Mapping by the U.S. Geological Survey indicates that methane hydrate deposits off the coast of the Carolinas are about 70 times greater than the amount of natural gas consumed by the United States in 1989. So vast are the deposits under the sea floor that more fresh water is believed to be tied up within them than exists in all the world's rivers. Each cubic meter of methane hydrate also contains about 0.8 cubic meter of fresh water. The problem is how is the gas distributed and how do you tell whether it is concentrated in a particular area or not. Large resources are thought to be buried off the coasts of Northern California, Oregon, Washington and Alaska, as well as in the Gulf of Mexico, she said.
Hydrate crystals are most stable under cold conditions.
But at 32 degrees, the pressure requirement is just 442 psi. Some deposits of methane hydrate, layered with seafloor sediments, are believed to be 3,000 feet thick, but these veins exist at depths of 10,000 feet beneath the sea. Experimental drilling programs have achieved this depth, but Paull said methane hydrate mining is more likely to begin in Arctic areas such as Alaska's North Slope, where persistent cold temperatures allow hydrates to exist at shallower ocean depths. Even in the Arctic, though, questions remain about whether methane hydrate resources can be exploited as a major new source of energy. But there probably are some sweet spots out there.