Pacific Gas and Electric built the Hunters Point power plant in 1929 and continued to expand it up until 1958 to its current capacity of four units. Since reaching an agreement with the City of San Francisco in 1998 to make every effort to close down the plant, output has dropped considerably. However, under a contract with the California Independent System Operator, the agency that controls the state's power grid, PG & E must run the power plant when the system operator deems it necessary.

Two of the four units were shut down in July 2000. The remaining two units operate under the Independent System Operation contract and use jet fuel and natural gas to generate a total capacity of 215 megawatts, enough to power 215,000 homes. The generator that uses jet fuel only operates during emergency peak demand.

A study by the Oakland-based Communities for a Better Environment found that the Hunters Point plant puts out 34 tons a year of nitrogen oxides, 151 tons a year of carbon monoxide, 37 tons a year of particulate matter and 8 tons a year of sulfur compounds.

All of these compounds can trigger respiratory problems and contributes to water quality and acid rain. PG & E says the Hunters Point power plant emits well below permitted levels having cut the output of nitrogen oxides 65 percent since 1994. According to PG &E, nitrogen oxides emissions were 30 percent below permitted levels.