Investigating Major Sources of Methane Emissions at US Landfills

Airborne remote sensing
observations were collected at
217 landfills
across 17 states in the US in 2023. We used these observations to
attribute emissions to major sources, including the landfill work
face, where new waste is placed at the landfill and gas-control infrastructure.
Methane emissions from the work face appeared to be more prevalent
than gas-control infrastructure emissions, with 52 landfills exhibiting
work face emissions out of the 115 observed landfills shown to be
emitting in 2023. Landfills with work face emissions were often the
highest emitters, especially sites with associated renewable natural
gas facilities, and the total average site emissions from these landfills
accounted for 79% of the observed emissions, indicating inefficient
gas capture at these sites. Landfills with work face emissions also
displayed the greatest disparity between observed emission rates and
hourly emission rates that we estimated using annual emissions reported
to the US EPA’s Greenhouse Gas Reporting Program. Work face
emissions present a major opportunity for methane mitigation: Observed
emissions from work face emitting-landfills in this study were equivalent
to 15% of US methane emissions from municipal solid waste landfills
in 2022, as reported in the 2024 Greenhouse Gas Inventory, though
these landfills accounted for only 4% of open sites in the US. As
the 217 landfills in this study cover only 17% of open landfills in
the US, the total mitigation potential is likely greater. Using remote
sensing, we find that the largest contributor to observed methane
emissions at US landfills is the landfill work face, an area of the
landfill often left out of the required monitoring and traditional
emissions accounting methods.