Reverse Electrodialysis (RED) is an electrochemical membrane process that utilizes the free energy of mixing two solutions of different composition. The most commonly envisioned application is the mixing of seawater and river water at river deltas around the world. RED for mixing seawater and river water thus constitutes a renewable source for electric power production close to many urban regions. The worldwide potential is estimated to hold an average output in the order of as much as 2 TW.
In this article, we have summarized the most important developments for RED since it was first discovered in 1954. RED represents a highly interdisciplinary research field and does not include membrane development alone. Challenges related to fluid mechanics, electrochemistry of electrodes, and traditional chemical engineering also constitute substantial parts of the research area for RED development. All these topics are discussed in this article.