Beyond Gas

Methane (CH₄), a tasteless, colorless, and odorless gas, is the primary component of natural gas. Gas utility companies add mercaptan, a sulfur-smelling chemical, so people recognize and report gas leaks when they occur.

Methane is one of the most potent greenhouse gases. Methane’s lifetime in the atmosphere is much shorter than carbon dioxide (CO₂), but methane is more efficient at trapping radiation than CO₂. Pound for pound, the comparative impact of methane is 25 times greater than CO₂ over a 100-year period.

[source: IPCC (2007). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. [S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. Cambridge University Press. Cambridge, United Kingdom 996 pp.]

Massachusetts has one of the oldest gas pipeline networks in the country, and more than 11% of it is made from leak-prone materials like cast iron and bare steel. Some of the pipes running under our streets are more than 100 years old.

When a gas leak is reported, the gas utility must assess the leak to determine if it poses a safety hazard. Gas leaks are graded into three categories:

• Grade 1: Potentially explosive leaks, should be repaired immediately
• Grade 2: Leaks that pose a potential future hazard, should be repaired within 12 months
• Grade 3: Non hazardous leaks, not required to be repaired unless…
• SEI: Pose a “significant environmental impact,” must be repaired within 2 years.

Climate advocates have fought hard to change regulations governing Grade 3 leaks. In the past, Grade 3 leaks never had to be repaired, no matter how much methane they released into the atmosphere. Legislative wins and regulatory changes in recent years mean gas utilities have finally started to measure the size of reported gas leaks. Those found to have “significant environmental impact” (SEI) are prioritized for repair, but the pace of repairs remains slow.

HEET, a Cambridge-based nonprofit working to cut carbon emissions, generates gas leaks maps using data reported by gas utility companies. They have maps of every town in Massachusetts. Check it out here.