Comparative study on the performance of the application of clean alternative fuels in SOFC/ICE hybrid power systems on electric aircraft

Solid oxide fuel cells (SOFC) have gradually become possible to be used in the aviation field because of their high efficiency and fuel flexibility. The number of internal combustion engines (ICE) that are already in use is large, which makes it difficult to completely abandon them in a short period. Hence, finding low-carbon alternative fuels is significant for the development of cleaner internal combustion engines. In this paper, different hybrid power systems configured with different fuels, i.e., hydrogen, methanol, liquid ammonia, isooctane, natural gas and gasoline, which consist of a solid oxide fuel cell and an internal combustion engine, are constructed to help find the optimal set of fuel and system structure by analyzing the power generation performance and weight of different systems. The results show that the hybrid power system with ammonia or methanol (except gasoline) as fuel presents the lowest actual fuel consumption rate (around 310 g/kWh). The hybrid power system with ammonia as fuel performs the highest power generation efficiency of 61.58%, and the corresponding power density is estimated at 0.556 kW/kg. In conclusion, the proposed system with ammonia as fuel has obvious advantages in fuel consumption rate, power generation efficiency, carbon emission reduction and fuel storage.