Home is Where the Pipeline Ends: Characterization of Volatile Organic Compounds Present in Natural Gas at the Point of the Residential End User

• DOI: 10.1021/acs.est.1c08298
• Publication Date: 2022-06-28T10:01:03Z
• Authors: Drew R. Michanowicz; Archana Dayalu; Curtis L. Nordgaard; Jonathan J. Buono...; Molly W. Fairchild; Robert Ackley; Jessica E. Schiff; Abbie Liu; Nathan G. Phillips; Audrey Schulman; Zeyneb Magavi; John D. Spengler
• Keywords: Volatile organic compound; BTEX

The presence of volatile organic compounds (VOCs) in unprocessed natural gas (NG) is well documented; however, the degree to which VOCs are present NG at point end use largely uncharacterized. We collected 234 whole samples across 69 unique residential locations Greater Boston metropolitan area, Massachusetts. were measured for methane (CH4), ethane (C2H6), and nonmethane VOC (NMVOC) content (including tentatively identified compounds) using commercially available USEPA analytical methods. Results revealed 296 NMVOC constituents NG, 21 (or approximately 7%) designated as hazardous air pollutants. Benzene (bootstrapped mean = 164 ppbv; SD 16; 95% CI: 134-196) was detected along with hexane (98% detection), toluene (94%), heptane cyclohexane (89%), contributing a total concentration NMVOCs distribution-grade 6.0 ppmv (95% 5.5-6.6). While exhibited significant spatial variability, over twice much temporal variability observed, wintertime benzene nearly eight-fold greater than summertime. By previous leakage data, we estimated that 120-356 kg/yr annual emissions throughout not currently accounted inventories, an unaccounted-for indoor portion. NG-odorant (tert-butyl mercaptan isopropyl mercaptan) used estimate NG-CH4 21.3 16.7-25.9) could persist undetected ambient given known odor detection thresholds. This implies may be underappreciated source both CH4 associated VOCs.