A Colorado-based power cooperative plans to close a coal-fired power plant in northwest Colorado earlier than initially expected.

Tri-State Generation and Transmission Association also announced plans to close a unit of a coal-fired plant in Arizona as well as procure additional energy through renewable sources and battery storage.

A Westminster-based cooperative with 45 members that serves four states, Tri-State filed an electric resource plan with the Colorado Public Utilities Commission, including a preferred plan funded through a federal program. The plan depends on PUC approval as well as funding through the U.S. Department of Agriculture Empowering Rural America (New ERA) program.

“Our ambitious plan, with federal funding, can accelerate clean energy investment and significant greenhouse gas emissions reductions at a lower cost than alternative scenarios, all while exceeding both industry-standard and heightened extreme weather reliability criteria,” Duane Highley, chief executive officer of Tri-State,
said in a news release. “We are clearly demonstrating how Tri-State remains the most reliable, affordable and responsible power supplier for our members both now and well into the future.”

Tri-State announced plans to close Unit 3 of the Craig Station Power Plan by Jan. 1, 2028 rather than the end of 2029.

The closure of Unit 1 by Dec. 31, 2025 and Unit 2 by Sept. 30, 2028 were previously announced. Tri-State owns Unit 3. Xcel Energy, Platte River Power Authority, Salt River Project and Pacific Tri-State jointly own Units 1 and 2.

Costs have increased even as demand is likely to decrease as three member systems withdraw from the cooperative in 2024 and 2025, Tri-State said in the news release.

“The benefits of federal funding would help us to address the stranded costs of retiring coal units, ensuring lower emissions while protecting rural consumers from increased costs,” Highley said. “With our local, state and federal partners, we will continue to work with our employees and the northwest Colorado community to support their transition.”

Tri-State also announced plans to retire Unit 3 of the Springerville Station in Arizona by Sept. 15, 2031 due to what the cooperative described as economic reasons.

At the same time, Tri-State announced plans to invest in the largest acquisition in the history of the cooperative in renewable and battery storage between 2026 and 2031. That includes 500 megawatts of wind power, 240 megawatts of solar power and 310 megawatts of battery storage.

Tri-State previously announced it will add 595 megawatts of solar power in 2024 and 2025.

“Our rapid transition increases clean energy used by our members to 50 percent in 2025 and 70 percent by 2030, benefiting members with lower and stable priced renewable energy resources,” Highley said. “Through 2043, our plan reduces costs to our members by more than $1.8 billion compared to business as usual.”

Tri-State seeks up to $970 million in grants and loans through the New ERA Program to help rural communities transition to renewable energy sources.

“We appreciate Tri-State’s commitment to decarbonization and are excited to see the benefits of more low-cost clean energy that the New ERA program can deliver for electric cooperative members and rural communities across our state,” said Will Toor, executive director of the Colorado Energy Office.

Stacy Tellinghuisen, deputy director of policy development at Western Resource Advocates, said the proposal builds on commitments from Tri-State to reduce greenhouse gas emissions.

“We commend Tri-State for developing a plan that ensures all its member cooperatives benefit from the transition to clean energy,” Tellinghuisen said. “ We encourage other utilities to tap into these critical federal funds to replace their expensive, polluting plants with cleaner resources.”