The California Independent System Operator Board of Governors has approved a pair of provisions advancing a major transmission intertie that will deliver Idaho wind energy to California and the Southwest, while opening additional energy resources for Idaho.
The Board voted Friday to accept a revision to its earlier conditional approval of the 500-kilovolt Southwest Intertie Project-North (SWIP-North) that allows consideration of a U.S. Department of Energy grant to help accelerate development of the intertie.
In a companion action, the Board also approved Great Basin Transmission LLC‘s application to become a participating transmission owner in the California ISO.
“Each of the actions is key to advancing a long-anticipated effort seen as a linchpin in strengthening Western electric grid connectivity, optimizing resource diversity, and giving California access to Idaho wind energy consistent with the California Public Utility Commission’s integrated resource planning,” CAISO said.
The 285-mile intertie project, estimated to cost about $1.23 billion, includes development of a new transmission line from Midpoint, ID to Robinson Summit, NV.
It would create an important transmission pathway by linking to a longer 600-mile line already carrying power from Robinson Summit to just south of Las Vegas, where it connects to the ISO system, CAISO said.
The DOE grant – a total of $331 million – will act as a bridge to speed the project’s construction.
When the ISO Board conditionally approved participating in the SWIP-North project in December 2023, Idaho Power had begun negotiations with Great Basin Transmission to acquire about 23 percent of the entitlements – approximately half of the northbound capacity – for energy to move north along the interties.
Negotiations and regulatory approval were expected to be completed by now, but funding negotiations are ongoing and Idaho Power still needs to seek regulatory approval, which would delay the project’s start, CAISO said.
Meanwhile, the DOE signed an agreement with Great Basin Transmission for the northbound capacity entitlements being negotiated by Idaho Power. The grant will initially fund Idaho Power’s share of the project, and the DOE will later sell the entitlements. For more information on the DOE grant, view the agency’s fact sheet.
"Granting approval for Great Basin Transmission to become a participating transmission owner in the ISO is another critical step for the project, enabling an agreement for the transmission developer to give operational control of its southbound capacity and half of its northbound entitlements on SWIP-North lines to the ISO."
That agreement will now go to the Federal Energy Regulatory Commission for review.
