Two groups of Cornell University researchers have split over the contribution to global warming by rising extraction of natural gas from shale beds through a process known as fracking.
Dueling papers in the journal “Climatic Change” dispute conclusions published in April that so-called unconventional gas production spews more heat-trapping compounds into the atmosphere than mining and burning coal.
The April research by Robert Howarth, a Cornell professor of ecology and evolutionary biology, and Anthony Ingraffea, a professor of civil and environmental engineering, overestimated leaks from fracked wells by as much as tenfold, Lawrence Cathles, a Cornell Geology professor, argues in a commentary posted online by the journal and provided by Cornell.
“In the short term, our energy needs should be satisfied mainly by those fuels having the fewest inherent environmental disadvantages,” Cathles and his co-authors concluded. “Those preferred fuels include natural gas.”
Howarth’s study, published in “Climatic Change Letters” said as much as 1.9 percent of the gas in a well escapes to the atmosphere during fracking, compared with 0.01 percent when completing a conventional gas well. That ruled out gas as a “bridge fuel” as more renewable energy is developed, he said.
A more reasonable estimate of gas lost during fracking is 0.2 percent, Cathles said.
Producers including Exxon Mobil Corp. have increased U.S. gas production by drilling horizontally through shale beds, exposing more rock than a vertical bore, and then fracturing it with a mixture of water, sand and chemicals.
Howarth’s data doesn’t adequately support the report’s finding that the heat-trapping “footprint” of shale gas is 20 percent higher than coal, Robert Harriss, chief executive officer of the Houston Advanced Research Center, said in an e-mailed message in April.
Harriss spent four years studying air pollution by oil and gas wells in the 1980s and 1990s. The research center is a nonprofit that has received funding from the oil and gas industry to study drilling techniques that cause less environmental damage.
Subsequent research by the U.S. Environmental Protection Agency and the United Nations Environment Programme support their conclusions, Howarth said today on a conference call.
Regulations are necessary to limit natural-gas venting from fracked wells because at current prices, companies would lose money by capturing the gas for sale, Howarth said. The EPA estimated a return of as much as 7 percent on capturing gas worth $4 a million British thermal units, he said.
Gas futures fell 5 percent to $2.35 a million British thermal units today on the New York Mercantile Exchange.
Cost to reduce all gas system leaks may be “astronomical,” Ingraffea said.