Wood and coal cofiring in Alaska—operational considerations and combustion gas effects for a grate-fired power plant

Abstract

Coal is the primary fuel source for electrical power generation in interior Alaska, with more than 600,000 tons burned annually at five different power plants. Woody biomass could be used as part of this fuel mix, offering potential environmental and economic benefits. In this research, debarked chips were cofired with locally mined coal at the Aurora Power Plant facility in downtown Fairbanks, Alaska. During two days of testing, aspen chips were successfully cofired with coal at average rates of 2.4 percent and 4.8 percent of total energy value. Combustion gases were analyzed during combustion of 100- percent coal, as well as at two different blends with aspen chips, for levels of carbon dioxide, carbon monoxide, oxygen, and nitrogen compounds. Carbon monoxide was suggested as the combustion gas most influenced by changes in woody biomass blend rate. The potential logistic and operational challenges when cofiring were also observed. Cofiring biomass at low levels in grate-combustion systems could be performed with relative ease, with only minor impacts on plant operations, including fuel storage, handling, and performance.

Citation

Nicholls, David; Wright, Zackery; Huang, Daisy. 2018. Wood and coal cofiring in Alaska—operational considerations and combustion gas effects for a grate-fired power plant. Gen. Tech. Rep. PNW-GTR-964. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 32 p.