The California Independent System Operator has released its draft 2024-2025 transmission plan, recommending 31 total projects costing an estimated $4.8 billion at buildout.
The vast majority of the projects – 28 of the 31 – are needed to strengthen reliability, meet load growth and adapt to changing grid conditions.
The draft 2024-2025 Transmission Plan also identifies a number of transmission upgrades that would be accomplished using grid-enhancing technologies – in this case, advanced conductors – to achieve required capacity ratings in the most cost-effective way possible.
“Our draft plan reflects the ISO’s proactive approach to transmission planning and underscores our ongoing collaboration with local, state, and regional partners to ensure California has the necessary infrastructure to deliver clean energy reliably and cost-effectively to consumers,” said Neil Millar, the ISO’s vice president for transmission planning and infrastructure development.
A public stakeholder call on the draft plan is scheduled for April 15, with comments due back to the ISO by April 29, 2025.
The plan is scheduled to be on the agenda at the ISO’s Board of Governors’ May meeting.
As drafted, the plan would accommodate the state’s forecasted load growth and critical resource development, including:
- More than 30 gigawatts (GW) of solar generation distributed across the state in solar development regions such as the Westlands area, the Tehachapi area, San Bernardino County, Riverside County, southern Nevada, and western Arizona;
- More than 7 GW of in-state wind generation in existing wind development regions, including the Tehachapi area;
- 2 GW of geothermal development, primarily in the Imperial Valley and southern Nevada;
- Access for battery storage projects co-located across the state with renewable generation projects, as well as stand-alone storage located closer to major load centers in the Los Angeles Basin, Greater Bay Area, and San Diego;
- 9 GW of out-of-state wind generation from Idaho, Wyoming and New Mexico, by enhancing mutually beneficial corridors from the ISO border in southeastern Nevada and from western Arizona into California load centers; and
- More than 4.5 GW of offshore wind with 2.9 GW in the Central Coast (Morro Bay call area) and 1.6 GW in the North Coast area (Humboldt call area).
The draft plan is designed to accommodate an increase in the year-over-year rate of peak demand growth from 0.99% to 1.53%.
In the Greater San Francisco Bay Area, the load growth is forecast to increase from 1.22% to 2.14%, with most of the growth coming from electrification of the transportation and building sectors of the state’s economy and an anticipated increase in data centers associated with artificial intelligence.
In putting together its annual transmission plan, the ISO works closely with the California Public Utilities Commission, the California Energy Commission and local regulatory authorities, and considers hundreds of detailed assessments and alternatives to find transmission solutions that are the most cost-effective and provide the greatest overall benefit, the grid operator said.
Those alternatives include transmission upgrades, preferred resources (such as storage), grid-enhancing technologies and remedial action schemes.
Projects recommended in the draft plan include:
- Greater Bay Area 500-kilovolt (kV) Transmission Reinforcement – new 500 kV line to supply the south Greater Bay area;
- San Jose B – Northern Receiving Station 230 kV Line – a new 230 kV line in the San Jose area;
- South Bay Reinforcement – reconductoring of five 115 kV lines and 115 kV system reconfigurations in the San Jose area;
- North Oakland Reinforcement – integrating two new 115 kV sources into north Oakland area and upgrading the capacity of existing 115 kV lines and substations in area;
- South Oakland Reinforcement – reconductoring of three 115 kV lines; and
- A number of smaller upgrades improving supply of load and access to other smaller resource zones.
