Is methane-hydrate fuel of the future?

Shale has the spotlight for now. But there's another, lesser-known substance with the potential to yield even greater quantities of natural gas: methane hydrate.

Hydrates consist of a lattice-like structure of frozen water molecules and methane. On the surface, they look like an ordinary block of ice. But when you hold a match to them, they burn—a visual cue signaling methane release.

- A lot of geoscientists are fascinated by hydrates because of how odd it is that you can take methane gas and add water and have it result in something with such a concentrated store of energy - said Peter Flemings, a member of the Energy Department's methane hydrate advisory committee and professor at the department of geological sciences at the University of Texas (Austin).

Hydrates form when methane and water combine under cold temperatures in a relatively high-pressure environment and are commonly found in arctic regions or in shallow sediments below relatively deep water along the outer continental shelf.

The Energy Information Administration estimates that hydrates contain more carbon than every fossil fuel available on Earth combined. EIA also reports that these ice-like structures could hold anywhere from 10,000 trillion to more than 100,000 trillion cubic feet of natural gas. By way of comparison, the administration, which acts as the independent statistical arm of the Energy Department, said in 2013 that there are just over 7,000 trillion cubic feet of technically recoverable shale gas deposits throughout the world.