[codewiz]

Because heat is pure entropy; it's what you ultimately end up with after electricity has been used to do work, and the process is irreversible due to the Second Law of Thermodynamics: https://en.wikipedia.org/wiki/Second_law_of_thermodynamics#G...

Only a difference in heat levels can still be converted to electricity, for instance by reverse Peltier effect: https://en.wikipedia.org/wiki/Thermoelectric_cooling

[creshal]

And on a space station, most of your heat differential is created by active cooling, so recovering that via Peltier elements is a bit… counter productive.

[choosername]

The Second Law of Thermodynamics just means the conversion can't be a hundred percent efficient. Indeed, I didn't think of that as a problem.