3 ms·

In theory, sure. Hydrogen fuel cells will spit out water as a waste product, that's probably the easiest way. You could directly burn the captured hydrogen or h

In theory, sure. Hydrogen fuel cells will spit out water as a waste product, that's probably the easiest way. You could directly burn the captured hydrogen or hydrox gas and power a conventional steam turbine. You'd then have to condense the exhaust gas, which is mainly steam, but that's not terribly complicated. The problem is that the amount of energy you get back would be fairly small in comparison to the input energy. It might not be economically practical. The amount of energy you can reasonably store per unit of input energy might not ever surpass the cost of the equipment to extract the energy and put it back into the grid. There's a minimum energy cost in separating water from salt. Salt dissociated into water has a lower energy state than separate salt and water molecules. You have to put that much energy back into the salt ions to pull them out of solution, and they will keep that energy until dissociated again. So you have to pay the cost of entropy, then pay for all the energy loss in the combustion, capture, and conversion stages. I'm not sure if you'd get enough energy out to ever be worth the trouble.

jimnotgym 3y ago
But is the cost any higher than reverse osmosis?
- calamari4065 3y ago
  The thermodynamic cost of separating salt from water is the same per molecule no matter what. It's a fundamental physical limit. RO can be more efficient than electrolysis. The major factor is that electrolysis wastes a good fraction of the input energy on heating the water. On the other hand, RO requires high pressures, which is energy intensive. RO is generally more efficient overall, but either way you have to pay the cost of reversing entropy.
  - jimnotgym 3y ago
    But the electrolysis technique gives you the opportunity to store the energy as hydrogen. This means you can use cheap surplus energy for the electrolysis and burn the hydrogen later when energy is scarce. RO does not have that property

jimnotgym 3y ago

But is the cost any higher than reverse osmosis?

calamari4065 3y ago
The thermodynamic cost of separating salt from water is the same per molecule no matter what. It's a fundamental physical limit. RO can be more efficient than electrolysis. The major factor is that electrolysis wastes a good fraction of the input energy on heating the water. On the other hand, RO requires high pressures, which is energy intensive. RO is generally more efficient overall, but either way you have to pay the cost of reversing entropy.
- jimnotgym 3y ago
  But the electrolysis technique gives you the opportunity to store the energy as hydrogen. This means you can use cheap surplus energy for the electrolysis and burn the hydrogen later when energy is scarce. RO does not have that property