Electrochemistry in hydrogen economy

The energy crisis in the early 1970's, the inevitable exhaustion of fossil fuels, as well as the polluting effect of the use of present fuels have been facts that have led to ambitious plans for developing a worldwide energy system based on hydrogen. The fields of research in Hydrogen Economy pertain to the production, transmission, storage, and utilisation of hydrogen. The purpose of this paper is to survey literature to obtain the current status of the electrochemical methods for producing and utilising hydrogen. The methods examined were narrowed down to the solely electrochemical methods, in other words photoelectrolysis and electrolysis for the production of hydrogen and fuel cell for the utilisation of hydrogen. After explaining the basic theory of photoelectrolysis a review of experimental results is given with the purpose of presenting the different cell realisations tested. This field is still young having been intensely studied for only about ten years, but because of its potentials the field is experiencing drastic expansion. As far as the production of hydrogen is concerned this technique will not be commercialisable for years. Conventional electrolysis methods produce about 4 % of the world's hydrogen. Their theory and state of the art are explained along with experimental results for improving these techniques. For the production of hydrogen on a large scale the non conventional electrolysis methods are foreseen as being very competitive, especially water vapor electrolysis. The theory related to these techniques and the current performance of experimental systems are examined. The understandinq of the theoretical basis of the fuel cell and its technological development was to a great extent carried out by projects funded by the U.S. space program up to the late 197O's. Interest in the fuel cell declined as space program funding ceased and has only recently revived. The high efficiencies exhibited by fuel cells has made them attractive in this time of energy-saving techniques. The theory and development of small-scale and power plant fuel cells are discussed. The high temperature fuel cells have advantages that seem to make them the probable choice for hydrogen utilisation method in the future.