Nov 012010
 
Sugar cane residue can be used as a biofuel
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Biofuels are back. This time they might even work

MAKE something people want to buy at a price they can afford. Hardly a revolutionary business strategy, but one that the American biofuels industry has, to date, eschewed. Now a new wave of companies think that they have the technology to change the game and make unsubsidised profits. If they can do so reliably, and on a large scale, biofuels may have a lot more success in freeing the world from fossil fuels than they have had until now.

The original 1970s appeal of biofuels was the opportunity to stick up a finger or two, depending on the local bodily idiom, to the oil sheikhs. Over time, the opportunity to fight global warming added to the original energy-security appeal. Make petrol out of plants in a sufficiently clever way and you can drive around with no net emissions of carbon dioxide as well as no net payments to the mad, the bad and the greedy. A great idea all round, then.

Sadly, in America, it did not work out like that. First, the fuel was not petrol. Instead, it was ethanol, which stores less energy per litre, tends to absorb water and is corrosive; people will use it only if it is cheap or if you force them to through mandatory blending. In Brazil, which turned to biofuels after the 1970s oil shocks, the price of ethanol eventually became low enough for the fuel to find a market, thanks to highly productive sugar plantations and distilleries powered by the pulp left when that sugar was extracted from its cane. As a result Brazil is now a biofuels superpower. North American ethanol is mostly made from corn (maize), which is less efficient, and often produced in distilleries powered by coal; it is thus neither as cheap nor as environmentally benign. But American agribusiness, which knows a good thing when it sees one, used its political clout to arrange subsidies and tariffs that made corn-ethanol profitable and that kept out the alternative from Brazil.

This still left the problem: using corn limits the size of the industry and pits it against the interests of people who want food. Boosters claimed that cellulose, from which the stalks, leaves and wood of plants are made, could if suitably treated become a substitute for the starch in corn. Both starch and cellulose consist of sugar molecules, linked together in different ways, and sugar is what fermentation feeds on. But cellulosic biofuel has so far failed, on an epic scale, to deliver. At the moment, only a handful of factories around the world produce biofuel from cellulose. And that fuel is still ethanol.

This is what companies working on a new generation of biofuels want to change. Instead of ethanol, they plan to make hydrocarbons, molecules chemically much more similar to those that already power planes, trains and automobiles. These will, they say, be “drop-in” fuels, any quantity of which can be put into the appropriate fuel tanks and pipelines with no fuss whatsoever. For that reason alone, they are worth more than ethanol.

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