The California Independent System Operator Board of Governors has approved the ISO’s 2024-2025 transmission plan, recommending 31 infrastructure projects to help meet projected load growth and changing grid conditions.
The plan identifies 28 transmission projects required to reliably supply the increase in forecasted demand related to electrification, particularly in the Greater San Francisco Bay Area, and to address load growth from electric vehicle use.
Three additional projects are needed to meet renewable generation requirements established in the state’s energy portfolios developed by the California Public Utilities Commission.
Altogether, the 31 projects would cost an estimated $4.8 billion at full buildout, which is projected to occur over the next 10 to 15 years.
Included in the approved upgrades are five reconductoring projects that use advanced conductors to add transmission capacity without having to incur the cost of building new lines. These and other grid-enhancing technologies have been part of the ISO’s transmission planning process for a number of years.
“This year’s transmission plan continues to reflect the ISO’s proactive approach to transmission planning and the ongoing collaboration we have with our local, state and regional partners,” said Neil Millar, the ISO’s vice president for transmission planning and infrastructure development. “We are working together to make sure California has the vital infrastructure needed to deliver clean, reliable energy as cost-effectively as possible to consumers.”
Transmission planning is a core responsibility of the ISO. The system operator produces an annual transmission plan based on a comprehensive assessment of the electrical system’s needs.
In the past, those annual plans typically assessed a 10-year horizon, but this year, in response to state legislation passed in 2022, the timeline was extended to 15 years to ensure enough lead time to analyze and approve transmission development, and for permitting and construction of approved projects.
Drafted in close consultation with the CPUC, the California Energy Commission and other local regulatory authorities, the 2024-2025 plan is based on state projections provided to the ISO in 2024 indicating that California needs to add more than 76 gigawatts of capacity by 2039.
This year’s plan was heavily influenced by the escalating rate of load growth forecast in the state and the need to provide reliable service during these rapidly changing circumstances, CAISO said.
The plan reflects a projected 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 due to electrification of the transportation and building sectors of the state’s economy and an anticipated increase in data centers used for artificial intelligence.
In putting together its annual transmission plan, the ISO also considers hundreds of options and detailed assessments of alternatives to find the most cost-effective transmission solutions possible. Those alternatives include transmission upgrades, preferred resources such as storage, grid-enhancing technologies, and remedial action schemes, it said.
Specific reliability-driven and policy-driven projects approved in the plan, most notably related to load growth in the Greater Bay area, 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 the north Oakland area and upgrading the capacity of existing 115 kV lines and substations in the area;
• South Oakland Reinforcement – reconductoring of three 115 kV lines; and
• A host of smaller upgrades improving supply of load and access to other smaller resource zones.
The plan was developed following extensive stakeholder engagement and multiple public presentations and solicitation of stakeholder comments.
