California leads US in renewable growth amid federal rollback as battery storage hits record high

As California governor Gavin Newsom asserted at the COP30 summit in Belém, the state has positioned itself as the most prominent American voice on climate in the absence of senior federal representation. Speaking to delegates, Newsom said: “We’re running the fourth-largest economy in the world [on] 67%, two thirds, clean energy on nine out of 10 days in 2025.” He added: “Outside of China, there’s only one other jurisdiction in the world – California – that has as much battery storage implemented.” According to The Guardian, his remarks framed California as a “stable, reliable” climate leader filling a gap while the federal administration retreats from many emissions policies.

The advance Newsom touted is concrete. The governor’s office announced on 13 November 2025 that California’s battery storage fleet has reached 16,942 megawatts, a figure the state described as a 2,100% increase since 2019 and equivalent to roughly one-third of the storage capacity the state says it will need by 2045 to meet its 100% clean electricity goal. The California Energy Commission reported in November 2025 that battery capacity had grown to 16,942 megawatts, calling the expansion “record growth” and emphasising that it includes both utility-scale projects and behind‑the‑meter systems.

Those gains form part of a broader build-out. State data released in June 2025 showed nearly 7,000 megawatts of new clean energy capacity were added in 2024, the largest single‑year increase in the state’s history. The governor’s office and the energy commission further note that since 2019 California has added more than 30,000 megawatts of clean energy and storage capacity, an expansion the state says is sufficient to meet roughly half of a record peak demand this year.

Industry and academic voices describe the shift as material but incomplete. Stanford professor Mark Jacobson told The Guardian that the change is “remarkable,” pointing to the role of solar and batteries in displacing fossil generation. Caiso, the non‑profit operator of the state’s main grid, has credited batteries with helping to avert rolling blackouts by storing daytime solar output for evening use. “Having a mix of resources that are capable of producing when needed is an important addition as we try to make this transition to renewable resources,” Caiso senior vice‑president Mark Rothleder said to The Guardian.

Yet the grid still relies on dispatchable resources. Natural gas remained the single largest resource for electricity production in 2024 even as generation from gas fell by 8% that year, according to the California Energy Commission. Nuclear generation contributed nearly 10% of statewide electricity in 2024, and many analysts stress that gas plants currently serve as a critical backstop during evening peaks and extreme weather events.

That reliance fuels debate over the pace and pathway of decarbonisation. Environmental campaigners and state reports argue batteries are already a cost‑competitive and cleaner alternative to many gas plants. A 2025 report from Regenerate California, co‑authored by Sierra Club campaigners and the California Environmental Justice Alliance, concluded that batteries can be less expensive, more reliable, and reduce toxic air pollution compared with peaking gas plants; Heena Singh of the alliance told The Guardian that batteries “can provide even more benefits because of their ability to ramp up so quickly.”

Politics at the federal level has sharpened the contest. The Guardian detailed a catalogue of federal actions under the current administration that have pulled back support for renewables or sought to expand fossil fuel development, including the termination of a $7bn programme to bring solar to low‑income communities and cancelled federal funding for offshore wind projects that had included west‑coast investments. The White House has also moved to resume offshore lease sales and blocked California’s rule phasing out new gas‑powered car sales by 2030, prompting legal and political pushback. The state attorney‑general’s office has created a unit dedicated to litigating federal rollbacks, and lawyers say vigorous legal resistance will continue.

California’s trajectory suggests a dual track: aggressive state action to deploy renewables and storage while defending those policies in the courts. State officials say the storage build‑out and the near‑record year of clean capacity additions in 2024 illustrate the momentum behind a decarbonised grid. Industry data shows utility‑scale solar output surged in 2025, with utility records indicating that solar produced tens of billions of kilowatt‑hours in the first eight months of the year, helping drive fossil‑fuel generation to a multi‑decade low of around a quarter of the state’s electricity mix by October 2025.

Still, technical and social challenges remain. Grid operators caution that solar and wind are intermittent and that the integration of increasingly large amounts of distributed rooftop solar, grid‑scale batteries, and demand‑flexibility measures will be necessary to reduce dependence on gas plants without compromising reliability. Environmental justice advocates emphasise that decisions about which resources remain online have community health implications, pointing to the air‑pollution benefits of retiring peaking gas plants that are often sited near disadvantaged communities.

For businesses involved in industrial decarbonisation, California’s experience is instructive: rapid deployment of batteries and solar can materially lower system‑level emissions and displace fossil generation, but achieving a reliable, fully decarbonised grid requires coordinated procurement, investment in storage and grid services, and policies that manage the transition for workers and communities dependent on conventional generation. The state’s officials and agencies frame their recent milestones as evidence that those pieces are beginning to fit together, while acknowledging the work ahead to meet the statutory goal of a 100% clean electricity grid by 2045.