Missouri municipal power plant to test burn engineered pellets

By Sue Retka Schill | September 04, 2013

Columbia (Mo.) Water and Light has approval from its advisory board to purchase biomass pellets for trial burns at the municipal power plant this winter. As part of its renewable energy program, CWL has been co-firing coal with waste wood chips since 2008 and has continuously explored the use of other biomass fuels, explained Tad Johnsen, director of water and light in a memorandum to the advisory board.

With the approval, CWL is planning test burns in January of engineered pellets developed in a collaborative effort between Missouri Corn Growers Association and Enginuity Worldwide LLC. Enginuity’s bid was to deliver 700 tons of the experimental fuel made from corn stover or a mixture of stover and grass for testing at a cost of $500 per ton. When including the cost of stack testing, fuels testing, engineering monitoring and analysis, furnace monitoring and measurement and incidentals, the total expected cost of a test burn is $375,000. CWL and Missouri Corn Growers have applied for a $125,000 grant from the American Public Power Association to help with costs.

Last October, the CWL conducted a test firing using miscanthus pellets with mixed results. While the pellets mixed well with the coal and were handled easily in the system that includes a front end loader, bucket elevator, screw auger and chute delivery to supply the stokers, the coal plant’s handling system created dust and degraded the pellets. In addition, although the pellets were covered with tarps in the outdoor storage area, wherever water could infiltrate, the pellets swelled and disintegrated. Recommendations following that test included making the pellets larger and weatherproofing or hardening them. Storage and handling should be either indoors or better protected from the weather. A separate fuel handling system should be used if the pellets are to be used in the current form that would feed them into the boiler fuel train at about the coal scale level of the boiler. And finally, any future test burns should be done in two phases that first tests the handling and combustion characteristics, and if successful, completes stack testing in a second phase.

In its bid to CWL to test the experimental pellet, Enginuity Worldwide addressed many of the issues uncovered in the miscanthus pellet test burn. “Based on the laboratory testing to date, it is not anticipated the EWW will experience any of the same handling or physical stability issues that were observed in the fall 2012 test burn of miscanthus pellets.” Enginuity has trademarked its process as eCARB, for environmentally continuous annually renewable biomass. The eCARB process produces a pellet that is specified to be 97 percent durable with a shape and size designed to work well when mixed with coal with minimal retrofits to handling systems. The company says its fuel is water resistant.  

Based in Columbia, Mo., Enginuity Worldwide is owned by Nancy Heimann. The company has several patent applications filed on the biomass fuel methods that describe it as including an adhesive comprised of a starch and a hydroxide. Further additives include a silicate, a viscosity agent, a preservative and a Btu additive, all of which are combustible materials.