Because of a recent breakthrough, scientists are gaining a better understanding of a potential new fuel source—gas hydrates—mysterious deposits of natural gas, which can be found below the ocean floor.

Scientists hope to someday mine these frozen undersea deposits, which are abundant in nature, found in marine sediments and in the Arctic. Hydrates are promising as an energy and petroleum feedstock resource because they hold vast reserves of methane. In fact, the methane in gas hydrates all over the world contains about twice the amount of carbon in all known fossil fuels on the planet, and that's according to a very conservative estimate.

Studying these hydrates, however, has proven to be exceedingly difficult. A piece of gas hydrates resembles ice. What's more, this crystalline solid melts when transported to the surface, emitting methane, which is a greenhouse gas.

But last summer, research ships in the Pacific Ocean off Oregon accomplished the unprecedented feat of bringing fully intact samples of gas hydrates to the surface for study, researchers announced this month at the joint meeting of the European Geophysical Society, the American Geophysical Union and the European Union of Geosciences in Nice, France. The ships explored an area of the sea floor dubbed Hydrate Ridge, where the hydrates are plentiful.

To obtain the samples, the ships relied on two new devices affixed to the end of drilling pipes. Thrusting a collection tube into the target material, both machines were able to seize a meter-long core. They then used pressure-driven valves to immediately seal the cores inside metal containers, which were brought to the surface. One device extracted a sample from 27 centimeters beneath the ocean floor while the other obtained it from 10 meters below the floor. The water was about 500 meters deep where the drilling took place.

When the researchers studied their samples using X-rays, they were astounded to discover bubbles of free methane gas—a colorless, odorless flammable gas used as a fuel. "Theoretically, in the presence of water and at the prevailing pressure and temperature when these cores were taken, free methane gas should not exist," says geologist Erwin Suess of the Research Center for Marine Geosciences (GEOMAR) who was aboard one of the ships.

"It is truly novel," concurs oceanographer James Kennett of the University of California, Santa Barbara.

Geophysicists will now focus on developing a process to free up the methane on the ocean floor—recognizing that this is integral to simulating greenhouse gas emissions and to eventually probing the reserves for commercial purposes.

Sources: Frozen Fuel Gas Surfaces
Rex Dalton
Nature, April 14, 2003
http://www.nature.com/nsu/030407/030407-14.html

Gas (Methane) Hydrates -- A New Frontier
U.S. Geological Survey Fact Sheet
http://marine.usgs.gov/fact-sheets/gas-hydrates/title.html

Gas Hydrate: What Is It?
U.S. Geological Survey
http://woodshole.er.usgs.gov/project-pages/hydrates/what.html