Principle
Solid oxide electrolyzer cells operate at temperatures which allow high-temperature electrolysis to occur, typically between 500 and 850 °C. These operating temperatures are similar to those conditions for an SOFC. The net cell reaction yields hydrogen and oxygen gases. The reactions for one mole of water are shown below, with oxidation of water occurring at the anode and reduction of water occurring at the cathode.
Anode: H2O ---> 1/2O2 + 2H+ + 2e-
Cathode: 2H2O + 2e- ---> H2 + 2OH-
Net Reaction: H2O ---> H2 + 1/2O2
Electrolysis of water at 298 K (25 °C) requires 285.83 kJ of energy in order to occur, and the reaction is increasingly endothermic with increasing temperature. However, the energy demand may be reduced due to the Joule heating of an electrolysis cell, which may be utilized in the water splitting process at high temperatures. Research is ongoing to add heat from external heat sources such as concentrating solar thermal collectors and geothermal sources.
Read more about this topic: Solid Oxide Electrolyser Cell
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