Washington, July 31 : Researchers from the University of Illinois have determined that the giant perennial grass Miscanthus x giganteus outperforms current biofuels sources.
Using Miscanthus as a feedstock for ethanol production in the US could significantly reduce the amount of farmland needed for biofuels, while meeting government biofuels production goals, the researchers reported.
Using corn or switchgrass to produce enough ethanol to offset 20 percent of gasoline use would take 25 percent of current US cropland out of food production, the researchers report.
Getting the same amount of ethanol from Miscanthus would require only 9.3 percent of current agricultural acreage.
"What we've found with Miscanthus is that the amount of biomass generated each year would allow us to produce about 2 1/2 times the amount of ethanol we can produce per acre of corn," said crop sciences professor Stephen P. Long, who led the study.
In trials across Illinois, switchgrass, a perennial grass, which, like Miscanthus, requires fewer chemical and mechanical inputs than corn, produced only about as much ethanol feedstock per acre as corn, according to Long.
"It wasn't that we didn't know how to grow switchgrass because the yields we obtained were actually equal to the best yields that had been obtained elsewhere with switchgrass," he said.
In field trials in Illinois, researchers grew Miscanthus x giganteus and switchgrass in adjoining plots. Miscanthus proved to be at least twice as productive as switchgrass.
"One reason why Miscanthus yields more biomass than corn is that it produces green leaves about six weeks earlier in the growing season," said Long. "Miscanthus also stays green until late October in Illinois, while corn leaves wither at the end of August," he added.
The growing season for switchgrass is comparable to that of Miscanthus, but it is not nearly as efficient at converting sunlight to biomass as Miscanthus.
According to Long, because Miscanthus is a perennial grass, it also accumulates much more carbon in the soil than an annual crop such as corn or soybeans.
"In the context of global change, that's important because it means that by producing a biofuel on that land, you're taking carbon out of the atmosphere and putting it into the soil," he said.