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Discussion in 'Environmental Discussion' started by Rybold, May 6, 2011.
Good science update.
Whereas CO2 absorbs infrared light to cause global warming, if we captured enough infrared light, could we reverese global warming at the same time? I don't think so, but this got me thinking.
Not really. Capturing the energy is precisely the problem.
Energy from the Sun is intercepted by the Earth, some of it is reflected, some of it is absorbed; that which is absorbed is (mostly) converted into heat which then causes the object heated to give of infrared radiation. Some of that radiation escapes the Earth. The difference between the amount that is absorbed and escapes is Global Energy Increase. CO2 prevents some of that escaping radiation (by re-absorbing it).
Therefore if we replace an infrared absorbing object with an infrared to electricity converter, and that electricity ends up as heat (which most of it does), then we are neutral with respect to Global Energy Increase. If we replace an infrared reflecting object instead (such as vegetation), then we are making the problem worse.
[I am ignoring any subtleties about particular frequencies and differing absorption rates by CO2 here, as it exceeds my knowledge on the subject.]
^But with less CO2, the heat can escape more easily, but we can use it to perform "work" first on the ground before escaping
Akin to the efficiency gained in a heat pump vs a heater
It is true that single junction crystalline silicon cells cannot capture anything beyond 1.1x10^(-6) on that graph.
But multijunction devices can reach higher efficiencies, and this seems to be another form of multijunction cell. Most existing 3- to 6-junction device appear to have a Germanium layer that reaches out to 1.9x10^(-6) on that graph, grabbing all the IR except the last two small lobes.