Lasted edited by Andrew Munsey, updated on June 15, 2016 at 1:22 am.
Discussion page for Directory:Space Based Solar Power.
On Nov. 18, 2007, Thomas E. Kasmer, invetor of the Directory:Hydristor Corporation wrote:
I would like to address the idea of orbital solar arrays collecting solar energy and beaming it to Earth via microwave transmission.
I would pity the bird, goose or airplane flying through the beam. 'Poof'.
That said, there are 2 cases of energy collection via the orbital mirrors. If the mirrors capture solar energy that would normally miss the Earth, then the transmission of the energy via microwave to the surface would result in that extra energy being dissipated and hence MORE global warming!
If the mirrors intercepted the energy destined to strike the earth, there would be additional weather disruptions due to this very large shadow cast on the Earth. Crops would also be affected by this.
There is the visual pollution in the sky during the day and the blocking of the heavens at night both for the individual and scientific observation of the night sky.
I wonder how the array would fare when hit by meteors like the Persoid meteor showers.
Then there is the solar wind pressure acting on such aa large 'sail'.
It wouldn't be long before somebody was selling advertising on the array like that which is done on the Goodyear blimp.
On a continual basis, the sun is striking the earth with the same intensity, whatever surface happens to be exposed. Likewise, on an equally continual basis, a given amount of heat energy is being radiated off the earth into space. It is in equilibrium.
I think you are right in saying that if the amount of surface being struck by the sun is increased, then the steady-state heat will increase. The question is one of extent. I'm guessing that the net gain would be extremely small, and that this effect would be essentially negligible.
Also, regarding the shadow cast by the solar array, my understanding is that the solar gain is continually 24/7, which would require that it not be in an orbit that would pass in front of the Earth, because that would mean it would pass behind the earth, which would rule out the 24/7 claim.
On Nov. 29, 2007, Mike Rudnick responded:
Yes, beaming energy to earth from a solar power satellite (SPS) definitely adds energy to the earth system -- no question about it. It does so in two ways. 1) Converting the microwaves beamed down to earth into usable grid electricity is not 100% efficient heat leaks into the environment during the conversion process. 2) Heat is also released into the environment when the electricity so produced is used.
However, to asses the goodness/badness of this, we have to consider the alternatives. Take fossil fuels. Burning them to supply power to the electric grid also frees the energy stored in the fossil fuel, thereby converting what was the potential energy stored in the fossil fuel into additional heat energy in the earth system.
In each case, for each unit of electric energy delivered to the grid, a corresponding amount of heat will eventually be set free into the environment. However, the conversion mechanism used to convert the potential energy stored in fossil fuel into electricity is fairly inefficient. So for every unit of electricity delivered to the grid, both that energy, and the waste energy freed while converting the fossil fuel potential energy into grid electric energy, is leaked into the environment. Much worse, greenhouse gases from burning the fossil fuel escape into the atmosphere. And this is the big problem. Those greenhouse gases trap solar energy from the sun into the earth system. It's sort of like the gift that keeps on giving long after the utility of the electricity generated has expired.
So to recap, SPS only adds energy, in the form of heat, into the earth system based upon the actual amount of energy beamed to earth. On the other hand, burning fossil fuel to power the grid adds 1) waste heat from the conversion process, 2) waste heat from using the electricity produced, and most importantly, 3) a large amount of additional heat trapped due to the release of the hothouse gases. I believe it is this last heating effect that is most significant.
Finally, I also believe the conversion efficiency of tuning fossil fuels into electricity (step 1 above) is much lower than the conversion efficiency of turning the microwaves beamed to earth into grid electricity.
So, for all these reasons (but especially the greenhouse entrapment), I believe SPS is a far superior source of energy to power the electric grid with respect to global warming. Moreover, I believe SPS-derived energy is likely to scale (be able to be grown) to provide us with clean power for the foreseeable future.
On a related topic, I believe SPS-derived energy is even superior to nuclear energy with respect to global warming, for two reasons. First, SPS microwave conversion to grid electricity is much more efficient than the conversion of nuclear reactor heat into grid electricity (think of those giant cooling towers emitting huge clouds of water next to nuclear reactors). Second, with SPS there's no nuclear waste or nuclear weapon proliferation issues.
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