Energy from fresh water/salt water junction
There's a video and a long article at:
According to Dutch engineer Joost Veerman, it's possible to tap this energy without damaging the environment or disrupting the river's busy shipping.
Working at Ben-Gurion University of the Negev, in Beer Sheva, Israel, he [Loeb] envisaged a tank with two chambers separated by a semipermeable membrane. With saltwater on one side and fresh on the other, osmosis would draw fresh water into the salty side, raising its pressure. This pressurised saltwater could then be piped through a turbine to generate electricity (see diagram). Loeb named this process pressure retarded osmosis (PRO) and patented it in 1973.
This sig may return, some day.