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New shale study refutes Cornell: Marcellus gas ... - PennLive.com

Marcellus gas has less impact on global warming than coal, according to a recent study by scientists at Carnegie Mellon University.

The peer-reviewed study published Aug. 5 in “Environmental Research Letters” appears to be a direct refutation of an April study from researchers Robert Howarth and Anthony Ingraffea at Cornell University that indicated that shale gas was worse for global warming than coal.

The Cornell study had a number of faults — acknowledged by its authors — including sketchy data that did not directly apply to Marcellus drilling operations.

The study looks specifically at Carnegie Mellon and the Marcellus' gas emmissions life cycle effect "associated with its production and consumption.

Marcellus gas is essentially no different from conventional natural gas, the study found, and 20-50 percent cleaner than coal to generate electricity.

"Marcellus shale gas emits 50 percent fewer emissions of greenhouse gases than any other coal plant in the United States," said co-author Chris Hendrickson."We favor the extraction of the Marcellus Shale natural gas as long as the extraction is successful in reducing the negative effects of economic, environmental and social."

Former DEP Secretary John Hanger praised the new study on his blog, saying that "demystifies and decimates the study by Professor Howarth hit piece that the journalist's NYT gas and other media have given so much attention. "

"However," Hanger said, "CMU study has received very little attention from the press so that the result remains that many people think Howarth is the last word on this important issue.”

The new study does support “green completions” — in which gas is captured during the earliest stages of production rather than being vented or flared into the atmosphere. Proposed shale gas rules from the EPA would require green completions.

“Green completion... would significantly reduce the largest source of emissions specific to Marcellus gas preproduction,” the study says, but it adds that such emissions are a small portion of the life cycle estimates.

The study’s authors said greenhouse gas emissions are not the only challenge when it comes to extracting shale gas.

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