Topeka ? The main utility company behind the controversial proposal to build coal-fired power plants in western Kansas also is considering constructing a nuclear plant.

Recently, Tri-State Generation and Transmission Association directed its staff to study whether to build a nuclear power plant in southeastern Colorado and to consider potential partners to help pay for construction.

In Kansas, Tri-State, which is based in Westminster, Colo., has partnered with Hays-based Sunflower Electric Power Corp. and a Texas company in the proposal to build two 700-megawatt coal-burning plants near Holcomb.

The $3.6 billion project was rejected by Gov. Kathleen Sebelius’ administration because of concerns about the plants’ annual emission of 11 million tons of carbon dioxide and its effect on climate change.

The Legislature has approved a bill to reverse that decision and build the plants, but Sebelius vetoed that measure. Supporters of the plants continue to work on ways through the Legislature and courts to get around Sebelius’ opposition.

Meanwhile, Tri-State’s board of directors is looking toward the development of a site near Holly, Colo., where the company already has secured water rights for a plant that could be either coal-fired or nuclear.

“We are looking into the long-term,” Tri-State spokesman Lee Boughey said. “We need to evaluate different resources.”

Boughey said Tri-State’s interest in possibly building a nuclear plant would have no effect on its proposal in Kansas, nor was it prompted by concerns that the Holcomb project will not get off the ground.

Tri-State sells power to 44 rural cooperatives that serve 1.4 million people in Colorado, New Mexico, Nebraska and Wyoming.

The company says it needs the Holcomb project because of increased demand in eastern Colorado.

But Stephanie Cole, a spokeswoman for the Kansas chapter of the Sierra Club, said Tri-State and other utilities should look toward conservation to reduce demand and the use of renewable energy sources, such as wind.

“Our position is that rather than assuming that we need more plants, we need to aggressively pursue conservation, efficiency and renewables,” she said.

Under the Holcomb project, Tri-State would own one of the 700-megawatt units, while Sunflower and Golden Spread Electric Cooperative of Texas would own the other. Only about 200 megawatts of the total 1,400 megawatts of power would be used in Kansas.