Study Says Gas May Be Worse Than Coal for Greenhouse Effect

Pittsburgh Post-Gazette
13 April 2011
By David Templeton

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 W. 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.

Carbon dioxide can remain 10 times longer in the atmosphere but the study says methane can be more damaging to climate in the short run.

According to the study, 3.6 percent to 7.9 percent of shale gas is lost to the atmosphere by venting from back-flow water released from wells and pressure valves, along with leaks that can occur in as many as 150 pieces of equipment used to produce, process and ship gas, and losses along the gas pipelines to market.

The study said the totals were calculated from various sources but reflect how much methane escapes into the atmosphere from venting or leaking over the lifetime of a well.

"The higher emissions from shale gas occur at the time wells are hydraulically fractured " -- the process of injecting liquids and sand under high pressure to break up rock formations deep underground to release natural gas. Methane mixed with fluids flowing back from the well can escape into the atmosphere.

It also can escape during other follow-up procedures after fracturing occurs, the study says.

The greenhouse effect of methane from shale gas, the study says, is at least 20 percent greater than the effect from coal, and could be as much as twice the effect.

As a result, Mr. 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 Mr. Howarth has long-held biases against the industry.

Matt Pitzarella, spokesman for Range Resources, a major Marcellus Shale drilling company based in Cecil, Washington County, 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."

Jan Jarrett, president and chief executive officer of Citizens for Pennsylvania's Future, a statewide environmental advocacy organization active in Marcellus Shale drilling issues, said she respects the research of Mr. Howarth and his Cornell research team.

But she also noted that the authors readily admit that some information used is questionable even if it is the best available data, making further studies necessary.

Mr. Howarth acknowledged that "yes, the data are limited and poorly documented. ... But they are the best available data, and we did the best job one can, I believe, in synthesizing these."

But even if shale gas does produces as much as or more greenhouse gas than coal, natural gas still causes fewer health and environmental consequences, Ms. Jarrett said.

"It is far cleaner with hardly any mercury or particulates and low emissions of [sulfur dioxide and nitrogen oxides], which are acid-rain and ozone-causing gases," she said.

David Templeton: or 412-263-1578.