[paul.fr]

I had never heard of them until last week. When i listened to Chris talk about mathane clathrates. What are they and what uses could we have for them?

[ukmicky]

Hi PAUL

I Cant tell you much apart from it is located on some of the continental shelves 200 - 300 meters down like those around north America.

Its a sort of ice, a crystallised form of water containing a lot of methane and it only remains stable in its crystallised form below a certain temperature and pressure. If brought to the surface it quickly melts releasing its methane content.

They used to think a massive release of methane stored at the bottom of the sea could have been responsible for previous periods of global warming like what occurred 55 million years ago and was released due to temperature rises or the ocean floor rising after earthquakes. However they no longer believe this to be the case as they tested the methane locked in ice core samples from greenland and the samples turned out to contain the isotope of methane which is formed on the surface of the earth which contains less deuterium than that which is formed found under the sea.

I THINK THATS CORRECT ?

[JimBob]

It is also postulated as the cause of the Permian extinction event. The cause was warming of the seas due to the Huge eruptions of the Russian basalt fields and the release of greenhouse gases which then added the extra temperature to the atmosphere again by green house gas. Good article on  clathrates and green house gases at:

http://www.realclimate.org/index.php/archives/2005/12/methane-hydrates-and-global-warming/

From the oil and gas perspective at:

http://marine.usgs.gov/fact-sheets/gas-hydrates/title.html

[DrDick]

A clathrate is a generic term meaning a small molecule has other small molecules surrounding it, and loosely bound to it.  If the surrounding molecule is water (as in the case of the methane clathrates referred to above), they can also be called hydrates.

These clathrates have properties that are somewhat different from the properties of either of the parent molecules.  These hydrates can be solid when the water would normally be a liquid and the alkane (e.g., methane or propane) would normally be a gas.

Dick