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Comment by mikepurvis | Hacker News Reader

Once you're on the surface you can sink a fair bit of heat into the ground. The issue in space is that you can't do convection, and there's nothing to conduct to, so you're really just left with giant, inefficient radiators.

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On the moon, wouldn’t heat be a useful byproduct? (At least during the night) so a combined heat and power station would put those radiators where the people are

Up to a point, but you'd still need a story for dealing with the surplus.

Also, if you want to actually turn heat into electricity with a turbine, then you need the ability to heat and cool your medium repeatedly [1]— locating power plants on shorelines is very convenient for this, since you have a heat source from your combustion, nuclear reaction, whatever, and then a functionally bottomless cooling source in the water.

[1]: https://en.wikipedia.org/wiki/Rankine_cycle

Nitpick: Are radiators very inefficient? I assume they're 100% efficient, just not very effective due to the limits of physics.

Depends on what you mean by efficient. I assume the previous commenter meant it isn’t efficient in terms of cost and space to build large radiators that aren’t very effective.

Yes, efficiency here is in the sense of the mass and volume of device required to dissipate X amount of heat energy, particularly in an environment where getting a lot of mass and volume up there is fabulously expensive.

Not a physicist, but I'd say it depends on what you define as parameter optimized against. For space, Id be interested in heat energy dissipated per unit time per kimogram per cargospace for exanple, where radiators suck compared to convection coolers

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