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Methane Capture Tested by SoCalGas on Pipeline Replacement Project

With the four-month-long natural gas storage well leak at Aliso Canyon still roiling, Southern California Gas Co. (SoCalGas) engineers said they have successfully tested a methane capture system on a 2.5-mile distribution pipeline replacement project.

Using compressed natural gas (CNG), the capture and reuse test was accomplished as part of the Sempra Energy utility’s multi-billion-dollar, multi-year Pipeline Safety Enhancement Plan (PSEP) mandated five years ago by state regulators after the San Bruno, CA, transmission pipeline explosion.

The work was completed last month in Atascadero in San Luis Obispo County. The utility crews captured gas emptied from a recently abandoned pipeline and saved the gas for later use, which SoCalGas said eliminated the noise and methane emissions that normally occur in traditional pipeline venting.

Crews had earlier decommissioned a 2.5-mile section of the 10-inch diameter pipe, which was recently replaced by a new pipeline in a new location. The old pipeline had to be completely emptied of about 150 Mcf.

"SoCalGas compressed most of it, and then pumped it into three large tanks so it could be put back into the system and used by customers," a spokesperson said.

Nationwide, emissions from gas utility distribution systems collectively represent less than 1% of the U.S. greenhouse gas emissions, but California's climate change policies call for drastic reductions in these emissions, and methane is at the top of the list for needing greater controls. The aftermath of the Aliso Canyon underground storage well leak has heightened those concerns (see Daily GPIJune 1).

As part of the PSEP program, for which SoCalGas expects to spend nearly $1.2 billion this year, the methane capture technique has satisfied engineers that it is something that can cut emissions and save gas supplies. Many more thousands of miles of pipeline may need to undergo pressure testing and/or replacement.

Calling the testing a "groundbreaking" innovation, Rick Phillips, senior director of the SoCalGas PSEP activities, said capturing methane that traditionally has been vented not only reduces noise and smells that can affect the general public, but "it also minimizes impacts to the environment. We will continue testing this new innovation in hopes of expanding its use for whenever its application may be suitable."

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