UAV METHANE MRV AS A TOOL FOR CIRCULAR ECONOMY MANAGEMENT

Reliable and scalable methane (CH₄) monitoring is essential both for near-term climate mitigation and for supporting circular-economy strategies focused on energy recovery and the reduction of losses along value chains. Unmanned aerial vehicles (UAVs) enable facility-scale measurements with high spatio-temporal resolution. However, most studies rely on point sensors that require repeated flights at different altitudes and interpolation from low-density datasets, leading to potentially high uncertainty under turbulent and variable wind conditions. Open-path optical sensors can increase the effective sampling volume and improve plume representativeness, but practical, field-ready frameworks remain relatively under-developed. This study presents an operationally oriented UAV mass-balance framework for facility-scale CH₄ quantification using a drone-mounted open-path TDLAS sensor. The method is demonstrated across three representative emission contexts in Italy. At an intensive dairy cattle farm, 24 tests were conducted over one year (two per month). UAV-derived model-corrected net enteric emissions ranged from 0.182 to 0.242 kg CH₄ AU⁻¹ day⁻¹ and were broadly consistent with IPCC reference estimates. At a natural gas compression facility, six tests were conducted under two operating configurations, with site-level emissions of 14.3 ± 4.1 and 11.9 ± 2.6 kg CH₄ h⁻¹, showing consistency with an independent Method 21 bottom-up estimate. At a municipal solid-waste landfill, four quantification flights yielded site-scale fluxes ranging from 3.7 to 11.5 g s⁻¹, with uncertainty dominated by meteorology. Overall, the results show that the proposed open-path framework is promising for facility-scale CH₄ assessment across different emission contexts, with performance primarily governed by wind stability. This supports more frequent, management-oriented monitoring in line with circular-economy objectives. However, the approach remains sensitive to meteorological conditions, particularly under non-steady flow and when wind speed is measured at a single near-ground location.