A new cogeneration system outside Seattle at King County’s West Point Treatment Plant is now using a waste byproduct of sewage treatment and turning it into electricity and heat to help run the plant.
This digester facility puts King County close to its goal of operating one of the nation’s first carbon-neutral wastewater utilities, it said.
Much of the heat and energy will be used for the plant’s operation, but additional electricity generated at the plant will be sold to Seattle City Light under an agreement reached in 2010.
The new system replaces a cogeneration facility that was taken offline in 2007 after 23 years of service. Since the opening of West Point in 1966, its raw sewage pump engines and hot water boilers have been powered by digester gas generated during the treatment process. Waste heat from plant process has been put to good use in keeping digesters warm.
Because of investments in energy conservation, renewable energy production and carbon and nutrient recycling, the division is 70 percent of the way to being carbon-neutral in its operations. King County hopes to have one of the nation’s first carbon-neutral wastewater utilities of its size.