Land Use Responsible for Biofuel Carbon Debt

A new study by the Nature Conservancy and the University of Minnesota concludes that biofuels by and large emit more GHGs than the fossil fuels they replace.

This conclusion comes mostly from examining land use factors. Since additional land is required to grow crops for fuel in addition to the current food and cash crops, the conversion of land from its previous use to the new use should be considered. Among major biofuel crops are corn and sugar cane for ethanol in the US and Brazil, and oil palms for palm oil in Southeast asia. These lands are converted from rain forests, bogs, and other agricultural land whose production is also displaced. For instance, rotation of corn and soybeans is good for the soil, but the demand for ethanol has increased the price of corn, displacing the soybean crop. And so on.

The standard calculation for corn ethanol carbon balance used to be negative, that is to say it required more energy for tractors, fertilizers, heating and so forth than it produced in ethanol, until a more complex calculation started taking into account new technology and the byproducts - the animal feed that can be made from used corn mash and stalks. Do people use the new technology, do they feed the byproducts to cows and would they do that if the production of ethanol hadn't increased the price of the usual animal feed? The calculation was pretty marginal to begin with. To me the conclusion to be drawn from the ethanol calculation is that it is easier to reduce GHG emissions by eating less meat than by using biofuels and hoping that high meat consumption makes the figures add up properly.

This is now a game of tennis, alternating between more and more complex calculations taking into account more and more factors, each new calculation giving a result that is the opposite of the previous one. Which one can you trust? Of course the Nature Conservancy is biased in favour of nature. The Renewable Fuels Association calls this new calculation a simplistic view of land use but does not offer offer any numbers except to say "Tar sands, by comparison, release some 300 percent more greenhouse gas emissions than traditional petroleum recovery." This presumably means that they may emit more than fossil fuels but fossil fuels will catch up with them. They also say deforestation is not caused by a policy decision to produce liquid biofuels, but by food production. Hmmm, so they're saying if you want to save the rain forests and the earth's climate, don't stop driving cars, stop eating food instead.

It's an odd argument, especially when accusing a serious research project of being simplistic.

Tags: biofuel ethanol Greenhouse Gas Energy Environment

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