News and analysis about energy in California with an eye toward renewables.

Power Lost by Shuttered Nuclear Plant May Be Replaced With Renewable Energy

The state grapples with how to replace power from the closed Son Onofre Nuclear Generating Station. | Photo: the city project/Flickr/Creative Commons License

The state agency responsible for regulating California's public utilities has proposed a plan for adjusting to the loss of power from the shuttered San Onofre nuclear power plant, and part of that plan involves generating a lot more renewable energy -- though environmental activists say the plan could be a lot better.

The proposed decision, released Tuesday by the California Public Utilities Commission, authorizes Southern California Edison to procure from 400 to 700 megawatts of electrical power from energy efficiency, demand response programs, energy storage, and renewable power generating capacity by 2022. San Diego Gas & Electric would be allowed to procure between 200 and 700 megawatts from similar sources.

That should go quite a ways toward replacing the power lost to the system when the beleaguered San Diego County nuclear power plant went offline in 2012, taking more than 2.2 gigawatts of generating capacity off the grid. But at least one environmental group involved in the proceedings is saying the proposal still allows the utilities to buy more gas-fired power, representing a net loss for the state's climate footprint.

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The San Onofre Nuclear Generating Station was officially shut down in June 2013 after a year and a half offline. The initial shutdown was prompted by a leak of radioactive steam in Unit 3. SCE, which operated the plant, is now engaged in what will likely be a protracted dispute with steam tub generator manufacturer Mitsubishi Heavy Industries over liability for the shutdown.

SCE owned 78 percent of San Onofre, with SDG&E owning another 20 percent. The City of Riverside was the owner of the remaining one percent and change.

"Today's proposed decision is a step in the right direction," said the Sierra Club's Evan Gillespie in a press release Tuesday. "However, the proposed decision also needlessly leaves the door open for utilities to propose the construction of new gas-fired plants in the future, which would constitute replacing a carbon-free energy resource with new fossil fuels."

The proposed decision, an imposingly wonky document running close to 200 pages, would also increase the amount of gas-fired power each utility can procure by 2022 by as much as 500 megawatts.

Complicating the issue is the fact that a significant number of existing gas-fired plants in California are expected to go offline in years to come due to state requirements that so-called "once-through" cooled thermal power plants be phased out in the state. Such plants pipe cooling water through heat exchangers to maintain a proper operating temperature without recirculating it. Power plant operators will likely be retiring almost 6,000 megawatts' worth of gas-fired power pants in the state to comply with recent State Water Quality Control Board regulations aimed at making power generation more water-efficient, and less damaging to coastal wildlife that doesn't like having heated water discharged into the ocean.

As a large number of those once-through power plants are sited on the south coast, and construction of new plants to replace them will likely focus on the same areas, especially in the western L.A. Basin. That's attracted the notice of environmental justice groups such as the California Environmental Justice Alliance, which has urged the CPUC to restrict utilities' new procurement to cleaner options like conservation and renewables.

Nuclear energy is not precisely a "zero greenhouse gas" power source, as construction of the plants, as well as refining nuclear fuel and eventual plant decommissioning, are quite energy-intensive. Still, on a "tons of carbon per megawatt" basis, natural gas-fired plants emit significantly more greenhouse gases than do nuclear power plants.

According to a 2011 study by the Intergovernmental Panel on Climate Change, Generation 2 nuclear power plants such as San Onofre emit 16 grams of CO2 for every kilowatt-hour of energy produced, when the plants' entire lifecycle from construction to decommissioning is taken into account. Natural gas-fired plants studied emitted 469 grams CO2 per kilowatt-hour, almost 30 times as much.

(In case you're wondering, onshore wind power came in just slightly cleaner than nukes at 12 grams CO2 per kilowatt-hours, while solar thermal troughs and silicon photovoltaic panels were marginally less climate friendly at 22 and 46 grams, respectively. PV's life-cycle emissions have likely dropped since then, as greater production allows more efficient manufacture.)

The CPUC is expected to reach a final decision on the proposed plan at a meeting scheduled for March 13.

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About the Author

Chris Clarke is a natural history writer and environmental journalist currently at work on a book about the Joshua tree. He lives in Joshua Tree.
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