Gas Hydrates in the Geo-System
Natural gas hydrates are solid, ice-like substances composed of water and gas that are formed under certain conditions on the ocean floor and in the permafrost regions of Siberia and Alaska. High pressure (> 50 bar) and low temperatures (< 5 °C) favour their formation. Thus the largest deposits by far can be found on the ocean floor, especially within the continental margins. At depths exceeding 500 metres, these regions provide the ideal conditions for the formation of gas hydrates.
Today, gas hydrates are the subject of intensive research all over the world. Scientists are particularly interested in two aspects: the effect of gas hydrates on the climate and their significance as potential energy reservoirs of the future.
Currently the primary focus of research is the potential influence of gas hydrates on the world's climate, as this sensitive mixture of frozen water and gas can break down as a consequence of even small changes in temperature. Should the methane gas escape into the atmosphere, its contribution to the greenhouse effect would be thirty times stronger than that of carbon dioxide.
The effects on the stability of the continental shelves would be equally severe. Here, gas hydrates act like a kind of cement that binds together the loosely settled deposits on the ocean floor. If this cement should dissolve, large masses of sediment could slide into deeper regions of the ocean. This would result in flood waves that would have drastic consequences for the densely populated coastal regions.
The high methane content of gas hydrates also makes them potentially exploitable reservoirs of raw materials. The total amount of gas that could be extracted from gas hydrates globally is estimated to be approximately 1,500 trillion cubic metres — about six times the presently known reserves of natural gas. In some countries, for example Japan, the decision has already been made to exploit these reserves commercially in the future.
Further interesting links:
• Gas Hydrate Research@GEOMAR• National Methane Hydrate Program (USA)
