3 ms·

But, could molten aluminum or other metal be used for energy storage? So, when the sun is shining and/or the wind is blowing, use the resulting electric power

by graycat 12y ago

But, could molten aluminum or other metal be used for energy storage? So, when the sun is shining and/or the wind is blowing, use the resulting electric power to heat the metal by, say, just simple resistance heating. Then when want to draw energy from the molten metal, just have some tubes made of metal with a higher melting temperature carry water to be converted to steam to turn steam turbines and generate power. Since I doubt I'm nearly the first to think of such a thing, I have to guess that the detailed engineering and costing makes it not worthwhile.

Sanddancer 12y ago
That's the exact system behind molten salt storage [1]. It's just now getting to the point where it's really feasible, but is something that's being researched for the exact areas you described. [1] http://en.wikipedia.org/wiki/Thermal_energy_storage#Molten_salt_technology http://en.wikipedia.org/wiki/Thermal_energy_storage#Molten_s...
dredmorbius 12y ago
Yes. You've got two options. One is the straight thermal route, the other is to run the aluminum oxidation process forward and backward, in which the aluminium is the cathode and oxygen from the air the anode. It's just like any other battery in that you're creating an electric potential difference and current flow directly.
- graycat 12y ago
  I wondered if it was necessary to boil water
  - dredmorbius 12y ago
    It's not necessary, but it's a good route. You could run a Stirling-cycle engine off a hot and cold end without a phase-change working fluid. But gas turbines are very efficient (and simple), and work best when working with the very high-level pressure gradient presented either by combustion (as with a jet engine) or live steam (with a pressure drop in the condensed state) as with a steam turbine. You could substitute other volatile working fluids, but water is cheap, abundant, and provides useful work at temperatures typically attainable in systems -- 100 - 1000 C (typically in the 200 C - 500 C range).

by graycat 12y ago

Sanddancer 12y ago

That's the exact system behind molten salt storage [1]. It's just now getting to the point where it's really feasible, but is something that's being researched for the exact areas you described. [1] http://en.wikipedia.org/wiki/Thermal_energy_storage#Molten_salt_technology http://en.wikipedia.org/wiki/Thermal_energy_storage#Molten_s...

dredmorbius 12y ago

Yes. You've got two options. One is the straight thermal route, the other is to run the aluminum oxidation process forward and backward, in which the aluminium is the cathode and oxygen from the air the anode. It's just like any other battery in that you're creating an electric potential difference and current flow directly.

graycat 12y ago
I wondered if it was necessary to boil water
- dredmorbius 12y ago
  It's not necessary, but it's a good route. You could run a Stirling-cycle engine off a hot and cold end without a phase-change working fluid. But gas turbines are very efficient (and simple), and work best when working with the very high-level pressure gradient presented either by combustion (as with a jet engine) or live steam (with a pressure drop in the condensed state) as with a steam turbine. You could substitute other volatile working fluids, but water is cheap, abundant, and provides useful work at temperatures typically attainable in systems -- 100 - 1000 C (typically in the 200 C - 500 C range).