Osmotic Pressure = Osmotic Power

[NotoriousNick]

Osmotic Power is driven by putting salinated water in a chamber with a permeable barrier; the other side is fresh water. The osmosis of water to the salinated chamber creates pressure, and therefore this pressure can be harvested to drive a turbine.

1. What is the actual physical mechanism of stored chemical energy that drives this work?

OR

Fresh water rivers entering into the sea, and this is reverse desalination.

My question is, how does this work?

I know that Energy + Salt Water = Fresh Water + Salt

And you could say, look at the reverse of this.
But:
A. We're not just mixing fresh water and salt, we're mixing freshwater and saltwater
B. What does the heat of vaporization have to do with this.


Thanks

 

[Borek]

Solutions of different concentrations have different chemical potential (Gibbs energy), and they will do something to equalize the potential, that's the driving force behind. As for mechanism you can think about kinetics of the transmission through the membrane - speed is proportinal to concentration of the substance that want's to get through. When concentrations on both sides of the membrane are different, speeds of transmission in both directions are different, and there is a net transport. When concentrations are identical, speed is identical and there is no net transport.

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