Switchgrass

Alliant Energy has burned switchgrass in the past, and is also exploring the use of switchgrass as part of its renewable resource fuels mix at its proposed hybrid generating stations in Marshalltown, Iowa and Cassville, Wisconsin.

Alliant Energy is one of only two utility companies in the country known to be working with switchgrass.

The Chariton Valley Biomass Project is an initiative to develop switchgrass, and other grasses grown in southern Iowa, as a supplemental fuel source for coal-fired power plants. The project is a cooperative effort between Alliant Energy, Chariton Valley Resource Conservation and Development and the U.S. Department of Energy. The project is in its 15th year of existence.

A yearly crop of 200,000 tons of switchgrass will be required to achieve the total commercial potential, displacing up to five percent of the low-sulfur coal consumed at Alliant Energy’s 725MW Ottumwa Generating Station (OGS) annually.

The major benefits of burning switchgrass are better air quality, especially lower carbon dioxide emissions, and development of a new crop for farmers. The CO2 is collected by the plant during the growth process, and then sequestered back into the ground through the roots. When the plant is harvested, the roots are left intact and the grass grows again the following year. There is plenty of discussion about the energy-opportunities of switchgrass, the testing that has recently ended provided many insights into growing, harvesting and processing switchgrass for any type of switchgrass-to-energy production.

Test burns completed

The Biomass Project's initial test burn took place in December 2000. It was an opportunity to validate that the concept of switchgrass as a supplemental fuel source worked and establish next steps.

The project team conducted a second interim switchgrass test at the OGS facility in Chillicothe, Iowa, in December 2003. Throughout the duration of the test, 1,500 tons of locally-grown switchgrass were co-fired with coal at OGS to produce electricity.

The final test was completed in May of 2006. The final numbers highlight the success of the three-month test. During nearly 1,700 hours that the test burn took place, the switchgrass burned in the plant’s boiler produced about 19,600 megawatt-hours or enough electricity to power nearly 1,900 average-sized homes for a full year. That’s a world record for energy produced from switchgrass. In the process, carbon dioxide emissions were reduced by about 51,000 tons and, because switchgrass absorbs carbon dioxide as it grows, the reductions are even greater. While OGS already burns low-sulfur coal, the sulfur content of switchgrass is so low that sulfur emissions were decreased by an additional 62 tons during the test burn.

Data from the test burn is being reviewed and studies will be done on the physical impacts of burning switchgrass in the OGS boiler as well as number crunching and analysis to see what it will take to begin an ongoing commercial operation at OGS or any other plant.

Press Release
May 25, 2006 - Record Setting Switchgrass Testing Comes to Successful End

Long-term economic impact

First conceived in the early 1990s, the project will potentially use up to 50,000 acres of marginal agricultural land — the majority set aside in the Federal Conservation Reserve Programs of southern Iowa and northern Missouri.

Project partners propose to co-fire biomass with coal to generate a sustained supply of 35 MW of biomass-derived electric power at OGS.

At commercialization, the project could require as much as 200,000 tons of biomass from 50,000 acres, involving as many as 500 farmers. The project team believes the rural economic development would improve standards of living in southern Iowa.

Additional benefits would include the security of using a domestic fuel for energy production, and enhanced quality of air, water and soil by utilizing switchgrass as a crop for marginal cropland.

Learn more about the Chariton Valley Biomass Project