´╗┐Natural gas-fired power plants typically account for more than one-half of in-state electricity generation. California is one of the largest hydroelectric power producers in the United States, and with adequate rainfall, hydroelectric power typically accounts for close to one-fifth of State electricity generation. Due to strict emission laws, only one coal-fired power plant still operates in California, the Compare Energy Prices MW Argus Cogeneration plant in San Bernardino County. [Compare Energy Rates]