(salty water + unpotable fresh water)
→ (salty water + potable fresh water + energy)
…with a few steps in between. Even if most of the power is used in running the plant, you end up with potable fresh water and no brine being dumped into the ocean, which is a net win.
Technical explanation : with reverse osmosis you have :
(salty water + energy )
→ ( fresh water + highly salty water )
So, reverse this process (call it osmosis plant ?) and you get energy … e.i. :
( fresh water + highly salty water )
→ (salty water + energy )
I think it’s more like:
(salty water + unpotable fresh water) → (salty water + potable fresh water + energy)
…with a few steps in between. Even if most of the power is used in running the plant, you end up with potable fresh water and no brine being dumped into the ocean, which is a net win.