Operator of Colstrip coal plant to buy out co-owner Puget Sound Energy, install some wind

BILLINGS, Mont. — The operator of Montana’s Colstrip coal-fired power plant said Monday it was buying out one of the site’s co-owners and plans to construct a wind farm nearby that would generate 600 megawatts of electricity.

Talen Energy Supply would acquire Puget Sound Energy’s 25 percent share of Colstrip’s two remaining coal-fired units under the deal. The units combined generate about 1,480 megawatts of electricity.

Talen currently has a 30 percent share of one of the units.

Colstrip owners have faced intense pressure from environmentalists and changing energy markets to shut down the heavily polluting plant, one of the largest coal-fired power producers in the U.S. West.

Houston-based Talen said the new wind turbines would complement — not replace — coal-fired electricity from Colstrip. The renewable energy project known as Silverthorn Wind would be built in Rosebud and Treasure counties and begin delivering power in 2026, Talen said.

Colstrip’s two older generating units — co-owned by Talen Energy and Bellevue-based PSE — shut down in 2020.

The transfer of PSE’s share in the remaining two units is effective Dec. 31, 2025. That’s when PSE faces a deadline to stop delivering electricity derived from coal to customers in Washington under a 2019 state law.

PSE will remain partially responsible for the environmental cleanup of the plant site.

Monday’s deal is subject to a 90-day review period by the plant’s other co-owners. It also needs approval from a federal judge in Texas, where Talen declared bankruptcy in May.

PSE sought to sell its stake in one of Colstrip’s four power-generating plants in 2019, but the deal fell through after utility regulators in Washington recommended the sale be rejected. PSE last year reached an agreement to buy 350 megawatts of power from the Clearwater Wind project north of Colstrip.