Federal regulators on Thursday renewed the license for California’s last nuclear power plant, ensuring Diablo Canyon will remain open until at least 2030 after years of debate over safety, climate goals and the state’s ability to keep the lights on.

The plant on the San Luis Obispo County coast, about 200 miles south of San Jose, provides roughly 9% of California’s electricity — enough power for nearly 4 million people — but its usefulness is being debated as battery storage has expanded, providing more stable renewable energy to the state.

California had planned to shut down Diablo by 2025. But after extreme heat waves in 2020 and 2021 strained the grid, Gov. Gavin Newsom and state lawmakers moved in 2022 to keep the plant operating longer. Thursday’s decision by the NRC allows that plan to move forward

As Newsom and state lawmakers moved to keep the plant operating, they directed PG&E, its owner, to pursue a license extension. The state also approved a $1.4 billion loan to PG&E to cover upgrades and relicensing costs, backed by guarantees from the Biden administration.

On Thursday, the Nuclear Regulatory Commission granted Diablo Canyon a 20-year lease renewal, until 2045.

“As California advances its clean energy and reliability goals, Diablo Canyon remains a stabilizing force on a dynamic grid,” said Jeremy Groom, acting director of the nuclear reactor regulation at the Nuclear Regulatory Commission, at a ceremony at the plant with hundreds of cheering PG&E employees. “It provides a steady source of carbon-free power during a period of rapid transition, supporting climate objectives while ensuring that the lights stay on at homes and businesses across the state.”

Newsom praised the decision, calling it “essential to building a safe, affordable, and resilient future for our state.”

To operate beyond 2030, PG&E will still need approval from the state legislature — setting up what could be another political fight over the plant’s future.

Opponents say the extension ignores longstanding concerns about earthquake risks and the plant’s use of more than 2 billion gallons of ocean water daily for cooling.

“We’re disappointed and concerned,” said Haakon Williams, executive director of the Committee to Bridge the Gap, an anti-nuclear group. “The Nuclear Regulatory Commission was always more beholden to industry than it should be. This shouldn’t be received as an assurance of the plant’s safety.”

Williams and other critics argue that since 2020, California’s rapid expansion of battery storage — which allows solar and wind energy to be used at night — has reduced the risk of blackouts.

Business leaders and energy advocates, however, say Diablo Canyon remains critical.

“At a time when California is trying to grow its economy, bring down costs and lead on climate, we cannot afford to lose power that is clean, stable and always available,” said John Grubb, interim president and CEO of the Bay Area Council, whose membership includes more than 350 large companies.

“This facility does something incredibly important,” he added. “It keeps the lights on when demand is high, when renewables aren’t enough and when reliability matters most. That’s not theoretical. That’s essential infrastructure.”

In the 1960s and early 1970s, PG&E proposed building numerous nuclear power plants along the California coast, including at Bodega Bay in Sonoma County and Davenport in Santa Cruz County. Due to local opposition, most were never built.

The Sierra Club supported the construction of Diablo Canyon. At the time, leaders said nuclear power would be less harmful than coal-fired power or new hydroelectric dams, particularly after PG&E agreed to move the plant from the environmentally sensitive Nipomo Dunes area near the Santa Barbara-San Luis Obispo County line to its location north of Avila Beach. That debate split the Sierra Club, leading to the resignation of its leader, David Brower.

After construction began on the plant in 1968, several previously unknown earthquake faults were discovered. Lawsuits, protests involving celebrities like singer Jackson Browne, studies and redesign work delayed its opening until 1985, when the first of its two massive reactors was finally turned on.

Since then, Diablo Canyon has never had a significant accident.

“Diablo Canyon meets the highest standards of nuclear safety and environmental protection,” said Paula Gerfen, PG&E’s senior vice president and chief nuclear officer, on Thursday, adding, in reference to federal and state authorities approving the license extension: “They are saying we are safe and we are environmentally sound and it doesn’t get any better than that.”

Blackouts and power shortages in 2020 and 2021 posed a major political risk to Newsom and Democrats pushing for the state to achieve 100% carbon-free electricity to combat climate change. Not only was former Gov. Gray Davis recalled from office in 2003 amid energy shortages, but Republicans were attacking California for its lack of reliability five years ago.

“Our leaders were worried about blackouts,” said Severin Borenstein, an energy economist at UC Berkeley. “It was a real concern that this could set back the movement to decarbonize the grid. That opened a lot of people up who had once said ‘we have to get rid of nuclear power’ to the idea we have to continue with Diablo Canyon.”

He noted that although battery storage plants have improved the situation dramatically, most only store 4 hours of electricity.

“Would we make the same decision now to keep Diablo Canyon open that we made a few years ago? I don’t know,” Borenstein said. “We hadn’t had the massive rollout of batteries. But there are still things Diablo Canyon can do that batteries can’t.”

California once had four nuclear power plants. Humboldt Bay near Eureka closed in 1976. Rancho Seco near Sacramento closed in 1989. San Onofre in San Diego County closed in 2013.

No new ones can be built under existing state law. Former Gov. Jerry Brown signed legislation in 1976 that prohibited the construction of new nuclear power plants in California until a permanent repository for spent nuclear waste is established by the federal government.

A plan to build a national nuclear waste storage site in the remote desert at Yucca Mountain, Nevada, stalled in the 1990s over opposition from environmentalists and Las Vegas casino owners. As a result, spent nuclear fuel rods that will remain radioactive for thousands of years continue to be stored on site at many of America’s 54 nuclear power plants, including Diablo Canyon.

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