Unique applications and improvements of reverse electrodialysis: A review and outlook

Reverse electrodialysis (RED) is a promising technology for extracting energy from salinity gradients. However, there are still barriers to the realization of its commercial application. Developing flexible methods of RED application is a feasible scheme. In this paper, we review and summarize unique RED applications in recent years. The review summarizes RED applications related to energy conversion, desalination technology, and water treatment and some improvements to standard RED. The electricity generated by RED or combined RED can be converted to hydrogen or other energy forms and stored in a battery for access at any time. RED heat engine expands RED application with conversion of waste heat to electricity. RED can be coupled with one or more desalination technologies to improve the power density of RED and minimize the influence of brine discharge from desalination technology on the environment. RED or combined RED can also be used for water treatment by direct or indirect reactions. The review also summarizes the improvements of electrodes, feed solutions, membranes and operation of membrane cell for RED. With the development of related technologies, RED will play an important role in an increasing number of fields.