A clean and reliable electricity grid is central to California’s climate neutrality and climate leadership. Recent climate-related events like heatwaves, wildfires, and drought highlight the urgency of transitioning to clean electricity and doing so reliably.
Modeling from GridLab and Telos Energy shows California can reach 85 percent clean electricity by 2030 while keeping the power on for its 40 million residents—even under stressful conditions like low hydropower generation, fossil plant retirements, and heatwaves similar to what caused rolling power outages in August 2020. An 85 percent by 2030 clean grid represents a faster transition than California’s renewable portfolio standard, which requires 70 percent clean electricity by 2030.
A companion report from Energy Innovation provides state policymakers with a set of no-regrets actions to effectively implement reliability insights from the modeling analysis.
Base Case Portfolio: The Base Case builds the most cost-effective portfolio of clean energy resources to meet an 85 percent by 2030 clean electricity goal, equivalent to a 75 percent by 2030 renewable portfolio standard goal. It relies solely on new solar, onshore wind, and battery storage, which are the cheapest resources. This pathway requires utility-scale solar deployment to double from the 2010-2020 average and battery storage to grow even faster.
Diverse Clean Resources Portfolio: This portfolio adds 4 gigawatts (GW) of offshore wind and 2 GW of geothermal to an otherwise cost-optimal 85 percent clean resource mix. Adding more diverse clean resources like geothermal and offshore wind results in a relatively lower buildout rate of solar, onshore wind, and battery storage by 2030. While California currently has no offshore wind and until 2022 hadn’t built a geothermal power plant in over a decade, new policies to support these technologies can spur development.
High Electrification Portfolio: The high electrification portfolio assumes California significantly electrifies its vehicles and buildings beyond any projected levels in the California Energy Commission’s California Energy Demand Forecasts, requiring more clean electricity to meet the 85 percent clean electricity by 2030 goal. Assuming the same geothermal and offshore wind buildout as in the Diverse Clean Resources case allows the state to meet this higher demand with a similar solar, onshore wind, and battery storage buildout as in the Base Case.
Adding geothermal and offshore wind resources has clear reliability benefits as California depends less on any single resource to meet demand, with the change mostly reducing utility-scale solar power and battery storage.
While the state has great solar resources, diversification reduces deployment risks due to land-use limits. Diverse resources help equally balance load and renewable generation across the year with less dependence on in-state gas generation during winter months.
Recent challenges, including the 2020 rotating power outages, underscore why the state must prioritize reliability in its clean energy transition and evaluate future power systems against a variety of stress conditions. The modeling shows California can move faster, while keeping the lights on. Greater resource diversity, regional coordination, and demand-side flexibility can help the state face various stressful conditions, while still retiring significant fossil fuel capacity in across the West by 2030.
Under all the studied stress conditions (or stressors), the state has enough power to serve demand—even on the very worst hour when the grid is most strained. This includes one case where nearly one third of remaining in-state gas capacity is retired by 2030.
The model runs each portfolio through every hour of eight historical weather-years, and requires an annual average of 85 percent clean electricity. The remaining 15 percent comes from in-state gas or economic imports by design. The portfolio has adequate power in every hour to meet demand and has adequate reserves even when wind and solar production are at their lowest levels.