Study: Shale gas may be dirtier than coal

Natural gas may burn cleaner than other fossil fuels, but when total greenhouse gas emissions are factored in from a leading extraction method, it is far dirtier than backers suggest, according to a new study from scientists at Cornell University.

In fact, the process of obtaining natural gas through hydraulic fracturing could greatly contribute to emissions of methane and carbon dioxide, making it dirtier than oil or coal, said Robert W. Howarth, lead author of the study, a preliminary version of which was posted today.

Researchers focused on the large amounts of methane that escape into the atmosphere during hydraulic fracturing, the controversial technique in which oil companies force millions of gallons of water, sand and chemicals into a well to break open shales and other dense rock formations and release natural gas. It also looks at the indirect emissions from equipment and vehicles used to extract, develop and transport the gas.

The Energy Department predicts that by 2035 domestic production of natural gas will grow by 20 percent, with gas from shales and other unconventional rock formations accounting for 75 percent of the total.

The oil and gas industry says natural gas could be key in reducing the nation’s dependence on foreign oil while also addressing concerns about climate change. But Howarth argues that more study is needed.

Russell Jones, senior economic adviser to the American Petroleum Institute, said after reviewing Howarth’s study, “we just didn’t find it a credible analysis.”

He said Howarth makes very strong conclusions based on limited and incomplete data. He also questioned the timing of the report’s release — a day before the U.S. Senate’s Environment and Public Works Committee holds a public hearing on hydraulic fracturing.