FERC on Jan. 21 approved an agreement between CAISO and LS Power to develop a transmission line that would deliver Idaho wind power into California and could help secure Idaho Power’s participation in the ISO’s Extended Day-Ahead-Market.

The commission’s order covers the Southwest Intertie Project-North (SWIP-North), a 285-mile, 500-kV line being developed by LS Power subsidiary Great Basin Transmission at an estimated cost of $1 billion (ER25-543).

The project, which will be jointly funded by CAISO and Idaho Power, will span northern Nevada and southern Idaho and link up with NV Energy’s One Nevada (ON) line to the south, providing 2,070 MW of transfer capacity southbound and 1,920 MW northbound.

The development agreement memorializes CAISO’s previous agreement to fund about 77% of the project, equal to Great Basin’s ownership share, in exchange for operational control of the company’s entitlements on the line, which will equate to 1,117.5 MW of southbound capacity and 1,072.5 MW of northbound capacity, with the balance in both directions being allocated to NV Energy.

In addition to facilitating transfers into California, the line offers Idaho wind power resources access to wholesale electricity markets in the Desert Southwest through the Desert Link line connected to the southern end of the ON line.

CAISO’s Board of Governors approved the development agreement during an October 2024 meeting despite opposition from some Idaho residents concerned about the path of the line. (See CAISO Board Approves Moving Forward with SWIP-N Transmission Line.)

In its filing with FERC, CAISO said it needed to pursue SWIP-North to support the California Public Utilities Commission’s resource planning portfolio calling for California load-serving entities to procure 1,000 MW of wind generation from Idaho. The ISO noted the proposed line is the only active project that would help fulfill that objective, making it the most timely and cost effective option. The project is expected to commence operation in 2028.

CAISO also said SWIP-North would provide additional economic benefits, such as improving California’s resource diversity and increasing the ability to reduce congestion costs on the parallel California-Oregon Intertie. The line also will assist California in reducing renewable energy curtailments and exporting its solar surpluses.

CAISO’s pursuit of the line likely has played a key role in Idaho Power’s leaning in favor of joining CAISO’s Extended Day-Ahead Market (EDAM) rather than SPP’s Markets+. (See CAISO’s EDAM Scores Key Wins in Contested Northwest.)

And last year, Ryan Atkins, NV Energy’s vice president of resource optimization and resource planning, pointed to SWIP-North and the EDAM’s growing transmission footprint when explaining the utility’s reason for choosing the CAISO market in comments to the Public Utility Commission of Nevada. (See Market Footprint Critical for EDAM Decision, NV Energy Says.)