Economix Blog: Another Look at Natural Gas

After my column on Wednesday about how the nation’s natural gas boom is helping reduce emissions of heat-trapping carbon, I received a bunch of e-mail arguing that gas obtained by hydraulic fracturing could, on the contrary, worsen climate change.

The main reason is that fracking wells — where water, chemicals and sand are pumped at high pressure into horizontal shafts to fracture shale rock deep underground — leak.

Cheap natural gas is helping to cut carbon emissions because power companies are using it to replace coal, a much dirtier fuel. But the benefits would be wiped out if a lot of the gas escaped into the atmosphere, because natural gas is mostly methane, which traps much more heat in the atmosphere than carbon dioxide.

One study last year suggested that replacing coal with gas would reduce greenhouse gas emissions only as long as the leakage of methane into the air from gas production did not exceed 3.6 percent.

The question is, how much do these wells leak? “There is a lot of debate over that,” noted Susan Brantley, a geoscientist who heads the Earth and Environmental Systems Institute at Pennsylvania State University. “It is very vitriolic.”

According to a draft of the Environmental Protection Agency’s annual inventory of greenhouse gases, methane emissions from natural gas production declined by 45 percent from 2006 to 2011, to about 48 million metric tons of CO₂ equivalent.

Andrew Revkin’s Dot Earth blog has covered this controversy exhaustively. And in January, the magazine Nature published a good account of the state of knowledge on the subject.

But the best answer is that we don’t have a definite answer. Different groups of researchers have come up with vastly different estimates of leakage, from around 2 percent to a whopping rate of 9 percent, found in a recent analysis of a gas field in Utah.

Ms. Brantley suggests that the National Science Foundation underwrite an exhaustive study that could bring some clarity to the issue. But will it have the money? Sequestration just cut some $350 million from its budget for 2013.

Article source: http://economix.blogs.nytimes.com/2013/03/22/another-look-at-natural-gas/?partner=rss&emc=rss