Cross posted by Katharine Sanderson on The Great Beyond
Two papers in Science yesterday have poured cold water on the promise of second generation biofuels.
Biofuels derived from the cellulosic, woody parts of plants are not having their greenhouse gas emissions properly accounted for, says Jerry Melillo from the Marine Biological Laboratory at Woods Hole. Melillo’s study suggests that changes in the way land is used, as a consequence of growing crops for biofuels, is not taken into account, and if it were then those biofuels would be shown to actually cause more greenhouse gases to be released than fossil fuels. Nitrous oxide emissions from increased use of fertilisers are a big part of the problem.
“The problem is, we have a finite amount of land where new crops could be grown. Melillo and colleagues now report that if biofuel crops replace food crops on current farmlands, then the clearing of forested land for additional food crops will release more carbon from the soil there than in the areas where the biofuel crops themselves are being grown,” says the press release.
In a related policy forum article, Timothy Searchinger from Princeton University and a bunch of colleagues point out flaws in the ways that carbon emissions are counted for cap-and-trade schemes in both Europe and the US.
They say that the assertion that fuels made from biomass can be counted as carbon neutral is wrong. “Harvesting existing forests for electricity adds net carbon to the air,” the report says. “If bioenergy crops displace forest or grassland, the carbon released from soild and vegetation, plus lost future sequestration, generates carbon debt, which counts against the carbon the crops absorb.”
“In the near-term I think, irrespective of how you go about the cellulosic biofuels program, you’re going to have greenhouse gas emissions exacerbating the climate change problem,” Melillo is reported as saying in Reuters.
Energy efficiency news says the report is damning for biofuels.
More bad news comes from a UNEP report, highlighted by the New York Times. The report calls for greater debate about biofuels before ploughing headlong into a completely biofuel-powered society, although it focuses mainly on first generation fuels, unlike the Science papers.
Image: Chris Neill, MBL