Wyoming’s largest utility, Rocky Mountain Power, will decommission its entire coal-fired power fleet in the state by 2039 while continuing to add wind, solar and battery storage to its six-state operating system, according to preliminary details of its 2021 Integrated Resource Plan.

RMP will retire 14 of its coal-fired power units across several states by 2030, and a total of 19 by 2040, RMP’s parent company PacifiCorp stated in a presentation to Wyoming utility officials late last week. 

PacifiCorp plans to add more than 3,700 megawatts of new wind power by 2040 throughout its six-state region, including in Wyoming.

For the first time, the utility’s system planning includes adding nuclear power. The Natrium nuclear power plant is slated to come online in 2028. Officials have said it will be located at one of the utility’s existing coal plant sites — either Jim Bridger, Naughton, Dave Johnston or Wyodak. 

The utility will add 2,726 megawatts of “advanced nuclear and non-emitting peaking resources” throughout its six-state system by 2040, according to PacifiCorp documents.

The utility’s plan includes retiring coal-burning units 1 and 2 at the Naughton power plant near Kemmerer by the end of 2025. A third coal unit at Naughton was converted to natural gas this year and is scheduled for retirement in 2030.

Coal units 1 and 2 at the Jim Bridger power plant outside Rock Springs will be converted to natural gas in 2024 in order to serve “peak” demand loads and help maintain system reliability. Coal units 3 and 4 at Jim Bridger will continue to operate through 2037 when the entire plant, including the natural gas-converted units 1 and 2, will be decommissioned.

The plan mostly maintains the schedule laid out in its 2019 IRP for exiting Wyoming coal, including the early retirement of the Dave Johnston coal-fired power plant at Glenrock in 2027.

New details in the IRP include schedules for myriad filings, applications and analysis to satisfy a series of new Wyoming policies aimed at either finding buyers for coal plants set for early retirement in the state or extending their life by adding carbon-capture-utilization-and-storage technologies. The policies also require public utilities such as Rocky Mountain Power to provide details for how their plans will maintain system reliability.

But the chance that those policies might actually extend the productive life of coal plants in the state seems increasingly slim, according to University of Wyoming energy economist Rob Godby.

“Despite the Wyoming actions, and [Montana’s], these actions don’t seem to have had an effect on slowing coal conversion/retirement/divestment in either state by PacifiCorp,” Godby told WyoFile via email.

Rocky Mountain Power and its parent company PacifiCorp will formally submit its full 2021 IRP to the Wyoming Public Service Commission on Wednesday Sept. 1. The submission kicks off months of review before the commission decides whether to approve, amend or deny the plans.

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