Increasing of efficiency of hydrogen energy storage system by the use of high-pressure electrolyser with metal hydride electrode

Abstract

The article describes the electrochemical process of hydrogen and oxygen generation by a membrane-less electrolyser having a passive electrode made of Ni and a gas absorption electrode made of metal hydride (LaNi5Hx). Such composition of the electrode stack materials (Ni - LaNi5Hx) makes it possible to generate hydrogen and oxygen during the half-cycles separately in time while maintaining the time intervals of the corresponding half-cycles. The last one indicates the stable capacitive characteristics of the LaNi5Hx metal hydride electrode. During the oxygen half-cycle, hydrogen is absorbed in the metal hydride electrode while oxygen is released at the nickel electrode and then removed into the oxygen storage system. During the subsequent half-cycle, the hydrogen absorbed by the metal hydride electrode is removed into the hydrogen storage system. We have studied the above electrolysis process with help of the laboratory experimental membrane-less electrolyser giving the possibility for generating, storing and compressing hydrogen in it. The use of a chemically active LaNi5Hx electrode will make it possible to implement a hydrogen energy storage system (electrolyser-storage system-consumer) and accordingly to increase the efficiency of the power plant by ≈ 8–10 %. It would be effective to use such high-pressure membrane-less electrolyser as an energy storage system element of an energy complex that receives electricity from the renewable energy sources (sun, wind).