I would like to add some additional information to Joe Nocera’s excellent Nov. 20 column, “Fracking’s Achilles’ Heel: It’s the Methane, But Maybe It Can Be Contained.”
As Mr. Nocera states, natural gas has an important environmental advantage over coal in that it produces only about half the carbon dioxide for the same heat generation. But this advantage is partially offset by methane (natural gas) leakage. Mr. Nocera references that methane is 28 times more powerful than CO2 as a greenhouse gas over the longer term. But according to Wikipedia, that number is correct for a time horizon of 100 years. For a time horizon of 20 years (which I believe is a more meaningful basis of comparison) methane is 72 times more powerful.
Dave McCurdy, president of the American Gas Association, has asserted that 1.5 percent of the produced natural gas is emitted from the point of production through delivery. Other estimates are higher. But based on the American Gas Association’s own estimate of 1.5 percent leakage and a 20-year time horizon, it is calculated that that leakage would trap about 36 percent of the heat trapped from the CO2 produced by burning the other 98.5 percent. This would mitigate more than half of the advantage that natural gas can have over coal.
The immutable laws of chemistry control the amount of CO2 emitted by burning natural gas or coal. But the amount of gas leakage is under human control and can thus be controlled by engineering and prudent expenditures. And it should.