In California, natural gas serves as an energy resource for several purposes. The California Energy Commission reports approximately 45 percent is used for electrical power generation; 25 percent is for industrial use; 21 percent is for residential use; and nine percent is for commercial use. To maintain an adequate supply of natural gas to these markets, Underground Gas Storage (UGS) reservoirs have been established to store large quantities of natural gas. The UGS program within the Geologic Energy Management Division (CalGEM) helps ensure that storage operations are conducted safely.
Depleted natural gas or oil fields function as gas storage reservoirs in this state. Natural gas is injected into the reservoirs under pressure and stored until withdrawn for use. There are 12 underground natural gas storage fields in the state with a total working gas capacity—the volume of gas available for the marketplace—of 375 billion cubic feet (6,000 cubic feet of natural gas is equivalent to one barrel of oil).
An underground gas storage facility in California
Underground gas storage regulations require that gas storage wells are structurally sound and that gas reserves are not lost.
Updated regulations (PDF), which took effect October 1, 2018, also mandate that underground gas storage operators have risk management and emergency response plans. They also expand the requirements to collect and manage storage project data, and perform regular testing and monitoring of wells within the project to protect public safety and the environment.
CalGEM is not alone on the emphasis on safety. For example, the California Air Resources Board requires air monitoring plans and detection for gas leaks.
** Operators: Compliance with the California Environmental Quality Act (CEQA) must be documented if your proposed project requires a discretionary permit or approval from CalGEM.