6 - Phosphoric acid fuel cells

Abstract

Publisher Summary Advances in materials have largely driven the development of fuel cells and Phosphoric Acid Fuel Cells (PAFCs) are no exception. This chapter presents a few significant advances of PAFCs. The liquid nature of the phosphoric acid electrolyte makes establishing a stable three-phase interface critical to achieving good power density and to the long-term operation of PAFCs, particularly at high current densities. Materials, structures, and processing methods to improve and stabilize this contact have been critical in the development of PAFCs. With the exception of membrane degradation, PAFCs have faced virtually the same challenges during their development over the past couple of decades. As the developers move toward higher temperatures for Proton Exchange Membrane (PEM) fuel cells, the lessons learned from PAFCs become more and more relevant. PAFCs are best suited for installations where the waste heat can be used or in applications where premium power is needed. Although the majority of installations operate off natural gas, PAFCs operating on hydrogen, propane, and digester gas have been demonstrated. Thus, stationary applications of PAFCs have been and are expected to continue to dominate for the foreseeable future.