September 19, 2022

Nuclear power provided about 10% of California’s total electricity supply in 2021

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In 2021, three nuclear power plants supplied about 10% of California’s electricity. Diablo Canyon, located in San Luis Obispo County, is California’s last operating nuclear power plant, and it supplied over 8% of California’s electricity in 2021. The remaining nuclear electricity supply was imported from the Palo Verde Generating Station in Arizona and the Columbia Generating Station in Washington.

California has the largest state economy in the United States and is the fourth-largest electricity producer in the nation, accounting for about 5% of U.S. utility-scale electricity generation in 2021. Because more electricity is consumed in California than is produced there, about 30% of its electricity supply is imported, and 36% of its nuclear electricity supply is imported, based on data from the California Energy Commission. Most of California’s imported nuclear power comes from Arizona and the remainder from Washington.

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After the San Onofre plant was permanently closed in 2013, Diablo Canyon became California’s last operating nuclear power plant. Diablo Canyon has two operating pressurized water reactor units, with a combined generating capacity of 2.2 gigawatts (GW). The facility is California’s largest single source of electricity; in 2021, it produced 64% of the state’s nuclear power supply (16,477 gigawatthours [GWh]).

In 2018, PG&E agreed to a settlement with state regulators, environmental groups, and labor organizations and agreed not to seek to renew the operating licenses for its two reactors, which will expire in 2024 and 2025. Given electricity reliability concerns, however, California recently approved legislation to keep Diablo Canyon operational until 2029 and 2030, and the state is also considering the option of further extending the plant’s life through 2035. The legislation includes a $1.4 billion loan from the state’s general fund to PG&E to cover the reactor unit relicensing costs.

Palo Verde Generating Station is the largest nuclear power plant in the United States and is located approximately 55 miles west of downtown Phoenix, Arizona. The facility operates three pressurized water reactors, with a combined capacity of 3.8 GW, which were commissioned in the late 1980s. In 2011, the Nuclear Regulatory Commission approved a license renewal to continue operating until 2047. In 2021, the facility produced 31,281 GWh of electricity, which supplied portions of Arizona, California, New Mexico, and Texas. Electricity imported from Palo Verde accounted for 34% of California’s total nuclear electricity supply.

The Columbia Generating Station, located near Richland, Washington, is the Northwest’s only commercial nuclear power facility and is the third-largest electricity generator in Washington State. Electricity produced at the 1.8 GW capacity facility accounted for 2% of California’s nuclear electricity supply. The reactor’s operating license was renewed in 2012, and it now expires in 2043.

Principal contributors: Slade Johnson, Katherine Antonio