Aliso Canyon

The Aliso Canyon natural gas storage facility near Los Angeles. 

The California Independent System Operator has proposed making permanent certain natural gas constraints it has in place in Southern California to deal with the reduced usability of the Aliso Canyon gas storage facility near Los Angeles.

CAISO in the summer of 2016 first initiated a stakeholder process to explore mechanisms and tools to support reliability due to the limited availability of Aliso Canyon, a major facility with an 86-Bcf capacity. Exacerbating the problem are the design of the Southern California Gas Co. system and increased electric load ramps that require instantaneous draws on the gas system, CAISO said.

Usage of the facility has been curtailed since a major leak that lasted from October 2015 to February 2016, with many local residents complaining it is still making them sick. There are efforts among state lawmakers and environmental groups to permanently close Aliso Canyon.

One method employed by CAISO, the "maximum gas constraint," allows the grid operator to limit the maximum amount of gas SoCal Gas and San Diego Gas & Electric can burn in certain regions, based on gas limitations.

The grid operator in its "Aliso Canyon Phase 5" initiative proposed making permanent the maximum gas constraint, which allows coordination between SoCal Gas and CAISO during periods when the gas system is constrained; the competitive path assessment, which allows CAISO to manually override the dynamic competitive path assessment to determine if transmission constraints caused uncompetitive conditions and allows supply limitations to be reflected in the market-mitigation process; and suspension of "virtual bidding" when the maximum gas constraint is causing market inefficiencies.

CAISO plans to file the tariff changes in mid-October for a Jan. 2, 2020 effective date.

CAISO implemented the maximum gas constraint on 14 days in 2018, or about 4 percent of the year, and four days so far in 2019, or about 3 percent of the year, records show.