Benzene in Natural Gas, and indoor leakage
2022-07-01 17:58:36.131798+02 by Dan Lyke 0 comments
Sigh. Yeah, think over the next few years we need to see about enough battery to pull us through the longer power outages (maybe with more solar), and running wire to phase out our gas appliances. Not only are the climate impacts of natural gas too large to ignore, lots of evidence is coming in about the local impacts. Of course the "more solar" part is hard, household photovoltaic might actually have higher lifetime CO2 emissions vs Sonoma Clean Power's carbon emissions profile, depending on time of day generation. And our roof is pretty small... And I hate to have more batteries involved in anything, because they have a limited lifespan...
New York Times: Gas Piped Into Homes Contains Benzene and Other Risky Chemicals, Study Finds
Abstract The presence of volatile organic compounds (VOCs) in unprocessed natural gas (NG) is well documented; however, the degree to which VOCs are present in NG at the point of end use is largely uncharacterized. We collected 234 whole NG samples across 69 unique residential locations across the Greater Boston metropolitan area, Massachusetts. NG samples 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 unique NMVOC constituents in end use NG, of which 21 (or approximately 7%) were designated as hazardous air pollutants. Benzene (bootstrapped mean = 164 ppbv; SD = 16; 95% CI: 134–196) was detected in 95% of samples along with hexane (98% detection), toluene (94%), heptane (94%), and cyclohexane (89%), contributing to a mean total concentration of NMVOCs in distribution-grade NG of 6.0 ppmv (95% CI: 5.5–6.6). While total VOCs exhibited significant spatial variability, over twice as much temporal variability was observed, with a wintertime NG benzene concentration nearly eight-fold greater than summertime. By using previous NG leakage data, we estimated that 120–356 kg/yr of annual NG benzene emissions throughout Greater Boston are not currently accounted for in emissions inventories, along with an unaccounted-for indoor portion. NG-odorant content (tert-butyl mercaptan and isopropyl mercaptan) was used to estimate that a mean NG-CH4 concentration of 21.3 ppmv (95% CI: 16.7–25.9) could persist undetected in ambient air given known odor detection thresholds. This implies that indoor NG leakage may be an underappreciated source of both CH4 and associated VOCs.