Idaho Power is seeking approval from the state regulator to deploy an additional 100MW of BESS to plug the gap left within its portfolio following the cancellation of a deal with IPP Savion.
Savion’s project, which would have co-located a 200MW solar farm with a 100MW BESS, was initially selected by investor-owned utility (IOU) Idaho Power as part of a 2023 all source request for proposals (RFP) to address a capacity deficit set to occur in 2026.
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The utility submitted an application with the Idaho Public Utilities Commission (IPUC) on December 27 2024 seeking approval of a certificate of public convenience and necessity (CPCN) to develop 100MW of additional BESS across two projects.
Savion hybrid BESS unable to meet 2026 COD
Although details were sparse at the time, Idaho Power revealed in a September 2024 filing that it was uncertain on the future of the hybrid BESS, as reported by Energy-Storage.news, after commissioners at Ada County rejected a development permit associated with the project during the third quarter of last year.
Idaho Power’s most recent filing reveals the project to be independent power producer (IPP) Savion’s proposed Powers Butte Energy Center that’s expected to encompass over 3,000 acres across Canyon and Ada counties, Idaho. Despite the setback, the recent filing reveals that Savion is continuing its permitting efforts.
However, Savion indicated to Idaho Power that it would no longer be able to deliver the project in time for summer 2026 to meet the utility’s capacity deficit, leading to negotiations between the two parties falling through.
The recent filing revealed that during negotiations with Savion, Idaho Power was also working with the developer of the second-most cost effective project on the RFP shortlist as a form of contingency.
Unfortunately for Idaho Power, the unnamed developer informed the utility that it would also be unable to meet the June 2026 commercial operation date (COD) due to transmission constraints.
Amended BESS order with Prevalon Energy
Instead of pursuing additional offtake agreements with other IPPs to fill the gap left by Savion’s Powers Butte project, Idaho Power decided to increase the capacity of two of its own BESS facilities.
The first of the two projects is Idaho Power’s Boise Bench BESS project which, if approved by the IPUC, will be increased in size from 150MW to 200MW. The utility has already received permission from the IPUC for the initial 150MW, after the regulator granted Idaho Power a CPCN on August 29, 2024.
Although the battery supply agreement for the Boise Bench project is redacted within the recent filing, it does reveal the BESS supplier to be Prevalon Energy – a wholly-owned subsidiary of Mitsubishi Power Americas. According to the filing, the two parties amended the original supply agreement on July 31 2024, allowing for delivery of the additional 50MW BESS in 2025, and also avoiding additional tariffs set to be imposed on lithium-ion battery imports.
The project is expected to encompass approximately 10 acres of land at the utility’s Boise Bench substation.
Prevalon is also working with IPP Innergex on doubling the capacity at two operational BESS projects in Chile, as recently reported by Energy-Storage.news.
New BESS supply agreement with Tesla
The remaining 50MW BESS will be installed at Idaho Power’s Hemingway substation located in Owyhee County, adding to 80MW/320MWh already under construction at the utility-owned site.
Although the initial 80MW is being supplied by systems integrator Powin Energy, the recent filing reveals that Tesla will be providing the additional 50MW BESS. Further details of the agreement were unavailable due to it also being redacted. Idaho Power expects Tesla to deliver the BESS during 2025 to meet the expected COD in June 2026.
Idaho Power has requested that the IPUC approve the CPCN for an additional 100MW BESS “as soon as practical” without conducting a hearing.
