Solid oxide fuel cells overall chemical reaction

Each of the two electrode reactions creates a characteristic potential difference across the interface solid electrode/electrolyte, which is different for the two reactions according to the different reactants. The overall cell voltage between the two electrodes, which are joined by the same electrolyte, allows the electrons generated at the anode (HOR) and consumed at the cathode (ORR) to create work in the external circuit. Hence, chemical energy released by the individual electrode reactions at the locally separated electrodes is directly transferred into electrical energy. This pathway is different from the combustion step in the classical thermomechanical power generation, where the oxidation of fuel and reduction of oxidant occur in the same volume element, thereby generating heat only. 

---