The Climate Threat in Your Front Yard

(Bloomberg View) -- Smokestacks and tailpipes may be the biggest and most obvious sources of greenhouse gases, but they're not the only ones to worry about. An invisible, underappreciated one is right in America's front yards: leaking pipes that carry natural gas into people's homes.

The good news is that scientists have devised a clever way to find these leaks, by attaching methane detectors to car bumpers -- they've used Google's "Street View" photography cars -- and driving along the city streets. It's a strategy that natural gas utilities should use to monitor their networks and seal the biggest leaks.

Utility companies and their state regulators have long known that some of their pipe networks are not air-tight, but their primary concern is leaks that threaten to explode. Even rather large leaks are often considered "nonhazardous" if they're venting into the air through someone's front lawn or via cracks in the sidewalk.

But leaked natural gas -- largely methane -- is a very hazardous greenhouse gas. Although it is not as ubiquitous as carbon dioxide, and remains in the air for only about a decade (compared with more than a century for CO2), methane is 80 times better at trapping heat. So even though leaks from city networks make up a small fraction of all methane leaks in the U.S., they can do significant climate damage.

They're also expensive. In Boston, an estimated $90 million worth of natural gas escapes the network every year -- a loss that gets passed along to customers. Cities outfitted with modern plastic or coated-steel pipes have very few leaks, while those with century-old cast-iron or bare steel pipes have thousands.

Putting those methane detectors on car bumpers is a way to quickly assess a city's leaks, and steer utilities toward the biggest offenders. In the places scientists have examined so far, a small number of large leaks account for an outsized share of the problem. By plugging just 20 percent of the leaks, utilities can cut their methane emissions in half.

State governments, which regulate utilities, should require utilities to monitor leaks, prioritize them and get to work plugging them. In California, officials are looking into mandating drive-by surveys. Other states are considering requiring that utilities repair leaks for environmental as well as public-safety reasons. Above all, states should no longer allow utilities to charge customers for the gas that escapes the system.

This is a case in which scientists have been able to deploy new technology both to identify the scope of a climate problem and to create a path toward solving it. Natural gas utilities -- and their state regulators -- should take advantage of the breakthrough.

--Editors: Mary Duenwald, Michael Newman

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