title: Black Carbon Emissions from Associated Natural Gas Flaring.
abstract: Approximately 150 billion cubic meters (BCM) of natural gas is flared and vented in the world annually, emitting greenhouse gases and other pollutants with no energy benefit. About 7 BCM per year is flared in the United States, and half is from North Dakota alone. There are few emission measurements from associated gas flares and limited black carbon (BC) emission factors have been previously reported from the field. Emission plumes from 26 individual flares in the Bakken formation in North Dakota were sampled. Methane, carbon dioxide, and BC were measured simultaneously, allowing the calculation of BC mass emission factors using the carbon balance method. Particle optical absorption was measured using a three-wavelength particle soot absorption photometer (PSAP) and BC particle number and mass concentrations were measured with a single particle soot photometer. The BC emission factors varied over 2 orders of magnitude, with an average and uncertainty range of 0.14 ± 0.12 g/kg hydrocarbons in associated gas and a median of 0.07 g/kg which represents a lower bound on these measurements. An estimation of the BC emission factor derived from PSAP absorption provides an upper bound at 3.1 g/kg. These results are lower than previous estimations and laboratory measurements. The BC mass absorption cross section was 16 ± 12 m(2)/g BC at 530 nm. The average absorption Ångström exponent was 1.2 ± 0.8, suggesting that most of the light absorbing aerosol measured was black carbon and the contribution of light absorbing organic carbon was small.
authors.affiliation: Civil and Environmental Engineering, University of Illinois Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Weyant
authors.affiliation: Department of Chemistry, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Paul B
authors.initials: PB
authors.lastname: Shepson
authors.affiliation: Department of Mechanical Engineering, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States.
authors.forename: R
authors.initials: R
authors.lastname: Subramanian
authors.affiliation: Department of Physics, Ateneo de Manila University , Quezon City, Philippines.
authors.forename: Maria O L
authors.initials: MO
authors.lastname: Cambaliza
authors.affiliation: Department of Chemistry, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Alexie
authors.initials: A
authors.lastname: Heimburger
authors.affiliation: Clean Air Task Force, Boston, Massachusetts 02108, United States.
authors.forename: David
authors.initials: D
authors.lastname: McCabe
authors.affiliation: Climate and Health Research Network, Bowdoinham, Maine 04008, United States.
authors.forename: Ellen
authors.initials: E
authors.lastname: Baum
authors.affiliation: School of Aviation & Transportation Technology, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Brian H
authors.initials: BH
authors.lastname: Stirm
authors.affiliation: Civil and Environmental Engineering, University of Illinois Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Tami C
authors.initials: TC
authors.lastname: Bond
mesh_terms: D000336:Aerosols / Q000032:analysis; D000393:Air Pollutants / Q000032:analysis*; D002244:Carbon / Q000032:analysis; D002245:Carbon Dioxide / Q000032:analysis; D005740:Gases; D008697:Methane / Q000032:analysis; D059206:Natural Gas; D009658:North Dakota; D000066388:Oil and Gas Industry; D053260:Soot / Q000032:analysis*
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D005740:Gases; D059206:Natural Gas; D053260:Soot; D002245:Carbon Dioxide; D002244:Carbon; D008697:Methane