Hydrogen from Splitting of Water

Hydrogen can be produced from splitting of water through various processes ranging from water electrolysis, photo(solar)-electrolysis, photo-biological production to high-temperature water decomposition. 

The total energy that is needed for water electrolysis increases slightly with temperature, while the required electrical energy decreases. A high-temperature electrolysis process might, therefore, be preferable when high-temperature heat is available as waste heat from other processes. 

Other Renewables Solar, Geothermal, Hydro, Biomass 

Alkaline electrolysers use an aqueous KOH solution as an electrolyte (Floch et al., 2007). Alkaline electrolysis is best suited for stationary applications that are operating at pressures up to 25 bar. Alkaline electrolysers have been commercially for a long time. The following electrochemical reactions take place inside the alkaline electrolysis cell  

With relatively high cost, low capacity, poor efficiency and short lifetimes, PEM electrolysers currently available are not as mature as alkaline electrolysers. It is expected that the performance of PEM electrolysers can be improved significantly by additional work in materials development and cell-stack design (Grigoriev et al., 2006). 

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