Overview of fuel processing options for polymer electrolyte fuel cell systems

The polymer electrolyte fuel cell (PEFC) is being developed for use in heavy- and light-duty transportation applications. While this fuel cell has been used successfully in buses and vans with compressed hydrogen as the on-board fuel [1,2], the fuel cell system must incorporate fuel processing (reforming) for any other on-board fuel to produce the hydrogen or hydrogen-rich fuel gas to be fed to the fuel cell stack. This is true even for alternative methods of storing hydrogen, such as use of a metal hydride or liquefied hydrogen. The ``fuel processing`` needed to recover the hydrogen includes providing the heat of dissociation of the hydride and cooling the hydrogen to the temperature of the fuel cell stack. Discussed below are some of the options being considered for processing of on-board fuels (other than compressed hydrogen) to generate the fuel cell anode gas, and the effects of fuel processing on system design, efficiency, steady-state and dynamic performance, and other factors.