Fracking The Debate Continues

Scientific American

Fracking Would Emit Large Quantities of Greenhouse Gases

"Fugitive methane" released during shale gas drilling could accelerate climate change

By Mark Fischetti

Add methane emissions to the growing list of environmental risks posed by fracking.

Opposition to the hydraulic fracturing of deep shales to release natural gas rose sharply last year over worries that the large volumes of chemical-laden water used in the operations could contaminate drinking water. Then, in early January, earthquakes in Ohio were blamed on the disposal of that water in deep underground structures. Yesterday, two Cornell University professors said at a press conference that fracking releases large amounts of natural gas, which consists mostly of methane, directly into the atmosphere—much more than previously thought.

Robert Howarth, an ecologist and evolutionary biologist, and Anthony Ingraffea, a civil and environmental engineer, reported that fracked wells leak 40 to 60 percent more methane than conventional natural gas wells. When water with its chemical load is forced down a well to break the shale, it flows back up and is stored in large ponds or tanks. But volumes of methane also flow back up the well at the same time and are released into the atmosphere before they can be captured for use. This giant belch of "fugitive methane" can be seen in infrared videos taken at well sites.

Molecule for molecule, methane traps 20 to 25 times more heat in the atmosphere than does carbon dioxide. The effect dissipates faster, however: airborne methane remains in the atmosphere for about 12 years before being scrubbed out by ongoing chemical reactions, whereas CO2 lasts 30 to 95 years. Nevertheless, recent data from the two Cornell scientists and others indicate that within the next 20 years, methane will contribute 44 percent of the greenhouse gas load produced by the U.S. Of that portion, 17 percent will come from all natural gas operations.

Currently, pipeline leaks are the main culprit, but fracking is a quickly growing contributor. Ingraffea pointed out that although 25,000 high-volume shale-gas wells are already operating in the U.S., hundreds of thousands are scheduled to go into operation within 20 years, and millions will be operating worldwide, significantly expanding emissions and keeping atmospheric methane levels high despite the 12-year dissipation time.

Howarth said he is particularly concerned about fracking emissions because recent data indicates that the planet is entering a period of rapid climate change. He noted that the average global temperature compared with the early 1900s is now expected to increase by 1.5 degrees Celsius within the next 15 to 35 years, which he called "a tipping point" toward aggressive climate change. More and more fracking would speed the world to that transition or undermine efforts to reduce emissions of CO2 and other greenhouse gases. The notion, Ingraffea said, that shale gas is a desirable "bridge fuel" from oil to widespread renewable energy supplies several decades from now "makes no sense" in terms of climate change.

Howarth and Ingraffea spoke from Cornell, where they also released a paper (pdf) that is about to be published by the journal Climatic Change, which details their analysis. It follows up on a paper they published in April 2011 that comprehensively analyzed emissions from fracking. The gas industry disputes that paper. So does Cornell geologist Lawrence Cathles, in a commentary in Climatic Change. He estimates that fugitive emissions are only 10 percent of what Howarth and Ingraffea maintain, and that shale gas would indeed be a good replacement for home heating oil and for coal used in power plants

Capturing the big belch of gas could prevent the problem. Ingraffea said capture is difficult because the gas is emitted along with the flow-back water, but a procedure known as a "green completion," in which special equipment traps the gas, has been shown to work. Regulators do not require that step, however, and the market price of methane is less than the cost of capturing it in that way, so drillers have no incentive to do so for economic reasons.

Scientific American 20th January 2012

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