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NatGas Pipe Replacement Correlates to Lower Methane Emissions, Leaks, Say Researchers

Leaks in urban natural gas distribution systems can be cut by up to 90% by systematically replacing aging pipe infrastructure, Stanford University research has concluded.

The study issued this week compared two metropolitan areas in Cincinnati, OH, and Durham, NC, with extensive replacement programs with New York City’s Manhattan borough. Researchers previously had data from Boston and Washington, DC. The study concluded that in the cities with pipeline replacement, there were 90% fewer leaks.

The study was published in the journal Environmental Science & Technology Letters.

"The surprise wasn't that replacement programs worked, but it was that they worked so well," said Stanford professor Robert Jackson of the Earth, Energy & Environmental Sciences department.

Jackson, who began the research at Duke University before moving to Stanford  a year ago, told NGI that he may research some West Coast metropolitan areas in the future.

Jackson and his research team drove vehicles equipped with methane-sensing technology developed by Silicon Valley-based Picarro and mapped leaks across 1,600 road miles in the three cities.

They discovered only one-tenth the number of leaks-per-mile in Durham and Cincinnati, where public-private partnerships have replaced outdated pipelines, compared to Manhattan, Boston and DC.

Researchers have mapped 3,400 gas pipeline leaks across Boston and 5,900 in DC, and the likelihood of a leak in those two cities is the same as Manhattan -- about 4.3 leaks/mile of pipe. By comparison, Durham and Cincinnati had 0.22 and 0.47 leaks/mile, respectively, Jackson said. In the larger cities, replacing aging pipes would involve digging through many more layers of roadway and involve higher costs than in smaller cities.

Cast and wrought iron pipelines are among the oldest energy pipelines constructed in the United States. Many were installed more than 60 years ago and still deliver natural gas to homes and businesses. However, the degrading nature of iron alloys, the age of the pipelines, and pipe joints design have greatly increased the risk involved with continued use of such pipelines, the Department of Transportation's (DOT) Pipeline and Hazardous Materials Administration (PHMSA) has been warning.

According to PHMSA data, there are more than 30,000 miles of cast iron pipe in 16 states and the District of Columbia, all in the East, South and Midwest, and many utilities have begun extensive replacement programs (see related story).

Three years ago researchers concluded that Boston's aging urban natural gas pipeline infrastructure was rife with leaks, according to a study by Jackson, who at that time worked with Boston University and Duke (see Daily GPINov. 28, 2012). Those researchers collaborated with Jackson's team on the latest research, as well as the U.S. Department of Energy, Gas Safety Inc. and Ohio State University.

"These emissions for Boston are quite high, but that would not hold for all cities," Jackson said.

He noted that gas pipeline safety has improved substantially in the United States, but there were still 18 fatalities and 93 injuries from pipeline incidents last year. He estimated that an additional $2 billion of natural gas was lost, mostly from aging pipelines.

"Infrastructure investments save lives, help the environment and, over time, will put money in people's pockets," said Jackson, a senior fellow at the Stanford Woods Institute for the Environment and at Precourt Institute for Energy.

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