CA AB2255

Requires the Public Utilities Commission (PUC) and Energy Commission to incorporate long-duration energy storage systems (capable of discharging at full capacity for at least 8 hours) into energy and resource planning.

Directs the Independent System Operator (ISO) to assess by March 31, 2021, whether long-duration energy storage is needed by 2030 to meet California's clean energy goals under specific modeling scenarios, then report findings to the PUC, Energy Commission, and Governor.

Authorizes the Governor, within 90 days of receiving the ISO's assessment, to determine whether to proceed with long-duration energy storage development and, if approved, direct the ISO to establish a competitive solicitation process and cost-recovery mechanisms for projects operational by December 31, 2030.

Requires the PUC to evaluate long-duration storage's role in grid reliability, renewable energy integration, and resiliency as part of integrated resource planning, and consider supporting measures including research, development, demonstration, procurement, and incentives.

Allows the ISO to withdraw its FERC application if federal regulators preempt state requirements, impose materially different mechanisms, or take actions that negatively impact California's 2030 and 2045 renewable energy and climate goals.