A new study to appear in Atmospheric Chemistry and Physics has found that burning and especially growing crops for many biofuels will probably raise rather than lower greenhouse gas emissions. Nobel prize-winning chemist Paul Crutzen and his colleagues have calculated that growing some of the most commonly used biofuel crops releases around twice the amount of the potent greenhouse gas nitrous oxide (N₂O) than previously thought, according to a report by Chemistry World.

Crutzen found out that microbes convert much more of the nitrogen found in fertiliser to N₂O than previously thought. The crops' microbes may convert 3 to 5 per cent (twice the widely accepted figure of 2 per cent used by the International Panel on Climate Change) of nitrogen to the dangerous greenhouse gas nitrous oxide.

The Nobel winner alleges that for rapeseed biodiesel the relative warming due to N₂O emissions is estimated at 1 to 1.7 times larger than the quasi-cooling effect due to saved fossil CO₂ emissions. The rapeseed biodiesel is very common in Europe, accounting for up to 80 per cent of the biofuel production. For corn bioethanol which is more common in the United States, the figure is 0.9 to 1.5.

Crutzen and his team claim only cane sugar bioethanol is a viable alternative to conventional fuels, with a ratio of under 0.9 and as little as 0.5.

However, critics were quick to blast Crutzen's new approach for determining the amount of nitrous oxide produced by plants. He did not use actual plants, as previous figures were found, but instead assumed that pre-industrial N₂O emissions, when no nitrogen fertilizers were used, are the same as natural N₂O emission. From there, determining how much N₂O we have now in the air, he analyzed this difference and calculated how much of it is tributary to the N₂O converted from fertilizers by microbes in plants.

"The significance of it is that the supposed benefits of biofuel are even more disputable than had been thought hitherto," said Keith Smith, one of the co-authors, to Chemistry World. "What we are saying is that [growing many biofuels] is probably of no benefit and in fact is actually making the climate issue worse."

The biofuel hype has received another blow as the Organisation for Economic Co-operation and Development (OECD) has issued a report for a recent Round Table on Sustainable Development which point out several problems with current biofuels, such as the potential for food shortages and damage to biodiversity. OECD has thus recommended that governments ponder the elimination of mandatory percentage targets while the matter is further assessed.

Paul Jozef Crutzen, who is Dutch, received the 1995 Nobel Prize in Chemistry with M. Molina and F. S. Rowland "for their work in atmospheric chemistry, in particular ozone depletion."