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Hydrogen production by electrolysis (green hydrogen) <\/p>\n
Through water electrolysis (electrochemical water splitting), pure H2 gas can be produced without emissions, with O2 formed as a by-product. The oxidation (anodic reaction) and reduction (cathodic reaction) occurring during water splitting take place in separate spaces, thus avoiding the formation of an explosive product mixture. The electrodes are separated by an electrolyte solution and a solid separator, or by a solid electrolyte replacing both, which ensures the ionic conduction required for the electrochemical processes. <\/p>\n
Alkaline water electrolysis is the most mature technology and has been used on an industrial scale to produce H2 for the past 100 years. In this process, an alkaline electrolyte solution (typically KOH solution) is electrolysed between the cathode and the anode. A porous diaphragm is used to separate the two cell compartments and thus prevent O2 and H2 from mixing. To reduce the electrical resistance caused by the solution layer between the electrodes (and with it the cell voltage), electrolysis cells separated by a proton exchange membrane (PEM) were developed. In these, the anode and cathode are pressed directly against each other through a membrane (similar to fuel cells). Pure water is oxidised on the anode side, while at the cathode the H+ ions migrating through the membrane are reduced to hydrogen at the same rate. <\/p>\n