Adios, Diablo Canyon

Updated October 1, 2018

By 2025, the reactors at the Diablo Canyon nuclear facility—the last of its kind in California—will begin the decades-long decommissioning process. And, for the first time ever, reactors will be retired with a plan already in place to prevent fossil fuels from filling the gap they leave in the grid.

NRDC and fellow environmental organization Friends of the Earth led the negotiations with Pacific Gas & Electric (PG&E), the northern California utility that owns the reactors near San Luis Obispo. Over several months, the parties reached a deal that would replace the reactors’ output with a combination of renewable energy, efficiency gains, smarter grid management practices, and storage technology.

Because California leads the nation on environmental issues, including pioneering auto emissions and building energy-efficiency standards, the state’s proposed phaseout of nuclear power provides a glimpse into the future energy grid for the United States: shrinking shares for nuclear and fossil fuels, rapid expansion of energy efficiency and renewables, and an embrace of emerging technologies.

The Devil and the Deep Blue Sea

Fans of nominative determinism—the idea that names shape destiny—could have seen trouble coming for Diablo Canyon. Naming a nuclear facility after Lucifer himself is asking for trouble. But there were a host of more practical reasons to mothball these reactors.

Diablo was controversial even during its construction in the 1970s. The plant’s seaside location, which enabled it to draw cooling water from the Pacific Ocean, sat near a well-known seismic fault. Two thousand protesters were arrested for occupying the site. Among the last arrested was the current NRDC director for western transmission, Carl Zichella, who was placed under arrest by the county sheriff in a show for reporters.

“We completely overwhelmed the San Luis Obispo County legal system,” Zichella remembers. “People were in and out of jail for weeks. Some, like the singer Jackson Browne, were arrested three times.“

Once the plant was in operation, new concerns arose. Its withdrawal and use of ocean water for cooling killed more than one billion fish in early life stages annually. But even without the specter of a disaster or that level of piscine carnage, there are solid reasons to shut down Diablo Canyon.

For example, you can’t swiftly ramp a nuclear plant up or down. The reactors rumbles along continuously, regardless of changes in demand or the other sources of electricity feeding into the grid. For that reason, Diablo Canyon has been blocking solar and other renewables from coming online.

Diablo provides about 6 percent of the power generation for California, and that output is basically constant and unchanging. When the sun shines bright or the wind blows hard, cheaper, cleaner renewable energy could provide that 6 percent. But it doesn’t have the chance, because Diablo Canyon keeps running and running even when it’s not needed. PG&E regularly wastes renewable energy as a result. The very existence of the Diablo Canyon nuclear facility disincentivizes PG&E from further investing in renewables. The two reactors are tied to the utility’s ankles like a ball and chain.

Replacing the Energy

Diablo Canyon produces about 17,000 gigawatt-hours of electricity per year. That’s a significant gap to fill, equivalent to the energy use of about three million homes. Rather than attempting to map out a strategy to address all that demand in 2016, nearly a decade before the reactors shut down, PG&E has taken the reasonable step of breaking the process into three stages to allow the utility to take advantage of technological advancements that emerge over the next nine years. The staging also allows PG&E to better serve the shifting electricity needs of its customers in the long term, especially if homes continue to become more energy efficient.

In the first stage, to begin in 2018 and run through 2024, PG&E has guaranteed the installation of 2,000 gigawatt-hours—the approximate annual consumption of 300,000 California homes—of energy-efficiency improvements such as home insulation or commercial air conditioners that use less electricity. During the second stage, which runs from 2024 to 2030, the utility will ramp up generation of renewable, greenhouse gas–free energy—enough to replace another 2,000 gigawatt-hours of Diablo Canyon’s output. That could be solar, wind, or other technologies that may not even exist today. Finally, after 2030, the plan envisions that 55 percent of PG&E’s energy will come from renewable sources, five percentage points higher than California state law requires. The assumption is that, by then, many technologies that are now in their infancy will be available. Improved storage techniques—such as batteries or pumping water to height to create potential energy, then running it back downhill and capturing the electricity using a turbine—are among the many possibilities.

The careful construction of this proposal sends a message to other utilities that operate nuclear reactors: You can replace reactors without increasing greenhouse gas output.

“The United States has close to 100 other aging nuclear plants,” says Ralph Cavanagh, codirector of NRDC’s energy program. “For the utility owners and customers of those plants, the replacement of Diablo Canyon with clean resources will be showing the way to a more reliable, lower-cost power system.”

Other U.S. nuclear power plants have been closing, and more will follow. The challenge now is to make sure that clean energy solutions are waiting in the wings instead of more fossil fuel generation. Diablo Canyon is the first step.

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