Though Southern California weathered last summer without major natural gas supply constraints that were feared as a result of the 2015–2016 leak from the Aliso Canyon storage field, a blast of cold weather this week has forced Southern California Gas Co. (SoCalGas) to withdraw stored gas from the still-damaged facility to maintain reliability.

The limited withdrawal was the first from Aliso Canyon in more than a year and was the result of a pipeline constraint, company officials said. The utility said it used only wells that state inspectors had reapproved for service following the leak.

State officials and the California Independent System Operator (CAISO) warned in April 2016 that the loss of Aliso Canyon could cause reliability problems during periods of peak demand. SoCalGas asked customers to curtail gas usage earlier this week, but the company still found it necessary to withdraw gas from storage on the morning of January 25.

Aliso Canyon helps supply gas service to 17 natural gas–fired power plants in the Los Angeles basin, in addition to a number of large hospitals and oil refineries. Those power plants total 9,503 MW in capacity and account for 70% of local capacity resources identified in the CAISO 2016 Local Capacity requirements for the Los Angeles area and 75% of the local capacity available to the Los Angeles Department of Water and Power Balancing Authority. None of the plants have dual-fuel capability.

No gas has been injected into the Aliso Canyon field since a leak that began in late 2015 spewed an estimated 100,000 metric tons of gas into the atmosphere before it was closed last February. The facility represents 64% of Sempra subsidiary SoCalGas’s storage capacity, 49% of its injection capacity, and 51% of its withdrawal capacity.

Though the storage field has not returned to full service, state regulators allowed it to reopen at a third of its previous capacity last week. However, a decision on resuming injections will not come until after state officials hold a pair of hearings on the subject in early February. The cause of the accident has still not been determined.

—Thomas W. Overton, JD is a POWER associate editor (@thomas_overton, @POWERmagazine).

Photo of Aliso Canyon courtesy Earthworks