July 2011

Pouring energy into biofuels

Many biochemists are working on alternatives to corn-derived fuel ethanol. 


That line in “America the Beautiful” about amber waves of grain was written as a testamony to our country’s abundance and ready opportunity to feed the hungry masses. But increasingly, America’s grains are feeding masses of hungry cars, not people. Nearly all gas in the U.S. contains 10 percent fuel ethanol, a product currently made by using yeast to ferment sugar derived from cornstarch. America produced about 13.2 billion gallons of fuel ethanol last year, making this the most common biofuel— fuel metabolically derived from living organisms as opposed to fossil fuels produced over hundreds of millions of years from long-dead organisms— in this country.

But while the corn lobby probably would be thrilled to keep ethanol made from their grain in the top spot, biofuel researchers have other ideas. They’re working toward new advances aimed at moving away from corn-derived fuel ethanol, such as engineering bigger and better grasses to pull more fuel from their vegetative tissues rather than their seeds and genetically modifying plants to make removing the sugar polymers that serve as a feedstock for fuels faster and easier. Others are working on modifying plants to produce energy rich oils preferentially instead of starch or teaching biofuel processing bacteria new tricks, such as making longer-chain alcohols that store more energy than ethanol, synthesizing biofuels out of proteins instead of sugars, or digesting sugar polymers directly and pumping out biofuels at the same time.

So instead of those amber waves of grain, America may eventually have green waves of switchgrass or miscanthus— or even waving cilia from fuel-making bacteria.

Going green

Although biofuel might seem like a hot topic at the moment, it’s really an old idea, explains Daniel Bush, professor and chair of the department of biology at Colorado State University.

“It’s just another way of transforming sunlight into a useful form of energy,” Bush says.

Plants do much of the work for us, he explains, by creating oils, simple sugars and sugar polymers such as starch and cellulose as products of photosynthesis. We can then process these products into ethanol, biodiesel (diesel fuel made from vegetable oil or animal fat) or other fuels. Though biofuels often have faded into the background during periods with low gas prices, Bush adds, they become more popular with every gas crisis.

Though biodiesel is more common in Europe, ethanol is king in the U.S. Fuel ethanol certainly has its benefits: it adds oxygen to gas, leading to a cleaner burn that produces less pollution, and it increases octane.

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