Shale gas & emissions - Jan 25
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Shale Gas a Bridge to More Global Warming
Stephen Leahy, IPS
Hundreds of thousands of shale gas wells are being "fracked" in the United States and Canada, allowing large amounts of methane, a highly potent greenhouse gas, to escape into the atmosphere, new studies have shown.
Shale gas production results in 40 to 60 percent more global warming emissions than conventional gas, said Robert Howarth of Cornell University in New York State.
"Shale gas also has a larger greenhouse gas footprint than oil or coal over the short term," said Howarth, co-author of a study called "Venting and Leaking of Methane from Shale Gas Development" to be published in the journal Climatic Change.
This latest study follows up on Howarth and colleagues' controversial April 2011 paper that provided the first comprehensive analysis of greenhouse gas emissions from shale gas obtained by hydraulic fracturing. That study found that when gas wells are "fracked", they leak large amounts of methane and pose a significant threat to the global climate.
"We stand by the conclusion of our 2011 research," said Howarth...
(24 January 2012)
REPORT: Venting and Leaking of Methane from Shale Gas Development:
Response to Cathles et al.
Robert W. Howarth, Renee Santoro, Anthony Ingraffea, Climatic Change
In April 2011, we published the first comprehensive analysis of greenhouse gas (GHG) emissions from shale gas obtained by hydraulic fracturing, with a focus on methane emissions. Our analysis was challenged by Cathles et al. (2012). Here, we respond to those criticisms. We stand by our approach and findings. The latest EPA estimate for methane emissions from shale gas falls within the range of our estimates but not those of Cathles et al, which are substantially lower. Cathles et al. believe the focus should be just on electricity generation, and the global warming potential of methane should be considered only on a 100-year time scale. Our analysis covered both electricity (30% of US usage) and heat generation (the largest usage), and we evaluated both 20- and 100-year integrated time frames for methane. Both time frames are important, but the decadal scale is critical, given the urgent need to avoid climate-system tipping points.
Using all available information and the latest climate science, we conclude that for most uses, the GHG footprint of shale gas is greater than that of other fossil fuels on time scales of up to 100 years. When used to generate electricity, the shale-gas footprint is still significantly greater than that of coal at decadal time scales but is less at the century scale. We reiterate our conclusion from our April 2011 paper that shale gas is not a suitable bridge fuel for the 21st Century.
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(19 January 2012)
Dueling Research: Fracked Shale Gas Worse For Climate Change Than Coal! Or, The Opposite!
Brantley Hargrove, Dallas Observer
In the rarefied halls of Cornell, the atmospheric-science equivalent of the gauntlet has been thrown. At stake is nothing less than the suitability of one of the most plentiful, domestically producible forms of energy in North America to replace a fuel speeding climate change and emitting tons of known carcinogens.
The question: Is unconventional gas extracted from formations like the Barnett Shale of North Texas the cleaner-burning bridge fuel to a new, sustainable age? Or does its production contribute massive quantities of a potent greenhouse gas sufficient to trump the mighty emissions of coal?
Depends on which side of that hall in Ithaca you ask. Last spring, research by Dr. Robert Howarth in the journal Climate Change Letters advanced the latter theory -- that as much as 8 percent of the produced methane escapes into the atmosphere at some point during its perambulation from bore hole to oven burner, or whatever end use, and may have a greenhouse-gas footprint up to twice the size of coal's...
Then a colleague of Howarth's at Cornell, Dr. Lawrence Cathles, published a study in the same journal last week, looking to torpedo his work. Specifically, Cathles challenges Howarth's fugitive emissions estimate. Howarth's number, Cathles notes, assumes the venting of huge quantities of valuable gas during the phases when the drill bit and well bore are removed, but before a well hits peak production -- something an energy company has no economic or safety incentive to do...
See also On Shale Gas, Warming and Whiplash
(9 January 2012)