Fuel Cells
SOFC convert chemical energy in the fuel directly into electricity without burning it, enabling high-ecient electricity and contribute to the CO2 reduction.It can use a wide variety of fuels, including natural gas, biomass and hydrogen.
Principles of Power Generation
The SOFC generates power at between 700°C and 1000°C by being supplied fuel gas (hydrogen, carbon monoxide, etc.) to the fuel electrodes and air (oxygen) to the air electrodes.
Methane (CH4), the main ingredient of the fuel gases inserted into the cell stack, and water vapor (H2O), which is contained in the exhaust fuel that is recirculated, become hydrogen (H2) and carbon monoxide (CO) inside the cell stack due to the internal reforming reaction that is a characteristics of SOFC.
Oxygen ions (O2-) that move from the air electrode side to within the electrolyte react with the hydrogen (H2) and carbon monoxide (CO) of the fuel at the interface between the fuel electrodes and electrolyte, emitting electrons (e-) while simultaneously generating water vapor (H2O) or carbon dioxide (CO2).
Meanwhile, after the electrons emitted by the oxygen ions have performed electric work through the outer electric circuit, they move to the air electrodes.
At the interface between the air electrodes and electrolyte, oxygen in the air (O2) reacts with the electrons that have moved over to produce oxygen ions, and these oxygen ions are captured in the electrolyte and move to the fuel electrode side.
In terms of overall power generating reaction, hydrogen or carbon monoxide reacts with oxygen to generate water or carbon dioxide, and electricity flows with the resulting electrons move through the outer circuit.
The air electrode is the cathode, and the fuel electrode is the anode.
