From MIT Technology Review (click here):
Experts now believe that the country has far more natural gas at its disposal than anyone thought three or four years ago. The revised estimates are largely due to advanced drilling techniques that make it economically feasible to extract the fuel from shale. And while the Marcellus is the most recently discovered and possibly the largest shale-gas deposit (covers PA, NY, VA and OH), others are scattered throughout the country.
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% 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.
Natural gas offers advantages over other fossil fuels. It burns cleaner than coal, producing much less carbon dioxide. Since coal-fired power generation is responsible for a third of U.S. carbon dioxide emissions, replacing at least some of that coal with gas could significantly reduce such pollution. And using natural gas to replace gasoline and diesel fuel in vehicles could reduce the country’s reliance on foreign oil.
“It doesn’t matter what the exact number is,” says Mark Zoback, a professor of geophysics at Stanford University. “The numbers are all so big it means we have an extremely large domestic resource that is going to play a significant role in the country’s energy future.”
The availability of vast natural-gas resources in the Marcellus shale and similar sediments around the United States has changed energy calculations in a fundamental way. The discovery of this large and seemingly economical new source of fossil fuel has surprised even geologists who have spent their careers studying the shale. Little wonder, then, that policy makers and politicians are just beginning to try to figure out what the discoveries mean.