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Methane Hydrate

Dateline: 01/03/00

By Alan Bruzel

What Is Methane Hydrate?

It is a clathrate (cage) compound consisting of a crystalline shell of ice molecules surrounding and trapping molecules of methane gas. (Methane, also known as natural gas, is widely used for fuel.) A completely filled methane hydrate structure contains 46 water molecules and 8 methane molecules. It has the appearance of water ice, but unlike ice, methane hydrate is stable only at high pressures and low temperatures. There is no covalent bonding between the water and gas molecules, so methane hydrate melts into water and methane gas.

Where Is Methane Hydrate Found?

Where conditions of temperature and pressure allow its existence: under the polar permafrost and in ocean sediments beneath 300 or more meters of water. Deposits may be several hundred meters in thickness.

Origin of Methane Hydrate

Under suitable conditions and over the course of millennia, the bacterial degradation of organic material to methane may have generated vast storehouses of methane hydrate.

How Much Is There on Earth?

It is estimated that there is at least twice as much carbon locked up in methane hydrate deposits, as there is carbon in all of the known fossil fuel reserves on Earth.

What Is Its Fuel Potential?

At room temperature and pressure, one volume of methane hydrate will liberate about 160 volumes of methane and a little less than one volume of liquid water. Understandably, countries with permafrost regions, or with nearby deep-ocean sediments are actively involved in methane hydrate research and development. These countries include: Brazil, Canada, India, Japan, Norway, Russia, the United Kingdom, and the United States.

Methane Hydrate and the Environment

Because methane is ten times more effective as a greenhouse gas than is carbon dioxide, deliberate care must be taken in mining methane hydrate reserves. Methane gas will generously contribute to global warming. For example, when oceans invaded the land and formed huge glacial sheets during the Ice Ages, the ensuing lower sea level may have ensured the return of milder climates by relieving pressure on oceanic methane hydrate deposits, allowing substantial liberation of methane gas and subsequent global warming.

What the Web Has to Say about:
Methane Hydrate

"Baked Alaska" Mud Volcano Discovered in North Atlantic
Sea floor volcano capped with methane hydrate. From Volcano World.

Flammable Ice: Methane Hydrate Opens Possibility for New Energy
A potential domestic energy source for Japan. From Trends in Japan.

Gas (Methane) Hydrates – A New Frontier
Importance in global warming, seafloor stability, and human energy needs. Factsheet from the US Geological Survey.

Gas Hydrates for Geophysicists
A geophysicist looks at gas hydrate structure and formation. From Ingo Pecher, University of Texas at Austin.

Harvesting Natural Gas from the Ocean Floor
Article by David Graham, Technology Review, considers energy potential of methane hydrate reserves.

Hydrates.org
Details of chemistry, biology, and possible fuel uses of gas hydrates.

Ice Worms From the Deep
News article from InSCIght magazine describing organisms living in methane hydrate.

Important Discoveries of Gas Under the Ocean Floor
Environmental concerns posed by use of methane hydrate. From Tom Fitz, Platypus magazine.

Introduction to Gas Hydrates
Types of gas hydrates and their chemistry. From John J. Carroll, AQUAlibrium.

Methane Gas Hydrate
Includes physical properties and estimated reserves. From the Geological Survey of Japan.

Methane Hydrate: A Surprising Compound
Laboratory production and analysis. Article by Katie Walter, Science and Technology Review.

Methane Hydrate: Past Friend or Future Foe?
Science Frontiers article considers the contrasting aspects of this material.

Methane Hydrates Program Plan
Long-range strategy for exploration and study. From the Office of Fossil Energy, US Department of Energy.

New "Ice Worms" Discovered in Gulf of Mexico
The inhabitants of methane hydrate formations. From the Minerals Management Service, US Department of the Interior.

Seismic Characterization of Methane Hydrate Structures
Analysis of geological structures holding methane hydrate. From Christine Ecker, Stanford University.

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