Feature

The trouble with biofuels

Canola

Canola can be used as a biofuel.

Credit: istockphoto

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The Evidence

Is this new re-assessment fair, however? More to the point, how can a source of energy be revered as a key fighter against climate change one moment and the next find itself labelled a greenhouse villain? What scientific evidence has produced this backlash?

In fact, several key studies have led to this re-evaluation, such as the study published in the prestigious journal, Science, in February 2008 by Joe Fargione, of the international conservation group, The Nature Conservancy. It showed that when rainforests, peatland, savannah or grassland are ploughed to prepare for crop planting, either for food or for fuel, massive amounts of carbon dioxide are released.

"People don't realise it, but soil is an extremely effective store of carbon dioxide and helps to protect our atmosphere," says Fargione.

For example, grasslands - like those of the American Mid-West - contain tiny fragments of decaying plants have been accumulating in the soil since the last Ice Age. When you plough up that land and burn its grass, in preparation for planting crops, you release that repository of carbon.

So, if you sow biofuel crops on virgin land, you start off by doing the worst possible thing you could to the atmosphere: you add significantly to its carbon content.

"For every unit of carbon you save in a year by growing a biofuel crop on an acre of new farm land, you will release 93 times that carbon by the simple act of ploughing it up," says Fargione.

Thus in South and North Dakota and Minnesota, classic American grassland states, more than 200,000 hectares of prime native land have been converted to farmland, mostly for growing biofuel crops, since 2000 - with an inevitable surge of carbon dioxide being put into the atmosphere: around 27 million tonnes, according to Fargione.

For good measure, the problem is increased because biofuel crops are often fertilised with chemicals derived from the petrochemical industry, in other words from fossil fuel sources. Again, this increases outputs of carbon dioxide.

As a result of findings like these, calls for cuts in biofuel production have begun to spread throughout the world, although in America - where they are grown to stimulate rural economies and reduce US reliance on oil imports rather than to combat climate change - experts say there is little chance of an immediate policy change.

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