Coal

Alliant’s Switchfuel Test Uses “Powerful Grass”

Issue 3 and Volume 105.

No, this isn’t about hippies and the 1960s, but it is about powerful grass. With the goal of replacing up to five percent of the fuel burned with biomass, Alliant Energy’s Ottumwa Generating Plant, a 650 MW coal-fired facility near the Missouri border 80 miles southeast of Des Moines, Iowa, has been retrofitted to burn switchgrass along with coal as part of a test project. The plant consumes 450 tph coal. To achieve the five percent replacement goal would require about 25 tph switchgrass, says Bill Morton, lead project engineer for Alliant Energy. It would take about 50,000 acres of land to grow that much switchgrass for a year.

The Ottumwa plant started burning switchgrass in November. By the end of January, the plant had burned 4,000 tons of the thick-stemmed, native perennial that is easily grown, harvested and baled in southern Iowa. The grass resembles straw and is packaged in large rectangular bales eight feet long and four feet wide. The bales are fed by conveyor into a machine that chops and grinds them into a dust that is blown into the furnace. Over the next few years, further tests will measure the impact the grass has on boiler efficiency as another 35,000 tons of switchgrass is mixed with coal. Testing will be completed by 2005.

Switchgrass produces about 6,400 Btu/lb, less than the 8,300 Btu/lb the plant’s coal yields. But a new emphasis on renewable fuels helped fund testing at the power plant. The state and federal governments contributed $4 million for the pilot project and another $4 million came from private partners, farmers and Alliant Energy.

Jerry Schnoor, a University of Iowa professor and co-director of the Center for Global and Regional Environmental Research, said in a 1999 report that CO2 emissions could be cut by nearly 177,000 tons per year and SO2 emissions – precursor to acid rain – by up to 113 tons per year if five percent of the coal were replaced with switchgrass.

Finding farmers willing to grow the fuel crop wouldn’t be easy for all power producers. The test’s partnership between local farmers and the power plant began to take shape in 1991. Much of the land in the region is not suitable for corn or soybeans-Iowa’s major cash crops. Much of it had been enrolled in a federal government program that pays farmers for idling low-quality farmland. “We have a lot of land that can produce grass well,” said Martin Braster, biomass project coordinator for Chariton Valley Resource Conservation and Development. “So we began researching what can be done with grasses.”

“At this point it is not really profitable to plant switchgrass as a cash crop and sell it for energy,” says Gary Kelderman, one of 100 farmers growing switchgrass for the plant. “It proves that these farmers are stewards of the land and this is just part of contributing to the future generations.”