title: Methane emissions from natural gas infrastructure and use in the urban region of Boston, Massachusetts.
abstract: Methane emissions from natural gas delivery and end use must be quantified to evaluate the environmental impacts of natural gas and to develop and assess the efficacy of emission reduction strategies. We report natural gas emission rates for 1 y in the urban region of Boston, using a comprehensive atmospheric measurement and modeling framework. Continuous methane observations from four stations are combined with a high-resolution transport model to quantify the regional average emission flux, 18.5 ± 3.7 (95% confidence interval) g CH4 ⋅ m(-2) ⋅ y(-1). Simultaneous observations of atmospheric ethane, compared with the ethane-to-methane ratio in the pipeline gas delivered to the region, demonstrate that natural gas accounted for ∼ 60-100% of methane emissions, depending on season. Using government statistics and geospatial data on natural gas use, we find the average fractional loss rate to the atmosphere from all downstream components of the natural gas system, including transmission, distribution, and end use, was 2.7 ± 0.6% in the Boston urban region, with little seasonal variability. This fraction is notably higher than the 1.1% implied by the most closely comparable emission inventory.
authors.affiliation: School of Engineering and Applied Sciences and Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138; kmckain@fas.harvard.edu.
authors.forename: Kathryn
authors.initials: K
authors.lastname: McKain
authors.affiliation: Nicholas School of the Environment and Center on Global Change, Duke University, Durham, NC 27708;
authors.forename: Adrian
authors.initials: A
authors.lastname: Down
authors.affiliation: Department of Earth and Environment, Boston University, Boston, MA 02215; Department of Biology, Hofstra University, Hempstead, NY 11549;
authors.forename: Steve M
authors.initials: SM
authors.lastname: Raciti
authors.affiliation: School of Engineering and Applied Sciences and.
authors.forename: John
authors.initials: J
authors.lastname: Budney
authors.affiliation: Department of Earth and Environment, Boston University, Boston, MA 02215;
authors.forename: Lucy R
authors.initials: LR
authors.lastname: Hutyra
authors.affiliation: Aerodyne Research, Inc., Billerica, MA 01821;
authors.forename: Cody
authors.initials: C
authors.lastname: Floerchinger
authors.affiliation: Aerodyne Research, Inc., Billerica, MA 01821;
authors.forename: Scott C
authors.initials: SC
authors.lastname: Herndon
authors.affiliation: Atmospheric and Environmental Research, Inc., Lexington, MA 02421; and.
authors.forename: Thomas
authors.initials: T
authors.lastname: Nehrkorn
authors.affiliation: Aerodyne Research, Inc., Billerica, MA 01821;
authors.forename: Mark S
authors.initials: MS
authors.lastname: Zahniser
authors.affiliation: Nicholas School of the Environment and Center on Global Change, Duke University, Durham, NC 27708; School of Earth Sciences, Stanford Woods Institute for the Environment, and Precourt Institute for Energy, Stanford University, Stanford, CA 94305.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Jackson
authors.affiliation: Department of Earth and Environment, Boston University, Boston, MA 02215;
authors.forename: Nathan
authors.initials: N
authors.lastname: Phillips
authors.affiliation: School of Engineering and Applied Sciences and Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138;
authors.forename: Steven C
authors.initials: SC
authors.lastname: Wofsy
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D001900:Boston; D008697:Methane / Q000032:analysis*; D059206:Natural Gas; D014507:Urbanization
chemical_list: D000393:Air Pollutants; D059206:Natural Gas; D008697:Methane
keywords: cities; greenhouse gas emissions; methane; natural gas distribution