Methane emissions from residential natural gas meter set assemblies.

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Energy Systems

Background:

• Residential natural gas meter set assemblies (MSAs) are known methane (CH4) emitters.
• Existing emissions factors for MSAs show significant variability.
• Previous studies may not have adequately accounted for emissions from regulator vents.

Purpose of the Study:

• To quantify methane emissions from residential MSAs in Calgary, Alberta.
• To compare empirical emissions factors with those used in greenhouse gas inventories.
• To assess the contribution of MSA emissions to city-level methane budgets.

Main Methods:

• Conducted targeted measurements of CH4 emissions from 37 residential MSAs.
• Utilized static chambers for regulator vent measurements.
• Employed a modified hi-flow sampler for fugitive emission detection.

Main Results:

• Emissions were dominated by pressure regulator vents (1.18 g CH4/h/MSA).
• Seven fugitive leaks were detected (0.018 g CH4/h/MSA).
• The total empirical emissions factor was 1.20 g CH4/h/MSA, approximately seven times higher than EPA estimates.

Conclusions:

• Residential MSA methane emissions may be significantly underestimated.
• Regulator vents are a critical, often overlooked, source of CH4 emissions.
• Further research into the causes of regulator vent emissions is needed for accurate mitigation and modeling.