Once scientists began looking for methane hydrate deposits, they weren't disappointed. They found them beneath Arctic permafrost and beneath the seafloor, especially in areas where one tectonic plate slides over another. These regions are known as subduction zones because the edge of one plate moves beneath another. For example, off the coast of Washington and Oregon, the Juan de Fuca plate is sliding underneath the North American plate. Like a piece of wood being drawn across the blade of a plane, the sediments, including hydrates, of the Juan de Fuca plate are removed by the rocky crust of the North American plate. This creates a ridge of hydrates that runs parallel to the coast.
Hydrate deposits have also been found in regions where large ocean currents meet. Blake Ridge is a formation located off the coast of South Carolina, in water ranging from 6,562 to 15,748 feet (2,000 to 4,800 meters) deep. Geologists believe the ridge formed during the Oligocene epoch, about 33.7 to 23.8 million years ago. The Greenland Sea opened up during this time, allowing huge amounts of cold, dense water to flow south along the Atlantic coast. As this cold water ran headlong into warm water being carried northward on the Gulf Stream, the currents slowed down and dropped large amounts of sediment. Organic material buried in these sediments eventually gave rise to a large amount of methane hydrate.
How much of this frozen fuel exists at Blake Ridge and other sites around the world? Some estimates put the amount of methane locked away in hydrates at anywhere from 100,000 trillion to 300,000,000 trillion cubic feet (2,832 trillion to 8,495,054 trillion cubic meters). Compare that to the 13,000 trillion cubic feet (368 trillion cubic meters) of conventional natural gas reserves remaining on the planet, and you can understand why jaws in the scientific community have dropped [source: Collett].
Of course, finding the hydrate deposits is one thing. As we'll see in the next section, getting them out -- and doing it safely -- is another thing entirely.