Buried Treasure


Gauging the (natural) gasSay "hi" to hydrateFreezing, but not coldUsing hydrateWarming worries





Gas hydrate could be a gigantic addition to global gas resources -- if these preliminary estimates are right.
U.S. Energy Information Administration.































Gas hydrate is right where it's needed -- off the coast of Europe, the United States and Japan. This worldwide distribution of gas hydrate could simplify future exploitation.
See "Animations..." in the bibliography).



A bright flame
The interest in gas hydrate flared last January when the Japan National Oil Corp. announced that it had found sandstone containing 20 percent gas hydrate off the coast of Japan, which now imports practically all of its energy. The hydrate was 250 meters below the seafloor in 900 meters of water

The new finding electrified -- can we say gasified? -- the energy biz. "What they found was extremely favorable," says William Dillon, who directs the USGS gas hydrate effort. "It was more than anybody expected, in coarse sediment with good permeability and porosity. It was filled with gas hydrate, and that's created a lot of interest worldwide in gas hydrates."

With a resource estimated at as much as 60 million trillion cubic feet, gas hydrate is the elephant in the fossil-fuel zoo.

Keep in mind that the preliminary estimates may be nothing more than educated guesses. The only other gas hydrate well was drilled into permafrost in Canada's Mackenzie Delta. The Japanese well, which sparked the excitement, is a small data set, observes Dillon. "This was the first offshore wildcat well anywhere in the world, and you can't carry that too far."

A cylinder bulges in the water ice portion, but is intact in the gas hydrate portion.
A sample containing water ice (on the left) and methane hydrate (on the right) was crushed lengthwise. The water ice bulged, while the stronger gas hydrate did not. Engineers need such basic knowledge to figure out how to exploit gas hydrate.
Courtesy the University of California, Lawrence Livermore National Laboratory, and U.S. Department of Energy.

However, as W. Steven Holbrook, who studies hydrates at the University of Wyoming, noted in an e-mail from a research vessel in the Atlantic Ocean, where he was making images of the Blake Ridge, a hydrate deposit off the coast of South Carolina, "Hydrates are extraordinarily widespread-- they occur on every continental margin on Earth" and contain 99 percent methane. He adds that the hydrate "is often underlain by a similarly thick zone of free gas -- bubbles of methane in the pore space -- which may provide an even more appealing target for exploration."

Drill, baby, drill
While exploratory oil and gas wells these days tend to be in cold regions and deep water, the gas hydrates appear in similarly awkward locations -- either under Arctic permafrost or below at least 500 meters of water. On the positive side, hydrates are found near such major energy-devouring regions as Japan, Europe and North America.

Even if gas hydrates are as common as the estimates say, nobody knows how to extract hydrates safely, and none is being used today, with the possible exception of one well in Siberia that may be inadvertently producing gas from hydrate.

Spinning globe shows deposits, also found off Africa, both coasts of South America , and surrounding both poles. Given the uncertainties, the U.S. Department of Energy does not expect gas hydrate to play a major role until 2015 or beyond. Before that, the Department wants to increase production from existing wells by, for example, raising the permeability of underground rocks that already supply gas.

The cost of production can kill the most promising energy plans, and Sassen says known deposits cannot be exploited economically with existing technology. Furthermore, what about global warming? Even though a unit of energy from methane makes less carbon dioxide than the same unit from coal or oil, the new source could actually accelerate global warming. We'll get to that shortly, but first things first:

What do we really know about gas hydrates?


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