The city of 602,000 plans to outfit a second landfill to pump methane gas from refuse by 2012, adding to an existing landfill in Arlington, Ore., where Seattle's garbage is taken by train, officials said.
The city first began getting electricity from the Arlington plant in October.
"This is part of our strategy," City Councilman Bruce Harrell, chairman of the council's Energy, Technology and Civil Rights Committee, told the Seattle Post-Intelligencer. "This is part of our vision."
A network of pipes moves the methane from the tons of garbage in the Arlington landfill into a compression facility, which sends it to internal combustion engines. The engines turn generators that produce 5.7 megawatts of electricity sent up the power grid, enough to supply about 5,600 homes.
Seattle uses about 1,132 megawatts, the Seattle City Light utility averages. About 89 percent of the utility's power comes from hydroelectric dams, 5.6 percent from nuclear energy, 3.4 percent from wind, 1.3 percent from coal and 0.5 percent from natural gas, the utility says.
The methane-extraction arrangement is part of a 20-year contract between the city and national garbage-management firm Waste Management Inc. of Houston, which built the system and charges the city about $2.5 million annually, Harrell said.