PacifiCorp’s ambitious renewables plan relies on new transmission lines

A robust expansion of high-voltage transmission infrastructure is making it possible for PacifiCorp to ramp up the wind and solar resources that will be feeding increased volumes of green energy into the Pacific Northwest in the coming years.

PacifiCorp this month released a “preferred portfolio” draft for its Integrated Resource Plan (IRP). The strategy includes a sharp reduction of coal-fired power plants over the next 10 years at the same time new wind, solar, and storage assets will come online. Included in the plan is the future completion of Gateway South, a 400-mile transmission line currently on the drawing board, which will ship renewable power into PacifiCorp’s service territories.

“By investing in transmission, we can extend the reach and flexibility of the grid so that more low-cost energy can be delivered to our customers,” said Chad Teply, senior vice president for Business Policy. “Making the necessary long-term investments to relieve transmission congestion will allow the development of additional renewable resources.”

Gateway South will stretch from the planned Aeolus substation in southeastern Wyoming to the Clover substation near Mona, Utah. The 500-kilovolt AC line will come with a path rating of 1,500 megawatts (MW). At the same time, PacifiCorp is currently adding a 140-mile segment to its Gateway West transmission line connecting Aeolus and the Bridger substation in Wyoming, which will also provide needed infrastructure to the IRP strategy.

Gateway South received approval from the Bureau of Land Management in late 2016; however, a utility spokesman told Daily Energy Insider that because some state and local permits were still pending, the completion of the project has been penciled in for 2023.

The completion of the new line will make it possible for PacifiCorp to then begin bringing the new renewable power online.

“These projects are dependent on the transmission line upgrades,” said PacifiCorp spokesman Spencer Hall.

Specifically, the timeline calls for more than 3,500 MW of new wind power coming online in Wyoming by 2025. That volume will increase to more than 4,600 MW by 2038 as additional generation is built in Wyoming and Idaho. New solar power will increase nearly 3,000 MW by 2028 and top 6,300 MW by 2038. Battery storage linked to solar generators will hit 600 MW in 2025 and then jump to more than 2,800 MW by 2038.

As a result, PacifiCorp expects around 7,000 MW of new renewables and storage by 2025 to supply its own customers and will also be added to the regional pool. “All of the renewable energy projects described in the IRP will be built to serve the needs of PacifiCorp customers first and foremost,” said Hall. “And as part of the Western energy grid, energy will continue to be bought and sold between utilities as well.”

The addition of the renewable power pouring into the PacifiCorp service territory along Gateway South and the rest of the company’s 16,500 miles of transmission lines will also allow the retirement schedule to be accelerated for 16 of its 24 coal plants currently in operation. “Coal generation has been an important resource in our portfolio … and will continue to play an important role as units approach retirement dates,” said Rick Link, vice president of Resource Planning and Acquisitions. “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.”

The shutdowns will begin with Wyoming’s Jim Bridger 1 plant in 2023 and will also include the retirement of Jim Bridger 2 some five years later. Both plants had originally been slated for shutdown in 2037. Next year’s retirement of the Cholla 4 plant in Arizona remains on schedule as is the utility’s recommendation to convert the Naughton 3 facility in Wyoming to a 247-MW natural-gas plant in 2020.

When completed, PacifiCorp plans to have cut 16 coal-fired plants totaling 2,800 MW by 2030, and a total of 20 of the two dozen plants and 4,500 MW by 2038.

“We are mindful that these resource decisions impact our thermal operations employees, their families and communities,” Teply said. “Our top priority is making certain our employees and communities remain informed about the changes ahead.”

The proposed IRP will be formally presented by Oct. 18 to the appropriate state regulators. Once approved, PacifiCorp can then start bringing those changes to fruition while bringing more renewable power to its customers.