Future
Engineering and permitting for a permanent switchgrass processing facility at Ottumwa Generating Station (OGS) are complete. Permission has been granted by the Iowa Department of Transportation for Alliant Energy to burn up to 5% switchgrass on a heat input basis while maintaining the ability to sell the resulting fly ash byproduct into the valuable concrete admixture market. Construction packages have been issued, and local contractors arrived on-site during late Spring of 2005 to begin building the new switchgrass processing facility. Construction of the $2.5 million storage and process building is scheduled for completion in the Fall of 2005.
The precursor to commercial operation, a 90-day (2,000 consecutive hour) continuous test burn of switchgrass co-fired with coal in the OGS boiler is the third and final stage of the project’s development process. The test burn is tentatively scheduled to begin in Winter/Spring of 2006. The third test burn is intended primarily to assess long-term impacts of burning switchgrass in the OGS boiler. Long term issues of most interest are:
- Slagging and fouling (build-up of molten ash material on boiler tubes and walls), and
- Potential corrosion impacts on the boiler.
Based on similar tests and commercial operations in Denmark carried out by Elsam Engineering (a member of the Chariton Valley Biomass Project’s engineering team), the long-term impacts of firing switchgrass at OGS are expected to be minimal and acceptable (within the typical range for firing just coal in the boiler). In addition to assessing long-term impacts, the project team will once again monitor and analyze air emissions, boiler efficiency and plant performance impacts, and fly ash impacts from cofiring switchgrass. Based on previous test results, cofiring switchgrass is expected to either improve or have no significant impact on all of these aspects of the power plant’s operations.
If the expected positive results are documented during this Long Term Test Burn, project partners will seek to enter into commercial operations (if economic conditions are attractive enough to warrant a viable business opportunity). Acquiring customers to buy “green power” from the project will be a critical element in enabling a commercially viable business. Commercial operations could begin as soon as possible after all performance analysis and reports are completed following the Long Term Test Burn, and as soon as sufficient supplies of switchgrass are located and contracted.
For more background information on the project, please see the following links: