Open-Path Laser-Based Remote Sensing for Broad-Area CO2 and CH4 Emissions Monitoring, with Specific Application to Diffuse Sources

Starting in 2013, Atmospheric and Environmental Research Inc. (AER) and team members from Spectral Sensor Solutions LLC (S3) (previously at Harris Corporation) developed GreenLITE™, a novel intensity modulated continuous wave (IMCW) laser absorption spectroscopy (LAS) instrument now capable of providing continuous monitoring of CO₂ and CH₄ over large open areas up to ~25 km². The initial system was developed with partial funding from the Department of Energy’s National Energy Technology Laboratory to provide continuous 2-D mapping of atmospheric CO₂ over areas up to 1 km², with the specific application to ground carbon capture and storage facilities. This resulted in deployment of the initial system for 6 months at an active carbon capture facility providing continuous and autonomous monitoring, reporting, and verification capability via a unique web-based data dissemination tool. In parallel with the first operational demonstration of the technology, the team expanded the measurement range to cover 5 km path-lengths with initial validation partially funded by the National Institute of Standards and Technology and carried out at the National Oceanic and Atmospheric Administration tall tower outside of Boulder, CO. In November 2015, the long-range CO₂ system was deployed to demonstrate 2-D mapping of the complex time-varying concentrations over 25 km² of downtown Paris, France, just prior to the 21^st Conference of Parties. The Paris deployment began as a 2-week proof-of-concept demonstration, but initial successful performance led to expanding the scope to continuous operations over a full year. The next generation of GreenLITE™ extended the equivalent capabilities to atmospheric CH₄ through an interchangeable transmitter design. This was initially tested at the S3 test range in New Haven, IN, and was followed by a field trial, led by TOTAL, in Lacq, France, in June 2017, which provided the opportunity for GreenLITE™ to demonstrate detection, location and quantification of leaks for both CO₂ and CH₄ in an oil and gas environment. Furthermore, the system demonstrated the sensitivity and precision required for environmental monitoring applications (<15 ppb CH₄, <1 ppm CO₂) while having the dynamic range needed for leak detection. The potential for quantifying emissions using the GreenLITE™ system was also demonstrated during the June 2017 campaign in Lacq. In June 2019, S3 and AER deployed the system in a new configuration with the purpose of determining emissions over a large tailing pond in the Alberta Oil Sands. GreenLITE™, being an integrated path measurement, has some distinct advantages for this type of diffuse source, which is currently a challenge for existing point measurement technologies due to the potential for spatial and temporal variations in addition to hazardous conditions for personnel. This paper will provide an overview of the GreenLITE™ system as developed to date, and will review various applications relevant to the oil and gas industry. We will discuss deployment details, results, and lessons learned from the various deployment scenarios that have been executed.