Purdue University researchers have taken the same yeast that ferments grapes into wine and transformed it into a superbug with an appetite for corn stalks, wood chips and other biological jetsam that it converts to ethanol.
Energy experts hope this difficult piece of genetic engineering will boost ethanol's fortunes as a gasoline additive and an extra income source for Midwestern farmers, as well as reduce air pollution from automobile exhausts.
Purdue's superbug squeezes 30 percent more ethanol from corn stalks and other organic waste because it has been engineered to expand its traditional diet. Although most yeasts specialize in digesting just one kind of sugar, Purdue's yeast consumes two. Besides eating glucose, the most common sugar in plant matter, it gobbles up xylose, another common sugar.
This modification, made by a team led by molecular geneticist Nancy Ho at Purdue's West Lafayette, Ind., campus, means that instead of just using corn kernels to make ethanol, it will now be feasible to use corn stalks and other waste material.
The United States currently produces about 1.5 billion gallons of ethanol annually, worth roughly $2 billion, from about 600 million bushels of corn, said Eric Vaughn, president of the Washington-based Renewable Fuels Association.
Within five years, the industry hopes to be selling $6.5 billion annually.
Most ethanol-laced gasoline is sold in big cities with air pollution concerns, because ethanol is a clean-burning way to raise octane that has been around for some time. Indeed, the once-widely advertised octane-booster called ethyl actually was grain alcohol.
More than 95 percent of Chicago's gasoline contains ethanol; in Downstate Illinois, only about 35 percent does.
Petroleum refineries can raise octane levels with ethanol instead of other chemicals-- benzene, toluene and xylene-- that are known to cause cancer, Vaughn said.
Finding ways to make ethanol from waste substances rather than corn is important to expanding its market.
"We could perhaps double the output of ethanol using corn," Vaughn said, "but after that, you'd start to drive up the price of corn, which farmers would love, but consumers wouldn't."
Swan Biomass Co. of Oakbrook Terrace, a privately held firm owned in part by Amoco Corp., plans to build a Midwest plant within a year to make ethanol commercially using Purdue's genetically engineered yeast. Investors in other parts of the country using their own new technology also plan to build ethanol plants, and the Energy Department, which finances most ethanol research, predicts a dramatic upswing in ethanol use as a fuel additive.
To encourage ethanol use, the federal government gives petroleum companies a fuel tax break of 5.4 cents per gallon when they market fuel that is 10 percent ethanol. One goal of the Energy Department is to see ethanol production costs drop enough so the subsidy eventually can be eliminated, said Gerson Santos-Leon, the department's ethanol team leader.
Swan Biomass is looking at several Midwestern sites, including one in Illinois, for its new ethanol plant, said company President Robert Walker.
"The first commercial applications are likely to be in producing ethanol from field wastes generated on farms or from wastes that result as crops are processed for sale," he said.
Illinois is both the biggest user and biggest producer of ethanol fuel, said Illinois Corn Growers Association spokesman Mark Lambert, using about 17 percent of the state's corn crop to make nearly 600 million gallons of ethanol. The state owes much of its ranking to Archer Daniels Midland Co. of Decatur and its distilleries.
A few decades ago, farm organizations pushed the term "gasohol" to describe ethanol-laced fuel, but that term has been dropped for marketing reasons, Lambert said.