Tri-State accelerates clean energy transition with new coal plant shutdown dates 

WESTMINSTER — Tri-State Generation and Transmission Association will retire two coal-fired power plants earlier than planned and bring renewable sources online more quickly, according to an announcement from the company.

The plans to ramp up the conversion to renewable sources comes as a result of increased federal funding, the organization said.

The power cooperative’s 2023 Electric Resource Plan, filed with the Colorado Public Utilities Commission, 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. 

“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, Tri-State CEO, said in a written statement. “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 includes the addition of 1,250 megawatts of new renewable energy resources and energy storage through 2031, the retirement of Craig Station coal plant in 2028, the addition of a dispatchable natural gas unit in 2028 with carbon capture and sequestration added in 2031, and the retirement of (Arizona-based) Springerville Unit 3 in 2031. With federal support, the utility hopes to reduce greenhouse gas emissions by 89% by 2030.

“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 proposals, which have yet to be approved, were applauded by the Sierra Club, which has been advocating for faster transition to renewable energy. 

“In 2022, Craig Unit 3 in Colorado emitted more than 2.8 million tons of CO2, more than 1,700 tons of acid rain-causing SO2, and more than 2,900 tons of ozone-causing NOx. Those emissions have caused an estimated average of over $75 million in increased health care costs each year from heart attacks, asthma attacks, and other diseases,” the club said, quoting the Environmental Protection Agency. 

“The emissions from these coal-fired plants have unnecessarily poisoned people and the planet for far too long,” Sarah Clark, Colorado field manager for the Sierra Club, said in a press statement. “As we look ahead to a clean-energy future, we’re committed to working with Tri-State and other stakeholders to support the impacted communities in Moffat County (Colorado) and Apache County (Arizona) to gain the educational and financial support they need to transition to good-paying, unionized jobs in the clean energy sector.” 

The Sierra Club also said, and Tri-State confirmed, that ratepayers will benefit to the tune of “more than $1.8 billion through 2043 compared to a business-as-usual scenario.”

Tri-State said it would, by 2031, bring on line:

• 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. 
• 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.

The Tri-State plan does require a new natural gas unit to meet demand during certain weather periods. Called “dispatchable,” the natural gas unit could be quickly brought on line when renewable sources are limited by clouds or lack of wind.

“This transformational plan outlines the most cost-effective path for Tri-State to meet our mission to serve our members with a reliable, affordable and responsible supply of electricity,” Highley said. “We look forward to continuing to work with our members, the Colorado Public Utilities Commission and stakeholders on a reliable, affordable and responsible path forward that meets our members’ needs and accomplishes our energy transition goals.” 

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.

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