The sources of electric power used in California have changed significantly between 2004 and 2014. The distribution of California’s energy sources, among natural gas, renewables (wind & solar), hydroelectric, and nuclear is shown in the following chart. California does not use coal or petroleum to generate electric power.
Nationally, on a percentage basis, coal use is on the decline and use of natural gas and renewables is on the increase in most states.
Check out the following NPR website, which is the source of the above charts, to see similar charts for all 50 states.