Methane continental/permafrost

Several hundred to several thousand feet beneath the ocean floor in permafrost and continental edge regions lies a potentially vast source of natural gas in excess of 10 cubic meters of gas hydrates, consisting largely of methane clathrate (53-55). Gas... 

In the longer term, an oil shortage can be expected in 40 to 50 years, and this will result in increased use of natural gas. The fossil fuel with the longest future is coal, with reserves for more than 500 years. The question whether natural gas reserves in the form of methane hydrate, in which more carbon is stored than in other fossil raw materials, will be recoverable in the future cannot be answered at present, since these lie in geographically unfavorable areas (permafrost regions, continental shelves of the oceans, deep sea). 

Methane itself is a greenhouse gas released in large quantities from cattle, termite mounds, rice paddy fields and swamps. The methane produced is the product of bacteria living under anaerobic conditions. In recent years focus has been directed towards a potential source of methane that represents both an opportunity and a threat. Methane has been found stored in the sediments of the continental shelf beneath the deep ocean, underneath the permafrost of the Arctic and in deep Antarctic ice cores (Figure 10.60). In these circumstances the methane is stored in the form of methane clathrates. Clathrates are structures formed by the inclusion of atoms or molecules of one kind, in this case methane, in cavities of the crystal lattice of another, in this case ice. The open, hydrogen-bonded structure of ice (see Chapter 4) lends itself to the formation of such caged structures. 

Many countries are investing in research into the extraction of methane from these clathrates. An exploration well drilled on land by Imperial Oil in 1971-1972 discovered methane clathrates under the Canadian Arctic permafrost at the edge of the Mackenzie Delta and the Beaufort Sea. This site is known as the Mallik gas hydrate field. It has become a major centre of research into methane clathrates with groups from Canada, the USA, Japan and India working under the umbrella organization known as the International Continental Scientific Drilling Program (ICDP). 

A third motivation for studying the behaviour of clathrate hydrates is their environmental implications. There are vast natural deposits of methane hydrates. These are both off-shore deposits, occurring in the continental shoulders of the ocean floor, and land-based deposits in permafrost regions. Some idea of the size of these deposits can be obtained from estimates of the energy reserve contained within these methane... 

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