this post was submitted on 09 Oct 2024
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Futurology

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[–] [email protected] 17 points 1 month ago* (last edited 1 month ago) (12 children)

The work addresses the thorny problem of waste heat. Thanks to the second law of thermodynamics, a small amount of heat will always be released into the planet's atmosphere no matter what energy source we use — be it nuclear, solar, or wind — because no energy system is 100 percent efficient.

"You can think of it like a leaky bathtub," study coauthor Manasvi Lingam, an astrobiologist at the Florida Institute of Technology, told LiveScience. A small leak in a bathtub that's barely filled doesn't let out a lot of water. But as the tub continues to get filled — and our energy demands grow — that tiny leak can flood the whole house, Lingam explained.

I thought the problem was that CO~2~ was acting like a blanket trapping in all the heat. Is this "heat leaking" really a problem? If so, what about solar cells then?

[–] filcuk 1 points 1 month ago (4 children)

Heat exchangers have >100% efficiency.
We just need to use those to move the extra heat outside the environment.

[–] [email protected] 3 points 1 month ago

The way they have >100% efficiency is if you are trying to increase the temperature, you can create new heat (which is extremely easy and can be done with essentially 100% efficiency) or you can move heat from elsewhere (creating new heat in the process as well, so it ends up being over 100% efficiency).

These incredibly high efficiency rates come from interpreting heat as success. It’s very easy to add heat to a system. It’s very hard to get rid of it.

Any system that moves heat from one area to another must necessarily produce more heat as well.

When your refrigerator cools your food, it vents hot air, adding more heat to the outside world than it removed from inside itself.

[–] [email protected] 3 points 1 month ago* (last edited 1 month ago)

This shouldn't be downvoted; it's a good point. I actually do expect that in a distant future that's positive, it would make sense to add artificial heat exchangers to the Earth.

The trick is that vacuum is a really good insulator, and theoretical maximum heat pump efficiency sinks down to "just" 100% gradually as the temperature gap gets larger. In order to move more heat, you have to make the heat exchangers pointed at the night sky hotter, so at some point you're bound to get diminishing returns.

[–] [email protected] -4 points 1 month ago (1 children)

Nothing in the universe has an efficiency over 100%.

[–] [email protected] 6 points 1 month ago* (last edited 1 month ago)

Depends how you define it. Heat exchangers do, because it's defined for them in terms of heat moved per heat generated. All conservation laws are still respected.

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