Water electrolyzer and system

An electrolyzer for generating hydrogen by the electrolytic dissociation of water employs anode and cathode half-cells, separated by a planar polymer-based solid electrolyte, and includes a water reservoir for independently maintaining a desired level of water in the anode and cathode half-cells. A hydrogen exit chimney extends vertically upward from each cathode half-cell and enters a separation chamber; a gas exit passageway therefrom is closed by a separation membrane that allows the passage of H 2 but rejects liquid H 2 O, while a return water passageway enters near the bottom of the cathode half-cell. The half-cells are preferably formed by molded plastic frames that are arranged as a cell stack containing a plurality of electrolytic cells, with flat metal anodes and cathodes being respectively sandwiched about the solid electrolyte membrane in each cell. A pair of flat crushable metal plates are located at each end of the cell stack adjacent a pair of pressure plates that exert axial squeezing pressure to seal the cells. Specially designed, dual metal-hydride cartridges are used to provide larger quantities of H 2 from a single cartridge; a high temperature metal hydride is provided in a rear region of the cartridge that is heated by an electrical resistance heater to a temperature of about 200 ° C. or above while room temperature metal hydride powder fills a front section of the cartridge.