Evaluation of SOFC Hybrid Systems for Automotive Propulsion Applications

The polymer electrolyte membrane (PEM) fuel cell is generally regarded as the fuel cell of choice for automotive propulsion applications. However, PEM fuel cell has several disadvantages such as the requirements of pure hydrogen, complex water management, and the hydrogen infrastructure. Despite having efficiency, cost, and fuel flexibility advantages, solid oxide fuel cell (SOFC) systems have not been considered for automotive propulsion, primarily due to the long start-up times of SOFC systems. Recently there has been some interest in using SOFC hybrids for propulsion applications. These hybrids are mainly: (1) a combination of SOFC and battery as a range extender type series hybrid vehicle and (2) SOFC and battery driving an electric machine combined with an internal combustion engine (ICE) driven system operating as a parallel hybrid vehicle. In this paper, a comparative study of the SOFC hybrid vehicle strategies for propulsion applications are presented, the performance of the systems are compared, and the feasibility and challenges are discussed