COLLECTION OF LEAKAGE STATISTICS IN THE NATURAL-GAS SYSTEM BY TRACER METHODS

Atmospheric tracer release techniques have been used to quantify low-l evel fugitive methane emissions from components and facilities in all sectors of the natural gas system in the United States. The emission d ata are collected as part of a program to extrapolate the emissions fr om the entire U.S. natural gas industry and thus reduce uncertainties in the environmental impact of increased natural gas use. In these exp eriments, the total methane emission from a site is measured by releas ing a tracer gas (SF6) at the natural gas facility to simulate the sou rce. Both methane and tracer levels are measured with real-time instru ments deployed in a mobile laboratory downwind of the site. A large ra nge of emission levels for the different sectors of the entire system was determined. Within any one group of a particular facility type the re is also much variability in the emission rates. The exact nature an d number of gas system components in a facility are important factors in determining its emission level.