CAISO’s Board of Governors on Dec. 14 Southwest Intertie Project-North (SWIP-N) — a 285-mile, 500-kV line in Nevada that would enable access to Idaho’s wind resources — in to the ISO’s 2022-2023 transmission portfolio.
The project is the only proposed line that would connect California’s load-serving entities to Idaho wind power. (See CAISO Pursuing Approval of New Line to Tap Idaho Wind.)
“This is a really exciting opportunity to open up some … really valuable resource diversity indexed straight to the California [Public Utilities Commission]’s integrated resource plans … and build on that legacy of transmission connectivity that exists across the West,” CAISO CEO Elliot Mainzer told the board before its vote.
The approval of SWIP-N diverges from the standard transmission planning process. The board already approved the ISO’s transmission plan in May. (See CAISO Board Adopts Revamped Transmission Plan.)
“This is a unique project, and it has quite a few differences from a conventional transmission plan approval decision … both because of the nature of the project and because of our negotiated arrangements with Idaho Power to access the capacity jointly,” Neil Millar, CAISO vice president of infrastructure and operations planning, told the board.
The project would require CAISO to assume entitlements from LS Power subsidiary Great Basin Transmission (GBT) on the existing One Nevada Transmission Line, which connects to the ISO via the Harry Allen substation north of Las Vegas. SWIP-N would connect with the existing line at the Robinson Summit substation near Ely, Nev. Both the ON Line and Robinson would need upgrades to accommodate the new project.
SWIP-N could be online by 2027, but the board’s approval is conditional on the Idaho Public Utilities Commission’s by Sept. 30. The CPUC also would have to reaffirm the need for Idaho wind power as part of its consideration of CAISO’s 2024-2025 transmission plan. And FERC would have to approve GBT’s tariff as a participating transmission owner and transmission revenue requirement.
Assuming everything is approved, CAISO expects it would file a project sponsor agreement with FERC in January 2025.
Jeff Billinton, CAISO director of infrastructure planning, reported that stakeholders generally supported the project, but some were concerned about costs. Millar noted the approval timeline allowed for plenty of opportunity for comment throughout 2024.
“Only after the FERC approves the project sponsor agreement do any cost-commitment issues arise; termination provisions go into effect,” he said. CAISO also then would begin a quarterly cost review process with LS Power. “So we believe that these gating checkpoints provide the right milestones, the right transparency [and] the right visibility.”
