CMU Scientists Publish New Study on Life-Cycle Greenhouse Effects from Marcellus Gas

Dr. James Hansen of NASA and Columbia University

Marcellus gas has less impact on global warming than coal, says the new study from Carnegie Mellon University. This peer-reviewed study was published August 5th in “Environmental Research Letters” and extends the April study from researchers Robert Howarth and Anthony Ingraffea at Cornell University. 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 Carnegie Mellon study looks specifically at Marcellus and the “life cycle greenhouse gas emissions” associated with its production and consumption.

Marcellus gas is essentially no different than conventional natural gas, the study found, and 20-50 percent cleaner than coal for producing electricity. “Marcellus shale gas emits 50 percent fewer greenhouse gas emissions than any U.S. coal-fired plant,” said study co-author Chris Hendrickson. “We favor extraction of Marcellus shale natural gas as long as the extraction is managed to minimize adverse economic, environmental and social impacts.”

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, which would significantly reduce the largest source of emissions specific to Marcellus gas production. However, such emissions are a small portion of the life cycle estimates, according to the CMU study.  “We still need to study other environmental issues, including use of water and disruption of natural habitats,” said co-author Paulina Jaramillo.  More information is here.

Dr. James Hansen, head of the NASA Goddard Institute for Space Studies and Adjunct Professor of Earth and Environmental Sciences at Columbia University, recently said that governments are acting as if they are oblivious to the fact that there is a limit on how much fossil fuel carbon we can put into the air. Fossil fuel carbon injected into the atmosphere will stay in surface reservoirs for millennia. A fraction of the excess CO2 can be extracted via improved agricultural and forestry practices, but we cannot get back to a safe CO2 level if all coal is used without carbon capture or if unconventional fossil fuels are exploited. Prior government targets for limiting human-made global warming are now known to be inadequate. Specifically, the target to limit global warming to 2°C, rather than being a safe “guardrail”, is actually a recipe for global climate disasters, according to Prof. Hansen.