Basin Electric Power Cooperative has chosen an eastern South Dakota site for a new $331 million power plant with turbines fired by natural gas and steam, the company announced Wednesday.

The Bismarck-based company said the site chosen for the proposed "combined-cycle" power plant is near White, S.D., and will be called the Deer Creek Station.

The plant is slated to be built on about 20 acres of land, about 12 miles northeast of Brookings, project coordinator Gavin McCollam said. It would have a capacity of about 300 megawatts, or roughly enough energy to power 300,000 homes, the company said.

If approved by regulators, construction would start in 2010, with completion slated for spring 2012, spokesman Floyd Robb said. The plant would employ up to 35 people, and up to 500 during construction, he said.

The electricity will be tied into existing transmission lines, the company said.

Natural gas for the plant will come from Basin's Great Plains Synfuels Plant near Beulah, northwest of Bismarck, Robb said. The gasification plant makes synthetic gas from lignite, a low-grade coal that is plentiful in North Dakota. The synthetic gas for the plant will be piped into the 1,249-mile Northern Border Pipeline, which crosses the Dakotas as it carries natural gas from Canada to the Chicago area.

The proposed combined power plant in South Dakota is a first for Basin, though more than 100 exist in the U.S., McCollam said.

"A combined cycle plant takes hot exhaust from the gas turbine, which would otherwise be exhausted to the atmosphere, and runs it through a heat recovery steam generator," McCollam said. "Those hot gases heat water to make steam, and that steam goes through a steam turbine. It increases the efficiency of the whole plant."

Said Robb: "It's generally considered a clean technology."

The plant would run up to 16 hours a day and is designed only as an "intermediate power supply," the company said.

"It won't run 24-7 - it will only run at times of increased demand," Robb said.

Basin generates 1,950 megawatts of power for 2.5 million customers in nine Midwestern and Western states. Robb said power demand from the co-op is growing at about 100 megawatts a year.

Basin began construction this month on a $1.3 billion coal-fired power plant near Gillette, Wyo., Robb said. The planned Dry Fork Station is slated to come on line in 2011, producing 385 megawatts of power, he said.

Basin also is planning a $1.5 billion coal-fired power plant in the Dakotas. Two sites are being considered for the plant in central South Dakota, either in the Pierre-Blunt area or the Mobridge-Selby area, Robb said. One site is being mulled in North Dakota near Basin's Leland Olds Station near Stanton, he said.

Robb said the company likely will choose the site late this year or early next. The proposed plant would produce up to 700 megawatts of power, he said.

"We would hope to have that plant on line somewhere in the neighborhood of 2014," Robb said.