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.
The study stunned the clean energy community, chiefly because it was so counter-intuitive. Not only does natural gas release none of the mercury and other poisons found in coal, it emits a fraction of the carbon dioxide when burned. But methane, the study points out, is a far more potent greenhouse gas, and fugitive emissions of it may render null any benefits it has as a low-carbon fuel. Howarth's takeaway: What kinda bridge fuel has a worse greenhouse footprint than coal? A shitty kind, that's what.
So, the anti-fracking crowd had a brand-new arrow in its quiver. And yet another item was added to the laundry-list of problems and unknowns associated with hydraulic fracturing for North Texas suburbs and towns all over America wrestling with the shale play.
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.
Cathles also questions Howarth's 20-year time frame because methane has a shorter half-life in the atmosphere than carbon dioxide, which tends to accumulate.
He was further puzzled by Howarth's choice not to evaluate coal and shale gas based on total emissions of both for electricity generation. After all, it's one of the few things coal is good for, and it accounts for most of its use. His approach, Cathles claims, ignores all the benefits of modern, efficient gas-fired power plants replacing the old, inefficient coal-fired plants like Dallas-based Luminant's Monticello and Big Brown plants.
All told, Cathles suggests, shale and other types of unconventional gas have half to a third the greenhouse footprint of coal.
Apparently there was some sort of mix-up over at the journal Climate Change. Howarth's reply to Cathles was supposed to run alongside the new study. It didn't, so if you're interested in reading a shorter version of his response (and Cathles response to his response) check out The New York Times's Dot Earth blog.