New technology expanding worldwide natural gas reserves

More natural gas is good news since it's the cleanest-burning fossil fuel and the one that generates the least greenhouse gases:

Shale is a sedimentary rock rich in organic material that is found in many parts of the world. It was of little use as a source of gas until about a decade ago, when American companies developed new techniques to fracture the rock and drill horizontally.

Because so little drilling has been done in shale fields outside of the United States and Canada, gas analysts have made a wide array of estimates for how much shale gas could be tapped globally. Even the most conservative estimates are enormous, projecting at least a 20 percent increase in the world’s known reserves of natural gas.

One recent study by IHS Cambridge Energy Research Associates, a consulting group, calculated that the recoverable shale gas outside of North America could turn out to be equivalent to 211 years’ worth of natural gas consumption in the United States at the present level of demand, and maybe as much as 690 years. The low figure would represent a 50 percent increase in the world’s known gas reserves, and the high figure, a 160 percent increase.