High Temperature PEM Fuel Cell Systems, Control and Diagnostics: Chapter 21

Design of high temperature PEM (HTPEM) fuel cell systems requires special consideration of the elevated temperatures, and proper heat integration. Due to the increased tolerance to impurities, such as CO, in the anode hydrogen fuel flow these systems have a high degree of flexibility when it comes to choice of fuel. The shift towards higher temperatures is not without challenges, the materials (membranes, catalysts, stack and system components) are further stressed while also less mature, system startup time is longer and performance is lower than Nafion-based systems. However, HTPEM fuel cell systems have the potential of obtaining comparable efficiencies with other fuel cell technologies and in some cases provide more advantageous solutions due to the ease of cooling, reduced requirements for fuel quality and the possibility of using more readily available fuels that require smaller investments in infrastructure [1–4]. The introduction of fuel reformers also introduce additional complexity to a fuel cell system, and require in turn proper control strategies in order to obtain reliable and efficient system performance. This chapter presents some of the challenges and strategies involved with HTPEM fuel cell system design, some of the considerations to make, and examples of different relevant control strategies and their potentials for use in real operating systems.