Laboratory Measurements of Biomass/Coal Co-Firing Products

A potential for increasing the use of biomass in the electric power industry is to co-fire biomass with coal in coal-fired power plants. Biomass is attractive as a co-firing fuel with coal for several reasons. Adding biomass to the fuel stream in a coal-fired power plant can potentially reduce emissions of NOx, SOx, and CO2 (that is absorbed during plant growth). Other environmental benefits ofbiomass/ coal co-firing occur when urban wood wastes that otherwise might be landfilled are used as co-firing fuels. In addition, certain biomass, such as wood, can have very low ash contents, decreasing the amount of ash that needs to be disposed and therefore reducing ash disposal costs. To address the issues associated with biomass/coal co-combustion, the products form the combustion ofseveral blends of selected biomass and coal will be analyzed using a molecular beam mass spectrometer (MBMS) system in conjunction with a variable temperature quartz-tube reactor. These studies represent part of a coordinated study between DOE-NREL, DOE-Sandia, and DOE-PETC to investigate co-firing. The biomass samples included in the present study are switchgrass, alfalfa stems, poplar, andwillow, and the coal samples include Pittsburgh #8, Illinois #6, and a Powder River Basin coal. The initial condition is combustion of blends of 5% and 15% biomass (on a thermal input basis) and coal at 1100?C in 20% O2 in helium. The combustion products of interest include alkali metals, NOx, SOx, and chlorine. Of particular interest will be whether there are any synergistic effects (positiveor negative) on the release of these products when biomass and coal are co-combusted. Contact (e-mail): [email protected]