Re:Nanofiber membrane makes seawater drinkable in minutes
by thisrod on Sunday July 11, 2021 @12:36AM
(#27798507)
> the oceans own water pressure, pushes water through the membrane and up into the tank on the beach
Unfortunately, that's not how pressure works. There's a 100m column of water above the salt side of the membrane, but there's also a 100m column of water in the pipe on the fresh side. Those columns generate an enormous pressure, but it's pushing from both sides, which doesn't help you get water through the membrane.
Re:Nanofiber membrane makes seawater drinkable in minutes
by yazaddaruvala on Sunday July 11, 2021 @01:25AM
(#27798655)
That’s why you have a pump to move the water horizontally into different tanks. Then there is a 100m column and a 95m column forcing the water through the membrane.
So the pumps still need energy by “very little” energy because they are doing relatively little work.
Re:Nanofiber membrane makes seawater drinkable in minutes
by erpellan on Monday July 12, 2021 @08:29AM
(#27809562)
That is the equivalent of having a 5m column on one side and being open to air on the other side.
There is no free lunch - for the membrane to experience 100m of water pressure on one side only, something else has to be reducing the pressure by the same amount on the other side.
What if we use the oceans water pressure in our benefit?
For example, deploy this membrane 100m under the ocean, and have a pipe from the membrane going into a tank on the beach nearby.
As we pump fresh water out of the tank on the beach, the oceans own water pressure, pushes water through the membrane and up into the tank on the beach. That way the pump on the beach requires “very little” energy to move the water horizontally on the surface.
The excess brine build up would still be an issue but that’s always an issue.