Cuadrilla plc’s hydraulic fracturing at its shale gas site in Lancashire led to an atmospheric venting of 4.2 tonnes of methane gas in one week, said the British Geological Survey (BGS).
The company, now 97% owned by Australian mining firm AJ Lucas, was operating in the Bowland shale (Preston) until the Government introduced a moratorium on fracking in 2019.
Earlier in July, Lucas said the future of hydraulic fracturing, commonly referred to fracking, in the UK remained open.(bit.ly/31QXNO6)
In September 2020, Cuadrilla announced it would reduce its operations on the border of Preston near Blackpool in the UK next year by 90% while it awaited the Government’s decision.(bit.ly/35IxMlo)
The emissions were detected at a nearby atmospheric monitoring station installed by researchers from The University of Manchester as part of a BGS-led environmental monitoring project project.
Elevated methane (CH4) concentrations (in air) were measured near the shale gas site over one week in January 2019.
The estimated total mass of methane emitted during the event was 4.2 (± 1.4) tonnes.
The BGS said that in terms of greenhouse warming potential, this was equivalent to 143 tonnes CO2 using the default 100-year time horizon conversion factor (GWP100), the annual electricity demand of 166 UK homes, or 142 London-New York flights.
The elevated methane was a result of releasing non-combusted methane from the flare stack at the site following operations to clean out the 2.3km deep shale gas well.
“The dangerous consequences of global warming are now beginning to become evident ” said Dr Jacob Shaw from the University of Manchester and lead author of the paper.
“Routine monitoring and scrutiny of the fossil fuel industry is crucial if we are to curb impacts, and also if we are to meet the UK Government’s Net Zero targets.”
Professor Rob Ward, policy director at BGS added that the study showed the importance of effective monitoring at oil and gas sites to establish the baseline to detect and quantify any emissions.
“Not only is this important for managing what might be a hazardous situation, it is also important for properly assessing greenhouse gas emissions.”
During the emission event, unmanned aerial vehicles (UAVs) were deployed to map the vertical and horizontal extent of the methane plume.
Researchers compared the data with two years of baseline measurements and took into account the season and wind direction.
Peak release rate was estimated to be approximately 70 g s-1, with an average over the whole week of 16 g s-1.
The BGS said: “The research found that independent estimates of methane emissions during the early stages of hydrocarbon development are not routinely made, nor are they generally understood for well development, well-unloading and well-stimulation activities.
“This may mean that greenhouse gas emissions are currently under-represented in lifecycle analysis of the overall carbon footprint of unconventional gas as an energy source. It will be important to include such processes in future greenhouse gas evaluations.”
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Professor Grant Allen, from The University of Manchester, added that the research showed atmospheric monitoring of shale gas activity was crucial to assess any role that the industry might have in the UK’s future energy mix, and whether or not it could be consistent with the country’s stated aim of achieving net-zero carbon emissions by 2015.
“This work informs that debate and provides new data on emissions from well-clearing activities that must be captured in industry life cycle assessments, and should be used to inform regulatory oversight and industrial practices surrounding venting activities such as the event quantified here.
“Such emissions should be avoided wherever possible.”
The work was supported by a grant from the Natural Environment Research Council as part of the NERC/ESRC Unconventional Hydrocarbons Research Programme, and grant funding from the Department for Business, Energy and Industrial Strategy (BEIS).