Do mobile screening technologies offer cost-effective methane leak detection?

Abstract:

There has been growing interest and investment in new methane-sensing technologies such as drones, satellites, and aircraft to reduce fugitive emissions more cost-effectively than work practices that exclusively use optical gas imaging (OGI) cameras or US EP Method 21 (M21). Most new technologies lack the spatial resolution to pinpoint leaking components, so they must be used in conjunction with OGI and M21 (or other close-range methods) to identify and diagnose individual emissions sources, differentiate fugitives from design emissions like allowable venting and combustion, and inform decision making for repairs. We refer to this hybrid approach as multi-visit leak detection and repair (MV-LDAR). MV-LDAR involves rapid screening for facility-level emissions, identification of high-emitting facilities, and selective on-site follow-up with close-range methods to confirm and repair individual leaks. To supplant OGI, MV-LDAR must achieve equivalent mitigation of fugitive methane emissions more cost-effectively. Here, the Leak Detection and Repair Simulator (LDAR-Sim) is used to evaluate emissions reductions and cost-effectiveness for facility-level screening.

Simulation results show that facility-scale MV-LDAR programs can achieve emissions reduction equivalence with OGI, but at high cost. Under a best-case scenario (no venting and no quantification error), the screening portion of MV-LDAR must cost less than $150 USD per facility to achieve cost parity with OGI-based LDAR. However, simulations with vented emissions and poor quantification accuracy lead to ranking errors that inflate follow-up costs. In these scenarios MV-LDAR costs more than OGI-based LDAR. Our work suggests that MV-LDAR must effectively direct follow-up to compete with exhaustive OGI. The biggest challenges facing MV-LDAR are design emissions and screening quantification error. A regulatory shift towards monitoring for all emissions, not just fugitives, could improve screening effectiveness.