February/March 2000
By the Mother Earth News editors
Farmers in Iowa have found that switchgrass, a marginal crop grown mostly for ground cover and hay bales, can also fuel power plants.
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Indeed, the waist-high prairie grass may prove to be an especially effective bio-fuel, given that it has already shown several advantages over its competition. While short-rotation woody crops like poplars take years to grow, switchgrass can be harvested annually; and, unlike corn, its extensive root system helps to prevent erosion and sustain soil health. Switchgrass also appeals to environmentalists who point to its value as a "carbon sink"; that is, it sequesters carbon in the soil and reduces C02 in the air.
"For the last ten years, the motivating factor for growing switchgrass in much of the central United States has been conservation/preservation," says Iowa State University Assistant Professor of Agronomy Lee Burras. "Now those lands are coming back into production and farmers are looking for [crop] alternatives. That's where the energy idea becomes very appealing."
In 1996, with support from tile U.S. Department of Energy, Chariton Valley Resource Conservation & Development Inc. began efforts to develop switchgrass into an energy cash crop. The compa ny plans to "test drive" the bio-fuel this spring at southern Iowa's Ottumwa Generating Station, where the brown, hay-like grass will be co-fired with coal. So far, researchers have found that one pound of switchgrass can replace about three quarter of a pound of coal, generating about 7,500 BTUs. That translates to one megawatt (MW) of electricity for every 1,500 acres of switchgrass. The goal at Ottumwa will be to use the herbaceous crop to generate 35 MW of electricity, or about 5% of the plant's total output, during testing.
If all goes well, a wider-scale switch to switchgrass could be just a planting season away.
-Peter Carter
