A few “superemitters” may be leaking half of Boston’s gas

We’ve been eagerly waiting for BU researcher Margaret Hendrick’s new study of gas leaks in Boston. It’s out, and it contains a shocker: a few gas leaks (7%, in the study) may account for half of all the gas being leaked in the city.

Hendrick’s study — just published in the journal Environmental Pollution — randomly selected 100 known leaks and measured how much gas each was emitting. Fifteen of them were Grade 1 leaks, which are supposed to be repaired immediately. Those were reported to the gas utility.  Overall, of all 100 leaks, seven accounted for 50 percent of the emissions.

The study found leak rates from 0.2 to 1,219 cubic feet per day. The average U.S. home uses approximately 200 cubic feet of natural gas per day.

The current US system for classifying leaks has three grades, based on gas concentration (higher concentrations are more explosive) and nearness to buildings. Grade 1 leaks are supposed to be fixed immediately, grade 2 leaks within a year, and grade 3 leaks at the utility’s discretion. But this grading system doesn’t consider the volume of methane emitted, and that’s critical for climate change because methane is 86 times more potent a greenhouse gas than carbon dioxide over its first 20 years in the atmosphere. Fixing all the gas leaks in Massachusetts would lower the state’s greenhouse gas footprint by 10%, according to Hendrick’s faculty advisor Nathan Phillips, and move us quickly toward our 2020 climate goals.

Hendrick’s study calls for an additional classification system that measures the volume of escaping gas. The gas leak allies working group, of which BostonCAN is a member, has drafted a model city ordinance that would establish this new classification system, and it may be introduced this month in the Boston City Council.

Meanwhile, what are the gas utilities and the state Department of Public Utilities doing to find and plug these “super-emitters?”

See an excellent article on the new study from “InsideClimate News.”