A baseline of atmospheric greenhouse gases for prospective UK shale gas sites

Shaw, Jacob; Allen, Grant; Pitt, Joseph; Mead, Mohammed Iqbal; Purvis, R. M.; Dunmore, Rachel E.; Wilde, Shona; Shah, Adil; Barker, Patrick; Bateson, Prudence; Bacak, Asan; Lewis, Alastair C.; Lowry, David; Fisher, Rebecca E.; Lanoisellé, M.; Ward, Robert S.

doi:10.1016/j.scitotenv.2019.05.266

Cited by 13 publications

(22 citation statements)

References 21 publications

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“…This is consistent with the measurements made by continuous stationary monitoring (Shaw et al 2020, submitted). Shaw et al (2020, submitted) measured [CH 4 ] above the median baseline (in westerly winds, see Shaw et al (2019)) for 117 h, over a 6-day period (11-16 January 2019) which coincided with UAV emission observations. Meanwhile, the UAV sampled intermittently within a 1.4 hour window, demonstrating temporal limitations of UAV sampling compared to continuous stationary sampling.…”

Section: Flux Results and Discussionmentioning

confidence: 65%

“…There were no cattle upwind of the UAVs during sampling. Baseline measurements conducted by Shaw et al (2019) over two years prior to fracking show that there are no significant upwind methane sources (in westerly winds), resulting in a flow of homogenous, well-mixed maritime background air. A DJI Spreading Wings S900 UAV platform (UAV3, see table 1 for details) flew downwind of nearby dairy farm buildings (referred to hereafter as cattle surveys).…”

Section: Experimental Descriptionmentioning

confidence: 99%

“…Furthermore, in conjunction with a flux technique such as the near-field Gaussian plume inversion (NGI) method (Shah et al 2019a), UAV sampling can be used to provide a rough flux estimate for the entire facility, bridging the gap between leak detection and precise inventory standard fluxes (Shah et al 2019b). The versatile nature of UAVs allows sampling to be dynamically adapted, to maximise in-plume downwind measurements, whereas stationary measurements depend highly on suitable wind conditions (Shaw et al 2019).…”

Section: Introductionmentioning

confidence: 99%

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Unmanned aerial vehicle observations of cold venting from exploratory hydraulic fracturing in the United Kingdom

Shah

Ricketts

Pitt

et al. 2020

Environ. Res. Commun.

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Unmanned aerial vehicle (UAV) surveys allow for rapid-response near-field sampling, downwind of emission sources, such as gas extraction sites, without the need for site access. UAVs can be used in emission source identification alongside instantaneous flux estimation. A UAV was used to sample downwind of the UK's first and only gas extraction site to use exploratory onshore horizontal hydraulic fracturing (fracking) of shale formations, in Little Plumpton, Lancashire. In-situ calibrated UAV methane mole fraction measurements were made from a neighbouring field on five sampling days between October 2018 and February 2019, during fracking, flow-back and flow testing. Methane emissions were identified on one of the five sampling days (14 January 2019), associated with known cold venting, following fluid unloading using a nitrogen lift. A near-field Gaussian plume inversion approach was used to calculate four instantaneous fluxes on this day (from four separate intermittent UAV flight surveys) with lower and upper uncertainty bounds of between 9-80 g s −1 , 23-106 g s −1 , 16-82 g s −1 and 34-156 g s −1 , respectively. The cold venting emissions observed on this single day were at least an order of magnitude higher than UAV methane fluxes calculated for nearby dairy farm buildings, also presented here. Identifying and quantifying these methane emission sources are important to improve the national emissions inventory and to regulate this developing UK industry.

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Section: Flux Results and Discussionmentioning

confidence: 65%

Section: Experimental Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Unmanned aerial vehicle observations of cold venting from exploratory hydraulic fracturing in the United Kingdom

Shah

Ricketts

Pitt

et al. 2020

Environ. Res. Commun.

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“…Consequently, the UK is uniquely placed to gather important new data by observing these early stages of the industry to address this knowledge gap. This has been demonstrated in Lowry et al (2020), Purvis et al (2019) and Shaw et al (2019), in which local climatological baselines of greenhouse gases and air quality components were defined at two UK sites proposed for hydraulic fracturing shale gas development. Further, Shaw et al (2019) developed a statistically derived algorithm for quick detection of CH 4 enhancements (such as emission events) based on exceedances of the baseline conditions.…”

Section: Introductionmentioning

confidence: 95%

“…Calibrations were performed during regular site maintenance visits (roughly every 3 weeks), using gas from three 40 L laboratory standards (filled by Deuste, Steininger GmbH, Germany, and certified on the WMO scale by EMPA, Switzerland) decanted into 6 L SilcoCan canister (Thames Restek, UK) for transport. Further detail on the calibration procedures and quality assurance measures used to ensure data quality can be found in Shaw et al (2019). Data from the UGGA instruments were corrected for small systematic errors associated with water vapor using the procedure outlined by O' Shea et al (2013).…”

Section: Monitoring Site Designmentioning

confidence: 99%

Methane flux from flowback operations at a shale gas site

Shaw

Allen

Pitt

et al. 2020

Journal of the Air & Waste Management Association

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We report measurements of methane (CH 4 ) mixing ratios and emission fluxes derived from sampling at a monitoring station at an exploratory shale gas extraction facility in Lancashire, England. Elevated ambient CH 4 mixing ratios were recorded in January 2019 during a period of cold-venting associated with a nitrogen lift process at the facility. These processes are used to clear the well to stimulate flow of natural gas from the target shale. Estimates of CH 4 flux during the emission event were made using three independent modeling approaches: Gaussian plume dispersion (following both a simple Gaussian plume inversion and the US EPA OTM 33-A method), and a Lagrangian stochastic transport model (WindTrax). The three methods yielded an estimated peak CH 4 flux during January 2019 of approximately 70 g s −1 . The total mass of CH 4 emitted during the six-day venting period was calculated to be 2.9, 4.2 ± 1.4(1σ) and 7.1 ± 2.1(1σ) tonnes CH 4 using the simple Gaussian plume model, WindTrax, and OTM-33A methods, respectively. Whilst the flux approaches all agreed within 1σ uncertainty, an estimate of 4.2 (± 1.4) tonnes CH 4 represents the most confident assessment due to the explicit modeling of advection and meteorological stability permitted using the WindTrax model. This mass is consistent with fluxes calculated by the Environment Agency (in the range 2.7 to 6.8 tonnes CH 4 ), using emission data provided by the shale site operator to the regulator. This study provides the first CH 4 emission estimate for a nitrogen lift process and the first-reported flux monitoring of a UK shale gas site, and contributes to the evaluation of the environmental impacts of shale gas operations worldwide. This study also provides forward guidance on future monitoring applications and flux calculation in transient emission events.Implications: This manuscript discusses atmospheric measurements near to the UK's first hydraulic fracturing facility, which has very high UK public, media, and policy interest. The focus of this manuscript is on a single week of data in which a large venting event at the shale gas site saw emissions of ~4 tonnes of methane to atmosphere, in breach of environmental permits. These results are likely to beresults are likely to be reported by the media and may influence future policy decisions concerning the UK hydraulic fracturing industry.

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