Switchgrass ethanol yields
Bioengineered varieties of dedicated energy crops such as switchgrass could triple cellulosic ethanol yields from current levels within a decade, a plant biotechnology expert said on Tuesday.
The first wave of commercial biomass ethanol plants will use readily available agricultural waste such as corn stalks or wheat straw to produce the biofuel, but crops grown exclusively for energy production promise much higher yields, said Anna Rath, director of business development at Ceres Inc.
Cellulosic ethanol is produced from plant matter broken down by enzymes and distilled into produce ethanol.
“If you’re thinking in terms of ethanol per acre, switchgrass is already as good as your average corn field at generating ethanol per acre, but it’s a much less mature crop than corn,” Rath told Reuters reporters at the Reuters Biofuel Summit by telephone from Thousand Oaks, California.
“With corn you’re getting a couple percent yield improvement year over year. With switchgrass we think there will be much greater breakthrough improvements, especially in the early years,” she said.
Traditional breeding methods could produce a switchgrass hybrid that could yield 10 to 12 tons of biomass per acre in the next five years, up from about 5 tons per acre currently, Rath said. Genetic engineering could push that to 12 to 15 tons per acre by 2015, she said.
Cellulosic ethanol yields could also grow from the current 70 to 80 gallons per ton of biomass to more than 100 gallons per ton as production costs decline and plants become more efficient, she said.
By comparison, the most efficient corn ethanol plants can produce just under 3 gallons of ethanol per bushel of corn, according to industry experts.
The average U.S. corn yield per acre in 2006 was about 149 bushels per acre, according to the U.S. Department of Agriculture.
U.S. ethanol plants produced about 5 billion gallons of ethanol in 2006, mostly from corn grain.
