California's Energy Sources: Renewables Leader, Fossil Transition, Nuclear Phase-Out

California has the most diverse and ambitious energy portfolio in the US.

Renewables (Dominant & Growing)

• Solar: #1 US (35%+ of in-state generation); utility-scale + rooftop (1.5M+ homes).
• Wind: Onshore (Tehachapi, Altamont, San Gorgonio) + emerging offshore (Humboldt, Morro Bay).
• Geothermal: The Geysers (Sonoma/Lake) = world's largest geothermal field (1.5 GW).
• Hydro: Sierra Nevada dams (Shasta, Oroville, Folsom) — ~10–15% (drought-sensitive).
• Biomass / Biogas: Agricultural waste, landfill gas.
• 2023 mix: ~35% renewable (RPS target: 60% by 2030, 100% clean by 2045).

Fossil Fuels (Declining)

• Natural gas: ~45% of generation (peaker plants, backup). Imports (pipeline + LNG).
• Oil: Minimal electricity; transport sector dominant.
• Coal: Near-zero (last plant retired 2022).

Nuclear

• Diablo Canyon (San Luis Obispo): 2.2 GW (2 units) — only remaining plant.
• Provides ~9% of generation; 24/7 baseload.
• Scheduled closure: 2024–2025 (extended to 2029–30 via state/federal support).
• No new nuclear planned.

Grid & Storage

• Battery storage: Explosive growth (5 GW+ installed 2023) — shifts solar to evening peak.
• Demand response: Flex Alert, smart thermostats, EV charging management.
• Interties: Imports from NW (hydro), SW (solar/wind/gas).

Policy Drivers

• SB 100 (100% clean electricity by 2045)
• Title 24 (building efficiency, solar mandate)
• Cap-and-trade, LCFS (transport)
• CPUC/CAISO market design

California = laboratory for global decarbonization. Challenges: reliability (heat waves), cost, land use, supply chains, equity.