[diggernet]

My understanding of this is that the amount of heat transmission depends on the temperature of your target. You point it at outer space (cold), and you get a win. You point it at some sort of IR collector (necessarily at ambient temperature, or higher), and you've lost your cooling ability.

[jdmichal]

Right. One must remember that the target sink is going to be throwing radiation right back at the source emitter. Theoretically, they will exchange energy until they reach equilibrium between emission and absorption. Luckily for us, it will take a long time to heat space up enough to make a difference...

This also ties into why a magnifying glass cannot make something hotter than its source of light.

https://what-if.xkcd.com/145/

"Lenses and mirrors work for free; they don't take any energy to operate. If you could use lenses and mirrors to make heat flow from the Sun to a spot on the ground that's hotter than the Sun, you'd be making heat flow from a colder place to a hotter place without expending energy. The second law of thermodynamics says you can't do that. If you could, you could make a perpetual motion machine."

[ohyes]

Thanks for that, it really helped me understand the problem with my thinking.

[haser_au]

So if you point it at a satellite, or the ISS, and run a generator? Would that be a good backup power source for solar currently used?

[diggernet]

That's a great question. The thought of an orbiting IR collector crossed my mind while typing that comment, but I didn't want to think about it hard enough to address that. :)

The "beam" this generates is really more of a floodlight than a spotlight, so only a tiny part of the energy would hit your satellite. If you could focus it down to a narrow beam which hit only your satellite, my gut feeling is that you would simultaneously be focusing the surface heat of the satellite onto your panel. So once again, your panel would only "see" a hot surface, and would lose the benefit of cold space.

Also, as others have calculated in other comments, the amount of energy coming from the sun dwarfs what these panels radiate, so you are better off just pointing your satellite collectors at the sun.

[jdmichal]

> Also, as others have calculated in other comments, the amount of energy coming from the sun dwarfs what these panels radiate, so you are better off just pointing your satellite collectors at the sun.

Especially in space! We lose a good amount of irradiation energy from the sun to the atmosphere.

[averagewall]

The ISS has no shortage of warmth. Their challenge is keeping cool. Adding IR heat will only make things worse and require the use of more (solar) energy to remove that heat again through its cooling panels, which themselves work like this invention by radiating IR heat into space!