The U.S. has a record 2,384 trillion cubic feet of recoverable natural gas, double the estimate nine years ago, an industry-sponsored committee said.

The estimate is the highest in the 48 years the Potential Gas Committee has assessed resources and exceeds by 486 trillion cubic feet the previous estimate in 2010, the panel said today in Washington. The increase was attributed to new evaluations of shale-gas resources, which are being accessed using hydraulic-fracturing techniques, also called fracking.

“It’s really shale gas that has exceeded expectations,” John Curtis, a professor at the Colorado School of Mines who led the study, said in Washington.

Fracking, in which water, sand and chemicals are shot underground to break apart rock and free natural gas trapped in shale, has brought a boom in energy production to Pennsylvania, Texas and Colorado, and lowered natural gas prices. A third of the total gas resources are in Eastern states such as Pennsylvania and Ohio, according to the committee.