One potential problem: you derive energy from converting freshwater to salt water. What do you do with all that salt water? You could cook it in the sun to evap

One potential problem: you derive energy from converting freshwater to salt water. What do you do with all that salt water? You could cook it in the sun to evaporate out the water and start the process over again, but you've basically made a solar energy plant. The cool thing about using membranes near rivers and the ocean is it uses the ocean as your solar energy plant. You could also place this device near natural dead seas to produce power... but that's basically what the article is proposing.