"EPA drastically underestimates methane released at (shale) drilling sites."

LA Times: “Drilling operations at several natural gas wells in southwestern Pennsylvania released methane into the atmosphere at rates that were 100 to 1,000 times greater than federal regulators had estimated, new research shows.”
“Using a plane that was specially equipped to measure greenhouse gas emissions in the air, scientists found that drilling activities at seven well pads in the booming Marcellus shale formation emitted 34 grams of methane per second, on average. The Environmental Protection Agency has estimated that such drilling releases between 0.04 grams and 0.30 grams of methane per second.
The study, published Monday in the Proceedings of the National Academy of Sciences, adds to a growing body of research that suggests the EPA is gravely underestimating methane emissions from oil and gas operations. The agency is expected to issue its own analysis of methane emissions from the oil and gas sector as early as Tuesday, which will give outside experts a chance to assess how well regulators understand the problem.
….Since their upper-end measurements were so much higher than the EPA’s estimates, the researchers attempted to follow the methane plumes back to their sources, said Paul Shepson, an atmospheric chemist at Purdue University who helped lead the study. In some cases, they were able to quantify emissions from individual wells.
The researchers determined that the wells leaking the most methane were in the drilling phase, a period that has not been known for high emissions. Experts had thought that methane was more likely to be released during subsequent phases of production, including hydraulic fracturing, well completion or transport through pipelines.
The airborne readings were a snapshot over two days, Shepson cautioned, and further research over a longer period and at other sites are needed to know whether the Pennsylvania measurements are typical.
….Last year, researchers from Stanford, Harvard and elsewhere reported in PNAS that methane emissions in the continental U.S. might be 50% greater than the EPA’s official estimates. Another study by Stanford researchers, published in February in the journal Science, also concluded that theEPA underestimates methane leakage from the natural gas industry and other sources.
….In February, Colorado became the first state to regulate methane emissions from the oil and gas sector, requiring the industry to detect and fix leaks and install equipment to capture 95% of methane emissions. Last week, Ohio adopted rules to get companies to reduce methane leakage from above-ground equipment used in natural gas development, like valves and pipelines. Those rules do not appear to address leaks during drilling.”