One of California’s largest energy utilities took a bold step in the 21st century electricity revolution with an agreement to close its last operating nuclear plant and develop more solar, wind and other clean power technologies.

The decision announced Tuesday by Pacific Gas & Electric Co. to close its beleaguered Diablo Canyon nuclear plant within the next decade runs counter to the nuclear industry’s arguments that curbing carbon emissions and combating climate change require use of nuclear power, which generates the most electricity without harmful emissions.

Instead, PG&E joined with longtime adversaries such as the Friends of the Earth environmental group to craft a deal that will bring the company closer to the mandate that 50% of California’s electricity generation come from renewable energy sources by 2030.

LATEST: It’ll take time — and $3.8 billion — to shut down the Diablo Canyon nuclear power plant >>


PG&E’s agreement will close the book on the state’s history as a nuclear pioneer, but adds to its clean energy reputation. California already leads the nation by far in use of solar energy generated by rooftop panels and by sprawling power arrays in the desert.

“California is already a leader in curtailing greenhouse gases,” said Peter Bradford, a former member of the U.S. Nuclear Regulatory Commission. “Now they’re saying they can go even further. That’s potentially a model for other situations.”

Under the proposal, the Diablo Canyon Power Plant in San Luis Obispo County would be retired by PG&E after its current U.S. Nuclear Regulatory Commission operating licenses expire in November 2024 and August 2025.

The power produced by Diablo Canyon’s two nuclear reactors would be replaced with investment in a greenhouse-gas-free portfolio of energy efficiency, renewables and energy storage, PG&E said. The proposal is contingent on a number of regulatory actions, including approvals from the California Public Utilities Commission.


The Diablo Canyon nuclear plant, built against a seaside cliff near Avila Beach, provides 2,160 megawatts of electricity for Central and Northern California — enough to power more than 1.7 million homes.

Tuesday’s announcement comes after a long debate over the fate of the plant, which sits near several earthquake fault lines. The Hosgri Fault, located three miles from Diablo Canyon, was discovered in 1971, three years after construction of the plant began.

Calls to close Diablo Canyon escalated after a 2011 quake in Japan damaged two reactors at the Fukushima Daiichi nuclear power plant there, leading to dangerous radiation leaks. In the aftermath of that disaster, state and federal lawmakers called for immediate reviews of Diablo Canyon and the San Onofre nuclear plant in San Diego County, which was still in use.


The San Onofre plant was shut down for good in 2013 as a result of faulty equipment that led to a small release of radioactive steam and a heated regulatory battle over the plant’s license.

In documents submitted to the federal Nuclear Regulatory Commission as recently as last year, PG&E said Diablo Canyon can safely withstand earthquakes, tsunamis and flooding.

Daniel Hirsch, director of the program on Environmental and Nuclear Policy at UC Santa Cruz, said PG&E’s agreement was thoughtful.

“It is not simply a decision to phase out the plant, but to replace it with efficiency and renewables,” he said. “So it is a very strong net gain for the environment.”


As the state boosts its energy efficiency goals and plans for renewables, including solar and wind power, Hirsch said, Diablo Canyon is “getting in the way.”

PG&E Chief Executive Tony Earley acknowledged the changing landscape in California, noting that energy efficiency, renewables and storage are “central to the state’s energy policy.”

“As we make this transition, Diablo Canyon’s full output will no longer be required,” he said. That eventually would make the nuclear plant too expensive to operate, Earley said during a conference call with reporters.

Hirsch tempered his approval with caution, saying that as long as the plant remains in operation, safety risks remain.


“Diablo really does pose a clear and present danger,” he said. “If we had an earthquake larger than the plant was designed for, you could have a Fukushima-type event that could devastate a large part of California.”

State senate leader Kevin de León (D-Los Angeles) echoed Hirsch by saying nuclear energy is “inherently risky, and the Diablo Canyon Power Plant is vulnerable to damage from natural disasters that could threaten the well-being of millions of Californians. This transition will make our energy sources less volatile, more cost-effective, and benefit the air we breathe.”

In the mid-2000s, the nation’s utilities had anticipated a nuclear renaissance that would usher in a new age of centralized power plants. Power companies submitted proposals to the U.S. Nuclear Regulatory Commission for 31 new reactors. President George W. Bush pushed federal loan guarantees to hasten nuclear plant construction.

However, instead of a renaissance, the nuclear industry began to unravel.


Duke Energy announced in February 2013 that it would close the Crystal River, Fla., nuclear plant after a steam generator replacement project led to cracks in the concrete reactor containment building. The plant became too costly to fix.

In May 2013, Dominion Resources Inc., permanently shut down the Kewaunee nuclear plant in Wisconsin after the power company said it was no longer affordable to operate the facility.

A month later, Southern California Edison permanently closed the San Onofre plant after the determining that fixing the new but faulty steam generators would prove too expensive.


Perhaps the biggest problem for the nuclear industry was the vast amount of natural gas that became available in the United States because of fracking.

Natural gas plants now are far cheaper to build and operate than a nuclear plant. A natural gas facility runs at about 8 or 9 cents a kilowatt hour compared with twice that much for a nuclear plant.

And the push for renewable energy has turned attention to solar and wind power to help reduce emissions and combat human-caused climate change.

“The unraveling of the renaissance was not a surprise to anyone who understood the workings of the power markets,” said Bradford, the former U.S. Nuclear Regulatory Commission member. He serves as an expert witness in legal proceedings across the nation.


Bradford said PG&E’s plan for Diablo Canyon shows the flaws in arguments by the nuclear industry that a clean-energy network requires nuclear.

“It’s a very tough day for people who have been advocating for massive nuclear subsidies,” Bradford said.

Even after Diablo Canyon closes, Southern California will still get a small percentage of its electricity from Arizona’s Palo Verde nuclear plant. Among the owners of the 4,000 megawatt nuclear plant in the Arizona desert are Southern California Edison, the Los Angeles Department of Water and Power and the Southern California Public Power Authority, whose members include municipal power companies supplying Glendale, Pasadena, Burbank and Anaheim.

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The impending closure of Diablo Canyon would leave just one nuclear plant on the West Coast, the Columbia Generating Station, about 200 miles outside of Seattle.

To craft Tuesday’s proposal, PG&E worked with the International Brotherhood of Electrical Workers Local 1245, the Coalition of California Utility Employees, the Natural Resources Defense Council, Environment California, Friends of the Earth and the Alliance for Nuclear Responsibility.

ivan.penn@latimes.com

samantha.masunaga@latimes.com


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UPDATES:

3:37 p.m.: This article was updated with additional reaction.

1:05 p.m.: This article was updated with comments from former U.S. Nuclear Regulatory Commission member Peter Bradford, and adds information about other nuclear power plants in Arizona and Washington.

12:18 p.m.: This article was updated with information about the growth of nuclear energy, problems facing the industry and an addition comment from PG&E chief Tony Earley.


9:18 a.m.: This article was updated with additional information about the proposal and with comments from Rep. Lois Capps.

8:24 a.m.: This article was updated with comments from UC Santa Cruz’s Daniel Hirsch and PG&E chief Tony Earley and with additional background information.

7:49 a.m.: This article was updated with background information.

This article was originally published at 7:15 a.m.