(source: Matthew Grimm)

The Environmental Defense Fund has put the cars that Google Street View deploys to map routes, houses and commercial buildings to a new use: Mapping natural gas leaks.

The EDF issued interactive maps on Wednesday that will pinpoint the size and location of thousands of natural gas leaks from distribution pipes that lie below Boston, Indianapolis and Staten Island, data collected by using three specially-equipped Google Street View cars that took measurements every half second.

The maps show that Indianapolis, which has installed plastic pipe, has four leaks. But in Boston -- where natural gas travels through cast iron pipes dating back as far as the late 1800s and steel pipe installed in an era before rust protection -- there are approximately 3,000 leaks, many of them in pressing need of repair. Staten Island falls somewhere in between.

Here's a screenshot of Boston:

source: Environmental Defense Fund/Google Earth Outreach

For interactive versions, click here.

The study is one of a series of 16 that EDF is conducting to figure out just how much natural gas is leaking all along the supply chain, from shale gas wells drilled with hydraulic fracturing to processing plants, pipelines, commercial vehicles, and homes. The results are critical because natural gas, or methane, is a potent greenhouse gas, with about 120 times the effect of carbon dioxide over a 20-year period. Many supporters of the shale gas boom have argued that natural gas emits about half the carbon dioxide as coal plants do in the combustion process, but even small quantities of natural gas leaks could erase that advantage.

But EDF said the mapping of the three cities did not enable it to estimate the rate of natural gas leakage at the city distribution level because of the wide variations. The Environmental Protection Agency has estimated that only 0.24 percent of natural gas leaks from the delivery system.

"This creates a new method that utilities and regulators can use to do a more efficient job at repair and replacement," said Mark Brownstein, an associate vice president and lawyer at EDF. "You now have the ability to prioritize by addressing the most serious ones first. You will get a bigger bang for the buck spent repairing utility infrastructure. It is good for the environment, ratepayers and ultimately for the utilities themselves because they will now be able to make a stronger case for the dollars that they are spending."

EDF plans to help Con Edison map and prioritize at least a thousand leaks that need repair.

EDF's chief scientist Steve Hamburg added that the organization hopes to team with Google to map the location of other pollutants, including carbon dioxide and other emissions from coal and natural gas plants. "This is the beginning of an important transition in how we collect data," said Hamburg. "It’s about the democratization of data, giving people the data to understand their environment in a different way."

Fixing the leaks is a time consuming and expensive business. National Grid, the Massachusetts utility that delivers gas to Boston homeowners, said that it will spend $1.8 billion on gas infrastructure over the next five years. Its Massachusetts network has 2,194 miles of cast iron pipe and 1,441 miles of steel lacking rust protection. At the current pace, it will take National Grid 26 years to replace that pipe, the company said.

"We applaud EDF for bringing more information into the decision tree," said Sue Fleck, National Grid's vice president of pipeline safety and compliance. "Better information leads to better decisions and better decisions keep the costs low." She said the new maps "give us a level of detail we’ve never had before." She said the leak data would also help the utility head off safety threats.

For homeowners and utilities, safety ranks higher than climate on the list of concerns. While few of the leaks pose safety hazards, on occasion leaks can lead to massive explosions. A natural gas explosion in April destroyed three commercial buildings in the state of Washington, for example; because it happened at night, no one was killed.

The American Gas Association says that utilities have reduced methane emissions by 20 percent since 1990 and are spending $19 billion on safety measures that can also reduce environmentally damaging leaks.

Cities in Beijing already use online maps to track pollution levels in major cities on an hourly basis. Certain applications show measurements taken by both the U.S. embassy or consulates and Chinese government agencies. But the measurements come from a limited number of locations (12 in Beijing).