SUMMARY

Reverse electrodialysis (RED) is a sustainable multi-membrane system that aims to convert salinity gradient energy into electrical energy. Redox mediators are typically used to convert ionic mixing into electricity at electrodes placed adjacent to a stack of membranes. However, replacing redox mediators with water splitting electrodes can enable the sustainable production of fuel (H2) and/or oxygen (O2). We aim to examine if a RED oxygen generation system could meet oxygen requirements for scuba diving. Evolving oxygen from water would enable the development of artificial gills, allowing for an inexhaustible supply of oxygen thus displacing the need to carry oxygen tanks. We show here that the oxygen evolution activation overpotentials are a significant fraction of internal resistance (77%) in a RED system with a small number of cell pairs (N=5). However, this resistance is nearly negligible (3.2%) as the number of cell pairs increases (N=500). We further com- pare the RED systems to four different battery-electrolysis systems (Li-ion, Ni-MH, Ni-Cd, and lead acid) to contextualize the performance of the RED oxygen generation system. For large (N=100+) systems, RED is comparable to a battery-electrolysis system if coupled with desalination.