A chunk of methane hydrate looks like a piece of ice. But it’s really highly concentrated molecules of methane — the chief constituent of natural gas — trapped in a cage-like lattice of ice. As it melts, huge amounts of methane bubble out. These hydrates have been an isolated curiosity in the lab for a century. But in the past couple of decades, researchers have discovered vast methane hydrate deposits, sometimes several hundred meters — maybe a thousand feet — thick in arctic permafrost and in deep ocean sediments around most of the continents.
In methane hydrates, the methane is so concentrated that one unit in the hydrate structures can release 160 times its volume in gas.
On the Blake Ridge of the North Carolina coast, a mile and a half below the surface, 300-square-mile area there holds enough methane to supply the United States with natural gas for 100 years. Today, methane hydrates have been detected around most continental margins. Around the United States, large deposits have been identified and studied in Alaska, the west coast from California to Washington, the east coast, including the Blake Ridge offshore of the Carolinas, and in the Gulf of Mexico. Scientists have known about methane hydrates for a century or more. French scientists studied hydrates in 1890. In the 1930s, as natural gas pipelines were extended into colder climates, engineers discovered that hydrates, rather than ice, would form in the lines, often plugging the flow of gas. These crystals, although unmistakably a combination of both water and natural gas, would often form at temperatures well above the freezing point of ordinary ice.
In 1964, i In a northern Siberian gas field named Messoyakha, a Russian drilling crew discovered natural gas in the “frozen state,” or in other words, methane hydrates occurring naturally. In late 1981, the drilling vessel Glomar Challenger, assigned by the National Science Foundation to explore off the coast of Guatemala, unexpectedly bored into a methane hydrate deposit. Unlike previous drilling operations which had encountered evidence of hydrates, researchers onboard the Challenger were able to recover a sample intact.
And that represents a lot of natural gas — some 80 thousand times the current natural gas reserves — with an energy potential of more than twice that of all other fossil fuels combined. But this immense resource is costly and dangerous to recover. There are drilling problems — especially from the seafloor where decomposing hydrates can cause underwater mudslides and even tidal waves.
And scientists are concerned that melting methane hydrates could contribute to global warming as the highly concentrated methane is released into the air. Next article … a scientist who says it’s already happened naturally — 55 million years ago.