ETHANOL often gets a bad rap as a biofuel, but accusations that it is too inefficient to replace petroleum may be misguided.
Ethanol makes up about 2 per cent of the fuel used for transport in the US, and recent studies have argued that it takes more energy to make than it provides. But when Alex Farrell at the University of California, Berkeley, and colleagues reviewed six studies on ethanol, they found that much of the data and many of the manufacturing practices cited were out of date (Science, vol 311, p 506).
The old studies also ignored useful by-products, says Farrell. With 鈥渃ellulosic鈥� ethanol from plant wastes, for instance, the main by-product is lignin, a renewable fuel that can power the bio-refinery.
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