The closure will test whether the facility’s 18,000 GWh of yearly output can be replaced entirely by new zero carbon resources and reduced usage. Under PG&E’s retirement plan, the utility says it can make up the generation gap entirely with energy efficiency, renewable resources and energy storage — all while costing customers less than continuing to operate the plant.
While it does not lay out the exact megawatt-for-megawatt replacements for Diablo Canyon’s output, the proposal gives a roadmap for how PG&E plans to procure enough renewables and reduce usage enough to replace the nuclear plant. Under the plan, PG&E would promise to obtain 2,000 GWh from efficiency by January 2025 and issue requests for offers for 2,000 GWh per year of greenhouse gas-free energy resources or efficiency by 2020.
The joint proposal also lays out the challenges the utility would face if it continued to operate Diablo Canyon.
The first is the uncertainty of electricity demand. The second challenge is a decreasing need for baseload generation. As renewables penetrations rise across a widening geographic region, the wind is likely to be blowing or the sun is likely to be shining somewhere, making those resources’ variability less of a problem.
The new need, the joint proposal argues, is for more flexible resources like geothermal power, concentrating solar with thermal storage, and pumped hydro storage. These would replace the highly inflexible baseload generation from the nuclear plant, allowing for better moment-to-moment grid balancing.
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