California requires that retail sellers of electricity, like utilities and Sonoma Clean Power, get 50% of their electricity from “eligible renewable energy resources” by the end of 2026.
Eligible are biodiesel, biomass, biomethane, fuel cell, geothermal, small hydropower (30 megawatts or less), conduit hydroelectric, water supply or conveyance system, incremental hydroelectric, municipal solid waste combustion, municipal solid waste conversion, ocean thermal, ocean wave, large-scale solar, tidal current and wind.
Not eligible are nuclear, large hydropower and rooftop solar.
Nuclear doesn’t qualify because critics fear the radioactive waste.
Large hydroelectric power is carbon free, but it doesn’t qualify because (1) California has lots of large hydro and to include it in the standards would greatly reduce the need to add more renewables, (2) environmentalists are concerned over the ecological effects of large dams, (3) climate watchers are concerned that large dams aren’t sustainable and (4) building those dams pollutes and destroys natural resources.
Rooftop solar doesn’t qualify because legislators are trying to encourage utility-scale transactions by large retailers. They think of rooftop solar as a reduction in demand rather than an increase in supply.