Production of Hydrogen by Electrolysis

A technically far-developed process is the electrolysis of water for the production of hydrogen, although only about 5% of the hydrogen is produced by means of electrolytic processes worldwide [5.21]. The efficiency is limited to smaller hydrogen capacities up to about 5000 m h and the availability of cheap electric energy, for example from water power. 

The complete process running in the electrolyser results from the sum of these two reactions  

The concentration of the electrolyte in the solution amounts to a mass fraction of usually 25-30%, the temperature is about 80 °C and the pressure depending on the required product pressure is 1-30 bar. The electrodes are corrosion-resistant, good electric conductors and support the formation of the gases by means of structured surface. 

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Chapman EA (1965) Production of hydrogen by electrolysis. Chem Process Eng 46 387-393... 

The simplest kind of cell construction, shown in Figure 19.19(d), suffices for the production of hydrogen by electrolysis of water and for the recovery of chlorine from waste HC1. The term filter-press cell is applied to this kind of equipment because of the layered construction. These two electrolyses are economically feasible under some conditions. Some details are given by Hine (1985). 

Morizonoa, T., Watanabe, K., and Ohstsuka, K., Production of hydrogen by electrolysis with proton exchange membrane (PEM) using sea water and fundamental study of hybrid system with PV-ED-EC, Mem. Fac. Eng., 31, 213-218 (2002). 

Industrial electrolyzers use electrodes and gas collection schemes optimized to produce the maximum amount of hydrogen using the minimum size equipment and minimum quantity of electric energy. Their basic principle of operation is an extension of the simple process described above. Equipment for the industrial scale production of hydrogen by electrolysis is available from a number of manufacturers. Some of these are ... 

Plant operating costs for the production of hydrogen by electrolysis and by propane reforming are compared in Table 10-3 for various sizes of... 

Volume production of hydrogen by electrolysis of water is achieved using one of the following process variants ... 

Anodic inhibition of stress corrosion cracking was first provided on an industrial scale in a large plant for the production of hydrogen by electrolysis of potassium hydroxide solution. After preliminary trials on a laboratory scale, the chemical industry s first anodically protected large-scale plant, a sodium hydroxide solution evaporator with a capacity of 142 t, was put into operation in 1968. Since then, plants have been equipped in the same way (Grafen 1971). 

An interesting project concerns plans to use fuel cells in the Antarctic base on Bechervaise Island. This project, supported by a grant of 600,000 from the Australian government, involves the production of hydrogen by electrolysis with wind energy and its use in low-power fuel cell units producing electric power and heat (Adamson, 2006). 

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