Thousands of natural gas leaks from pipelines under Washington D.C.

Natural gas leaks plotted across the skyline of Washington D.C. Natural gas is both explosive and a potent greenhouse gas.
Promo image Copyright © 2014 American Chemical Society

Natural gas, an explosive and potent greenhouse gas, just leaking out from all over the underground utility pipelines in Washington D.C.? It's true, according to a study released in the journal Environmental Science & Technology.

Lost and unaccounted

"Lost and unaccounted" or LAU -- that's what the Pipeline and Hazardous Materials Safety Administration (PHMSA) calls the gas that enters a distribution network but is not metered out to customers. Meter errors can influence this percentage so LAU is not an exact accounting of the leaking gas.

Finding LAU gas could save lives already. Natural gas explosions caused 17 deaths, 68 injuries, and $133 million per year, on average, between 1991 and 2001 according to PHMSA records analyzed by the authors of the paper. We sympathize with those who have suffered the pain and tragedy these statistics represent, but we also need to direct attention to the fact that these leaks contribute disproportionately to global warming.

Largest source of the greenhouse gas methane

Natural gas leaks are "the largest anthropogenic source of the greenhouse gas methane (CH4) in the U.S.," according to a new paper which cites the EPA as their source for this claim.

Remember, methane's potential to contribute to global warming over the next 20 years is 86 times higher than that of carbon dioxide, in spite of multipliers like the 21x cited by EPA, which apply over a 100-year time span.

Mapping methane leaks

Thank goodness scientists are developing new methods of detecting methane leaks, and ultimately holding utilities accountable. The method consists first of driving around with a monitor that maps the concentrations of gas in the air against GPS coordinates. This data can be analyzed for peaks of gas in excess of the expected background levels.

The study can differentiate natural gas leaks from biological sources of methane (e.g. Senators full of hot air?) by fingerprinting certain carbon isotopes in the gas, and by measuring the amount of ethane and propane found together with the methane.

In 19 locations where a significant peak in gas levels was found, the scientists measured gas levels in manholes, where the gas can build up to explosive levels. In 12 of those 19 locations, they found what experts define as grade 1 leak, which is "an existing or probable hazard to persons or property, and requires immediate repair or continuous action until the conditions are no longer hazardous."

A grade 1 leak represents a build up of gas to above 4%, which is close to the lower explosive limit of 5%. Some of the manholes tested had concentrations as high as 50% methane. This level is so high it won't explode due to lack of oxygen -- but with air everywhere that doesn't make the situation safe!

Incentives for action

Naturally, the research team advised the local distribution company about the leaks measured at levels that "require immediate repair." Then they went back four months later. Imagine their surprise to find that 9 of the 12 manholes STILL had levels of methane that represent an immediate hazard to life and property! (We wonder if criminal investigations can be started now, or do we have to wait until someone dies?)

The report cites several barriers to pipeline repair and replacement:

cost recovery for pipeline repairs by distribution companies is often capped by Public Utility Commissions (PUCs). Furthermore, consumers often pay for all or most of the lost-and unaccounted-for gas through user fees, meaning that the local distribution company has less financial incentive to fix leaks than might be predicted from the value of lost gas alone.

A 2013 report by E. J. Markey to the U. S. House Natural Resources Committee estimated that Americans paid more than $20 billion between 2000 and 2011 on lost and unaccounted for gas. The evidence in this newest report, and the methods employed, should prompt immediate action -- not just in Washington but in cities around the globe -- to save money and lives.

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