Clean firm power is the key to California's carbon-free energy future

Authors: Cohen A, A Olson, C Kolster, DG Victor, E Baik, JCS Long, JD Jenkins, K Chawla, M Colvin, RB Jackson, SM Benson, SP Hamburg

California’s government has set ambitious goals to eliminate greenhouse gas emissions, starting with electricity. A 2018 law mandated that, by 2045, all retail sales of electricity in the state must derive from carbon-free sources. Jerry Brown, who was then the governor, issued an accompanying executive order requiring the entire state, not just the electric sector, to zero-out net emissions also by 2045. Policymakers have to grapple with achieving these goals. Reducing emissions in the economy as a whole will increase demand for electricity, which will be used to power cars and heat buildings in place of fossil fuels. Energy planners estimate that such electrification will increase California’s peak demand for electricity from 50 gigawatts today to 100 gigawatts midcentury.

The Environmental Defense Fund and the Clean Air Task Force convened three groups of energy system experts to model California’s electricity system in order to figure out how the state might make that much affordable, clean, and reliable electricity. Groups from Princeton University, Stanford University, and Energy and Environmental Economics (E3), a San Francisco-based consulting firm, each ran separate models that sought to estimate not only how much electricity would cost under a variety of scenarios, but also the physical implications of building the decarbonized grid. How much new infrastructure would be needed? How fast would the state have to build it? How much land would that infrastructure require? Although each of these models offered its own depictions of the California electricity system and independently explored the ways it would be optimized, they all used the same data with respect to past conditions and they all used the same estimates for future technology costs. Despite distinct approaches to the calculations, all the models yielded very similar conclusions. The most important of these was that solar and wind can’t do the job alone.

If wind and solar are pushed to do all the heavy lifting themselves, the system requires enormous excess generating capacity and storage (most of which is seldom used) to provide reliable electricity and completely drive out greenhouse emissions. This strategy ends up being much more expensive and much more demanding of land and infrastructure than other possible pathways.