Even before a catastrophic well failure turned Aliso Canyon into an international greenhouse-gas pariah, the natural gas storage facility was one of the industry’s worst climate polluters. Carbon dioxide flowed from its heavy machinery, and methane seeped from valves and equipment. Only two other underground fields in the United States discharged more greenhouse gases in 2014, according to an analysis of the most recent U.S. Environmental Protection Agency data.
As Porter Ranch residents prepare to return home and regulators tighten well-safety rules, the long-term environmental costs of storing pressurized gas remain. The facility in the hills above the San Fernando Valley emitted 206,268 combined tons of natural gas, carbon dioxide and other pollutants in 2014, roughly the same amount as 43,000 cars driven for a year.