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Biofuels May Hinder Antiglobal-Warming Efforts

Carbon Emissions Could Increase As Land-Use Shifts



Environmental Capital

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Some scientists have praised biofuels because growing biofuel feedstock would remove gases that trap the sun's heat from the air, while gasoline and diesel fuel take carbon from the ground and put it in the air. However, some earlier studies didn't account for one hard-to-measure factor: the decision by farmers world-wide to convert forest and grasslands to grow feedstock for the new biofuels.

The Renewable Fuels Association in the U.S. said that "biofuels alone are not the silver bullet" for the world's energy or environmental challenges. It said earlier analyses of greenhouse-gas reductions show corn-derived ethanol reduces greenhouse gas emissions by 22% on average, though those studies didn't include the effect of changing land use.


"We absolutely assert that ethanol production and use is a responsible way to address the environmental, energy and economic challenges the world faces today," spokesman Matt Hartwig said. He said the group's researchers will study the papers and formulate a response.

Land-use changes can have big and unintended consequences, such as food shortages and reduced biodiversity. For example, when forests or grasslands are converted for agricultural use, it leads to a large, quick release of carbon when the existing plant life is destroyed and the soil is tilled. Even if biofuels are grown on cropland previously used to grow food, farmers tend to then clear other forests and grasslands and grow the food elsewhere.

"Even if we're dramatically wrong, it's hard to get to a result that says you get a benefit over 50 years," said Timothy Searchinger, a researcher at Princeton University and a co-author of the paper on corn-based ethanol.

In the second study, researchers found that the effect of biofuels varied hugely, depending on where and how they were produced. For example, an increasing amount of land in Brazil is being used to grow sugarcane for ethanol. Converting the undeveloped land into sugarcane fields releases CO2. It would take 17 years for the positive effect of using sugarcane ethanol from those fields instead of petroleum-based fuels to overcome the CO2 farming the land put into the air. Draining and clearing peatlands in Malaysia and Indonesia to grow palm oil emits so much CO2 that palm biodiesel from those fields would have to be burned for more than 420 years to counteract it.

David Tilman, an ecologist at the University of Minnesota and co-author of the second paper, said the biofuel industry needs to seek more efficient sources for biofuels, such as various kinds of waste and nonfood crops such as switchgrass grown on degraded land. A researcher from the Nature Conservancy, an environmental advocacy group, was also a co-author.

Their study's funding came from the National Science Foundation and the University of Minnesota's Initiative on Renewable Energy and the Environment, according to Mr. Tilman. The other paper relied on funding from various indirect sources, including the Hewlett Foundation and the Agriculture Department.

Write to Gautam Naik at

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