Use of Satellite Remote Sensing for Characterizing Long-term Methane Emissions from Smaller-Scale Fugitive Emission Sources

Abstract Description: Research on methane (CH4) emissions has long been focused on large-scale emission sources, such as oil, gas, coal extraction, agricultural lands, etc. Smaller sources with relatively lower emissions have been under-studied due to the lack of cost-effective monitoring technologies. However, the combined total emission from smaller sources has been found to be significant. For example, 70% of total CH4 emissions in the continental US originate from facilities emitting < 100 kg/hr.

Satellite remote sensing technologies have been widely used to detect and quantify CH4 emissions, also with a primary focus on larger emission sources. This study evaluated the feasibility of characterizing the long-term CH4 emissions from smaller-scale, fugitive methane emission sources, utilizing the wastewater treatment plant (WWTP) as the study site. High spatial resolution Sentinel-2 satellite images of a WWTP plant in Canada, taken between 2019 and 2023, were processed to retrieve CH4 column concentration distributions. Digital image processing techniques were developed for extracting the time- and space-varying features of CH4 emissions, which revealed daily, monthly, seasonal, and annual variations. Emission hotspots were also identified and corroborated with ground-based measurements. Despite limitations due to atmospheric scattering, cloud cover, and sensor resolution that affect precise ground-level concentration assessments, the findings revealed the dynamic nature of fugitive GHG emissions from the WWTP, indicating the need for continuous monitoring for the purpose of developing the emission inventories for these sources.

In addition to WWTP, the satellite imagery method has also been used for evaluating CH4 emissions from a cattle feedlot in Canada. The results indicate the promise of utilizing satellite imagery for cost-effectively characterizing fugitive CH4 emissions from smaller-scale sources, guiding the design of subsequent ground-based monitoring for accurate quantification of emissions.