Treadmill Decarbonization Doesn’t Help

Treadmill Decarbonization Doesn’t Help

Two nuclear reactors at the Diablo Canyon plant in California are being forced to shut down in 2024 and 2025. When nuclear reactors are taken off the grid, fossil fuel use and the emissions that go along with them consistently increase. Independent groups have estimated that California will emit an extra 15.5 million metric tons (MMT) of global warming emissions due to the retirement of Diablo Canyon. In an attempt to prevent that from happening this time, bill SB 1090 was passed in 2018 requiring Diablo Canyon electricity generation to be replaced with clean energy.

The California Public Utilities Commission (CPUC) voted on June 24th to approve a procurement package composed of 11.5 GW of clean energy resources that will come online by 2026. The CPUC proclaimed it a “historic decision” to fulfill “clean energy and electric reliability goals.” It was widely presented in the media as a win. There are two major flaws with this perception.

First, the procurement order isn’t likely to happen as proposed. The CPUC modified their proposed order, which initially included 1,500 MW of new fossil fuel resources, to please stakeholders — just for this vote. Instead of outright requiring additional capacity from gas plants the California Energy Commission will complete additional analyses to inform the preferred system portfolio (PSP) decision later this year. It is likely that new fossil resources will be included in that PSP.

Reliability is the issue. The CPUC is charged with ensuring a reliable electricity grid and recently received a lot of backlash, largely incorrectly, for pursuing environmental goals at the expense of reliability during the August 2020 blackouts. In the approved procurement order the CPUC cited many reasons to believe that reliability will be a concern including retiring dispatchable resources in the 2023-2026 timeframe, expected increasing demand, and an emergency procurement order that was already needed to meet the demand reliably for Summer 2021. Even with the emergency procurement, the California Independent System Operator (CAISO) President recently told the press that the “single biggest variable” to avoiding rolling blackouts will be energy conservation by consumers — doing things such as setting the thermostat at 78 degrees and that “every time it gets really, really hot in the western United States”, customers will be asked to help.

To hedge on the side of reliability the initial proposed procurement order required new dispatchable fossil fuel resources. The State Water Resources Control Board is also considering whether the Redondo Beach gas plant should be given another two-year extension to comply with the regulations and avoid retirement to assist with reliability. The Water Board is in charge of regulating power plants that use once-through water cooling like Diablo Canyon.

In the approved procurement order the CPUC made its position clear that building new fossil fuels resources is the best option — they have just postponed it until after further analysis is completed to justify this position.

“When considering all of these factors, we are faced with a series of difficult choices. On balance, we find that allowing some incremental and efficient natural gas generation at utility scale or at Combined Heat & Power (CHP) facilities, at existing sites, is preferable to the public safety risks posed by widespread outages or allowing the proliferation of diesel backup generators in an emergency. It is also preferable to retaining inefficient plants that have outlived their useful lives and are significantly higher-emitting than their newer alternatives.

We also note that the risks are asymmetrical: failure to provide insurance to keep grid reliability is a far greater threat to public confidence and public health than running state-of-the-art fossil-fueled generators a few extra hours a year. In addition, adding a small amount of efficient natural gas capacity will not necessarily lead to an increase in the generation from fossil-fueled units overall, but rather will likely lead to less dispatch of the higher-emitting and less efficient units.”

This would not be necessary if the older and less efficient fossil-fueled generators were replaced with renewables instead of replacing a clean firm source like Diablo. Instead, all of the firm resources in the procurement, 2,500 MW of dispatchable peak load from 5 pm-10 pm and 2,000 MW of high capacity factor generators like geothermal, are there just to write off Diablo Canyon’s generation [hopefully] without increasing emissions or reducing reliability.

None of the resources proposed to replace Diablo Canyon are as resilient to extreme weather — not even gas or geothermal. The once-through cooling system from the ocean is heat and drought resistant. The long fuel cycle lets the power plant ride out any storm without concern for fuel security.

Second, part of this procurement represents treadmill decarbonization. Instead of moving toward a cleaner and lower-carbon energy system, treadmill decarbonization just runs in place by swapping one clean energy source for another. It is widely accepted by energy systems experts and the Department of Energy that keeping existing nuclear plants online is essential to meeting decarbonization goals.

The procurement order calls for a lot of new clean electricity capacity. This is commendable and necessary to address climate change. Just how ambitious is it? Overall Diablo Canyon provides approximately 10% of the state’s energy portfolio. Despite having a very high portion of electricity from renewable sources, Diablo Canyon alone is equivalent to 27% of California's combined solar, wind, and geothermal generation using just 1/10th of the capacity.Data from https://www.energy.ca.gov/data-reports/energy-almanac/california-electricity-data/electric-generation-capacity-and-energyCalifornia would have to more than double the wind power capacity across the state just to make up for one nuclear power plant — and do it in just five years. The CPUC procurement order states,

“Many of the resources retiring in the 2023-2026 timeframe are either firm or dispatchable resources, which are not easily replaced by as-available variable renewables in terms of their capacity factors and values, as well as their impact on grid operations.”


Some proponents of renewables claim that closing nuclear power plants will get them out of the way of cheaper renewables, saving money for the ratepayers. That claim has not been realized. Just for the closure of Diablo Canyon, ratepayers will have to shoulder $437 million in the form of higher electricity prices to support the local economy, community support programs, and more than 1,300 lost jobs. Instead of paying almost half a billion dollars to force clean energy off the grid, that investment could have gone to building more clean energy.

The bottom line is that this procurement order was amended to make it seem like we are even running in place when in reality we will be going backward.

Cartoon by Seaver Wang