Remote sensing of fugitive methane using retroreflector-based Differential Laser Absorption Spectroscopy (DLAS) system on a UAV pair

Methane is one of the most potent greenhouse gases in our atmosphere, with various anthropogenic factors increasing its prevalence. Methane has 28 times greater heating capacity than carbon dioxide and its atmospheric concentration has increased roughly from 800 parts-per-billion (ppb) in the early 1900s to an alarming 1800 ppb in 2016. With approximately 3.2 million abandoned wells in the US, mitigating fugitive emissions was designated a high priority by the Biden administration.While we have ample satellite or tower data that provide global or point concentrations/flux of greenhouse gas emissions, we have little understanding of localized “topology” of emission and transport. Without that knowledge we do not know where our hidden carbon offenders lie and thus cannot mitigate leaks. Several COTS methane sensors in use can provide some information at scale on methane presence or information on concentration but they are fixed systems. They are not able to scale or be adaptive to varied terrain and operations, or to 3D mapping of intricate and complex topographies, with high resolution both of spatial characteristics as well as low methane concentrations. To address the issues mentioned above, through this SBIR effort, we offer the solution of remote sensing of fugitive methane using Retroreflector-Based Differential Laser Absorption Spectroscopy (DLAS) system on a UAV pair—termed our RetraSpectra™ system. Standalone DLAS systems based have demonstrated to be a reliable and accurate method of detecting low-concentration levels of fugitive gases. However, measurements without the use of a dedicated retroreflector are often noisy (function of the environment) and thus, cannot be scaled to measure larger columns of interest. Utilizing a DLAS on one UAV and a retroreflector on another UAV, larger spatial columns of fugitive leaks can be measured in significantly less time as compared to currently used manual methods. Another advantage of having a retroreflector on one of the UAVs is the dynamic scanning capability over areas of interest, as compared to having a stationary retroreflector. In Phase I, Censys Technologies Corporation aims to develop and demonstrate a proof-of-concept measurement of the novel measurement system whilst optimizing COTS components for use. Subsequent phases of development will include fine-tuning for commercialization purposes and measurement of other gases of interest.