Carbon advantage of biofuels may be overstated
Friday, October 23, 2009
The world's policymakers and scientists have made a critical error in how they count biofuels' contribution to human-generated greenhouse-gas emissions, according to a paper published Thursday in the journal Science.
Although the article addresses a wonkish subject -- how to measure the environmental impact of energy sources such as ethanol and wood chips, which absorb carbon as they grow but release it back into the atmosphere when they're burned -- it has broad implications. The method undercounts the global-warming contribution of some bioenergy crops, the team of 13 researchers wrote, because it doesn't factor in what sort of land-use changes might occur to produce them.
"We made an honest mistake within the scientific framing of the debate, and we've got to correct it to make it right," said Steven P. Hamburg, chief scientist at the Environmental Defense Fund and one of the paper's authors.
When calculating the greenhouse-gas emissions limit, government officials in the United States, Europe and elsewhere do not count the carbon that biofuels release when they are burned. But carbon is released when a producer clears and burns trees, even to grow a crop destined for the biofuels market. Officials also established a legal system that limits emissions from energy use but not from land-use activities such as clearing forests.
In recent months, researchers have begun to worry that bioenergy crops could replace the world's forests and savannahs on a huge scale unless climate policies start to take full account of how these crops' production affects greenhouse-gas concentrations. None of the major climate regimes -- including the Kyoto Protocol, the European Union's carbon market and the House-passed climate bill -- account for the carbon released by changing land use for biofuels.
"If you only count part of the carbon, you set up a set of incentives that are all wrong," said Jae Edmonds, a chief scientist at the Energy Department's Pacific Northwest Laboratory.
Changing the accounting system poses a political challenge, as evidenced by the criticism bioenergy producers heaped on the report.
Tom Buis, chief executive of the ethanol trade association Growth Energy, said his group opposes a change in accounting procedures.
"In truth, there's no new science in this report," he said in a statement. "It's a policy proposal, trying to get a new standard that would limit the ability of developing countries to provide food and fuel -- and would keep our own nation addicted to imported oil."
House leaders realized they needed to make a change before passage of the climate bill co-written by Energy and Commerce Chairman Henry A. Waxman (D-Calif.) and Rep. Edward J. Markey (D-Mass.), but they ran out of time. In a June 24 letter to House Speaker Nancy Pelosi (D-Calif.), Waxman and Agriculture Committee Chairman Collin C. Peterson (D-Minn.) wrote: "We do not have time to resolve these details before House passage. . . . But we want you to know that we are both committed to developing appropriate provisions so that we can have a complete resolution of this important matter."
Hamburg said his organization is beginning to set up a process in which an array of interest groups, including farmers, forest owners and scientists can meet to try to craft a solution to the problem.
Dan Lashof, director of the Natural Resources Defense Council's climate center, said he hopes the paper in Science will prompt "some focus on the need to address this," adding: "People don't really understand the challenge of addressing emissions from bioenergy in a comprehensive and scientifically valid way."
Timothy D. Searchinger, the paper's lead author and a Princeton University research scholar, said it is urgent that officials correct the accounting issue before these incentives make the less environmentally friendly forms of bioenergy more entrenched.
"You think it's hard to solve now?" he asked. "If you don't solve it now, it just doesn't get solved."