Study Finds Methane Emissions From U.S

A study published today in Environmental Science & Technology finds methane emissions from U.S. local natural gas distribution systems, including Southern California Gas Co.’s (SoCalGas), are 36 to 70 percent lower than current estimates by the U.S. Environmental Protection Agency.

Researchers concluded the reductions were due to infrastructure modernization and increased investment in leak prevention by utilities. This included upgrades in metering and regulating stations, changes in pipeline materials, and better instruments for detecting pipeline leaks &mdash as well as regulatory changes.

“SoCalGas recognizes the importance of reducing emissions and these findings validate our long-term efforts to modernize our infrastructure to enhance safety, safeguard reliability and reduce emissions,” said Bret Lane, chief operating officer of SoCalGas. “SoCalGas will continue to work with regulatory agencies, researchers and the community to prudently invest resources in our system and protect our environment.”

Led by Regents Professor Brian Lamb in WSU’s Laboratory for Atmospheric Research, the study provides the most comprehensive set of direct measurements of emissions from the distribution system to date. They estimate that emissions from the distribution system are between 0.1 and 0.2 percent of the natural gas delivered nationwide. SoCalGas’ natural gas system has among the lowest emissions rates in the country despite it being the largest.

SoCalGas participated in the study to help increase knowledge about methane emissions across the country and to better understand the impact of infrastructure maintenance and modernization efforts.

SoCalGas’ voluntary emissions reduction efforts began more than two decades ago &mdash well before any mandatory programs, such as California’s Global Warming Solution Act (AB 32), went into effect &mdash and include:

•More than 800,000 tons of emissions reductions: As an original member of EPA’s Natural Gas STAR program in 1993, SoCalGas implemented practices resulting in the reduction of more than 800,000 metric tons of carbon dioxide equivalent.

•Eliminated cast iron pipe: SoCalGas eliminated all cast iron pipe from its system more than two decades ago, and established a comprehensive risk-based approach to replacing pipe on its system. Cast iron pipe has been identified with significant leak issues in other regions in the U.S.

•Modernized infrastructure: SoCalGas replaced pre-World War II transmission pipe, updated its metering and regulating facilities and modernized its distribution system with plastic pipe. The company will invest $6 billion to improve the safety, performance and reliability of its pipeline system over the next four years.

•Leak surveys: SoCalGas regularly monitors emission levels from transmission, distribution and gas storage facilities in compliance with federal and state regulations and requirements.

The study, which was supported by the Environmental Defense Fund, 13 major natural utilities, including SoCalGas, and engineering and environmental consulting firms, updates data from the 1990s. The researchers took direct measurements in multiple cities from 230 randomly selected, representative underground pipelines and 229 stations where natural gas is measured and regulated.

The participating natural gas utilities own and operate 19 percent of the nation’s distribution pipeline mileage and account for 16 percent of the total gas delivered to customers in 2011.


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