Powering Strong Communities

Tri-State Generation Files Electric Resource Plan with Colorado Utility Regulators

Tri-State Generation and Transmission Association on Dec. 1 said that it filed its 2023 electric resource plan with the Colorado Public Utilities Commission.

Tr-State noted that the filing includes as its preferred plan an Inflation Reduction Act scenario that would be enabled by funding through the U.S. Department of Agriculture’s Empowering Rural America program. 

Tri-State’s preferred plan identifies the addition of 1,250 megawatts of new renewable energy resources and energy storage through 2031, the retirement of the coal-fired 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 the coal-fired Springerville Unit 3 in Arizona 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,” Tri-State said.

Tri-State is a power supply cooperative of 45 members, operating on a not-for-profit basis, including 42 utility electric distribution cooperative and public power district members in four states.

The investments in Tri-State’s preferred plan are contingent on approval by the PUC and an Empowering Rural America program award from the USDA. 

Tri-State said it 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.  

The resources will be procured as a mix of power purchase agreements and owned resources. 

In addition to these resources, Tri-State said it 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.

“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,” it noted.

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.

With federal funding to reduce greenhouse gas emissions, and offset closure and stranded asset costs, Tri-State’s preferred plan proposes a retirement date of the Arizona-based Springerville Station Unit 3 by Sept. 15, 2031, pending Colorado PUC approval of Phase 1 of the 2023 ERP filing.

The early retirement date of Springerville Station 3 would largely be due to economic factors, Tri-State said.

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,” it said. 

In order to be responsive to the New ERA Program’s criteria prioritizing GHG reductions through 2031, Tri-State’s preferred plan calls for the reduction of emissions across its system, including reducing emissions associated with Colorado wholesale electricity sales by 89% by 2030, relative to a 2005 baseline, exceeding the state’s emissions reduction requirements.  

Tri-State also said it continues to support energy efficiency and demand management with its members.

All of the ERP scenarios include applicable Colorado energy efficiency targets and a Colorado demand response target of 4% beginning in 2025. Tri-State also identifies energy efficiency and demand response in New Mexico and Wyoming.  

Tri-State said it worked closely with a diverse group of members and stakeholders, including environmental non-governmental organizations, state agencies, and industry-developer groups in advance of its 2023 ERP filing.  

In addition, certain components of Tri-State’s preferred plan are supported by a Stipulation that requests that the PUC approve certain elements of the scenario and commit to support the acquisitions and retirements for which a USDA award is being sought. 

The Stipulation was reached with Tri-State members Mountain View Electric Association and Otero County Electric Cooperative, the Colorado Energy Office, Colorado Utility Consumer Advocate, Colorado Solar and Storage Association, Western Resource Advocates and the Sierra Club.

Tri-State noted that the electric resource plan is subject to review, modification, and approval by the PUC, and input by intervenors.

The plan is also subject to change depending on a U.S. Department of Agriculture Empowering Rural America program award, as well as changes in technologies, markets and “the regulatory landscape, and each resource plan Tri-State files over time reflects these changes as they occur,” Tri-State said.

Phase II of the 2023 ERP will reflect relevant changes next year.  

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