Tuesday, September 17, 2013

EPA Estimates Significantly Overstate Greenhouse Gas Emissions From Natural Gas Wells

From The Wall Street Journal, "U.S. Overstates Leaks by Gas-Drillers, Says Study: University of Texas Researchers Challenge Methane Emissions by Fracking" by Russell Gold:
Natural-gas drilling sites aren't leaking as much methane into the atmosphere as the federal government and critics of hydraulic fracturing had believed, according to the first study of emissions at multiple drilling sites.

The study, led by researchers at the University of Texas at Austin and published on Monday by the Proceedings of the National Academy of Sciences, is likely to ease some concerns about the impact of natural-gas extraction on the climate.

Measuring emissions at 190 sites, the study found less "fugitive methane" than previous work by the Environmental Protection Agency and some university researchers, which relied on estimates. Methane, the primary ingredient in natural gas, is a potent greenhouse gas.
But the measurements of gas emissions found that wells emitted about 20% less greenhouse gases than the EPA had estimated—which is less than the amount emitted by burning coal.
As a mathematical note, a 20 percent decrease is equivalent to a 25 percent increase. Starting from the estimate, the reality is 20 percent less (using 100 as an example of the estimate, 80 is 20 percent less than 100). Starting from the reality, the estimate is 25 percent more (100 is 25 percent more than 80). The EPA has overstimated the greenhouse gas emissions from natural gas wells by 25 percent.

From a global warming perspective, the heat trapping impact of methane gas is 20 times that of carbon dioxide (CO2). The EPA's overestimation of the amount of methane gas released is equivalent to saying that 5 times or 500 percent more carbon dioxide was released than actually occurred. (20 times 25 percent is 500 percent which also equals 5).

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