NOVELTY - An electrochemical cell system includes electrochemical cell(s) having a hydrogen electrode and an oxygen electrode with an electrolyte membrane disposed in between and in intimate contact with the oxygen electrode; and a compartmentalized storage tank having two fluid storage sections (44, 46) separated by a movable divider, and in fluid communication with the electrochemical cell.    USE - For use as fuel cell to provide electricity e.g. in space station.    ADVANTAGE - The inventive system may be charged in electrolyzer mode by photovoltaic cells attached to the outside of an orbiting space station. Since the inventive system is regenerative and does not require the use of pumps, it can serve as a stand-alone system for electrical needs. Additionally, the inventive system has increased reliability relative to conventional systems because it has fewer moving components. It can operate in both low gravity and zero gravity environments, as the need arises. Finally, since the inventive system uses fewer parts and integrates others, it is more compact than the conventional system.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method of operating the electrochemical system, comprising introducing water to the oxygen electrode; electrolyzing the water to form oxygen, hydrogen ions and electrons, where the hydrogen ions migrate through a membrane to the hydrogen electrode; directing the oxygen to an oxygen storage section of the compartmentalized storage tank, where the oxygen increases the pressure in the storage tank and moves the movable divider which forces the water to move from the storage tank to the oxygen electrode; moving the electrons to the hydrogen electrode; and reacting the hydrogen ions and the electrons to form hydrogen.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic diagram of a low gravity electrochemical cell system.    Electrochemical cell (30)    Hydrogen flow field (32)    Oxygen flow field (34)    Water flow field (38)    Media divider (40)    Compartmentalized storage tank (42)    Fluid storage sections (44, 46)    Movable divider (48)