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.

[–] CanadaPlus@lemmy.sdf.org 3 points 2 months ago* (last edited 2 months 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.

[–] YeetPics@mander.xyz -4 points 2 months ago (1 children)

Nothing in the universe has an efficiency over 100%.

[–] CanadaPlus@lemmy.sdf.org 6 points 2 months ago* (last edited 2 months 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.