Kirkland-based National Energy Systems Co. has sold a 125 megawatt power plant in northwest Washington to Puget Sound Energy.

The utility bought the natural-gas-fired power plant in Sumas, Wash., from Sumas Cogeneration Co., a unit of National Energy Systems.

The approximately $30 million transaction also gives PSE part ownership in a 3.7-mile pipeline that brings natural gas to the Sumas plant from the main Canadian gas-transmission pipeline into Washington state.

Built in 1993, the power plant is a combined-cycle cogeneration facility. The utility estimated in 2007 that it will need approximately 2,600 average megawatts of new electricity supply by 2027, roughly equivalent to the power load of two cities the size of Seattle.