Hydrogen generation from water electrolysis - possibilities of energy saving

Abstract

Hydrogen production via electrolysis of water from alkaline aqueous electrolytes is a well-established conventional technology. However, due to high energy requirements of about 4.5-5 kWh/m(n)(3) H-2 in most industrial electrolysers, the cost of hydrogen produced in such a way is n high. This is a limiting factor for the use of this method on a large scale, except in countries where the electricity is very cheap. There were various attempts to improve this process, like zero-gap cell geometry, developmentof new diaphragm materials, development of new electrocatalytic materials for electrodes, etc. We tried here to use ionic activators to reduce energy consumption. Two types of activators, both ethylenediamine complexes of cobalt, were used separately or in combination with some molybdates. The activation energies were significantly decreased in the presence of single ionic activators. However, the best results regarding the activation energy reduction were obtained when combinations with the molybdate were used. On the basis of the results of our experiments there is a strong indication that the activation with ionic activators reduces energy needs per mass unit of hydrogen produced for more than 10% in some cases, compared to those of non-activated electrolytes. (C) 2003 Elsevier Science B.V. All rights reserved.