Four units at coal-fired power plants in Wyoming are set to close years earlier than previously scheduled, according to a draft plan released Thursday by their owner.

Jim Bridger 1 would close in 2023, five years ahead of the retirement year assumed by PacifiCorp in its 2017 plan. Jim Bridger 2 would go offline in 2028, four years earlier than previously planned. Both units had a lifespan estimated to extend until 2037.

Naughton units 1 and 2 would be set to close in 2025 under the new draft, four years ahead of their 'end-of-life' date in 2029.

PacifiCorp also advanced the closure dates for units at power plants in Craig, Colorado, and Colstrip, Montana, which are partially owned by the company. Craig 2 would shut down in 2026 while Colstrip 3 and 4 would go offline in 2027.

While the retirement of the Craig unit is pushed back by a year compared to the company's previous plan, the Colstrip units would be closing nearly two decades before their 'end-of-life' date.

In addition to those seven coal-fired units which would see earlier retirement, 12 units are set to be closed by 2037. In Wyoming, those closures include all of Dave Johnston by 2027, Jim Bridger 3 and 4 in 2037, and Naughton 3, which will be converted to natural gas next year.

"We are mindful that these resource decisions impact our thermal operations employees, their families and communities," Chad Teply, PacifiCorp's senior vice president for business policy and development, said in Thursday's announcement. "Our top priority is making certain our employees and communities remain informed about the changes ahead and that we work in concert with everyone involved to develop plans that help them transition through this time of change."

By 2038, PacifiCorp would only continue operating four of the 24 coal units currently running. Those 20 retirements will reduce coal-fueled generation capacity by almost 2,800 MW by 2030 and nearly 4,500 MW by 2038.

It's another blow to Wyoming's coal industry, which has struggled to regain its footing following the most recent bust. Mining jobs have declined in recent years and two companies, Cloud Peak Energy and Blackjewel, filed for bankruptcy this year.

Blackjewel locked workers out of its Eagle Butte and Belle Ayr mines, leaving some 500 without jobs. A bankruptcy judge on Wednesday approved a plan to sell the mines to the subsidiary of an Alabama-based operation.

PacifiCorp, meanwhile, is pivoting to renewable sources for energy generation, aiming to add 3,500 MW of new wind capacity by 2025 and growing that figure to 4,600 MW by 2038. Some 1,500 MW is currently under construction, including wind farms in Wyoming, as part of the company's Energy Vision 2020 initiative.

By 2024, PacifiCorp, which operates as Rocky Mountain Power in the state, plans to grow its wind generation capacity in Wyoming by 1,920 MW.

Wyoming would also see the company expand its solar energy generation capacity, with 1,415 MW of new solar paired with 354 MW of battery storage to be phased in between 2024 and 2038.

Utah, Oregon and Washington would also see such solar development, with Utah to get an additional 3,000 MW of solar and 635 MW of battery storage.

"Coal generation has been an important resource in our portfolio, allowing us to deliver reliable energy to our customers, and will continue to play an important role as units approach retirement dates," Rick Link, the company's vice president of resource planning and acquisitions, said in Thursday's statement.

"At the same time, this plan reflects the ongoing cost pressure on coal as wind generation, solar generation and storage have emerged as low-cost resource options for our customers," he added.

PacifiCorp is also going forward with the construction of a 400-mile transmission line known as Gateway South, connecting southeastern Wyoming and northern Utah. That's in addition to the 140-mile Gateway West transmission line currently being built in Wyoming.

On Thursday, the company began a two-day meeting to gather public input. The company says the public has been involved in its resource plans from "the earliest stages and at each decisive step."

The draft released Thursday is part of the company's 2019 Integrated Resource Plan, which shows how the company expects to meet customer needs in the most cost-effective manner over the next 20 years.

The company will file its final 2019 plan with state regulatory commissions by Oct. 18.

"The transition in how we meet our customers' energy needs is underway," Link said. "Witha focus on lower-cost renewable resources and strategic transmission investments, this plan allows us to continue to deliver the reliable and low-cost energy our customers need as we embark on a phased and well-managed coal transition that minimizes impacts to our thermal operations workforce and communities."

With the entire Dave Johnston plant set to be closed in 2027, PacifiCorp may end up replacing the facility with a wind generation project, as it has done in other instances.

PacifiCorp Communications Director Spencer Hall, who is based in Salt Lake, told K2 Radio News on Thursday that the company currently has no plans for the facility beyond 2027. Any redevelopment of the site would require years of reclamation work and likely new permitting.

With eight years of coal-fired operations left at Dave Johnston, it could be several years before the company formulates a plan for the plant's future, Hall said.