Methane emissions from natural gas extraction and distribution.

CH4 has come under increased scrutiny in recent years following the creation of the Global Methane Pledge (GMP), which requires signatory countries to reduce their 2020 CH4 by 30 % by 2030. In order to aid reduction efforts in sectors like the oil and gas (O&G) industry, legislation such as the Oil and Gas Methane Partnership 2.0 (OGMP 2.0) has been brought into effect. This requires O&G operators to report emissions through measurement based techniques. This thesis focuses on improving mobile measurement methodologies responsible for the detection of CH4 emissions, firstly from domestic natural gas distribution and secondly from offshore O&G platform flaring. Methodologies used in the detection of fugitive emissions from natural gas distribution were adapted based on instrumental limitations, to allow the detection of smaller emissions at a higher spatial resolution. Additionally, source assignment was included as a core part of the methodology to avoid CH4 emissions from other sources being associated with natural gas emissions. The deployment of this methodology within the cities of York and New York City showed that there were many very small fugitive emissions as opposed to a few large emissions, additionally, other sources, namely domestic pyrogenic emissions, were shown to provide a large contribution to city-wide CH4 emissions. Detection of CH4 from offshore flaring has become increasingly difficult as flares become more efficient. The final part of this thesis proposes a new approach to detect and quantify emissions from a highly efficient flare using a large research aircraft. Platform emissions may be modelled through dispersion modelling software before sources are
assigned to enhancements using NOx : CO2 enhancement ratios. Additional work within this section compared the emissions of other flares within the same region to demonstrate how much of a reduction in CH4 emissions a highly efficient flare results in.