Rocky Mountain Power (RMP), PacifiCorp’s division in Idaho, Utah and Wyoming, says it will no longer retire its Utah coal-fired power plants early, and it plans to adopt carbon capture technology at its existing brownfield power plant sites in Wyoming.

The development came in RMP’s update to its 2023 Integrated Resource Plan (IRP). Less than a year ago the utility said it would retire its Hunter and Huntington coal-fired units by 2032. Now RMP is proposing to return to the retirement schedule from its 2021 IRP.

That would mean the two units at Huntington would continue to burn coal until 2036 and the three units at Hunter would do so until 2042.

Rocky Mountain Power said these changes were driven by U.S. Environmental Protection Agency’s
(EPA) approval of Wyoming’s state Ozone Transport Rule (OTR) plan, the stay of EPA’s
disapproval of Utah’s state OTR plan, extensions to the assumed operational life of new natural
gas generating resources, energy storage acquisition strategy, forecast load demand, higher coal
prices and natural gas and wholesale power market price updates.

“PacifiCorp’s coal resources will continue to play a pivotal role in following fluctuations in renewable energy as the remaining coal units approach retirement dates,” the company said in its 2023 IRP update. “EPA’s approval of Wyoming’s ozone plan and the stay of EPA’s disapproval of Utah’s ozone plan results in fewer restrictions on coal-fired operation than were assumed in the 2023 IRP.”

Additional investments in the updated plan include new wind and solar resources, the conversion of two coal-fired units to natural gas peaking units, growth in demand response and energy efficiency programs, an advanced nuclear resource and energy storage.

The IRP update shows a decrease in renewable acquisitions compared to RMP’s prior plans, and it had previously intended to replace the Huntington and Hunter coal-fired units with nuclear power.

RMP intends to acquire the following resources, according to the IRP:

With support from South Korea’s SK Group, RMP also announced it had formalized a Memorandum of Understanding (MOU) to collaborate with 8 Rivers to evaluate a potential carbon capture project at one of the utility’s existing brownfield power plant sites in Wyoming.

The project would utilize solid fuel-fired Allam-Fetvedt Cycle (AFC) technology, which would include syngas fired power generation with inherent carbon capture. The technology is an integration of commercially available gasification technology and the AFC technology. The Allam-Fetvedt Cycle is an oxyfuel process invented by 8 Rivers that uses carbon dioxide to drive a turbine to generate power.  Rocky Mountain Power has been evaluating potential carbon capture projects at its Wyoming coal facilities since 2018. 

“Rocky Mountain Power has been diligently engaged in the process to comply with Wyoming’s desire to implement carbon capture at the company’s coal generating units in Wyoming,” said James Owen, Rocky Mountain Power vice president for environmental, fuels and mining. “The partnership and collaboration announced today is a major step forward in determining if carbon capture technologies can bring benefits to our customers in Wyoming at a reasonable cost.”

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