More Leakage Than Expected From Colorado Wells


In just two days flying over oil and gas operations in Colorado’s Front Range, scientists found nearly three times as much methane, a powerful greenhouse gas, as regulators estimated to be coming from the sites.

And methane levels weren’t the only surprise. The scientists from the National Oceanic and Atmospheric Association (NOAA) recorded seven times the amount of benzene (a registered toxic gas) as inventory estimates and twice as high levels of other chemicals that contribute to ozone pollution. Breathing ozone can trigger a variety of health problems including chest pain, coughing, throat irritation, and congestion. It can inflame the linings of the lungs and repeated exposure can permanently scar lung tissue.

Emission estimates or ‘inventories’ are the primary tool that policy makers and regulators use to evaluate air quality and climate impacts of various sources, including oil and gas operations and, according to this study, those estimates are way off, said the lead NOAA scientist Gabrielle Petron in a press release. Their study confirmed their findings from earlier research performed from 2008-2010, which took place on land.

Using a technique called mass-balance, the researchers calculated that during their two flight days, oil and gas operations in the Denver-Julesburg Basin emitted about 19 metric tons of methane per hour, 75 percent of the total methane emissions (the rest came from animal feedlots, landfills and wastewater treatment plants).
That’s about three times as large as an hourly average estimate for oil and gas operations based on Environmental Protection Agency’s (EPA’s) Greenhouse Gas Reporting Program (itself based on industry-reported emissions).

The scientists also combined their measurements from the two-day flight with chemical analysis of air samples in the laboratory to calculate how much other chemicals were in the air. They determined the levels of Benzene emissions from oil and gas to be about 380 pounds (173 kilograms) per hour, compared with a state estimate of about 50 pounds (25 kilograms) per hour. Benzene is an air toxic chemical that comes out of car and truck tailpipes. Now the new results suggest that it also comes out of oil and gas operations.

Another class of chemicals called volatile organic compounds (VOCs) also turned out to be higher than expected. A subset of these VOC chemicals contribute to ground-level ozone pollution—a big problem for the northern Front Range which has been out of compliance with federal health-based 8-hour ozone standards since 2007, according to the EPA.