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Miscounting bioenergy benefits may increase greenhouse gas release

October 23, 2009

EAST LANSING, Mich. - A fixable error in the way carbon is counted in current U.S. climate legislation and in the Kyoto Protocol could undermine efforts to reduce greenhouse gas emissions by using biofuels, says a premier group of national environmental and land use scientists.

"The promise of biofuels made from biomass is huge, from both climate mitigation and economic perspectives," said Phil Robertson, Michigan State University professor of crop and soil sciences and one of the authors of the paper "Fixing a Critical Climate Accounting Error" published in the Oct. 23 issue of the journal Science. "But the promise could come up short if we don't pay attention to the details. One of the most important details is how the benefits of carbon capture are tallied. If we miscalculate the carbon benefits, we may find out later that our policies and practices are counterproductive; that they don't have the positive impact on climate that we want them to have."

Robertson also is a member of the Great Lakes Bioenergy Research Center, a partnership between Michigan State and the University of Wisconsin-Madison funded by the U.S. Department of Energy to conduct basic research aimed at solving some of the most complex problems in converting natural materials to energy.

The paper authors point out that the greenhouse gas consequences of bioenergy can vary widely, depending on where the plants used to produce the energy are grown. For example, fast-growing biofuel crops grown on abandoned farmland can capture more carbon than existing plants and so reduce greenhouse gas emissions. This is because the biofuel crop absorbs more carbon from the atmosphere than would otherwise be stored. But if existing forests are cut down and replaced with bioenergy crops, the carbon released from the soil and mature trees, plus the loss of future carbon storage, is greater than the carbon captured by the bioenergy crops.

Current carbon accounting measures mistakenly exempt all the carbon dioxide emitted from bioenergy, regardless of the source. According to a number of studies, including one by the U.S. Department of Energy, applying current carbon accounting measures globally could lead to the loss of most of the world's natural forests.

"The error is serious, but readily fixable," said Tim Searchinger of Princeton University and lead author of the paper. "The solution is to count all the pollution that comes out of tailpipes and smokestacks whether from coal and oil or bioenergy and to credit bioenergy only to the extent it really does reduce greenhouse gas emissions."

"To avoid environmental regret later and protect both private and public investments, we need to get the carbon calculations correct from the start," Robertson added. "Michigan is particularly well positioned to benefit from correct carbon accounting practices. As the market grows for cellulosic biofuels, Midwest producers will benefit by growing biofuel crops on land not now being used for food production. Correctly crediting our carbon from the start will help to ensure the long-term market value for these fuels, protecting early investments by farmers and refiners. Just like with financial audits, it's important for carbon audits to be correct. We don't want to find out later that we've built an industry on a false premise. Ultimately, we need to mitigate climate change and we need practices in place that do so."

Michigan State University