High performance ammonia-fueled SOFC hybrid system for decarbonizing heavy-duty transportation applications

Solid oxide fuel cells (SOFCs) are being targeted as an attractive power generation technology that can potentially operate on ammonia without the need for any pre-reforming enabling direct conversion of ammonia to power. In this work, an ammonia-based SOFC-Gas turbine (GT) system concept is proposed and evaluated for the mobility sector using multi-scale modeling tools. The model integrates a three-dimensional multiscale SOFC stack simulation with balance-of-plant component modeling to estimate system-wide performance. The industrial scale stack simulation is based on a high power-density gadolinia-doped ceria (GDC) electrolyte-based cell architecture and also includes a microkinetic mechanism to evaluate ammonia decomposition. System efficiency, overall pressure ratio, electrochemical utilization and turbine inlet temperature are evaluated and analyzed through carefully designed parametric trade studies. Transportation relevant performance metrics are evaluated for the system on both volumetric and gravimetric basis. Normalized fuel storage volumes, system specific power and specific energy are defined and estimated for the proposed system concept. The analysis suggests that fuel storage volumes for ammonia are higher than contemporary fossil fuels but comparable to alternative fuels such as CNG and hydrogen for heavy-duty transportation. Model-predicted performance of the proposed hybrid system estimates efficiencies over 60 % for pressurized operation, specific power of nearly 0.50 kW kg−1 and a specific energy of over 2.5 kWh kg−1.