Biofuel Debate Rages Ever Onward

LONDON - Sep 21/07 - SNS -- A recent article by chemist Paul Crutzen in the magazine Chemistry World asserts there is no net benefit to the environment from producing and burning biofuels and that they may actually produce more greenhouse gas emissions than petroleum.

Crutzen argues that growing some of the most commonly used biofuel crops releases around twice the amount of the potent greenhouse gas nitrous oxide than previously thought -- wiping out any benefits from not using fossil fuels and, worse, probably contributing to global warming.

Other experts are critical of Crutzen's paper, saying that while the method is elegant, there is little evidence to show fertilized plants yield between 3% and 5% nitrous oxide (N2O).

Princeton University nitrogen researcher Simon Donner says Crutzen's basic assumption that pre-industrial N2O emissions are the same as natural N2O emissions, is "probably wrong" because plants are grown in places with nitrogen rich soils.

"It is possible we are indirectly increasing the 'natural' source of N2O by drawing down the soil nitrogen in the world's agricultural regions,' Donner told Chemistry World.

Chemistry World's Zoe Corbyn writes, "Others dispute the values chosen by Crutzen to calculate his budget. Stefan Rauh, an agricultural scientist at the Institute of Agricultural Economics and Farm Management in Munich, Germany, says some of the rates for converting crops into biofuel should be higher. 'If you use the other factors you get a little net climate cooling,' he said."

The work is currently subject to open review in the journal Atmospheric Chemistry and Physics, and Crutzen himself has declined to comment until that process is completed. But the paper suggests that microbes convert much more of the nitrogen in fertilizer to nitrous oxide than previously thought -- 3 to 5%, which is twice the widely accepted figure of 2% used by the International Panel on Climate Change (IPCC) to calculate the impact of fertilizers on climate change.

For rapeseed biodiesel, which accounts for about 80% of the biofuel production in Europe, the relative warming due to nitrous oxide emissions is estimated at 1 to 1.7 times larger than the relative cooling effect due to saved fossil CO2 emissions. For corn bioethanol, dominant in the US, the figure is 0.9 to 1.5. Only cane sugar bioethanol -- with a relative warming of 0.5 to 0.9 -- looks like a better alternative to conventional fuels.

In the wake of the findings comes a recent report prepared by the OECD for a recent Round Table on Sustainable Development, which questioned the benefits of first generation biofuels and concluded that governments should scrap mandatory targets. Richard Doornbosch, the report's author, says both the report and Crutzen's work highlights the importance of establishing correct full life-cycle assessments for biofuels.

"Without them, government policies can't distinguish between one biofuel and another -- risking making problems worse," he said.