Switchgrass, the prairie plant that once fueled the buffalo herds of the American Great Plains, may one day fill automobile tanks in a bioengineered form that’s cheaper and yields more ethanol than the original variety.
Researchers showed that by manipulating lignin, a compound that stiffens plants, they were able to produce a variety that resulted in 38 percent more biofuel with lower pretreatment costs. Modified switchgrass required 4 to 5 times less cellulase, an enzyme used to break down fiber, according to a report in the Proceedings of the National Academy of Sciences.
Switchgrass can grow 10 feet high with pencil-thick stems, and has the potential to reduce U.S. dependence on foreign oil, according to the Department of Energy. The grass grows quickly and captures solar energy, using water “very efficiently,” according to the Oak Ridge National Laboratory, a U.S. facility based in Oak Ridge, Tennessee. It lives for more than 10 years and allows for multiple harvests, the study authors wrote.
“The transgenic plant materials require less severe pretreatment and much lower cellulase dosages to obtain ethanol yields equivalent to yields in controls,” wrote lead author Chunxiang Fu, a scientist at the Samuel Roberts Noble Foundation in Ardmore, Oklahoma. “These transgenic switchgrass lines and the approach are valuable for developing improved cultivars of biofuel crops.”
Ethanol is mixed now with gasoline to make auto fuel. Nearly half of U.S. gasoline contains up to 10 percent ethanol to boost octane or meet air quality requirements, according to the Department of Energy.
13 Billion Gallons
The U.S. will produce almost 14 billion gallons of ethanol from corn in 2011, according to the U.S. Energy Information Administration. That is based on a calculation of 0.9 million barrels of ethanol produced daily in the U.S., according to the Energy Department. Prices of ethanol have gained 44 percent in the past year. Denatured ethanol for March delivery fell 1.2 cents, or 0.5 percent, to $2.453 a gallon on the Chicago Board of Trade.
Switchgrass once stretched across tens of millions of acres of the American plains before settlers, farming and other development confined the prairie grass to parks and nature preserves. Some farmers today grow it for livestock or ground cover to control erosion. Cultivating switchgrass as a fuel crop would require minor changes, according to the Department of Energy.
The improved switchgrass may help more than just ethanol, the authors wrote. It may help with newly emerging biofuels such as butanol, isobutene, and “green gasoline,” made from the cellulose in plants.