Fingerprinting and accounting urban methane leaks

Background/Question/Methods

Methane has substantial greenhouse warming potential and is the principle component of natural gas.  Fugitive natural gas emissions could be a significant source of methane to the atmosphere.  However, the cumulative magnitude of natural gas leaks is not yet well constrained.  We use a combination of mobile and stationary methane monitoring to evaluate the atmospheric flux of methane to the atmosphere from the Boston urban area.  By sampling natural gas from commercial distribution networks and measuring ratios of carbon and hydrogen isotopes, we differentiate biogenic methane from natural gas leaks.

Results/Conclusions

We identify numerous methane leaks in the Boston area, including instances in which methane concentrations reach hazardous levels.  The isotopic fingerprints of gas from some leaks suggests thermogenic sources.  Reducing natural gas leaks from distribution networks in Boston and elsewhere could reduce the greenhouse warming impact from urban areas, improve safety for natural gas utility workers, and avoid utility customer spending for natural gas that is not used.