Image credit: Stephen Williams, lights of Jackson WY seen from Snow King Resort
Are there "dirty" hours when the California electric grid is producing a lot of CO2 per kWh, and "clean" hours with low CO2 output? It seems that midday should have lower CO2/kWh compared to other hours, if a large fraction of power across the state is generated by solar photovoltaics (PV) during these hours. Looking at data, Beyond Efficiency did in fact find a midday reduction in CO2 emissions per kWh generated for 2014 onward.