March 5, 2013

In Focus: Methane leaks could cloud future for natural gas

Experts strive to learn whether the benefits of gas for the climate outweigh its dangers.

By JULIET EILPERIN The Washington Post

WASHINGTON - Two guys in a black Pontiac Vibe cruise the streets of Washington's residential neighborhoods. The only sign of what they are up to is a gray plastic tube hanging out of the trunk. And the fact that they get out of the car frequently to place a black box on manhole covers and study its readings.

click image to enlarge

Bob Ackley, left, a gas leakage specialist, and Robert Jackson, a professor of environmental sciences at Duke University, prowl streets for gas leaks In Washington, D.C.

Washington Post/Jahi Chikwendiu

click image to enlarge

Bob Ackley, a gas leakage specialist, uses a combustible gas indicator to test the outpouring of methane gas from a manhole in the affluent Spring Valley neighborhood of Washington, D.C.

Washington Post/Jahi Chikwendiu

Measuring how much methane gas is leaking from pipes under the District of Columbia could help answer a key policy question. As natural gas production expands in the United States, do its benefits for the climate far outweigh its dangers?

Methane, the main component of natural gas, is about 25 times more powerful as a heat-trapping gas than carbon dioxide, the largest human contributor to climate change; the atmospheric concentration of methane has doubled since the start of the Industrial Revolution.

While it largely dissipates in a few decades and there is far less of it in the atmosphere than CO2, it continues to drive global warming. Depending on how much leaks out in the journey from wellhead to homes and factories, some experts say, it could be enough to offset the advantages natural gas has over coal.

"We don't have enough data to develop sound policy going forward," said Steven Hamburg, chief scientist of the advocacy group Environmental Defense Fund. He noted that natural gas has a complex supply chain with "different geographies and geologies" along the way.

Hamburg is spearheading a $10 million two-year effort to measure methane emissions along the nation's supply chain. As activists and energy executives debate the natural gas industry's impact and the Environmental Protection Agency weighs whether to impose new regulations, Hamburg said, "it's critically important" the country develops a better data set on methane leaks.

The group has brought together academics, environmentalists and industry representatives to track different stages of natural gas extraction, production and transmission and will issue its initial report in May.

Other teams are also working to unlock the puzzle.


Bob Ackley spent January driving the city for 10 to 12 hours a day, usually with a researcher riding alongside. Ackley, who runs a methane-detection company, is part of a six-person group financed by Duke University's Nicholas School of the Environment that has collected data on thousands of methane leaks under Washington's roads.

On a recent trip through the city, Ackley took the wheel while Duke professor Robert Jackson tracked real-time methane concentrations that an instrument stashed in the car's trunk fed into a computer. Periodically the readings would spike to unsafe levels, with as much 32 percent methane escaping from a single manhole.

Last fall, the team published the results of a similar survey of Boston, which showed the city's aging infrastructure had 3,356 leaks. "Washington is at least as leaky as Boston, if not more," Jackson said. "It looks like it has both more leaks and bigger leaks than Boston."

Researchers disagree about how much methane is leaking into the atmosphere.

Cornell University's Robert Howarth has estimated somewhere between 3.6 percent and 7.9 percent of methane escapes during the production life cycle of shale gas; the Massachusetts Institute of Technology countered with a study saying it is just a fraction of that amount.

University of Colorado research scientist Gabrielle Petron, who also works in the National Oceanic and Atmospheric Administration's global monitoring division, said the rate of increasing atmospheric methane concentrations has accelerated tenfold since 2007. She said it will take a few more years to determine whether the natural gas boom helps explain the change.

"All we've done now are snapshot measurements," she said.


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