Shale Gas Boom Releases More Methane

credit: LA Times

Carbon dioxide is bad enough but methane is a 20-30 times more potent greenhouse gas.  Scientists are worried about the huge amounts of methane that could be released to the atmosphere from melting permafrost in the Arctic region; yet there is a methane source closer to home over which we have some control that is widely underestimated.  New research of natural gas operations in Pennsylvania shows that monitored wells are released 100 to 1,000 times the amount of methane into the air than the EPA previously estimated. The study of seven well pads in the booming Marcellus shale region was published in the Proceedings of the National Academy of Sciences. On average each well site emitted 34 grams of methane per second based on airborne measurements compared to the EPA's current estimate of 0.04 to 0.30 grams per second. The study adds to a growing body of scientific evidence that indicates shale gas operations are polluting the air as well groundwater. Methane is about 9% of the US greenhouse gas emissions greenhouse gas.

The Pennsylvania shale gas boom is in a coal region and many of the wells there penetrate coal beds containing methane which flows to the surface because drillers use negative pressure in the well bore to capture valuable supplies of ethane and butane. The disparity between the latest airborne readings and EPA's estimates shows the shortcomings of regulators who rely on energy companies for data. Researchers at prestigious universities estimated last year that actual emissions of methane may be as much as 50% greater than official estimates. EPA has been ordered to come up with ways to cut methane emissions from oil and gas operations. The agency is set to release its own analysis of the problem soon. Colorado, also experiencing a shale gas boom, became the first state to regulate methane emissions from the oil and gas industry requiring a capture rate of 95% in February. One of the justifications for switching from coal to natural gas as a fuel has been its lower carbon footprint. But high methane leakage rates may make natural gas less of a "clean" alternative. A leakage rate of just 1.7% cancels benefits of gas over diesel, however a leakage rate beyond 7.4% would be necessary to put natural gas at a disadvantage to coal. EPA's current leakage estimate for natural gas operations--one increasingly viewed as too small--is 1.5%