Can I identify a flare with a performance issue: Satellite monitoring – Directed methane monitoring

Summary

Satellite monitoringRemote sensing using satellite technology is emerging as a powerful tool for investigating methane emissions of all kinds. Where a large number of flares are operated over wide or inaccessible… can be used to monitor for flares with higher than normal methane emissions. Several technologies are now available, and further systems and services are being launched in the coming years.

The technology can be broadly classed in to two types of activity:

1. Wide area survey – in which the spatial resolution is low. An example of this is the Tropomi sensor onboard the Sentinel-5P satellite. Monitoring of this kind can identify trends in total methane emissions within a region.
2. Directed satellite monitoring – The satellite is directed towards specific locations and monitored with a higher resolution. GHGSat and MethaneSat are examples of this technology.

There are advantages and challenges associated with both technologies.  Both require additional information – such as visible imagery or thermal data (VIIRS) to differentiate flaring from other potential sources of methane, such as  venting.

This entry focuses on directed measurements where the satellite is measuring the spectral signature of methane. It is different to technologies that infer methane emissions from other data sources such as the thermal signature (see VIIRS)

In addition to satellite operators, there are a growing number of service organisations that will process publicly available or privately sourced data and use analytics to give insights to an operator.

How it Works

• The satellite is positioned with a low-altitude polar orbit designed to give global coverage and tasked towards a chosen location.
• Methane is measured using multi-spectral imaging using sunlight that is scattered back to space by Earth’s surface and atmosphere. Gases of interest, such as methane, have a unique spectral fingerprint.
• The sensor measures the total-column of methane in the atmosphere – It is not differentiating between background methane or emissions from different sources that overlap vertically.
• The image quality is dictated by the resolution of the imager. Targeted measurements offer much higher resolution than regional measurements with individual images being 100m or less.
• Converting image data in to emission rates requires additional data inputs, most notably windspeed. Information on metered gas volumes is required to derive deeper insights into flare efficiency.
• Ground truth of satellites based upon controlled release experiments are ongoing – with reported emissions >200kg/h so far presented. At this scale the satellite will identify an unlit flare, but not the residues of incomplete combustion.

Quantifying methane emissions from the global scale down to point sources using satellite observations of atmospheric methane

Daniel J. Jacob et al.

Satellite instruments for observation of methane in the shortwave infraredA wavelength just greater than that of the red end of the visible light spectrum but less than that of microwaves. Infrared radiationhas a wavelength from about 800nm to 1… (SWIR). Area flux mappers are designed to quantify total methane emissions on regional to global scales. Point source imagers are designed to quantify emissions from individual point sources by imaging the atmospheric plumes.

Figure 1