CAISO Pursuing Approval of New Line to Tap Idaho Wind
Project Would Help Calif. and Idaho Meet Renewable and RA Needs, ISO Officials Say
SWIP-N would give California access to Idaho wind resources.
SWIP-N would give California access to Idaho wind resources. | DOE
CAISO is moving quickly to gain approval for a proposed transmission line that would allow California to meet targets for tapping Idaho wind resources while helping both states bolster their resource adequacy.

CAISO is moving quickly to gain approval for a proposed transmission line that would allow California to meet targets for tapping Idaho wind resources and help both states bolster their resource adequacy profiles.  

The ISO is seeking to acquire enough entitlements on the Southwest Intertie Project–North (SWIP-N) to import 1,000 MW of wind energy from Idaho, aligning with the plans to access Idaho wind that have been set out in utility integrated resource plans filed with the California Public Utilities Commission.  

“Transmission development is needed to access out-of-state wind resources and this project is the only known transmission project that can enable access to Idaho wind resources,” CAISO said in a slide presentation shown during a Nov. 7 stakeholder meeting to discuss SWIP-N, which is being developed by LS Power subsidiary Great Basin Transmission (GBT).  

SWIP-N would link to the One Nevada (ON) line at Robinson Summit in Nevada and run north 285 miles into Idaho, providing 2,070 MW of transfer capacity southbound and 1,920 MW northbound. The ON line is connected to the Desert Link, which extended CAISO’s operational boundary to the Harry Allen substation north of Las Vegas when it went into service in 2020. 

The entitlement structure for SWIP-N would provide GBT with 1,117.5 MW of north-to-south capacity and 1,072.5 MW of south-to-north capacity, with the balance in both directions allocated to Nevada-based NV Energy.    

CAISO is considering a proposal to leverage a transmission use and capacity exchange agreement (TUA) between NV Energy and GBT that would allow the ISO to acquire most of GBT’s entitlements on the SWIP-N line and ON line rather than building a new, roughly 500-mile transmission line to reach Idaho’s resources. Under the plan, Idaho Power would assume 500 MW of south-to-north capacity on the line to support winter RA needs.  

The plan was spelled out in a Nov. 1 letter Idaho Power sent to CAISO CEO Elliot Mainzer expressing interest in partnering with the ISO to fund SWIP-N as a “joint regional policy-driven project.” It would also give the Boise-based utility access to the Desert Southwest wholesale power market.   

Under the plan, CAISO and Idaho Power would share the more than $1 billion cost for the line — or about $3.8 million per mile, which the ISO said is close to the per-mile costs for other competitively procured transmission projects in the region. The ISO would fund 77.2% of the project, with Idaho Power picking up the rest. Based on the TUA, CAISO would pay no additional costs for assuming GBT’s entitlements on the ON line.  

“Transmission infrastructure is a primary key enabler to a cost-effective, reliable and clean energy future. Idaho Power believes that cost effective transmission is a no-regret investment,” Idaho Power said in the letter. “All feasible scenarios related to electric grids of the future will continue to heavily utilize interregional transmission infrastructure.” 

During the Nov. 7 meeting, CAISO told stakeholders SWIP-N will help Idaho and California meet their resource portfolio needs while sharing project costs, reducing the cost to California ratepayers. The ISO also said the project has the advantage of being shovel-ready. 

Still, construction of SWIP-N is contingent on Idaho Power and GBT reaching an agreement that is conditioned on CAISO’s approval of the project, FERC’s approval of the agreement between Idaho Power and GBT, and an Idaho Public Utilities Commission (IPUC) determination that the project will provide sufficient benefits to Idaho Power to justify the cost.  

If CAISO approves the project, Idaho Power will file for approval with the IPUC by year’s end and the project could begin operating by 2027.  

Stakeholder Feedback

CAISO stakeholders participating in the Nov. 2 meeting generally supported the SWIP-N proposal.  

“We appreciate the CAISO’s due diligence in exploring these opportunities to reduce the overall project cost to California ratepayers,” said Pushkar Wagle, managing consultant at Flynn Resource Consultants. However, Wagle questioned whether the project’s cost estimates were being downplayed.  

“You presented the numbers in terms of dollars per mile; that’s clearly one metric to look at it. Another metric is what’s dollars per megawatt or dollars per kilowatt-year?” Wagle said. “The way the models are run is basically they’re trying to minimize the overall cost of procurement, so if you plug in these numbers, you might get totally different answers.” 

Biju Gopi, CAISO senior manager of transmission interface coordination, emphasized that the cost shouldn’t be a significant concern. “Resource choices are generally stable and cost is not so much a factor as compared to other elements like resource potential limits [or] transmission limitations,” he said.  

But Kanya Dorland, senior analyst with CPUC’s Public Advocates Office, echoed Wagle’s comments. 

“SWIP-N has been studied for almost 10 years as both a public policy and economic project and each time it’s determined that its costs outweigh the benefits,” Dorland said. “It sounds positive that Idaho Power would contribute, but is the benefit-cost ratio greater than one with this new arrangement, or would it be better with a [Department of Energy] loan?” 

CAISO requested that GBT pursue a DOE loan to finance construction of the project, but Gopi was not aware if it was awarded.  

Gopi again highlighted that the goal of the project — to access Idaho’s wind resources — outweighs potential costs.  

“We’re pursuing this project not as an economic-driven project but as a policy-driven project,” Gopi said. “CPUC requirements do require us to plan for integrating wind resources from Idaho into California.” 

CAISO expects to seek conditional approval for SWIP-N from the board by early December. Full approval is conditioned on Idaho Power receiving IPUC approval for the line by June 2024, GBT applying to become a participating transmission owner in the ISO by July 1, 2024, and FERC’s acceptance of GBT’s transmission owner tariff and transmission revenue requirement rate structure. 

Stakeholder comments on the proposal are due to CAISO by Nov. 21. 

CAISO/WEIMOnshore WindTransmission Planning

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