for National Geographic News
Ethanol made from a prairie grass shows promise as a viable fuel that could be much more environmentally friendly and energy-efficient than corn ethanol, a new study says.
Ethanol is often touted as a cleaner-burning gasoline alternative that lessens dependence on oil. (Get the basics on greenhouse gases and global warming.)
But a key criticism of the biofuel is that large amounts of fossil fuels are required to farm and refine it.
Switchgrass ethanol, though, can yield 540 percent more energy than is required to produce it, the new study says.
Part of the reason switchgrass ethanol is more energy efficient is that the whole plant is used. Corn ethanol, by contrast, is made only from kernels.
In addition, producing and burning switchgrass ethanol releases 94 percent less greenhouse gas than burning gasoline does, the researchers found.
Corn ethanol production and use emits 22 percent less greenhouse gas than gasoline, according to the October 2007 issue of National Geographic magazine.
In any form, ethanol is far from being a silver bullet for environmental and energy woes, however.
A UN study published last year, for example, found that the booming liquid-biofuel industry could spawn deforestation, deplete soil nutrients, and undermine food security.
The new study, published today in the Proceedings of the National Academy of Sciences, highlights some of the ways that switchgrass ethanol may help defuse these concerns.
For example, unlike corn—the most common ethanol source in the U.S.—switchgrass shouldn't threaten food availability.
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