Dive Brief:

• The California Independent System Operator (CAISO) on Monday issued a 20-year draft transmission outlook plan for the first time, detailing the long-term infrastructure required to achieve clean energy goals in the grid operator’s footprint.
• The draft outlook, developed along with the California Public Utilities Commission and California Energy Commission, assumes that the state will need to add around 120 GW of new resources — including utility-scale solar, energy storage, offshore wind, and out-of-state clean energy — to the system by 2040, in order to meet the rising demand for electricity.
• “There is a critical need for more proactive, long-term transmission planning and coordination,” CAISO President and CEO Elliot Mainzer said in a statement, adding that “this type of forward-looking planning and coordination is essential to meeting the state’s energy policy goals in a reliable and cost-effective fashion.”

Dive Insight:

California is aiming to supply 100% of its electric retail sales with renewable and zero-carbon resources by 2045, a target that — along with the electrification of transportation and other sectors — is driving the need for rapid development of renewable resources and energy storage over the next couple of decades. 

This build-out will also necessitate significant transmission additions to connect out-of-state energy, as well as other generation pockets, CAISO noted in the draft outlook. The system operator has a 10-year transmission planning process; however, given that transmission requires long lead times thanks to permitting processes and right-of-way acquisitions, it concluded that a longer-term blueprint is essential. 

In the 20-year outlook, the energy agencies accounted for the resources needed to meet California’s 2045 goals and put together a “starting point” scenario, which took into consideration CAISO’s forecasted 2040 peak load, subtracted the contribution of forecasted behind-the-meter resources, and then factored in a projected reduction of 15,000 MW of natural gas-fired generation. 

The result was a scenario that called for 37 GW of battery storage, 4 GW of long-duration storage, around 53 GW of utility-scale solar, 24 GW of wind generation, and more than 2 GW of geothermal energy. The system operator then mapped resources to the regions they are required in, thereby identifying areas that need additional transmission build-out. 

The result points to the need for a significant build-out of transmission to beef up the existing CAISO system, as well as connect offshore and out-of-state wind, projected to cost roughly $30.5 billion. 

“California is working very diligently to ensure resource adequacy during this transition to a carbon-free system,” Mainzer said. Last year, he added, 79 clean energy projects were brought online in the state, the largest number in a single year. 

“This improved transmission planning and coordination with regulatory agencies and other partners will help ensure that California can sustain and even exceed that pace and meet the challenge of achieving a reliable clean-energy grid,” according to Mainzer. 

The ISO’s 10-year transmission plan was also developed at the same time, and recommends approving $2.9 billion of projects in a bid to boost grid reliability and facilitate more renewable energy. If approved by the ISO Board of Governors in March, those projects could begin later this year.