Spokane-based Avista Utilities’ Kettle Falls Generating Station is the first wood waste–fired power plant in the U.S. built solely to generate electricity. The facility annually burns about 500,000 tons of wood waste from Pacific Northwest and Canadian lumber mills.
Built in 1983, the Kettle Falls plant burns wood waste to produce steam, which runs a turbine and generator that can produce a maximum output of 53 megawatts of electricity. The plant also operates a natural gas-fired combined-cycle combustion turbine that produces 8 MW, bringing the electricity output of the entire plant (including biomass and natural gas-fired operations) to 61 MW; enough electricity to power nearly 46,000 homes.
Kettle Falls received POWER’s Energy Conservation Award in 1984 and an Environmental Excellence Award from Washington State in 1985, and it was inducted into the Power Plant Hall of Fame in November 2000. Before the plant was built, local wood waste was commonly burned in open wigwams, creating air pollution. Kettle Falls has made the burning of millions of tons of waste unnecessary by using it as fuel to generate electricity.
Avista’s focus has centered on wood waste of various types. Wood waste – called hog fuel – is fed into a seven-story furnace/boiler and burned, creating heat. The boiler walls are made up of rows and rows of pipes filled with a closed loop of water, super-heated by the burning hog fuel. The optimal burning temperature is 2,000 degrees, resulting in a steam temperature of 950 degrees. The steam drives a turbine which turns a generator, creating electricity.
The existing 30 year old well house pump station that provided water for the boilers had outlived its usefulness. A new well house pump station was constructed and ControlFreek Inc was contracted to provide for the pump station controls. A set of photos detailing the biomass fuel generation process at Avista’s Kettle Falls Generating Station can be found in an Avista album on Flickr.