California is the second state after Hawaii to establish a 100% carbon-free energy goal for its electric grid. In late August, the state legislature passed Senate Bill 100 (SB 100) which created a 100% clean electricity standard by 2045 and also altered California’s current renewable portfolio standard (RPS). Previously, California’s RPS mandated 50% of the state’s retail electricity sales come from renewable sources by 2030, but following passage of SB 100, that figure is now modified to 60%.

To achieve the 2045 goal, however, SB 100 takes a broader approach by explicitly instructing California’s energy agencies to “plan for 100% of total retail sales of electricity in California to come from eligible renewable energy resources and zero-carbon resources…” Qualifying zero-carbon sources include nuclear as well as natural gas with a carbon-capture system (CCS), so long as the CCS prevents the emission of any greenhouse gases.

Implementing California’s clean energy standard, however, raises questions regarding whether achieving 100% zero-carbon electric grid is feasible even with the inclusion of nuclear and natural gas facilities with CCS technology, particularly for two reasons:

1. In 2016, PG&E announced it was closing Diablo Canyon by 2025, a nuclear generating facility in southern California responsible for producing almost 18,000 GWh annually of carbon-free electricity. California regulators voted to shutter Diablo Canyon in January 2018.  
2. No utility has demonstrated that CCS technology can successfully be scaled up to the levels SB 100 would require.

Under these circumstances, acquiring up to 40% of carbon-free electricity from scarcely available (nuclear) or unproven (CCS) sources of energy will be challenging. That said, California consistently leads the nation in solar energy installations. It is likely that renewable sources of energy will generate more than the 60% mandated by 2030, but it might still not be enough to achieve the state’s carbon-free mandate.