Methane leaks are a truly insidious contributor to climate change. They're not as well-publicized as CO2 emissions, but are 120 times more potent. They're invisible, have no smell, and can be found almost everywhere natural gas pipes are located.
Over the past two years, Google Earth Outreach and the Environmental Defense Fund have been testing Google Street View vehicles outfitted with methane sensors, driving them through U.S. cities to determine the pervasiveness and severity of methane leaks. The results of the pilot mapping program reveal thousands of leaks emanating from the streets of Staten Island, Indianapolis, and Boston.
In Boston and Staten Island, where pipes are older and made from leak-prone materials, leaks occur on average once per mile driven. Indianapolis has newer, less corrosive pipes, and as a result, leaks occur only once per 200 miles.
Here's the leak map for Boston. Note that yellow leaks have the same climate impact as driving 100 to 900 miles each day, while orange leaks have the same impact as driving 1,000 to 9,000 miles. There are only a few red leaks, but they're especially bad. They have the climate change equivalent of driving over 9,000 miles each day.
Here's the much less unsettling map for Indianapolis:
Interactive maps are available here.
EDF and Google started with a number of controlled release experiments, releasing different amounts of methane into the air to see whether wind and other factors would obliterate the signal from leaks. "We found that we really could discriminate small, medium, and large leaks based on patterns of methane concentration. At first I myself was very skeptical, but we found that very repeatable signatures are associated with leaks of different sizes," said Joe von Fischer am Associate Professor at Colorado State University who is working on the project, during a conference call.
Note that the leaks are in no way physically harmful to residents. Immediate and potential threats are addressed quickly by utilities, but non-hazardous leaks are generally just monitored and resurveyed periodically until pipes are replaced.
Physical and environmental harm are two very different things, however, and these new maps could offer a renewed sense of urgency to utilities hoping to mitigate environmental damage. By pointing out the most severe methane leaks, the maps give utilities a clear place to start (and gives residents a focal point for protest).
National Grid, a utility that pipes in natural gas to Boston, already plans to spend $1.8 billion to upgrade the city's gas infrastructure. It's also paying close attention to EDF's mapping project. "Basically, what we’re trying to do is deepen our understanding on how methane is released from the system," said Susan Fleck, Vice President of Pipeline Safety for National Grid. "There's a significant investment that comes with these improvements that will affect customers."
Don't see your city on the maps? EDF plans to map more cities and pollutants in the future.