Environmental baseline monitoring for shale gas development in the UK: Identification and geochemical characterisation of local source emissions of methane to atmosphere

• Published in: The Science of the total environment Vol. 708; p. 134600
• Main Authors: Lowry, David, Fisher, Rebecca E., France, James L., Coleman, Max, Lanoisellé, Mathias, Zazzeri, Giulia, Nisbet, Euan G., Shaw, Jacob T., Allen, Grant, Pitt, Joseph, Ward, Robert S.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.03.2020
• Subjects: Baseline surveys; Carbon isotopes; Ethane; Methane; Mobile measurement; Methane; Mobile measurement; Baseline surveys; Carbon isotopes; Ethane
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.134600

[Display omitted] •Seasonal surveys to identify CH4 sources near planned unconventional gas extraction.•Mobile measurement of CH4 and C2H6 with subsequent GIS mapping.•Sample collection for carbon isotope analysis of CH4.•Characterization of methane sources into fossil fuel, waste and farming categories.•Potential fugitive emissions from unconventional gas could be identified. Baseline mobile surveys of methane sources using vehicle-mounted instruments have been performed in the Fylde and Ryedale regions of Northern England over the 2016–19 period around proposed unconventional (shale) gas extraction sites. The aim was to identify and characterise methane sources ahead of hydraulically fractured shale gas extraction in the area around drilling sites. This allows a potential additional source of emissions to atmosphere to be readily distinguished from adjacent sources, should gas production take place. The surveys have used ethane:methane (C2:C1) ratios to separate combustion, thermogenic gas and biogenic sources. Sample collection of source plumes followed by high precision δ13C analysis of methane, to separate and isotopically characterise sources, adds additional biogenic source distinction between active and closed landfills, and ruminant eructations from manure. The surveys show that both drill sites and adjacent fixed monitoring sites have cow barns and gas network pipeline leaks as sources of methane within a 1 km range. These two sources are readily separated by isotopes (δ13C of −67 to −58‰ for barns, compared to −43 to −39‰ for gas leaks), and ethane:methane ratios (<0.001 for barns, compared to >0.05 for gas leaks). Under a well-mixed daytime atmospheric boundary layer these sources are generally detectable as above baseline elevations up to 100 m downwind for gas leaks and up to 500 m downwind for populated cow barns. It is considered that careful analysis of these proxies for unconventional production gas, if and when available, will allow any fugitive emissions from operations to be distinguished from surrounding sources.