  Federal data shows gasoline sold in the U.S. last year contained about 10 percent corn ethanol.
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The University of Michigan scientists dispensed with the timescale-based approach altogether, eliminating the need for policy decisions about which timeframes should be used. Instead, their research provided an overview of eight years of overall climate impacts of America’s multibillion-dollar biofuel sector.
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Although European officials have warned of the limitations of the use of lifecycle analyses in assessing the climate impacts of bioenergy, the EPA has been steadfast for more than five years in its attempts to create a new regulatory framework that would continue to embrace the approach.

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