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Salinity gradient

A constant supply of ocean energy

Salinity gradient power generation is a renewable energy source available 24 hours a day. It is therefore complementary to more variable sources of energy like wind, wave, and solar.

Today, the most advanced salinity gradient technology is Reverse ElectroDialysis (RED). With RED, energy can be harvested from the difference in the salt concentration between seawater and fresh water. RED uses stacks of alternating anion and cation exchange membranes to generate electricity.

Progress to date

The potential of salinity gradient power is considerable. The energy released from 1 m3 fresh water is comparable to the energy released by the same m3 falling over a height of 260 m. The availability and predictability of salinity gradient energy is very high, and therefore makes it a solid baseload energy source.

A pilot plant, powered by FUJIFILM membranes, is currently running in the Netherlands at the Afsluitdijk. Here, seawater of the North Sea meets fresh water of the Ijsselmeer. Further developments to improve the membrane performance (high power density generation) and cost effectiveness are ongoing.