The best way I can think of to describe the problem with this is "We decided the greenhouse effect wasn't bad enough, so we committed to capturing as much of the sun's energy here on Earth as humanly possible! Lowering the Earth's albedo to about 15% everywhere we can reach can't possibly be a bad idea, right?"
Energy good. Get more energy!
The deal, is that if you collect that energy, and then USE it-- it becomes ENTROPIC ENERGY. EG--- **HEAT**
We already are trapping a great deal of heat in our atmosphere because of increasing greenhouse gas levels-- While reflecting a substantial amount of solar energy into space as visible light (which is not absorbed by the atmosphere.) If you absorb that energy, and then put it to use, you GREATLY increase the amount of energy staying in the earth's atmosphere.)
Hence, the absurd quip about the "Over unity" LEDs. They operate by driving the LED at "Just under" the band-gap energy thresholds, and relying on thermal oscillations to push electrons over the gap, and thus emit photons. When that energy is absorbed and then radiated as a photon, it can be kicked back out into space, if directed properly. SO--- Either you build stations on the ground that collimate beams of low intensity LED emissions into very high intensity ones, and shoot them out into space, and just accept that the atmosphere is going to just absorb a great deal of it--- OR--- Put the things into space elevators, and beam it out up there. Either way, you are GOING to need something that is "over unity" like that, to eliminate the heat from the earth's environment-- and you are going to need to deploy it on a massive scale, if you go Kardishev I.
@SMJJames
Oh indeed! I *DID* say this was a BAD idea, that I DO NOT endorse it, and that it is NOT sustainable, did I not? I just said it was something that "Could be done". Not that it was practical, desirable, efficient, nor sustainable.