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Recent Biomass/Fine Coal Test Burn Proves Successful

Despite significant progress in the production of ethanol and biodiesel, biomass accounts for less than 4% of U.S. energy consumption. This stems from obstacles like seasonal availability, low energy density, and the capital investment required to use biomass. Likewise, using fine waste coal is hindered by problems with handling, storage, and transportation. Co-Firing biomass and fine-coal waste in a briquetted form may eliminate these obstacles for both fuels. Coal/biomass briquettes are more amenable to drying without dust problems; they can be stored, moved, and processed in existing infrastructure; and they expand the distance to economically transport the biomass.

Photographs of a reclaimed surface mine in East Kentucky showing the weed fields that were harvested for the production of the fine coal/biomass briquettes.

To demonstrate the feasibility of this approach, a trial to burn engineered fuels made from coal and biomass was conducted in early December at the East Kentucky Correctional Complex (EKCC) in West Liberty, Kentucky. The test burn was led by Darrell Taulbee and Jim Neathery, CAER researchers. Co-briquetting biomass with fine coal has been under development at the CAER for several years as a way to use biomass in conventional coal-fired furnaces as well as a means to utilize the fine coal that is often discarded to waste impoundments. This approach is particularly attractive for coal-fired stoker boilers, like those at the prison. There was also a start-up company, KeLa Energy, which participated in the test burn by providing fuel pellets also made from coal and biomass.

Four fuel formulations weighing about one ton each were tested; two were briquetted fuels and two extruded-fuel pellets. Biomass contents ranged from 10 to 17% and included sawdust, processed sorghum, and weeds. The weeds, which performed well during the tests, were taken from reclaimed strip mines and fallow fields in Eastern Kentucky, lands that are not used for growing food crops and which are located nearby to sources of waste coal.

Combustion of fine coal/biomass briquettes in a stoker furnace at the EKCC.

The demonstration burn was successful in that the samples burned and the ash discharged from the grate without significant modification to the boiler operation. More importantly, the emission of two major pollutants, sulfur dioxide and nitrogen oxides (SO2 and NOx), were substantially reduced. Two of the engineered fuels prepared from samples of the coal now being used at the prison exhibited average reductions of approximately 26% and 15% for NOx and SO2, respectively. A third fuel prepared with a lower-value fine coal exhibited analogous reductions of 14% and 11%. More striking were the results from the fourth fuel, prepared by Kela Energy from a high-Btu, low-ash fine coal, which exhibited a 42% reduction in NOx and a 39% reduction in SO2 emissions.

We hope the success of this test burn will help spur a domestic industry that supports the use of Kentucky's energy resources, particularly our abundant biomass resources, while simultaneously providing a more environmentally-friendly, cleaner-burning fuel. We also anticipate that these tests will help to advance Kela Energy's effort to construct their first commercial plant in the coming months.

Contact Dr. Darrell Taulbee