UAS-Methane: An unmanned aerial system for the remote sensing of methane flux

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The goal of this proof of concept project is to develop and test an integrated new unmanned aerial system (UAS) remote sensing platform for the measurement of 3-dimensional methane concentration fields and emission flux. Our technology approach is to integrate a rotary-hovering UAS with a scanning open-path tuneable-diode-laser absorption spectrometer (TDLAS) and use it to rapidly retrieve time-evolving methane plume concentration fields over local scales (1m to 1 km). A real-time measurement and visualisation of 3D plume advection would facilitate the calculation of hotspot emission flux and serve gas-leak applications - an application relevant to NERC greenhouse-gas source apportionment science with transferability for a range of industries. There is an urgent technological need to meet this science and impact challenge. National anthropogenic methane inventories and industrial life cycle analyses are at present a best guess of fugitive emissions extrapolated for various component source-types. Natural (biogenic) sources of methane are also poorly characterised by measurement. As agreed at the 21st Conference of the Parties (COP-21) in Paris in 2015, currently estimated anthropogenic methane inventories must now include validation by measurement to meet and monitor ambitious 2050 emissions targets. UAS-based measurement offers an appropriate technology ripe for development for this purpose. The vertical profiling, manoeuvrability, and viewing geometry of UAS offers unique sampling for local-scale remote sensing applications and site-wide monitoring. This proposal seeks to develop such a capability from concept to prototype and builds on the team's experience in development of UAS for other environmental science applications.UK expertise and infrastructure in the use of UAS technology for environmental science lags behind an emerging international community that promises to revolutionize understanding of local scale processes across several NERC themes (see Figure 1). We build on our experience in developing and flying in situ UAS measurement systems to develop a new remote sensing UAS TDLAS scanning technology. The project develops a new flux concept and addresses practical challenges in sensor-platform integration. The integration of TDLAS with UAS is commensurate with TRL 3/4 (non-integrated components), while data telemetry and the tomographic inversion algorithms we seek to use to derive flux from concentration measurements are all conceptual (commensurate with TRL 2). We will develop and test this integrated technology to TRL 5/6 criteria (bench test and validation) such that a working prototype platform may be ready for field trial at the conclusion of the project. To summarise, our concept is to retrieve methane flux by remote sensing on a UAS platform. The technology to address this concept is the development an integrated UAS-TDLAS platform with a scanning gimbal. And the proof required to validate the concept will be a validated dataset, which uses tailored tomographic algorithms to invert concentration measurements for methane flux.