Powercells Fuel Processing Development and Its Application in APU System With a PEM Fuel Cell

Fuel cell systems constitute a clean and efficient alternative to fuel combustion for stationary and mobile applications. One potential market for these systems is Auxiliary Power Units (APUs) for heavy duty vehicles in which an on-board fuel reformer is coupled with fuel cells. Fuel Cell APUs have within the next few years a good chance to reduce fuel consumptions and air pollution as well as improve driver’s environment by avoiding the necessity of truck idling. However , despite the potential of these technologies to reduce the environmental impact and improve energy efficiency of road transport , both technical and economic barriers need to be overcome for these technologies to be successfully introduced in mass markets.  One challenge is to develop an efficient reformer system that can convert commercial diesel into a hydrogen rich gas stream of sufficient quality for PEM fuel cells. Development of fuel cell systems and reformer technology for automotive applications started for more than a decade ago within the Volvo Group. PowerCell Sweden AB was spun-out from AB Volvo in 2008 to continue the development and commercialization of fuel cell power systems , diesel-fuel reformers and reformate tolerant LT-PEM fuel cells. During the spring 2013 PowerCell has demonstrated a viable fuel cell APU , based on its proprietary reformer and fuel cell technology. The demonstrated APU is a stand-alone unit that runs on commercial diesel and produces 2.5kW electric energy with 23.5% net efficiency. The fuel processing for PEM fuel cell APUs requires several steps in order to convert diesel into a hydrogen rich gas stream with low concentration of carbon monoxide (CO) and sulfur species. PowerCell’s system consists of an autothermal reformer followed by a desulphurization unit and CO clean-up by using water-gas-shift reaction and preferential oxidation reaction before it can be fed into the fuel cell. The last step in the reformer system is the catalytic burner in which the anode-off gas from the fuel cell is combusted and the released heat is utilized to generate steam for the autothermal reformer. This paper reviews several reformer generations and solutions developed by PowerCell. The paper also examines what characteristics and requirements of the automotive fuel cell APU that are important to consider in the design and integration of the fuel processor.