The US has far more natural gas at its disposal than anyone thought three or four years ago:
The U.S. consumes about 23 trillion cubic feet (TCF) of natural gas a year, according to the Department of Energy’s Energy Information Agency (EIA). The Potential Gas Committee (PGC), an organization headquartered at the Colorado School of Mines, put the country’s potential natural-gas resources at 1,836 TCF in a biennial assessment released in June. That’s 39 percent higher than its estimate of two years earlier. Add to that the 238 TCF that the EIA has calculated in “proved reserves” (the gas that can be produced given existing economic conditions) and the PGC pegs the future supply at 2,074 TCF. In other words, there is enough natural gas to supply the country for 90 years at current consumption rates. Even if we used natural gas to totally replace coal in generating electricity, domestic supplies would last for 50 years.Almost all the newfound resources are in shale deposits, which are now estimated to contain 616 TCF of recoverable gas, says John Curtis, a professor of geology and geological engineering at the Colorado School of Mines and director of the Potential Gas Agency, which provides technical assistance to the PGC. Supplies in the Appalachian basin alone are calculated at 227 TCF, with the Marcellus accounting for the bulk of that. And Curtis says he expects that even more shale gas will “be in the mix” in the committee’s next assessment.
Indeed, some geologists believe that gas supplies in the Marcellus and other shale deposits might be even more abundant than the PGC estimates. In January 2008, Lash and Terry Engelder, a colleague at Pennsylvania State University, calculated the amount of recoverable gas in the Marcellus deposit at 50 TCF. But initial drilling efforts in the region have gone so well that Engelder now puts the recoverable supply of gas at 489 TCF. If that’s correct, it makes the Marcellus the second-largest natural-gas field in the world; only a massive offshore reserve shared by Iran and Qatar is larger.