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Monday, December 31, 2012

Mapping Natural Gas Leaks From Aging Urban Pipes


Scientists from Boston University and Duke University took equipment that detects methane — the main constituent of natural gas — on a 785-mile van ride through Boston’s streets. The result, published in the journal Environmental Pollution, is a map showing more than 3,300 spikes in gas concentrations representing leaks of various sizes.

Most of the leaks are minor, but some could pose an explosion risk and they add up to a lot of lost money and an unnecessary source of greenhouse gas emissions. According to a thorough 2009 report in Pipeline and Gas Journal on gas leaks from our antiquated distribution system:
Fugitive methane emissions from distribution mains account for 32 percent of methane emissions from the U.S. natural gas distribution sector. Cast iron pipelines contribute the most to these emissions, despite representing only 3 percent of the miles of the U.S. distribution mains.
This situation is deeply reminiscent of similar issues with leaky old water mains — some are a century old — in aging cities. Infrared imagery to spot possible gas leaks from drilling sites and pipelines can be used to spot urban leaks. Here’s a closeup image of some Boston’s distribution-system leakage:

Scientists have reported finding methane concentrations reflecting 3,356 leaks in the natural gas distribution system in Boston. This illustration shows spikes in methane levels in parts per million (ppm). The background level is 2.07 ppm.
 
Environmental Pollution Scientists have reported finding methane concentrations reflecting 3,356 leaks in the natural gas distribution system in Boston. This illustration shows spikes in methane levels in parts per million (ppm). The background level is 2.07 ppm.
 
Here’s a view from the “cockpit” during their Boston leak-detection tour:

Scientists crisscrossing hundreds of miles of streets in Boston with instruments that detect elevated levels of methane, the main constituent in natural gas. Thousands of leaks were identified.
 
 (NYT, 11/20/2012)

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