3.5. Salinity gradient power
Salinity gradient power makes use of the potential energy
available when saltwater and freshwater mix. The pressure
induced by the movement of water across a membrane can be
used to run turbines via a process known as ‘‘Pressure-Retarded Osmosis.’’ This process is illustrated below in Fig. 10. The latest
research development of this energy system uses reverse electrodialysis ion-exchange membrane stacks in microbial reverseelectrodialysis cells, to capture salinity-gradient energy from
ammonium bicarbonate salt solutions, which is able to produce
greater energy as well as greater recovery of the energy [55].