A High-Resolution Satellite Survey of Methane Emissions from 60 North American Municipal Solid Waste Landfills

Multiple campaigns to measure methane emissions from municipal solid waste (MSW) landfills across North America using a constellation of nine high-resolution (30 m pixels) satellites equipped with short-wave infrared sensors (SWIRS) were conducted. The purpose of the survey was to evaluate emission estimates using the integrated mass enhancement (IME) method for a range of landfills equipped with gas collection systems. We report a geometric average emission estimate of 481 kg CH₄ h^-1 across 60 active MSW landfills from 697 site observations with 457 discrete plumes and 247 nondetect observations from 2021 to 2024. Minimum and maximum observations were 116 and 6422 kg h^-1, reflecting considerable variability, likely due to method uncertainty, environmental conditions, and management practices. Gas collection efficiency (CE) was assessed for a subset of 25 landfills that were routinely measured for one calendar year. When these instantaneous emission estimates were compared to gas collection data at the time of the observation, 15 of 25 sites were found to have greater CEs than were assumed in modeling data that informed the 2023 U.S. greenhouse gas inventory. Measured (38-96%) and modeled CEs (65-90%) were poorly correlated (r² = 0.18), which suggests that limitations exist for reconciling the data with values used to assemble inventories.