Biofuels May Disperse More
Greenhouse Gases Than Oil
September 22, 2007
A renewable energy source designed to reduce greenhouse gas emissions is contributing more to global warming than fossil fuels, a study suggests.
Measurements of emissions from the burning of biofuels derived from rapeseed and maize have been found to produce more greenhouse gas emissions than they save.
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Other biofuels, especially those likely to see greater use over the next decade, performed better than fossil fuels but the study raises serious questions about some of the most commonly produced varieties.
Rapeseed and maize biodiesels were calculated to produce up to 70 per cent and 50 per cent more greenhouse gases respectively than fossil fuels. The concerns were raised over the levels of emissions of nitrous oxide, which is 296 times more powerful as a greenhouse gas than carbon dioxide. Scientists found that the use of biofuels released twice as much as nitrous oxide as previously realised. The research team found that 3 to 5 per cent of the nitrogen in fertiliser was converted and emitted.
In contrast, the figure used by the International Panel on Climate Change, which assesses the extent and impact of man-made global warming, was 2 per cent. The findings illustrated the importance, the researchers said, of ensuring that measures designed to reduce greenhouse-gas emissions are assessed thoroughly before being hailed as a solution.
“One wants rational decisions rather than simply jumping on the bandwagon because superficially something appears to reduce emissions,” said Keith Smith, a professor at the University of Edinburgh and one of the researchers.
Maize for ethanol is the prime crop for biofuel in the US where production for the industry has recently overtaken the use of the plant as a food. In Europe the main crop is rapeseed, which accounts for 80 per cent of biofuel production.
Professor Smith told Chemistry World: “The significance of it is that the supposed benefits of biofuels are even more disputable than had been thought hitherto.”