The European Environment Agency Scientific Committee writes that the role of energy from crops like biofuels in curbing warming gases should be measured by how much additional carbon dioxide such crops absorb beyond what would have been absorbed anyway by existing fields, forests and grasslands.
Instead, the European Union has been “double counting” some of the savings, according to the draft opinion, which was prepared by the committee in May and viewed this week by The International Herald Tribune and The New York Times.
The committee said that the error had crept into European Union regulations because of a “misapplication of the original guidance” under the United Nations Framework Convention on Climate Change.
“The potential consequences of this bioenergy accounting error are immense since it assumes that all burning of biomass does not add carbon to the air,” the committee wrote.
European Union laws “need to be reviewed to encourage bioenergy use only from additional biomass that reduces greenhouse gas emissions,” the committee wrote. Estimates of emissions saved by using crops for energy should instead focus on biomass that would “maintain or build carbon stocks in plants and soils,” it adds.
The draft opinion is not binding; some findings could change before the committee issues a final version, probably in coming weeks. Even so, the implications could be significant if European Union authorities come under pressure to adjust their rules on biofuels.
Farmers and fuel companies may no longer be able to use as wide a variety of crops to meet targets that were agreed upon three years ago to generate 10 percent of transportation fuel from renewable sources by 2020.
The committee suggested that bodies like the International Energy Agencyand the United Nations could be forced to lower their forecasts for the amount of energy from plants and crops that could be generated in the future.
The opinion comes at an awkward time for the European Commission, the European Union’s executive body.
The commission already is agonizing over how much to tighten the rules on biofuels to curb a phenomenon called indirect land use change, in which areas containing high stores of carbon dioxide, like grasslands, peat lands or forests, are stripped to produce food crops.
The committee attributed some of its findings to work by Tim Searchinger, a research scholar and lecturer at Princeton who has written extensively about accounting for emissions from biofuels.
In one example attributed to research by Mr. Searchinger, the committee wrote:
“Clearing or cutting forests for bioenergy crops releases large stores of carbon into the atmosphere and may reduce ongoing carbon sequestration if the forest was otherwise still growing. Bioenergy crops will absorb carbon that offsets the emissions from their combustion, but it may take decades for this carbon absorption (which offsets emissions) to catch up to the lost carbon storage and forgone carbon sequestration of the forest.”
The committee’s opinion backs up earlier criticism by environmental groups including Birdlife International and the European Environmental Bureau, which likened the carbon accounting error by European Union officials to a“subprime carbon mortgage that it may never be able to pay back.”
The committee is not ruling out the use of biofuels, however, and in other examples it identified optimal sites for planting bioenergy crops, including former tropical forests now overrun by grasses that frequently catch on fire.