What are “Superemitters” & Why are they Important to Keeping PA’s Air Clean?

The rapid development of the natural gas industry in Pennsylvania has induced a series of new concerns for those living in the state and Marcellus region. Of these worries, emissions from well sites have garnered much attention, particularly methane emissions.

Methane is one of the main components of the natural gas harvested through unconventional drilling’s hydraulic fracturing process. Though extractors have safeguards to prevent any leakage of the gas, these systems do have failures. The EPA reports that the natural gas and petroleum industry were responsible for 31% of the total methane emissions in 2017, the highest of any category recorded.

Not all wells are to blame, though, as only a small proportion of wells bear the blame for the vast majority of methane emissions. These are appropriately called “superemitters”. Superemitters can be understood as individual well sites that emit significantly higher amounts of methane than others. However, there is no definitive definition. Research published this year in the journal Environmental Science and Technology explores the identification of superemitters, and just how many there are in the Marcellus region. Through an extensive, multi-year study, researchers analyzed air quality around a sample of hundreds of active well sites across the Commonwealth. Their results yielded two important findings: first that emissions data from the EPA significantly underreported emissions estimates and second, that a staggering 77% of total emissions came from only 10% of their sample well sites. Adjusted for the proportion of methane specifically, 93% of methane emissions came from the same 10% of sites. Though the research does not explicitly characterize what would constitute a superemitter, their research does empirically demonstrate the phenomena.

The question now would be how to identify and correct the issues with this 10 % of sites and curb total emission rates. The first step, identification, will be a time-consuming process, given that there are approximately 10,000 individual well sites active in Pennsylvania, but technological advancements can help with efficiency. Technology such as infrared cameras is currently being used by pipeline companies and inspectors to seek out leaks along the lines. Though the technology to identify the specific chemical makeup of a leak is not currently operational, simply identifying leaks and gauging their severity would expedite the process. Once superemitters are identified, work to stop the leak and prevent further leaks could be done. There are mutually beneficial outcomes of identifying and remedying these superemitters. For the natural gas companies, each leak is lost profit with their products literally spilling into the air. For the regulatory agencies such as the Department of Environmental Protection who conducts inspections of these wells, their process would become more efficient. Known superemitters would rise to a higher priority for inspection, and consequently, air quality would improve.