title: Methane destruction efficiency of natural gas flares associated with shale formation wells.
abstract: Flaring to dispose of natural gas has increased in the United States and is typically assumed to be 98% efficient, accounting for both incomplete combustion and venting during unintentional flame termination. However, no in situ measurements of flare emissions have been reported. We used an aircraft platform to sample 10 flares in North Dakota and 1 flare in Pennsylvania, measuring CO2, CH4, and meteorological data. Destruction removal efficiency (DRE) was calculated by assuming a flare natural gas input composition of 60-100% CH4. In all cases flares were >99.80 efficient at the 25% quartile. Crosswinds up to 15 m/s were observed, but did not significantly adversely affect efficiency. During analysis unidentified peaks of CH4, most likely from unknown venting practices, appeared much larger in magnitude than emissions from flaring practices. Our analysis suggests 98% efficiency for nonsputtering flares is a conservative estimate for incomplete combustion and that the unidentified venting is a greater contributor to CH4 emissions.
authors: Department of Chemistry and ‡Department of Earth, Atmospheric and Planetary Sciences, Purdue University , 560 Oval Drive, West Lafayette, Indiana 47907, United States.
authors: Dana R
authors: DR
authors: Caulton
authors: Paul B
authors: PB
authors: Shepson
authors: Maria O L
authors: MO
authors: Cambaliza
authors: David
authors: D
authors: McCabe
authors: Ellen
authors: E
authors: Baum
authors: Brian H
authors: BH
authors: Stirm
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002245:Carbon Dioxide / Q000032:analysis; D006801:Humans; D008697:Methane / Q000032:analysis*; D059206:Natural Gas; D009658:North Dakota; D010414:Pennsylvania; D014481:United States
chemical_list: D000393:Air Pollutants; D059206:Natural Gas; D002245:Carbon Dioxide; D008697:Methane