Tri-State announces closure of Craig Station Unit 3 in 2028

Tri-State Generation and Transmission Association says rural electricity consumers across four western states will benefit from reliable power and lower costs, with clean energy investment and greenhouse gas emissions reductions accelerated by federal funding, in a long-term strategy announced this week. 

The not-for-profit wholesale power supply cooperative’s 2023 Electric Resource Plan (ERP), filed with the Colorado Public Utilities Commission (CoPUC), includes as its preferred plan an Inflation Reduction Act (IRA) scenario that would be enabled by funding through the U.S. Department of Agriculture’s (USDA’s) 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,” said Duane Highley, Tri-State CEO. “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’s preferred plan identifies the addition of 1,250 megawatts (MW) of new renewable energy resources and energy storage through 2031, the retirement of Craig Station in 2028, the addition of a dispatchable natural gas unit in 2028 with carbon capture and sequestration added in 2031, and the retirement of Springerville Unit 3 in 2031. With sufficient federal funding support, the plan results in accelerated system-wide emissions reductions and an 89% reduction in greenhouse gas emissions in Colorado by 2030, relative to a 2005 baseline.  

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

The investments in Tri-State’s preferred plan are contingent on approval by the CoPUC and a New ERA award from the USDA. “Federal funding in support of our preferred plan would be transformational for Tri-State and our members,” said Highley.  

1,250 megawatts of new renewable energy and energy storage investment by 2031 

Tri-State will invest in the largest resource acquisition in its history, including 1,250 MW of geographically distributed renewables and battery storage between 2026 and 2031, including:  

– 500 MW of wind resources; 

– 200 MW of wind resources with storage hybrids; 

– 310 MW of storage, including standalone 100-hour iron air batteries, standalone 4-hour batteries, and 4-hour batteries with wind and storage hybrids; and 

– 240 MW of solar resources.  

These resources will be procured as a mix of power purchase agreements and owned resources. In addition to these resources, Tri-State is adding 595 MW of new solar resources in 2024 and 2025 that were previously announced in 2020, bringing a total of 920 MW of solar resources on Tri-State’s system by 2031. In 2031, Tri-State will have a total of 1,374 MW of wind resources.

Craig Station Unit 3 retire, natural gas plant with carbon capture supports resilience  

With resource costs increasing and Tri-State’s load reduced from three member systems terminating their contracts to withdraw from membership between 2024-2025, all of the scenarios modeled retire Craig Station Unit 3 by Jan. 1, 2028, to improve system economics. The retirements of Craig Station Unit 1 by Dec. 31, 2025, and Craig Station Unit 2 by Sept. 30, 2028, were previously announced. 

Craig Station Units 1 and 2 are jointly owned by Xcel Energy, Platte River Power Authority, Salt River Project, PacifiCorp and Tri-State. Tri-State owns Unit 3.

“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,” said Highley. “With our local, state and federal partners, we will continue to work with our employees and the northwest Colorado community to support their transition.”    

To meet industry-standard Level 1 reliability metrics and Tri-State’s heightened extreme weather Level 2 reliability metrics, the preferred plan adds a 290 MW combined-cycle natural gas unit in 2028, with carbon capture and sequestration added in 2031. The dispatchable power plant balances renewable resources to ensure reliability, and is forecasted to operate with a low capacity factor until carbon capture and sequestration is operational.  

Above, steam rises from the Craig plant on a cool fall morning. Tri-State announced the station will be closed earlier than initially planned. CAITLIN WALKER/herald times file photo