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Can we imagine a large laser beam that sends energy into space in the form of light? (long wave infra red? Or another wave length that goes all the way through the atmosphere). If we were to feed this big beam with electricity made of ambiant energy (not fossil fuel, not nuclear), would this contribute to reducing the heat on earth?

It would look like a massive waste of energy, but from a pure system perspective, such a waste would be a way to reach an equilibrium. We would essentially be dumping into space the extra energy we have imported into the system by burning fossil fuel.

Please point it out if I am voicing thermodynamics profanities or why such apparatus would be technically not achievable.

Disclaimer: I am not a phycicist nor an engineer. I trust experts help us focus on what is the most effective way to fight climate change, which is to reduce the greenhouse effect by cutting down on emissions of CO2, methane and the like. I ask this question humbly because I am genuinely curious to fill in some gaps in my understanding of thermodynamics and nurturing this curiosity prevents me from becoming cynical or pessimistic. Sorry if my question is dumb or grotesquely science-fictionish

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  • $\begingroup$ you are asking a honest question and it is not dumb,radiating heat out into space is a thing spectrum.ieee.org/… sciencealert.com/… newscientist.com/article/… this type of cooling can be scaled up to cool buildings but cooling our planet is on a totally different scale. $\endgroup$ Mar 12, 2022 at 18:38
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    $\begingroup$ Beaming heat into space is what the Earth naturally does, and carbon dioxide traps it in the atmosphere. $\endgroup$
    – Gimelist
    Mar 12, 2022 at 23:21
  • $\begingroup$ Your question is nicely science-fictionish :) Good thought experiment question $\endgroup$
    – naught101
    Mar 16, 2022 at 1:52

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If we were to feed this big beam with electricity, would this contribute to reducing the heat on earth?

No.

The Earth's energy imbalance is estimated to be 0.77 watts per square meter. Multiplied by the Earth's surface area, that is equivalent to 393 terawatts. The electrical energy generated by all of humanity is about 25000 terawatt hours per year. Dividing by a year yields 2.85 terawatts.

This factor of greater than 100 discrepancy does not account for how incredibly energy inefficient most lasers are. Multiply that factor of more than 100 discrepancy by at least five (and that's assuming 20% efficiency, which is a bit high). We would need to ramp up electricity generation by a huge amount to make even a small dent in the Earth's energy imbalance by beaming energy into space via lasers.

References:

Norman G. Loeb, et al. "Satellite and ocean data reveal marked increase in Earth’s heating rate." Geophysical Research Letters 48.13 (2021): e2021GL093047.

yearbook.enerdata.net, World Energy & Climate Statistics – Yearbook 2021.

phys.org, Laser sets records in power and energy efficiency.

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    $\begingroup$ "We would need to ramp up electricity generation by a huge amount" Not to mention what happens if that generation isn't CO2 neutral ;-) $\endgroup$
    – Jan Doggen
    Mar 15, 2022 at 10:38
  • $\begingroup$ The more fundamental thing is that converting dispersed heat into condensed energy in any form is anti-entropic - it's not possible. I did wonder if you could (theoretically) hijack the earth's existing energy flows to e.g. use a heat pump to move more energy into the rising edge of the Hadley cell, to get it to part of the atmosphere where radiation would be more likely to escape, but I suspect a) that would require more energy than it would move, and b) the earth's already gonna do that, probably. Maybe you could speed it up though? $\endgroup$
    – naught101
    Mar 16, 2022 at 0:25

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