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Why can't the heat be converted to electricity?
by choosername 10y ago
Why can't the heat be converted to electricity?
- heeen2 10y agoI think you need a temperature gradient to generate electricity from heat
- siculars 10y agoThe space station is in, uh, space. I'm fairly certain a temperature gradient could be arranged.
- seer 10y agoIt's actually the complete opposite - space is not "infinitely cold" it's more like "infinitely isolating" - like the perfect giant thermos. Space suits for example have a whole layer of water tubes just to cool down the astronaught, otherwise they will pass out from their own body's temperature.
- naasking 10y agoIndeed, black body radiation isn't very effective at dissipating heat!
- creshal 10y agoThe ISS has an 28 tons active cooling system that barely radiates away as much heat as a one ton HVAC unit on Earth (70kW). It's hard to generate a temperature gradient when you're blasted from the unfiltered Sun on one side, and reflected IR from Earth.
- deelowe 10y agoAnd surrounded by a near vacuum.
- deelowe 10y agoAnd yet thermos has somehow made billions by assuming the opposite.
- oxymoron 10y agoSome of it probably could be, but the effiency of those processes are low enough that you'd still have a heat problem. Also, recall that the energy originated with the solar panels to start with. It's a very wasteful way of generating electricity compared to the solar panels, so although it might be worth considering to recover some of the energy investment and eliminate a fraction of the heat, the net output of such a process will probably be an order of magnitude lower than the initial energy investment.
- codewiz 10y agoBecause 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#General_significance_of_the_law 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 https://en.wikipedia.org/wiki/Thermoelectric_cooling
- deleted 10y ago[deleted]
- creshal 10y agoAnd 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 10y agoThe 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.