Blackouts and California’s Clean Energy Transition

This policy brief examines the rolling blackouts in California during a historic heat wave in August 2020, arguing that the outages were caused by a combination of extreme weather and insufficient resource capacity rather than the state's clean energy goals. The author contends that a diverse portfolio of flexible, clean resources—including battery storage and green hydrogen—is essential for 21st-century grid resilience against climate-driven extreme weather.

• The August 2020 rolling outages in California were driven by multiple factors, including a historic heat wave, near-record electricity demand, a reduction in wind output, limited import capacity, and gas generators tripping offline. The document rejects the narrative that aggressive clean energy goals or renewable energy were the primary cause of these outages.
• Climate change is increasing the frequency and severity of extreme weather events that overwhelm grids designed for 20th-century conditions. Examples include a heat wave where Death Valley reached 130°F, a "derecho" wind storm in Iowa and Illinois with speeds up to 106 miles per hour, and tornadoes on the East Coast caused by Hurricane Isaias.
• Fossil fuel and nuclear power plants are not perfectly reliable and can experience forced outages or reduced capacity during heat waves because the water required for cooling may become too warm to function effectively.
• Battery storage is identified as a critical resource for meeting evening peak demand. In July 2020, California had 216 MW of batteries in commercial operation, with a projected increase to 923 MW by the end of the year if queued projects were completed. This capacity is compared to the 1 GW (two 500 MW waves) that CAISO shed on a single Friday.
• To improve grid resilience, the document proposes moving away from centralized, fossil-dominated portfolios toward a diverse mix of flexible resources. This includes solar PV for midday peaks, battery storage for fast-ramping evening demand, carbon-free green hydrogen, and dispatchable demand flexibility. It also suggests prioritizing electricity service for critical loads, such as emergency responders and medical equipment, as seen in a utility's approach in Colorado.

APA

RMI (2020). Blackouts and California’s Clean Energy Transition. https://rmi.org/resources/blackouts-and-californias-clean-energy-transition/

Chicago

RMI. Blackouts and California’s Clean Energy Transition. 2020. https://rmi.org/resources/blackouts-and-californias-clean-energy-transition/.

Wikipedia

{{cite report |author=RMI |title=Blackouts and California’s Clean Energy Transition |date=18 August 2020 |url=https://rmi.org/resources/blackouts-and-californias-clean-energy-transition/ |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{rmi2020blackouts, author = {{RMI}}, title = {{Blackouts and California’s Clean Energy Transition}}, institution = {RMI}, year = {2020}, month = aug, url = {https://rmi.org/resources/blackouts-and-californias-clean-energy-transition/}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }