Among the most promising alternatives are fuels derived from biological material. Currently, the main biofuel used in the United States is ethanol distilled from kernels of corn. There are about 140 corn ethanol refineries nationwide, which produce more than 5 billion gallons a year. But critics say that corn ethanol alone won't meet the president's goal of 35 billion gallons of alternative fuels in 10 years, because cultivating corn to use only its grain would take up too much land. According to the National Environmental Trust, producing 35 billion gallons of ethanol annually would require putting an additional 129,000 square miles of farmland-an area roughly the combined size of Kansas and Iowa-into corn production.
One way to reach the president's objective is offered by Chris Somerville, professor of biological sciences at Stanford University and director of the Carnegie Institution's Department of Plant Biology. Somerville advocates increasing the production of cellulosic ethanol, which is distilled from the fermentation of sugars from the entire plant, not just the grains.
''To expand beyond 12 billion gallons, we need to use the body of the plants rather than use the seeds,'' Somerville said. He will discuss his research at 8 a.m. Saturday, Feb. 17, at the annual meeting of the American Association for the Advancement of Science in San Francisco.
The ideal plant: A perennial grass
The body of a plant is composed of polysaccharides, such as cellulose, which can be converted to ethanol by fermentation. Using the entire plant body as a starting raw material will result in a higher yield of ferme