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Forward with biofuels

Cellulosic biofuels are part of an emerging US energy policy, from which other regions can learn.

The energy law signed on 19 December by President Bush lays out a bold mandate for biofuels. As well as broadly ensuring that the United States remains home to the largest biofuels industry in the world in the coming decade, the law takes an important step forward by recognizing that all biofuels are not created equally. From 2016, refiners must begin to switch to cellulosic ethanol and other advanced biofuels that do not rely on corn sugars, and these fuels will have to meet new standards for reducing greenhouse-gas emissions compared with standard petrol.

That's the good news. The bad news is that, in the short term, this mandate will merely bolster the corn ethanol empire, which is far from ideal given the accumulation of evidence against the current generation of biofuels. The latest research suggests that any fuel that competes with food also encourages farmers around the world to expand their operations into native lands. Doing so causes a spike in emissions — from carbon once locked up in plants and soil — that might well outweigh the long-term benefits of the biofuels themselves.

Cellulosic ethanol, which can be produced from prairie grasses, municipal waste or just about any carbon-based materials, might well resolve these problems by expanding the feedstock away from food crops (see page 880). Exciting research is also under way on a third generation of synthetic biofuels — designer fuels secreted by specially engineered microorganisms. But although such 'novel molecules' could resolve a host of infrastructure issues that are unique to ethanol, they don't amount to much more than fancy corn fuels unless the feedstock question is resolved. From a research and development perspective, the priority must remain cellulosic conversion.

Money and talent are flowing into the energy arena from both private and public sectors, but these technologies have yet to advance beyond the realm of pilot plants and press releases. The next few years will be critical as the industry tries to bridge the gap from demonstration projects to commercial-scale production. If the new biofuels fulfil their promise, they may well naturally supplant corn ethanol, in which case the mandate will have done what it is supposed to do. If not, Congress may need to step in again.

All of this should serve to remind policy-makers that the science of biofuels is still evolving, as are the tools for tracking greenhouse-gas emissions. It also underscores the need for sustained attention to energy issues (including energy efficiency, a doubling of which would enormouslyamplify the benefits of biofuels). That sounds like a truism but in fact would represent a novel and important shift from the episodic, crisis-driven attention paid to this issue in decades past. Fortunately this is starting to happen. When the United States enacted a comprehensive energy law in 2005, lawmakers touted it as the first major reform in 13 years. Congress passed another major bill in December, and global-warming legislation may well be just around the corner.

Across the Atlantic, European nations are struggling with the same issues — and still have time to learn from the United States' mistakes. Rather than promoting all biofuels, they should ensure that their policies support those second-generation technologies that will provide the biggest pay-off. The European Commission recently released a plan targeting biofuels for 10% of transportation fuels by 2020. Commission president José Manuel Barroso said the proposal would create “the most comprehensive and sustainable system anywhere” for certifying greenhouse-gas emissions from biofuels. The European Union and its member states need to ensure that they follow through.

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Forward with biofuels. Nature 451, 865–866 (2008).

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