Biofuels - facts and fiction
19th February, 2007
The claims for biofuels make it seem truly a wonder crop. Mark Anslow separates the wheat from the chaff
Claim 1: You get more out than you put in
For more than 15 years, David Pimentel, Professor of Ecology and Agriculture at Cornell University in New York, and his colleague, Professor Tad Patzek at Berkeley, have published peer-reviewed research showing that biofuels give out less energy when burnt than was used in their manufacture.
By using a ‘cradle-to-grave’ approach – measuring all the energy inputs to the production of ethanol from the production of nitrogen fertiliser, through to the energy required to clean up the waste from bio-refineries – they have shown that while it takes 6,597 kilocalories of nonrenewable energy to produce a litre of ethanol from corn, that same litre contains only 5,130 kilocalories of energy – a 22 per cent loss.(1)
Their work has been fiercely attacked by the biofuel lobby, who argue that Pimentel and Patzek include too many ‘energy input’ costs, and fail to give credit to the other, useful ‘co-products’ created in the process of refining biofuel.(2)
Neither objection stands up under closer scrutiny. In fact, corn uses more herbicides, insecticides and fertiliser than any other crop(3); and...
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