Hyperspectral Thermal Infrared Imaging of Fugitive Methane Emissions from Flare Stacks

Mark Norman1,^{1,\star}, Stephane Boubanga1^{1}
^{\star} : mark.norman@telops.com
1^{1} Telops, Inc.
Mots clés : infrared, imaging, hyperspectral, methane
Résumé :

Fugitive methane emissions represent a significant contribution to environmental pollution and anthropogenic climate change. Methane is among the most infrared-active naturally occurring molecules and represents an 80X increase in atmospheric warming potency when compared to . The need for reliable and cost-efficient methane detection technology is critical to mitigating the environmental damage caused by fugitive emissions. Infrared hyperspectral imaging is a high capability technique suitable for the detection, identification, and quantification of both localized point-source emissions and diffuse emissions from a dispersed source. In this work, a miniaturized version of an infrared hyperspectral imaging system was deployed on an aircraft for airborne detection of methane emanating from a flare stack at a municipal wastewater treatment plant during a two-day measurement campaign in February 2023. The system used was a Hyper-Cam Airborne Mini Longwave camera operating from 7.7 – 11.8 microns (1300 – 910 ) at 10 spectral resolution. This region is coincident with characteristic infrared absorption lines of methane. The camera has a Stirling-cooled 320 × 256 pixel focal plane array (FPA) detector with a nominal field-of-view (FOV) of 13.5 × 10.9o. A Michelson interferometer is employed to temporally modulate the incoming passive infrared radiation such that a full infrared spectrum is obtained at each pixel of the FPA via a Fast Fourier Transform (FFT). Two reference blackbody sources are integrated into the camera for automated radiometric calibration of the detector. A high-definition visible boresight camera is also integrated into the system for collecting ground reference images. The entire optical head of the system is mounted onto a stabilization platform to provide vibrational damping and to angle the camera at a maximum displacement of 14o to capture hyperspectral images over an area centered about the target position. Preliminary results indicate inefficient burn-off of methane from the plant processes such that the facility could potentially contribute to elevated levels of the greenhouse gas in the local environment over time. Details of the hyperspectral imaging system, airborne measurement parameters, and quantitative processing of the data still in progress will be presented. It is hoped that these types of measurements can be shared with such facilities as feedback to help further refine their burn-off processes and to minimize the amount of unnecessary methane released into the environment.

Work In Progress