Western U.S. utility PacifiCorp advanced the retirement date of four of its coal-fired units and announced plans to convert two others to run on natural gas as part of a broad long-term plan to reduce its reliance on coal-fired power plants.

In its 2021 integrated resource plan, released Sept. 1, PacifiCorp showed how it will shut down more than three-fourths of its coal-fired generating capacity by 2040. The plan spells out a replacement power generation portfolio that includes energy storage resources, demand-side management, new solar, new wind and advanced nuclear, a first for the utility, which is part of Berkshire Hathaway Energy.

According to S&P Global Market Intelligence data, PacifiCorp owns about 11,300 MW of generating capacity, with more than 5,200 MW of coal and nearly 2,900 MW of gas. The company also has more than 2,900 MW currently under contract, split almost equally between wind and solar resources.

PacifiCorp's current coal portfolio totals full or partial ownership interests in 22 units at nine plants. The 2021 integrated resource plan, or IRP, advances the retirement date of four units compared to dates stated in the 2019 IRP. One unit's planned retirement date was extended by two years in the 2021 IRP compared to the previous plan.

One notable change from the 2019 plan is to convert two units at the Jim Bridger plant in Sweetwater County, Wyo., to operate on natural gas as peaking units starting in 2024. PacifiCorp, which owns a two-thirds interest in each of the plant's four units, planned on retiring Bridger unit 1 at the end of 2023 and Bridger unit 2 in 2028. Now, all four units are to be retired in 2037. Idacorp Inc. subsidiary Idaho Power Co. owns the remaining one-third interest in the plant.

Among other changes compared to the 2019 plan, PacifiCorp moved up its planned exit from the remaining two units of the Colstrip plant in Rosebud County, Mont., by two years, to 2025. PacifiCorp's ownership interest totals 10% of each unit.

At the three-unit Craig (Yampa) plant in Moffat County, Colo., PacifiCorp owns a roughly 19% interest in each of units 1 and 2. It postponed its exit of the unit 2 interest by two years, to 2028, compared to its 2019 IRP, to align with coal resource exit plans of other owners, including Xcel Energy Inc.

PacifiCorp has small ownership interests in the two-unit Hayden plant in Routt County, Colo., operated by Xcel Energy, and moved up its planned exit of those interests from 2030, identified in the 2019 IRP, to 2028 for unit 1 and 2027 for unit 2.

The 2021 IRP includes no new natural gas-fired resources through 2040 but contemplates the retirement of more than 1,500 MW of existing resources, including the two Jim Bridger units that are to be converted. According to the IRP, unit 3 at the Naughton plant in Lincoln County, Wyo., which was converted from coal to natural gas in 2020, is to be retired in 2029. All six units at the Gadsby plant near Salt Lake City, consisting of the three Gadsby units from the first half of the 1950s and three Gadsby Gas Peakers added in 2002, are to be retired in 2032. The Hermiston plant in Umatilla County, Ore., which began operating in 1996, is to be retired in 2036. Other gas plants continue operating until as late as 2054.

Resources to be added under the 2021 IRP include 6,181 MW of storage resources, including co-located batteries, stand-alone batteries and pumped hydro; 5,628 MW of new solar; 4,290 MW from energy efficiency programs; 3,628 MW of new wind; 2,448 MW of direct load control programs; and 500 MW of advanced nuclear in 2028, with an additional 1,000 MW further into the future. The resource plan also includes two additional segments of PacifiCorp's Energy Gateway transmission build-out and the 290-mile, 500-kV Boardman-Hemingway transmission line to be built with Idaho Power.