Application of Reverse Electrodialysis Power for Oxygen Generation in Undersea Diving

With continued growth of marine exploration and underwater missions, there is a need to design new diving technologies. Currently, dive time limited by scuba tank weight volume. The use an electrolysis system, powered battery, for driving chemical reactions could be introduced produce steady supply oxygen during dives. However, batteries have capacity, are heavy, detrimental the environment when disposed. Developing electrochemical technology that utilizes resources abundantly available diver (salt water) drive evolution reaction would expand duration sustainability ocean Reverse electrodialysis (RED) multi-membrane system aims convert salinity gradient energy into electrical energy. Redox mediators typically used ionic mixing electricity at electrodes placed adjacent stack membranes. replacing redox with water splitting can enable sustainable production fuel (H 2 ) and/or (O ). We aim examine if RED generation meet requirements diving. Evolving from development artificial gills, allowing inexhaustible thus displacing carry tanks. Here we propose where instead air tank, carries cell, L volume dilute solution, cylinder other compressed gases breathing (Fig. 1a). A cell comprised alternating anion cation exchange membranes separated channels high low concentration solutions (HC LC) 1b). made up repeating units, which consist pair selective solution channels, between anode cathode chambers. Salt ions in migrate due two based this flux electric flux. show here activation overpotentials significant fraction internal resistance (77%) small number pairs (N=5). nearly negligible (3.2%) as increases (N=500). further compare systems four different battery-electrolysis (Li-ion, Ni-MH, Ni-Cd, lead acid) contextualize performance competing For large (N=100+) long (10 hr) dives, comparable size system. 500 membrane pairs, 10.8 weighs 29 kg. Typical 12 tanks weigh 16 kg, Li-ion battery 1 hour is, 2.2 3.5 kg (19.2 32.6 10 dive). Figure 1. (a) Configuration divers using surrounding seawater, fixed volume, additional carried diver. (b) Schematic cell. Oxygen hydrogen produced reactions.