Wednesday, June 21, 2006

Successful Switchgrass Burn Test Completed

Switchgrass is often cited as one of the most promising energy crops that could be grown in the U.S. for a variety of biomass processes, including direct combustion or use as a feedstock for a cellulosic-ethanol processing project. However, for all its hype, there are currently few actual examples of its use. This week, however, RenewableEnergyAccess.com (REA) brings us news of a successful and promising application of switchgrass crops co-fired with coal.

REA reports that the Chariton Valley Biomass Project, which is managed by Chariton Valley Resource Conservation & Development (RC&D) Inc. and co-funded by the U.S. Department of Energy, the U.S. Department of Agriculture, Alliant Energy, and other project partners, just ended a three-month test burn of switchgrass with coal at the Ottumwa Generating Station in Chillicothe, Iowa.

By the end of the test burn on May 12, 2006, the Chariton Valley Biomass Project team, led by Chariton Valley RC&D Inc., Alliant Energy (and its subsidiary, Interstate Power and Light Company) and assisted by numerous Iowa-based team members and others spanning from Portland, Oregon to Denmark, said they accomplished the following during the three-month test burn:

  • Delivered, processed, and burned 31,568 bales of locally grown switchgrass totaling 15,647 tons as renewable fuel for generating electricity at Ottumwa Generating Station (OGS).

  • Generated 19,607,000 kilowatt-hours of electricity from the renewable switchgrass fuel. That is enough electricity to provide 100% of the electricity needs for an entire year for more than 1,874 average Iowa homes. This is a world record for electricity generation from switchgrass.

  • Processed and burned switchgrass as fuel at OGS for more than 1,675 hours since mid-February 2006. Processing hours per day have improved significantly since the beginning of the test burn, with the facility operating without downtime nearly continuously throughout the past month of the test burn.

  • Reduced emissions of sulfur dioxide (SO2) from OGS by about 62 tons due to the extremely low sulfur content in switchgrass. The coal used as fuel at OGS is low-sulfur coal, but not as low in sulfur as the switchgrass, which contains only about 0.1% sulfur (by weight).

  • Reduced emissions of carbon dioxide (CO2), the primary greenhouse gas, by a total estimated amount over 50,800 tons through reductions at the power plant, and because the switchgrass absorbs carbon dioxide from the air during its growth cycle and stores a portion of the absorbed carbon in its deep root system -- this also improves the soil conditions on the fields where the switchgrass is grown.

  • Generated about 626 tons of fly ash, which has been approved for sale from the power plant for use in concrete and other valuable byproducts. The ash is what is left over from the switchgrass after it is burned in the boiler. This ash is collected at the power plant along with ash produced from the coal.

  • Demonstrated that the processing system designed, installed and operated by the project team throughout the test burn can be operated reliably at and above its designed process rate of 12.5 tons per hour, especially if the switchgrass delivered to the facility contains moisture contents of 12% and under. The average moisture content of switchgrass burned throughout the test burn has been about 13%.

  • Replaced about 12,060 tons of coal purchased from Wyoming with renewable switchgrass that was planted, grown, harvested, stored, delivered and processed by local Iowa farmers.

  • Generated an estimated 19,600 Renewable Energy Credits (RECs) that have received independent third-party certification under Environmental Resource Trust's EcoPower program. This program certifies the amount of power generated during the test burn that resulted from a renewable energy source, and allows the project team to market the RECs to companies, government organizations, and/or residential consumers who are willing to pay a small premium to ensure that a portion of their energy purchases go to a renewable power generator. Purchasing these RECs can help companies and government organizations meet their environmental goals.


  • The project team believes the processing system demonstrated for this project would also be well suited for application in facilities that would create ethanol and/or other co-products from switchgrass.

    It's good to see this kind of actual demonstration project being completed for switchgrass applications. Co-firing itself is not particularly new or untested with many coal-fired power plants in the United States already co-firing with agricultural and forestry residues. Use of dedicated energy crops, like switchgrass, is not too different but probably has a few subtle differences that ought to be ironed out in projects like this.

    In my honest opinion, we need to be aggressively pursueing the development of a sizable cellulosic biomass industry in the United States to grow, harvest and/or recover sizable quantities of biomass from both dedicated energy crops and from agricultural, forestry and urban residues. The biomass could either provide feedstock for co-firing for electricity generation, for cellulosic ethanol production, or for syngas production via gasification (this produces quite a bit of electricity as well and the resulting syngas could be put to a variety of uses including conversion to synthetic liquid fuels, conversion to ethanol, and additional electricity generation or some combination thereof).

    As the DOE and USDA have determined, over a billion dry tons of biomass could be sustainably harvested each year (see this report) and we ought to be putting some or all of that to good use...

    [BTW, the graphic accompanying this post is a picture of the a "D-Stringer" machine which automatically pulls apart switchgrass bales to be fed into the Ottumwa power plant's burner unit.]

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