Combining Methane Measurement Methods on an Active UK Gas Leak: A Case Study from the UK

August 2024

A summary of Dowd et al (2024) peer-reviewed paper “First validation of high-resolution satellite-derived methane emissions from an active gas leak in the UK”. 

Summary written by Bex Hadfield and Sarah Cheesbrough.

A large methane leak near Cheltenham was identified by National Centre for Earth Observation (NCEO) researchers in 2023 whilst observing the area with a satellite operated by GHGSat. The leak source was verified as natural gas by a mobile ground-based survey from Royal Holloway, University of London (RHUL). The information was shared with the utility company, who worked to fix the pipeline, ending a minimum 11-week leak estimated to have been the equivalent to the electricity consumption of 7,500 homes.  

This case study demonstrated for the first time, a UK methane emission being detected from space and validated by ground-based surveys to reduce fugitive methane emissions.  

Satellites have proven effective at detecting methane emissions, however many of the verifications of satellite data with ground-based measurements have been on ‘controlled releases’ where gas is intentionally released from a location to identify how effectively the satellite can detect the leak. This real-world methane leak was identified as an opportunity to test different technologies simultaneously on a real gas leak. 

Observing the Leak

While tasking a GHGSat satellite to take a series of images over a landfill site near Cheltenham, the NCEO research team found a large source of methane coming from elsewhere in the imaged area on the 27 March 2023. 

Figure 1 shows the timeline of events.  

• By 20 April, the persistence of the gas leak was confirmed with further data. GHGSat informed the utility company who began repairs one month after the first detection. 
• GHGSat continued to image the site, recording variable emission rates, with a peak methane flux of ~1375kg/h detected. Figure 2 shows the satellite-derived emission plumes. 
• On the 26 May, ground-based surveys from RHUL began. The RHUL surveys verified the location, source type (using ethane-to-methane ratios), and emissions rates. This confirmed the leak was from a gas distribution pipeline during its upgrade from old metal pipes to new plastic ones.  
• In early June, GHGSat observed a reduction in the size and strength of the methane plume before the leak was fixed on 13th June.  
• No emissions were observed by GHGSat above its 100kg/h minimum threshold by 16 June, 3 days after the leak was fixed.  
• Two further ground-based surveys confirmed no enhanced methane concentrations in the area. 

Figure 1 Timeline of events during the observation period of the gas leak (Dowd et al. 2024). Mobile-derived survey fluxes are in green, satellite-derived fluxes are in blue.

Figure 2 Total column CH4 (ppb) observation from GHGSat satellites, showing the variability in the size and shape of the emission plume (Dowd et al, 2024).

The Measurements

The results from the measurement period demonstrate that the GHGSat satellite-derived flux measurements are broadly in agreement with the surface-based mobile measurements taken by RHUL. The variability between the two methods is expected, due to the methods not capturing data at the same time, with changes in the pressure through the pipe experienced during the engineering works.  

Though simultaneous data collection was attempted, on the dates and times when the mobile vehicles were in situ the site was covered by cloud. Satellites such as those used in this study which operate in Short Wave Infrared wavelengths, cannot detect methane when cloud cover is present. Wind conditions also limited the measurement opportunities and influenced uncertainty within the flux estimates for both observation methods. The possibility of detection at a tall tower site 30km away which is part of the UK DECC (Deriving Emissions linked to Climate Change) network was also considered, although it is not designed to detect fugitive emissions and is a sparse network. Simulations were run and it was determined that it was unlikely this type of gas leak would be detected by the UK DECC network.   

Satellite Emission Detection Opportunity 

This real-world example exemplifies the value satellites can bring to identify and monitor events, with comparable capability to ground methods, to reduce emissions. This can provide value (and confidence) to many stakeholders including private companies and government bodies seeking to identify and reduce harmful emissions.  

GHGSat has been the leading asset-level methane-detecting satellite company since launching their first satellite in June 2016. The capabilities of GHGSat are set to continue improving with work on the next generation of satellites underway. Whilst other providers are joining the market with MethaneSat and CarbonMapper satellites being launched in 2024. (see our blog on satellite capability comparison). This improving capability will make this data more accessible for the detection of fugitive methane leaks in an operational way.  

New Greenhouse Gas legislation such as regulation (EU) 2024/1787 (recently produced for the European energy sector) is beginning to ask for evidence of site-level methane measurements. This presents the space sector with a clear opportunity to act as independent verifiers. The space sector needs to work with independent ground monitoring surveyors to validate the accuracy of satellite observations to increase confidence and understanding in its monitoring capabilities. This research by NCEO demonstrates a progressive step towards this in the UK.  

Further information 

The full scientific paper published in 2024 is available at this link.  

For UK-based organisations there is currently an opportunity to explore GHGSat data, through the Methane Monitoring Data Supply for the UK Programme, a partnership between Satellite Applications Catapult and GHGSat, funded by the UK Space Agency. This programme provides access to GHGSat archive data, as well as opportunities to request new sites.  

Contact ch4.data@sa.catapult.org.uk for further information.  

References 

Dowd, E., Manning, A.J., Orth-Lashley, B., Girard, M., France, J., Fisher, R.E., Lowry, D., Lanoisellé, M., Pitt, J.R., Stanley, K.M. and O’Doherty, S., 2024. First validation of high-resolution satellite-derived methane emissions from an active gas leak in the UK. Atmospheric Measurement Techniques, 17(5), pp.1599-1615.