Idaho Power is moving forward with plans to construct two new natural gas-fired power plants — one near Twin Falls and one in Elmore County — as rapidly growing electricity demand threatens to outstrip the utility’s current generating capacity across its service territory.
Two New Facilities in the Pipeline
The two proposed plants, named South Hills and Peregrine, would together add roughly 800 megawatts of generating capacity to Idaho Power’s system. The South Hills facility, located near Twin Falls, is targeted for completion in the summer of 2029. The Peregrine plant in Elmore County is expected to come online a year later, in the summer of 2030. If construction begins on schedule — as early as 2027 — each facility would take approximately two years to complete.
The projects would become the fourth and fifth natural gas plants in Idaho Power’s generating portfolio, and the company expects them to be the most efficient gas-fired resources it operates. Planning and permitting work began back in 2021.
Demand Growing Faster Than New Resources Can Keep Up
Idaho Power spokesperson Eric Hackett pointed to growth across multiple sectors — residential, commercial, and agricultural — as the primary driver behind the need for additional capacity. “With growth comes more demand across all of our service territory. That growth is across multiple sectors, anything from residential and irrigation,” Hackett said.
Even substantial recent investments in renewable energy have not been enough to stay ahead of rising demand. The utility has added roughly 500 megawatts of renewable resources since 2021 and expects another 500 megawatts of renewable energy and battery storage to come online within the next several years. Despite that progress, Hackett acknowledged the challenge: “Even with all that addition, growth is simply outpacing those new resources.”
Idaho Power’s current system peak demand stands at approximately 4,000 megawatts. That figure is projected to climb above 5,000 megawatts as population and economic growth continue across southern Idaho and the broader Treasure Valley region, which has seen significant residential and commercial development in communities including Nampa, Caldwell, and Middleton in Canyon County.
How Idaho Power Currently Generates Its Power
Idaho Power’s existing generation mix relies heavily on hydroelectric dams, which supply roughly 40 percent of the utility’s energy. Natural gas currently accounts for about 20 percent of supply, with wind, solar, and battery storage resources making up another 20 percent. The addition of South Hills and Peregrine would meaningfully expand the natural gas share of that portfolio as the utility works to maintain reliability while transitioning toward cleaner generation sources.
The growing strain on the region’s energy infrastructure is not isolated to electricity. A drought emergency declaration has already raised concerns about water availability across portions of the West, which could also affect hydroelectric output — a critical component of Idaho Power’s supply. For more on regional water pressures, see the drought emergency affecting reservoir levels across the region.
What Comes Next
Construction on both facilities could begin as early as 2027, pending regulatory approvals and continued permitting progress. Canyon County residents and businesses that rely on Idaho Power should expect the new capacity to be phased in between 2029 and 2030. The utility has not announced a specific cost figure for the projects at this stage.
As development continues to reshape communities across the Treasure Valley and beyond, infrastructure demands — from roads to power — are intensifying. For updates on infrastructure projects affecting southwestern Idaho, visit Idaho News for statewide coverage.