Brian Whatcott wrote:
Briefly:
Take one forty ft vertical tube filled with saline.
Take one forty ft vertical tube filled with fresh water.
Connect them with a little engineering help - at the top.
....
The boiling point of water at the top of a sealed 40 ft column of
water is near ambient.
So, it doesn't take much heat to boil the brackish water,

A nice idea, but unfortunately, the vast bulk of the energy used by the
distiller is not used in heating the water to the boiling point, but in
performing the phase change from liquid to gas. I believe this is a
constant regardless of the surrounding pressure.

The same principle works with ice keeping things cold. It is not so
much the fact that the ice is colder than your drink that keeps it cold
for so long, but rather that the energy required to accomplish the phase
change from solid to liquid requires a bunch of energy.

- Dan best