SOFC operating with ammonia: Stack test and system analysis

• SOFC stack was operated with pure and diluted ammonia.
• A model was designed based on experimental results showing effect of internal cracking.
• System analysis shows NH3 based system more efficient than equivalent H2 based one.
• Results of diluted ammonia show an additional route for efficient power production.

Ammonia has been studied as a potential energy vector and suitable fuel for Solid Oxide Fuel Cells (SOFCs). The use of ammonia could guarantee high electrical efficiency, with a carbon free and high energy density fuel. This study analyzes the potential of a power generation system based on a SOFC fueled by NH3. Experimental tests on a SOFC short stack were developed using both pure and diluted ammonia. The tests demonstrated the operation of the concept and highlighted possible advantages in terms of thermal equilibrium. Decomposition of ammonia introduces an endothermic reaction that permits heat absorbance in the anode and a better control of stack temperature. Based on tests results, a thermodynamic model of a complete system was designed and studied. The results demonstrate that the ammonia fueled SOFC is more efficient than an equivalent hydrogen fueled one, due to the cooling effect of internal reactions that reduces ancillaries energy consumptions related to cathode air flow.