Prospects for using switchgrass as a feedstock to make cellulosic ethanol have been getting plenty of headlines around the country over the past several months. But farmers shouldn’t plan on producing switchgrass for that market anytime in the near future, says Ken Goddard, extension specialist with the University of Tennessee (UT) Biofuels Initiative. “It will probably be at least 8-10 years before the first full-scale commercial refinery for cellulosic ethanol made from switchgrass is on line,” he predicts.
Goddard is currently finishing up a four-year-long switchgrass growing project with five farmers in western Tennessee. Purpose of the project, involving 91 acres of switchgrass, was to take a closer look at on-farm considerations – yield potential, weed control, fertilizer requirements, equipment needs, etc. – related to producing switchgrass. Switchgrass produced in the project was used to replace coal at an electricity-generating plant in Alabama.
Project results confirm that, while yield potential of switchgrass can be high, it does take time to get the crop established. “In the first year, we saw yields of 1-2 tons of dry matter/acre,” reports Goddard. “That jumped to 4-5 tons dry matter/acre by year two and 6-12 tons/acre by the third year. Once it is established, though, it doesn’t require much in the way of fertilizer or other inputs.”
This spring, UT researchers launched a follow-up project in eastern Tennessee. The 16 farmers involved have planted more than 700 acres of switchgrass to supply a pilot-scale cellulosic ethanol biorefinery near Vonore, TN. (See “Switchgrass-Fueled Ethanol Plant Proposed For Tennessee,” eHay Weekly, July 29). All of the farms involved in the project are located within a 50-mile radius of the Vonore plant. “That’s necessary because of the costs associated with transporting large amounts of switchgrass any distance,” Goddard explains.
Determining which enzymes can efficiently be used to transform biomass feedstocks like switchgrass into cellulosic ethanol is the major hurdle to full-scale production at this point, Goddard says. “There’s a mad rush on right now to find enzymes that can be produced in abundance and at low cost.”
Goddard estimates there could be as much as 70 gallons of ethanol in a ton of switchgrass dry matter. “So with a yield of 7 tons of switchgrass/acre, the amount of ethanol produced would be almost 500 gallons/acre,” he says.
In July, the U.S. Department of Energy (DOE) announced $240 million in federal funds will be awarded over a five-year period to nine small-scale cellulosic biorefineries in the U.S. DOE says the funding will further President Bush’s goal of making cellulosic ethanol cost-competitive with corn-based ethanol by 2012. Two of the nine DOE projects will use switchgrass as a feedstock, while the remaining plants will use other non-use feedstocks including corn stover and forest wastes such as sawdust and forest thinnings. To see a list of projects go to www.energy.gov/media/Small_Scale_Biorefineries_Matrix.pdf.
To contact Goddard, phone 865-441-1123 or e-mail firstname.lastname@example.org.
To learn more about the University of Tennessee’s Biofuels Initiative, go to