From The Economist print edition
More suggestions that biofuels are not an environmental free lunch
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ONCE upon a time, biofuels were thought of as a solution to fossil-fuel dependence. Now they are widely seen as a boondoggle to agribusiness that hurts the environment and cheats taxpayers. A report commissioned by the United Nations endorses neither extreme. It gives high marks to some crop-based fuels and lambasts others. Meanwhile, two papers published in Science, a leading research journal, provide further reasons for caution. One suggests that the knock-on effects of growing biofuel crops, in terms of displaced food crops and extra fertiliser (an important source of a greenhouse gas called nitrous oxide), make the whole enterprise risky. The other points out a dangerous inconsistency in the way the Earth’s carbon balance-sheet is drawn up for the purposes of international law.
The UN report gives ethanol from sugar cane (which Brazil makes) a clean bill of health. In some circumstances it does better than just “zero emission”. If grown and processed correctly, it has “negative emission”—pulling CO2 out of the atmosphere, rather than adding it. America’s use of maize for biofuel is less efficient. Properly planted and processed, it does cut emissions; done poorly, it is more polluting than petrol. As to biodiesel palm oil grown on cleared tropical forest, when the destruction of the trees and release of CO2 from the cleared soil are accounted for, the crop is filthy—and worse than that if the forest was growing in peat, as is often the case.
The amount of ethanol produced for transport tripled from 17 billion litres in 2000 to 52 billion litres in 2007 and is set to rise further. But the world’s population is also rising, so competition for land between fuel and food is hotting up. This competition is the subject of Jerry Melillo’s paper in Science. Dr Melillo, of the Woods Hole Marine Biological Laboratory, and his colleagues have attempted to model how an expansion of biofuels might change world agriculture during the 21st century. They concentrate on the likely future—cellulosic biofuels made from whole plants such as fast-growing grasses, rather than the food-cum-biofuel crops of today. They reckon Africa is the best place to grow biofuels, and the one that will lead to most carbon capture in the long run. But they also show that the widespread growth of biofuel crops is likely to cause a net global release of greenhouse gases during the first half of the century, as land is cleared and fertilisers are scattered liberally. In the right circumstances the CO2 account, they reckon, could move into profit by mid-century, but the nitrous oxide account never does.
Tim Searchinger’s Science paper, meanwhile, looks at the way the accounts are drawn up in the here and now. Dr Searchinger, who works at Princeton University, and his collaborators point out that the rules for assessing compliance with the Kyoto protocol (which are also included in the version of America’s climate bill that passed the House of Representatives) are biased in favour of biofuels because they fail to account for emissions from land cleared to grow such fuels. Combine that observation with Dr Melillo’s modelling and you have a recipe for some perverse incentives indeed.
Sadly, settled international standards on biofuels or on a trading system that includes their carbon-cutting benefits are probably a long way off. Two more items on the “too busy to do” list of the Copenhagen conference on climate change.
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