CAISO Responds to Load Growth, Proposes $4.6 Billion of New Transmission Facilities To Boost Reliability

April 1, 2025

In its 2024–2025 Draft Transmission Plan (Draft Plan) released on March 31, the California Independent System Operator (CAISO) proposed the development of 31 new transmission projects with an estimated cost of $4.8 billion. Of that total, 28 projects costing an estimated $4.6 billion are reliability-driven projects needed to respond to a rapid escalation of load growth.

In the last four years, the need for new resources needed to meet load has grown from 1,000 megawatts (MW) per year to a forecasted 5,000 to 7,000 MW per year. Increasing rates of load growth have been driven by a proliferation of data centers, especially in the San Francisco Bay Area, and by California’s push to electrify the transportation and building sectors to achieve clean energy and greenhouse gas emission-reduction goals. The year-over-year growth rate of peak demand has increased, especially in the Greater Bay Area, where the 2035 peak load forecast will require an additional 2,000 MW compared to the previous planning cycle.

To address rapid load growth in the Greater Bay Area, the proposed projects include a new 500 kilovolt (kV) transmission line to supply the south Bay Area and a new 230 kV transmission line in the San Jose area that will connect two projects authorized in the CAISO’s 2021-2022 Transmission Plan. The CAISO will conduct a competitive solicitation to select the sponsors who will construct, own, and operate these projects.

Overall, the Draft Plan is designed to connect 76 gigawatts (GW) of new electric generation that the state will need by 2039.

Developed in close coordination with the California Public Utilities Commission (CPUC) and the California Energy Commission, the Draft Plan continues these agencies’ efforts to better synchronize resource planning and transmission planning. The transmission projects are needed to maintain reliability and to connect 76 GW of new resources that the CPUC concluded are required by 2035 to meet load growth and achieve zero-carbon goals. The projected resource needs include 30 GW of new solar generation, 7 GW of in-state wind resources, 9 GW of out-of-state wind, and 4.5 GW of offshore wind, split between the Morro Bay call area on the Central Coast and the Humboldt call area on the North Coast.

In this planning cycle, the CAISO has continued its consideration of Grid-Enhancing Technologies—including advanced conductors (high temperature, low sag), dynamic line ratings, power flow controllers, and topology optimizations—as alternatives to capital investments or for deployment in proposed projects.

Following stakeholder meetings on April 15 and comments due on April 29, the CAISO Board of Governors will review and adopt the Final Transmission Plan in May.