Biofuel could cause more carbon problems
By CHEE CHEE LEUNG - The Age | Saturday, 09 February 2008
NO CARBON CURE? Biofuel crops like sugarcane may actually create more greenhouse gases than they save by replacing traditional fossil fuels, two studies have found.
Growing crops to produce biofuels — seen as part of the solution to global warming — is actually increasing greenhouse gas emissions, scientists report.
Two separate US studies, published in the journal Science, show that changes to land use associated with growing food-based biofuels produce the greatest source of emissions.
The Australian Conservation Foundation said the new findings, released on Thursday, provided a "timely warning" about the need for caution.
"Biofuels aren't any panacea," said the foundation's rural landscapes campaigner, Corey Watts. "By rushing headlong into the biofuels area, we could really produce some nasty global consequences."
But groups representing the biofuel industry said the studies did not reflect the Australian situation. "A lot of our ethanol and biodiesel is produced from existing crops," said Bruce Harrison, chief executive officer of the Biofuels Association of Australia. "We haven't torn down any rainforests to do that."
One study found that converting forests and grasslands to produce food-based biofuels in Brazil, South-East Asia and the US created a "biofuel carbon debt", releasing 17 to 420 times more carbon than the annual greenhouse gas reductions they achieve by replacing fossil fuels.
The scientists looked at carbon released into the air when soils are overturned and existing vegetation rots or is burned away. In one case, they found it would take 423 years to repay the carbon debt incurred by converting an Indonesian peatland into a biofuel plantation.
But even changing existing US farmland from food to biofuel crops will increase emissions, researchers say, as forest and grasslands elsewhere become replacement sites for crop cultivation.
The second study, which estimated emissions from this land use change, found that corn-based ethanol nearly doubled greenhouse emissions over 30 years, and increased greenhouse gases for 167 years.
The two research projects included scientists from the University of Minnesota, Princeton University and Iowa State University.
Stephen Schuck, manager of Bioenergy Australia — a government and industry forum — said the new papers depicted a "worst case scenario". But he said the industry was moving away from using food crops.
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