Scientists believe biofuels may contribute to global warming

Scientists found that growing some of the most commonly-used biofuel crops released around twice the amount of the greenhouse gas nitrous oxide (N2O) than previously thought - wiping out any benefits from not using fossil fuels and probably contributing to global warming.

The findings means that the supposed benefits of biofuel are more disputable than had been previously been thought, says Professor Keith Smith of the University of Edinburgh, a co-author of a research paper that has been published on the study. Growing many biofuels was probably of no benefit and in fact was making the climate issue worse, said Professor Smith.

Scientists conducting the study used a different approach to calculating the nitrous oxide conversion factor than used by the International Panel on Climate Change (IPCC). Their findings suggest that microbes convert much more of the nitrogen in fertiliser to N2O than previously thought - three to five per cent or twice the figure of two per cent used by the IPCC.

For rapeseed biodiesel, which accounts for about 80 per cent of the biofuel production in Europe, and corn bioethanol, which is dominant in the US, the relative warming as a result of N2O emissions was larger than the cooling effect attributable to saved fossil C02 emissions. Only cane sugar bioethanol looked like a viable alternative to conventional fuels.