Quantification of emissions from methane sources in Indianapolis using an aircraft-based platform

Methane is an important greenhouse gas that is 20 times more potent than CO ₂. Urban environments have been shown to be significant sources of methane with emissions much larger than currently reported in inventories. This discrepancy suggests that there remain a number of insufficiently characterized methane sources in urban environments. Using cavity ring-down spectroscopy, flask sampling, and a mass balance approach, we determined methane emission fluxes downwind from the city of Indianapolis with an aircraft-based platform. Emission rates from specific sources of methane (e.g. landfill and wastewater treatment plants) were investigated to determine the importance of each source to the total area-wide emission flux. As part of a collaborative effort called the Indianapolis Flux Experiment (INFLUX), this study will help us gain understanding of the magnitude of source-specific methane emissions as well as the potential energy equivalent of these biogas emissions should they be captured to generate heat or electricity.