Novel hydrogen generator: storage based on metal hydrides

A novel electrochemical system has been developed which integrates hydrogen production, storage and compression in only one device, at relatively low cost and high efficiency. The prototype comprises a six electrode cell assembly using an AB5 type metal hydride and Ni plates as counter electrodes, in a KOH solution. Metal hydride electrodes with chemical composition LaNi4.3Co0.4Al0.3 has been prepared by high frequency vacuum melting followed by high temperature annealing. X-Ray phase analysis showed typical hexagonal structure and no traces of other intermetallic compounds belonging to the La-Ni phase diagram. Thermodynamic study of the alloy has been performed in a Sieverts type apparatus produced by Labtech. Ltd. In the present prototype during charging, hydrogen is absorbed in the metal hydride and corresponding oxygen is conveyed out of the system. Conversely, in the case of discharging the hydrogen stored in the metal hydride it is released to an external H2 storage. Released hydrogen is delivered into the hydrogen storage up to a pressure of 15 bar. In this work, a compact unit integrating production, storage and compressing hydrogen is proposed as one device at relatively low cost and higher efficiency than a classical electrolyser. It is anticipated that the device will be integrated as a combined hydrogen generator in a stand alone system associated to a 1 kW fuel cell