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California Proposes Methane Emission Rule; SoCalGas Calculates Aliso Leak at 4.62 Bcf

California air pollution regulators on Tuesday issued proposed regulations for greenhouse gas (GHG) emissions standards for all oil and natural gas facilities, including methane emission requirements for gas storage facilities.

A public hearing is scheduled July 21 in Sacramento.

"The proposed regulation covers GHG emissions, predominantly methane, from oil and natural gas production, natural gas gathering and boosting stations, and natural gas processing, as well as from natural gas storage and transmission compressor stations," said the California Air Resources Board (CARB).

The proposal includes both "active and idle" equipment and components, which would include the Southern California Gas Co. (SoCalGas) Aliso Canyon underground gas storage facility in Los Angeles, now shuttered, as storage wells are being tested (see Daily GPIApril 21).

The Sempra Energy gas utility said last Friday it was working on a mitigation plan for the methane released during the four-month Aliso leak (Daily GPIFeb. 18).

SoCalGas calculated that 4.62 Bcf of gas escaped over the four-month period, or 84,200 metric tons (mt) of emissions. The calculation is lower than the preliminary estimate by CARB of 5.22 Bcf, or 94,500 mt, which were "rough estimates" based on 11 days of flyover measurements at the 3,600-acre storage field site.

"SoCalGas has signed letters of intent with several California dairies to manage methane emissions, and will finalize its mitigation plan in the coming months," a spokesperson said. The ultimate plan would be consistent with CARB guidance that multiple sources be included, including dairies and landfills.

The Environmental Defense Fund (EDF), an advocate for national research and planning on methane emissions, lauded the CARB for the methane proposal but criticized a "serious loophole" that it said may provide industry with a disincentive longer term to seriously address the problem.

"If finalized, it will give California one of the most comprehensive methane standards in the world, encompassing both new and existing facilities both on land and offshore," an EDF spokesperson said. EDF is critical of a proposed "step-down" provision allowing operators to shift to less rigorous methane monitoring requirements if they fail to find leaks over a specified number of inspections.

EDF's Tim O'Connor, California oil and gas director, said the step-down provision would "give oil and gas companies strong motivation not to find or report their leaks; that's a huge step backward."

Under the provision, operators could receive an exemption from a quarterly requirement to conduct leak detection/repair work. Instead, they would be allowed to comply with inspection requirements only once a year.

"Research has shown that leaks from equipment malfunctions and poor maintenance lead to significant emissions that are not reflected in emission inventories," said O'Connor. He urged California to have a permanent mandatory quarterly inspection schedule.

Separately, CARB, the California Energy Commission and California Public Utilities Commission are hosting a two-day workshop on Monday and Tuesday in Sacramento on methane emissions, which is to include presentations by federal/state government, environmental, academic and think tank experts.

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