A Cornell University study is drawing criticism from the Marcellus Shale industry by concluding that methane produced from shale gas has as large or even larger "greenhouse gas footprint" than coal.
The study, led by Robert Howarth, a Cornell professor of ecology and environmental biology, says methane leaking or venting from Marcellus Shale wells, and also during the processing and transportation of natural gas, will contribute "substantially to the greenhouse gas footprint of shale gas" in the next 20 years.
Published this week in the journal Climactic Change Letters, the study focuses on a 20-year time period for methane's greenhouse gas impact because the gas doesn't last in the atmosphere as long as carbon dioxide produced by coal burning.
As a result, Howarth said in an interview, natural gas "is not as clean as advertised," and using it as a transitional energy source to break our dependence on coal may not be wise energy policy.
"Society should truly look for cleaner fuel. Society needs aggressively to work to solve climate change and use less energy and use solar and wind power. But shale gas will make the (greenhouse gas) problem worse over the next several decades," he said.
The natural gas industry questioned the accuracy of the study's conclusions.
Energy In Depth, representing the nation's independent natural gas and oil producers, issued five major criticisms of the study ranging from what it describes as the authors' previous wavering about data used in the study, acknowledgement of errors and restatements of findings.
The producers also criticize the study's use of the 20-year time period to analyze greenhouse gases rather than 100 years. It also said the study uses questionable data along with assumptions that don't stand up to scrutiny, while claiming Howarth has long-held biases against the industry.
Matt Pitzarella, spokesman for Range Resources, a major Marcellus Shale drilling company based in Cecil, Pa., said the industry would lose $6 billion a year if up to 7.9 percent of shale gas were being lost to the atmosphere. Such releases would not only pose safety risks, but provide a great loss in revenues for drilling companies.
The U.S. Environmental Protection Agency, he said, has estimated that slightly higher than 1 percent of methane is lost in the production, processing and transport of natural gas, but the industry has reduced that total to less than 1 percent.
"Any time there is a report that is mostly filled with assumptions, you have to question it and any findings that are six times higher than the federal government's findings," he said. "Natural gas is a very clean source of energy from any perspective. In the grand scheme of things, it is a very good source of energy."