Evaluating methane emission quantification performance and uncertainty of aerial technologies via high-volume single-blind controlled releases

Abstract

Methane (CH4) from oil and gas (O&G) activities is a known contributor to global anthropogenic methane emissions and recent research has demonstrated that a small fraction of large emitters contribute to the majority of total emissions. In this study, we perform a single-blind evaluation of the quantification capabilities of three airplane-based technologies (Bridger Photonics’ Gas Mapping LiDAR, Carbon Mapper’s Global Airborne Observatory, and GHGSat-AV) with a focus on large emitters (10-2,000+ kg h-1 CH4). In two 2021 campaigns, metered natural gas was released concurrently with overpasses by the tested technologies. Results were submitted by operators in a three-stage unblinding process. All teams detected 100% of releases above 50 kg h-1 CH4. The teams report parity slopes of 0.35 to 1.06, with R2 values of 0.35 to 0.78. After 10-meter anemometer wind measurements were unblinded, two out of three teams significantly reduced variance in the parity slope, highlighting the importance of accurate wind data. After half of metered release volumes were subsequently unblinded, improvement was mixed. These results suggest that multiple commercially available technologies can reliably detect larger point-source methane emissions, with varying quantification performance and trade-offs between survey area coverage and instrument sensitivity.

Technological Maturity of Aircraft-Based Methane Sensing for Greenhouse Gas Mitigation

“…While not included in the present study, Bridger Photonics' Gas Mapping LiDAR has been independently tested elsewhere in single-blind and location-blind studies. 3,14,19 This study fills important gaps in previous literature. In particular, this is the first independent single-blind test of Scientific Aviation and MethaneAIR (Chulakadabba et al, 2023 18 used a collaborative technology validation experimental design in which the MethaneAIR team had editorial control over the publication of their results, with input from Stanford).…”

“…13 While detection capabilities vary by platform and technological approach, under ideal measurement conditions, aircraft can detect emissions below 100 kg (CH 4 )/h, and in some cases, below 10 kg (CH 4 )/h. 3,14,15 In contrast, most wide-area satellite have a detection limit around 1,000−1,500 kg(CH 4 )/ h, although targeted systems such as the GHGSat satellite and Maxar's WorldView-3 have detected emissions under, ideal conditions, as low as 200 and 30 kg(CH 4 )/h, respectively. 16,17 As companies and governments increasingly rely on aircraft methane management, accurately assessing these technologies' capabilities becomes increasingly important.…”

“…Top anthropogenic methane sources and targets for emissions reductions are the oil and gas sector, waste management, and agriculture . Conventional methods for detecting and quantifying methane emissions are time and labor intensive, with limited scalability due to reliance on individual site visits with methane detectors or optical gas imaging infrared cameras . Greenhouse gas inventories continue to use a so-called “bottom-up” method for estimating emissions, which underestimate emissions from the oil and gas sector compared to results from measurement surveys .…”

Measuring Carbon Dioxide Emissions From Liquefied Natural Gas (LNG) Terminals With Imaging Spectroscopy

“…The uncertainty bounds are generated by assuming ±25% errors of the mix ratio length minimum threshold α l , fetch radius r c and wind speed U 10 . We use ordinary least squares regression to assess quantification accuracy (Rutherford et al., 2023; Sherwin et al., 2023). The scenario with r s = 300 m demonstrates the best performance (Figure 1).…”

Toward Multiscale Measurement-Informed Methane Inventories: Reconciling Bottom-Up Site-Level Inventories with Top-Down Measurements Using Continuous Monitoring Systems

“…Four snapshot measurement technologies were used for the baseline measurements: an optical gas imaging (OGI) camera paired with a Hi-flow sampler that encompasses the entire emission source, a drone-based mass balance technology provided by SeekOps Inc. (“SeekOps”), an aerial LiDAR plume identification system provided by Bridger Photonics (“Bridger”), and satellite measurements provided by GHGSat. All four technologies have undergone controlled tests and field trials, with the results made public in peer-reviewed studies. − During the 6 month enhanced monitoring phase, operators conducted weekly audio, visual, and olfactory (AVO) inspections and monthly leak detection and repair (LDAR) surveys using either OGI cameras or Bridger measurements. Additionally, operators submitted monthly bottom-up inventories and installed CMS on some or all of their enrolled sites during this phase.…”