Tidal power seems great but I do get concerned when there is talk of power from ocean currents. That could be catastrophic if it changed the thermal exchange of the world.

On the other hand, something very cool from Australia is way to use wave energy. You could use wave mechanical energy to turn a generator to produce electricity to power an electric motor to force water through a membrane to create fresh water. What they are doing is skipping the electricity part. They use wave mechanical energy force water through a membrane to create fresh water. It sounds really good. It just floats in the waves making fresh water and the output brine is low concentration. ...Just sayin'...