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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[quicknote]

for your question! The actual physical mechanism of stored chemical energy that drives this work is known as osmosis. Osmosis is the movement of water through a semi-permeable membrane from an area of low solute concentration (in this case, the fresh water side) to an area of high solute concentration (the salinated water side). This movement occurs due to the difference in concentration of solutes (such as salt) on either side of the membrane, which creates a pressure gradient. This pressure is what drives the movement of water molecules and can be harnessed to do work, such as driving a turbine.

As for your question about the reverse desalination process, you are correct in thinking that this is essentially the reverse of the process where energy is added to salt water to produce fresh water. In the osmotic power system, the energy is harnessed from the movement of water molecules, rather than being added to the system.

The heat of vaporization, or the amount of energy required to convert a liquid into a gas, is not directly involved in the osmotic power process. However, it is related to the concept of osmosis as it is the driving force behind the movement of water molecules through the semi-permeable membrane. The movement of water molecules from an area of low solute concentration to an area of high solute concentration is driven by the desire to equalize the concentration on both sides, which is known as the chemical potential. This chemical potential is related to the heat of vaporization, as the movement of water molecules is driven by the difference in energy between the two sides of the membrane.

I hope this helps to clarify the process of osmotic power and the role of osmosis and heat of vaporization in this system. Let me know if you have any further questions.