Diablo Canyon Proposal Caps 50 Years of Clean Energy Success

The proposal by PG&E and a diverse array of groups, including NRDC, to close the Diablo Canyon nuclear power plant – the last operating nuclear plant in the state -- and replace it with clean energy led by energy efficiency and renewable resources signals the culmination of a half-century arc of California’s clean energy policy. (Blogs by my colleagues Rhea Suh and Ralph Cavanagh provide further details about this groundbreaking proposal.)

Diablo Canyon Nuclear Power Plant Pacific Gas and Electric Company

In 1974, I was about to enter high school in the smoggy San Fernando Valley. Joni Mitchell and Jackson Browne were on the radio. And Jerry Brown was elected governor for the first time.

It was a pivotal time for the energy sector. OPEC’s oil embargo the previous fall had raised the price of oil six-fold. Dozens of nuclear plants were planned or under construction, untarnished as yet by the partial meltdown at Three Mile Island. And public demands for clean air and clean water had been given force of law by passage of the Clean Water Act and the Clean Air Act.

In California, as elsewhere, utility companies were proposing vast fleets of power plants to meet projections of rapid growth in demand. Some 60 to 70 nuclear plants were proposed for the California coastline, roughly one every 10 miles from Mexico to the Oregon border. They were to be sited along the coast for easy access to the vast amounts of water needed to cool the enormous plants. But arrayed against the plants was a diverse coalition of opponents. Environmental advocates and local activists were doing everything they could to block construction in the courts and the streets, arguing that energy efficiency and renewables were cheaper and cleaner options. In one of my first political acts as an adult, in 1978 I joined that effort by joining the protests against the Diablo Canyon plant at Avila Beach.

Abalone Alliance armband Peter Miller

The California Legislature bridged this gulf with a remarkable political compromise that brought together the opposing sides in a shared mission. The Warren-Alquist Act, passed in 1974, agreed with the activists that the state should invest in energy efficiency when it was a cheaper alternative to building new power plants and a full array of energy sources should be considered, including renewables, to meet the needs of California utility customers. But the Act also agreed with the utilities that new plants should be built if necessary to meet demand, and created a new state authority that could override local concerns and approve siting of new power plants. In 1974, it was unclear which of these competing visions would prevail.

It will take 50 years to conclusively answer that question. But at long last, in 2024, California’s final operating nuclear power plant will begin to shut down for good. The settlement proposal provides a clear path to close the Diablo power plant and replace it with clean energy resources. It will save money for PG&E’s customers, provide support to the local community and workers for a just transition, end the nuclear facility’s destructive impact on the marine ecosystem, and speed the arrival of our clean energy future.

Energy efficiency has long ago been proven to be the cleanest, cheapest, and fastest energy resource for California. Building codes and appliance standards ensure that all new homes and appliances get more efficient year after year. Utility programs help customers reduce their demand for electricity and drive the adoption of more efficient equipment, homes, and offices. And RD&D into clean energy technologies helps ensure that new products continue to emerge. Since the 1970s, investments in energy efficiency have avoided the need for at least 30 large power plants in California and saved its consumers nearly $100 billion in lower utility bills.


The past decade has also seen dramatic reductions in the cost of wind and solar. Now new renewable power can be brought online for less than the cost of operating Diablo Canyon. Levelized bid prices for new utility-scale solar projects are now well under 5 cents per kilowatt-hour and many large wind projects come in well below 4 cents per kWh. And tens of thousands of homes and businesses are installing rooftop solar panels every year. The future of the California electric grid will be dominated by these abundant and inexpensive new sources.

Increased reliance on intermittent resources like wind and solar will require an evolution away from the traditional model of simply dispatching power plants to meet demand. In the future, storage technologies like batteries will store excess generation until it is needed and demand response technologies like smart thermostats will reduce the need for power when it’s most expensive. Together, these devices will form the backbone of the efficient and clean electric grid of the 21st century.

Closing Diablo makes more room for clean energy

Some may ask, doesn’t it make sense to keep Diablo operating given the threat of global warming? The answer is that there is less room on California’s electricity grid for large, inflexible baseload resources like Diablo, which are operated either all on or all off.  They can’t be ramped up and down when renewable energy like wind and solar is available to flood into the electricity system. California Independent System operator already has to curtail solar generation in the middle of sunny days, a problem that is expected to get worse. Replacing Diablo with lower cost clean energy resources and adding storage and demand response capabilities will allow California to meet and exceed the state’s 50 percent renewables mandate.

Today, the U.S. energy sector once again finds itself in a time of stormy change. The impending threat of catastrophic climate change requires dramatic reductions in greenhouse gas emissions. Volatile fossil fuel markets and public demands for clean air, clean water, and a secure future impose enormous pressures on the power gird and the myriad companies that keep the electricity that we take for granted flowing. The Diablo Proposal provides a beacon to guide other states and countries as they try to steer for calm waters. It also shows that it is possible to bring diverse stakeholders together around a common mission to minimize environmental impact, maximize economic benefits, and protect vulnerable communities. 

About the Authors

Peter Miller

Western Energy Project Director, Energy & Transportation program

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