California’s SB 100 bill has committed the state to decarbonize its power grid, with a goal of 60% renewable energy by 2030 and 100% clean electric retail sales by 2045. Meeting these decarbonization goals will not only necessitate siting solar and wind power projects and building transmission at unprecedented rates, but also require deliberate measures to maintain reliability.

In a new report prepared for Carbon Free California, “Retaining Diablo Canyon: Economic, Carbon, and Reliability Implications,” Brattle consultants explore how retaining the Diablo Canyon Nuclear Power Plant – California’s largest carbon-free electricity production source, which is currently scheduled to close in 2025 – can help address reliability concerns while accelerating progress towards the state’s climate goals. The authors conclude that keeping Diablo Canyon online until 2045 will help California decarbonize more quickly, reliably, and at lower total cost.

The report provides a robust assessment of the impact of retaining Diablo Canyon across a range of scenarios. It provides five key insights:

  • Retaining Diablo would displace gas-fired generation and emitting imports, especially during the first 10 years of the plant’s extended life;
  • Retaining Diablo would reduce cumulative emissions by approximately 40 MMT CO2, while also lowering other local air pollution from gas-fired plants;
  • Retaining Diablo would provide insurance for meeting both reliability standards and carbon goals in the event clean energy deployment rates do not double and future dispatchable clean technologies (e.g., NGCC with CCS or H2) do not materialize at scale;
  • Retaining Diablo would reduce system costs by more than $4 Billion by avoiding burning natural gas in California and gas/coal for imported energy, and by reducing capital and fixed costs for other resources otherwise needed to meet clean energy and reliability goals; and
  • Retaining Diablo could greatly help enable California to achieve a potentially accelerated goal of a carbon free-grid by 2035, by lowering the cost of accelerated compliance by $5 Billion. Diablo would also make earlier compliance feasible by providing more time for the state to more than quadruple its current annual deployment rate of solar and wind, while delaying the need for carbon capture and sequestration (CCS) on NGCCs, or other novel technologies.

The full report – authored by Principal Dr. Samuel Newell, Senior Associate Dr. Wonjun Chang, Research Associate Ragini Sreenath, and Principal Dr. Dean Murphy – is available below.

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