In 1999, petroleum supplied an estimated 1% of the state's electric power production, natural gas 47%, coal 1%, nuclear power 17%, hydroelectric power 21%, and other sources about 13%. California ranks 3rd among the 50 states in crude oil reserves and fourth in crude oil production. California utilities own and operate coal-fired power plants across the southwest. This electricity shows up as "imports" in federal accounting. California utilities buy electricity from out-of-state suppliers if it is less expensive than in-state operation. Installed electric capacity (utility and nonutility) was 53.2 million kW in 1999. In the same year, total electrical output was 191.6 billion kWh.
Originally ordered by the Pacific Gas and Electric Co. in 1966, the Diablo Canyon nuclear power plant near San Luis Obispo has been a source of controversy ever since 1971, when an earthquake fault line was discovered offshore, 2.5 mi (4 km) from the plant. After years of delays and demonstrations by environmental groups, the first unit of the plant began operation in November 1984, the second reactor in 1985, for a total of four reactors at two plants operating in the state, with a net capacity of over 4,500 MW. (The other plant is the San Onofre facility near San Clemente.)
In 1999, retail sales of electric power in the state totaled 221 billion kWh, of which roughly 30% went to commercial businesses, 33% to home consumers, and 27% to industries. In part because of the mild California climate and the state's aggressive 20-year effort to improve energy efficiency, utility bills are lower than in many other states. In 2000, per capita energy consumption in California was 252 million Btu (63.5 million kcal), or 46th among the states.
Crude oil was discovered in Humboldt and Ventura counties as early as the 1860s with the first year of commercial production occurring in 1876. It was not until the 1920s, however, that large oil strikes were made at Huntington Beach, near Los Angeles, and at Santa Fe Springs and Signal Hill, near Long Beach. These fields added vast pools of crude oil to the state's reserves, which were further augmented in the 1930s by the discovery of large offshore oil deposits in the Long Beach area.
The state's attempts to retain rights to tideland oil reserves as far as 30 mi (48 km) offshore were denied by the US Supreme Court in 1965; state claims were thus restricted to Monterey Bay and other submerged deposits within a 3-mi (5-km) offshore limit. In 1994, however, California banned any further oil drilling in state offshore waters because of environmental concerns, high operating costs, and resource limitations. In 1998, state and federal offshore resources accounted for 21% and 19% of state oil and gas production, respectively. The state's largest oil companies include Chevron, with headquarters in San Francisco, and Los Angeles–based Atlantic Richfield.
California's proved oil reserves as of 31 December 2001 were estimated at more than 3.6 billion barrels, 16% of the US total and 3rd behind Alaska and Texas. Petroleum production in 2002 totaled 707,000 barrels per day, 12% of the US total. Marketed production totaled 360.6 billion cu ft (10.2 billion cu m) in 2002; proved reserves were nearly 2.7 trillion cu ft (0.08 trillion cu m) in 2001. In 2001 there were 1,244 active natural gas wells in the state.
California has been a leader in developing solar and geothermal power as alternatives to fossil fuels. As of the end of 1998, geothermal, wind, and solar energy electric generation amounted to 5.1 billion kWh, or nearly 4.4% of the total electric generation for the state. About 73% of the geothermal, wind, and solar electric capacity nationally comes from California.