Plight of Phoenix: how long can the worlds 'least sustainable' city survive?

[NNadir]

9. I've read quite a bit about membranes. They are not free energy.

The basic thermodynamics of seawater or any form of brine is that one needs to invest energy to overcome the entropy of mixing.

In the case of membranes, the energy consumed comes from pressurizing one side of the device; basically the energy comes from a pump.

The path may change the amount of energy that is lost to entropy, but it cannot eliminate it. The States of California and Arizona might try to repeal the 2nd law of thermodynamics, but the repeal will have no effect on physics.

Membranes foul, and this is a key element of membrane (and solid phase extraction) technology. There are ways to address this problem, but they are not simple and they all will have some environmental impact.

And then there is the matter of what to do with the salt that remains. While salt is a food, transportation and industrial commodity, the demand for it is not so high as to completely address the amounts that massive desalination would involve. This means that the salinity of ecosystems will be changed, resulting in significant damage to ecosystems or their complete destruction, as has happened in the Colorado delta, an ecosystem that has been completely destroyed, and saline concentrations are the reason.