title: Toward a better understanding and quantification of methane emissions from shale gas development.
abstract: The identification and quantification of methane emissions from natural gas production has become increasingly important owing to the increase in the natural gas component of the energy sector. An instrumented aircraft platform was used to identify large sources of methane and quantify emission rates in southwestern PA in June 2012. A large regional flux, 2.0-14 g CH4 s(-1) km(-2), was quantified for a ∼ 2,800-km(2) area, which did not differ statistically from a bottom-up inventory, 2.3-4.6 g CH4 s(-1) km(-2). Large emissions averaging 34 g CH4/s per well were observed from seven well pads determined to be in the drilling phase, 2 to 3 orders of magnitude greater than US Environmental Protection Agency estimates for this operational phase. The emissions from these well pads, representing ∼ 1% of the total number of wells, account for 4-30% of the observed regional flux. More work is needed to determine all of the sources of methane emissions from natural gas production, to ascertain why these emissions occur and to evaluate their climate and atmospheric chemistry impacts.
authors.affiliation: Departments of Chemistry, Earth, Atmospheric and Planetary Science, and Aviation Technology, Purdue University, West Lafayette, IN 47907.
authors.forename: Dana R
authors.initials: DR
authors.lastname: Caulton
authors.forename: Paul B
authors.initials: PB
authors.lastname: Shepson
authors.forename: Renee L
authors.initials: RL
authors.lastname: Santoro
authors.forename: Jed P
authors.initials: JP
authors.lastname: Sparks
authors.forename: Robert W
authors.initials: RW
authors.lastname: Howarth
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Ingraffea
authors.forename: Maria O L
authors.initials: MO
authors.lastname: Cambaliza
authors.forename: Colm
authors.initials: C
authors.lastname: Sweeney
authors.forename: Anna
authors.initials: A
authors.lastname: Karion
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Davis
authors.forename: Brian H
authors.initials: BH
authors.lastname: Stirm
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Montzka
authors.forename: Ben R
authors.initials: BR
authors.lastname: Miller
keywords: greenhouse gas; hydraulic fracturing; unconventional gas
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