original article:
http://www.nytimes.com/2011/04/12/business/energy-environment/12gas.html
snippets:
Natural gas, with its reputation as a linchpin in the effort to wean the nation off dirtier fossil fuels and reduce global warming, may not be as clean over all as its proponents say....
The problem, the studies suggest, is that planet-warming methane, the chief component of natural gas, is escaping into the atmosphere in far larger quantities than previously thought, with as much as 7.9 percent of it puffing out from shale gas wells, intentionally vented or flared, or seeping from loose pipe fittings along gas distribution lines. This offsets natural gas’s most important advantage as an energy source: it burns cleaner than other fossil fuels and releases lower carbon dioxide emissions.
“These are huge numbers,” he said. “That the industry would let what amounts to trillions of cubic feet of gas get away from us doesn’t make any sense. That’s not the business that we’re in.”
Methane leaks have long been a concern because while methane dissipates in the atmosphere more quickly than carbon dioxide, it is far more efficient at trapping heat. Recent evidence has suggested that the amount of leakage has been underestimated. A report in January by the nonprofit journalism organization ProPublica, for example, noted that the Environmental Protection Agency had recently doubled its estimates for the amount of methane that is vented or lost from natural gas distribution lines.
The study combined these emissions with studies of other methane losses along the processing and distribution cycle to arrive at an estimated total methane loss range from 3.6 to 7.9 percent for the shale gas industry.
When all is factored together, Mr. Howarth and his colleagues conclude that the greenhouse gas footprint of shale gas can be as much as 20 percent greater than, and perhaps twice as high as, coal per unit of energy.
Mr. Hawkins also said that too little was known about just how much methane was being lost and vented, and that studies like Mr. Howarth’s, while needed, relied on too slim a data set to be considered the final word.
“This is a huge and growing industry, and we just don’t have the information we need to make sure that this resource is being developed as cleanly as it can be,” Mr. Hawkins said.
