Another clue was that offshore drilling sometimes brought up blocks of material resembling dense, cloudy ice that fizzled and disappeared when brought to the surface. Drilling offshore of North and South Carolina provided more definitive clues. Burning iceA chunk of methane hydrate is dense and milky, yet it floats like ordinary water ice. Released at the ocean floor, methane hydrate rises, fizzing like an Alka Seltzer as it discharges its gaseous contents. This is roughly the amount of natural gas an average California family burns for heating and cooking every month.
Methane hydrates occur in patches along the coastlines of most continents.
The total deposit may exceed 700,000 trillion cubic feet, or about twice the energy contained in all known fossil fuel resources worldwide, Kastner said. 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.