A dual-platform approach for quantifying methane emissions at site level

The increasing atmospheric concentrations of carbon dioxide (CO2) and methane (CH4) from anthropogenic activities pose a major challenge for climate change mitigation. Methane, with a global warming potential 28 times greater than CO2 over a 100-year period, is the second most impactful greenhouse gas (GHG) and requires urgent attention. Effective CH4 reduction hinges on addressing emissions at the level of industrial facilities (natural gas), landfills, and farms. Consequently, the development of reliable tools for site-specific emission detection and quantification is critical for implementing targeted mitigation strategies.

Recent advancements in CH4 atmospheric measurement techniques have enabled in situ mobile technologies deployed on aircraft, cars and now unmanned aerial vehicles (UAVs). UAVs can sample dispersion plumes at both point and facility scales, particularly in challenging locations where traditional methods may fall short (Liu et al., Atmospheric Measurement Techniques, 2024). Here we describe a dual-ground/air approach combining simultaneous CH4 measurements from mobile (car mounted) and aerial (drone-based) systems. This integrated method provides complementary data, offering improved coverage into methane plume dynamics and spatial distribution.

The UAV system employs an ABB LGR GLA131 sensor and 3D wind measurements on a high endurance octocopter with advanced autopilot capabilities, enabling precise detection and quantification of methane sources. The mobile platform features the MIRA Ultra Mobile LDS, delivering high resolution, ground-level emission mapping. Together, these platforms enhance the accuracy and scope of CH4 monitoring efforts.

We present measurements at sites revisited from earlier work that relied only on mobile measurements (Liu et al., Science of The Total Environment, 2023). This earlier work revealed that top-down estimates of methane emissions from waste and livestock in Cyprus exceeded bottom-up national inventory values by 160% and 40%, respectively. Integrating car- and drone-based mapping enables three-dimensional plume characterization providing an enhanced plume sampling and hence more precise quantification estimates. It sheds light on plume development, dispersion, and variability. This framework is particularly advantageous for tackling emissions from diverse and mixed sources such as agricultural operations, industrial facilities, and landfills, where complex environmental and topographical factors influence methane behaviour.