Comparison of hydrogen production and electrical power generation for energy capture in closed-loop ammonium bicarbonate reverse electrodialysis systems

Currently, there is an enormous amount of energy available from salinity gradients, which could be used for clean hydrogen production. Through the use of a favorable oxygen reduction reaction (ORR) cathode, the projected electrical energy generated by a single pass ammonium bicarbonate reverse electrodialysis (RED) system approached 78 W h m(-3). However, if RED is operated with the less favorable (higher overpotential) hydrogen evolution electrode and hydrogen gas is harvested, the energy recovered increases by as much similar to 1.5 x to 118 W h m(-3). Indirect hydrogen production through coupling an RED stack with an external electrolysis system was only projected to achieve 35 W h m(-3) or similar to 1/3 of that produced through direct hydrogen generation.