Methane hydrates represent the largest source of hydrocarbons in the earth’s crust.
Methane clathrate (CH4•5.75H2O), also called methane hydrate, hydromethane, methane ice, fire ice, natural gas hydrate, or gas hydrate is a solid clathrate compound (more specifically, a clathrate hydrate) in which a large amount of methane is trapped within a crystal structure of water, forming a solid similar to ice. Originally thought to occur only in the outer regions of the Solar System where temperatures are low and water ice is common, significant deposits of methane clathrate have been found under sediments on the ocean floors of Earth.
The worldwide amounts of carbon bound in gas hydrates is conservatively estimated to total twice the amount of carbon to be found in all known fossil fuels on Earth.
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