A cautionary tale of identifying the source of a methane plume over the North Sea
Data collected from the Facility for Airborne Atmospheric Measurements (FAAM) research aircraft has been analysed to try and identify the source of a plume of methane observed over the North Sea. A recently published article explains that initial analysis suggested the methane was being emitted from the gas field area, but important analysis of carbon isotopes in the methane revealed that leaked gas was not the main component of the plume.
The energy sector accounts for about a third of all greenhouse gas emissions in the UK, including a number of offshore gas fields in the seas around Britain. Reducing methane emissions is a way to reduce global warming, but if effective measures are to be taken to reduce methane emissions, we must first find out exactly where it’s coming from.
Methane in the Arctic: Measurements, process studies and Modeling (MAMM) project aims to study Arctic methane using ground and airborne measurements. During summer measurement campaigns in 2012 – 2014 across Scandinavian wetlands, NCAS scientists on the Atmospheric Research Aircraft (managed by FAAM) took the opportunity to make measurements over gas and oil fields in the North Sea on its way back to the UK. The aim was to provide an estimate of methane emissions, identify their sources, and evaluate whether the methods used are fit for purpose.
On one particular occasion, when weather conditions were ideal, the FAAM aircraft circuited North Sea gas fields with the aim of intercepting any fugitive methane gas. Initial analysis of the amount of methane and its location suggested that it was being emitted from the gas field area, and this was also supported by dispersion modelling. However, analysis of carbon isotopes in methane revealed that fugitive gas could not have been the primary component of the plume. As methane is often measured without analysis of its carbon isotopes, this finding presents an important cautionary tale. The MAMM researchers have developed recommendations for how best to conduct analyses of methane plumes in the future to try and avoid potential misdiagnosis of their sources.
This is the latest in a series of journal articles based on the MAMM project field work. The article is initially behind a paywall, but will become freely available after six months. If you’d like to request a copy, get in touch with the lead author Michelle Cain.
You can read Michelle's blog about this research here.
Image courtesy of John Pyle.