Optical Sensor Fusion for Identification and Visualization of Fugitive Greenhouse Gas Emissions

This paper presents a sensor fusion between three non-gas sensing optical devices, to present a low-cost and accessible alternative to optical gas imaging systems used in detecting fugitive greenhouse gas (GHG) emissions in the wastewater sector. Gas visualization and quantification require sensors that fall within the absorption spectrum of a target greenhouse gas, that the environment has a sufficient background temperature difference, and that the gas is captured in the frame. We propose using three optical-based sensors; a Hyperspectral Camera, FLIR Thermal Camera, and a Spectroradiometer as an integrated system to identify and visualize gases. The cameras were mounted on a gimbal for stabilization and a custom 3D printed mount was developed to hold all three sensors at the same focal point. A custom-built acrylic chamber with variable flow speeds and a blacked-out background was used for controlled methane (CH4) and nitrous oxide (N2O) releases to test the validity of the integrated system. Results showed the uncooled thermal camera can identify methane and nitrous oxide leaks, with the radiometer able to capture the methane absorption spectrum. The hyperspectral camera, however, was unable to capture gas images, future work will require a full-frame camera with a higher spectral range.