Google Street View cars outfitted with special sensors have identified hundreds of small but steady methane leaks lying beneath the streets in three US cities.
The specially equipped cars drove the streets of Boston, Staten Island, and Indianapolis sniffing out minor gas leaks for a pilot mapping project in conjunction with the New York-based Environmental Defense Fund and local utility companies. EDF released the findings online Wednesday, along with a set of interactive maps.
The leaks identified by this study do not represent a safety threat but do add up to a large volume of smog-inducing, greenhouse gas emissions, EDF chief scientist Steven Hamburg told reporters during a media briefing about the pilot program Wednesday.
While utilities are federally mandated to address large gas leaks that pose hazards to property and people, smaller, chronic leaks typically fall by the wayside until the pipes can be fully replaced, Mr. Hamburg said.
“This work creates an important tool for helping to understand where the largest of these leaks are and where the dollars that are being spent to modernize and upgrade gas systems can best be utilized,” Hamburg said.
National Grid, a utility company that operates pipelines in Boston and Staten Island, plans to use the data gathered through this pilot program to prioritize replacement of aging pipelines, Susan Fleck, National Grid’s Vice President of Pipeline Safety, told reporters during the briefing.
The problem appears to be particularly pervasive in cities with aging infrastructure. In Boston and Staten Island – both of which rely on many pipes that are more than 50 years old – the sensors detected an average of one leak per every mile driven. Many cities in the Northeast rely on similarly aging infrastructures. By contrast, Indianapolis – which has invested heavily in updated natural gas pipes – yielded an average of just one leak per 200 miles driven.
For its part, Massachusetts adopted a uniform classification system for prioritizing repairs of leaks in natural gas pipelines in a new law signed by Gov. Deval Patrick (D) on July 7. The EDF report highlights this law as a point of progress in developing a process to plan and fund long-term pipeline upgrades.
Methane is a potent greenhouse gas that can have a short-term impact on climate up to 120 times greater than carbon dioxide, says Louis Derry, a professor of earth and atmospheric sciences at Cornell University in Ithaca, N.Y. Over the long term, however, methane is not a major factor in altering climate because it persists in the atmosphere for only 10 to 20 years, he says.
“Even if methane is not a major climate player, curbing emissions is the right thing to do because it will reduce the danger of small leaks growing into larger, more dangerous leaks and will help to improve overall air quality,” Professor Derry says. (Methane is a contributing factor in the formation of ozone and smog.)
The release of these findings in a user-friendly format could help to secure public buy-in for costly infrastructure improvements, Derry suggests.
Replacing pipelines “is expensive, nobody wants to pay for it, and nobody wants to have their street dug up,” he explains. The visualizations offered by the EDF maps could persuade the public to put up with rate increases and the nuisance of lengthy construction projects to overhaul corroding pipelines.
The most encouraging aspect of this study, Derry says, is its role as an illustration of the technological leap in sensing capabilities. Until just a few years ago, these measurements would have been collected by hand and individually processed in the laboratory, he says. Today, for about $50,000, researchers can affix a sensor capable of taking a reading every second to the roof of a car or the wing of an airplane.
“This is a highly, cost-effective way to cover large areas that just wasn’t possible a few years ago,” he says. That capability could be used to follow up in an area where pipes have been replaced to see whether the replacement was effective in curbing emissions. It could also be employed to measure other emissions such as water vapor or carbon dioxide.