Post by Hill on Mar 28, 2015 7:04:38 GMT
Gas hydrates may play important roles in the global carbon cycle and rapid climate change and they may be a potential source for future exploitation of methane as an energy resource.
This map, duplicated with placemarks on the GE globe, shows the approximate location of methane hydrates (also known as clathrates ) on continental slopes, continental rises, and tundra.
In the ocean depths where the shallow continental shelves drop off to toward the deep ocean basins, lie the continental rise and continental slope. Much sediment with high organic content is deposited here in an area of near freezing temperatures and crushing pressures. As organic material in the sediment breaks down, it releases methane gas. The pressure is so great that instead of bubbling to the surface, it becomes a frozen ice that is part water and part frozen methane (a clathrate ). A chunk of this material will burn when exposed to a flame. Allowed to simply melt, it will release a large quantity of methane gas, as much as 30 liters of gas for each liter of methane hydrate. Herein lies a hope and a danger.
Estimates of the volume of these deposits predict anywhere from 300 to 3000 years of methane fuel tied up in known and predicted deposits. But practical methods of mining the deposits have yet to be developed and drilling on the slopes have the potential of destabilizing them and creating giant slumps could move a large enough volume of water to cause tsunamis.
Another proposal, even further from reality with present technology, is to inject carbon dioxide gas into the deep ocean sediments to form CO2 clathrates, thus removing it from the atmosphere and thus cutting down on greenhouse gasses.
But there is a darker side to methane ices, which also have formed in the Arctic tundra and are held deep in the permafrost. As global temperatures continue to rise, permafrost is melting. The amount of frozen methane deposits thawing will increase. Methane, which is ten times more efficient as a greenhouse gas than carbon dioxide, will cause the temperature to increase more, raising sea levels and ocean temperatures, in turn releasing more methane. The oceanic methane theoretically will remain stable as the oceans get deeper and sea floor pressures increase. But, if the oceans warm, and they are already warming (though at a slower rate than the atmosphere) a critical point could be passed and large releases of methane gas from the continental slope deposits could occur, adding much more greenhouse-enhancing methane to the atmosphere. Climate change would surge ahead.
This post was originally creating in the old Google Earth Forum. You can see the discussion in THIS THREAD.
Ammonium hydrate V_3.kmz (4.93 KB)
This map, duplicated with placemarks on the GE globe, shows the approximate location of methane hydrates (also known as clathrates ) on continental slopes, continental rises, and tundra.
In the ocean depths where the shallow continental shelves drop off to toward the deep ocean basins, lie the continental rise and continental slope. Much sediment with high organic content is deposited here in an area of near freezing temperatures and crushing pressures. As organic material in the sediment breaks down, it releases methane gas. The pressure is so great that instead of bubbling to the surface, it becomes a frozen ice that is part water and part frozen methane (a clathrate ). A chunk of this material will burn when exposed to a flame. Allowed to simply melt, it will release a large quantity of methane gas, as much as 30 liters of gas for each liter of methane hydrate. Herein lies a hope and a danger.
Estimates of the volume of these deposits predict anywhere from 300 to 3000 years of methane fuel tied up in known and predicted deposits. But practical methods of mining the deposits have yet to be developed and drilling on the slopes have the potential of destabilizing them and creating giant slumps could move a large enough volume of water to cause tsunamis.
Another proposal, even further from reality with present technology, is to inject carbon dioxide gas into the deep ocean sediments to form CO2 clathrates, thus removing it from the atmosphere and thus cutting down on greenhouse gasses.
But there is a darker side to methane ices, which also have formed in the Arctic tundra and are held deep in the permafrost. As global temperatures continue to rise, permafrost is melting. The amount of frozen methane deposits thawing will increase. Methane, which is ten times more efficient as a greenhouse gas than carbon dioxide, will cause the temperature to increase more, raising sea levels and ocean temperatures, in turn releasing more methane. The oceanic methane theoretically will remain stable as the oceans get deeper and sea floor pressures increase. But, if the oceans warm, and they are already warming (though at a slower rate than the atmosphere) a critical point could be passed and large releases of methane gas from the continental slope deposits could occur, adding much more greenhouse-enhancing methane to the atmosphere. Climate change would surge ahead.
This post was originally creating in the old Google Earth Forum. You can see the discussion in THIS THREAD.
Ammonium hydrate V_3.kmz (4.93 KB)
