An integrated configuration of a fuel cell and an auto-thermal ethanol reformer has been studied conceptually for high temperature (HT) and low temperature (LT) polymer electrolyte membrane fuel cells (PEMFCs) for a 5 kW, stand-alone power unit. It is found that the integrated reformer-HT fuel cell system can operate in an auto-thermal mode using a Co-Fe/Zn catalyst to reform aqueous ethanol at 500 degrees C to produce hydrogen with about 3% of CO which is tolerable for an HT-PEMFC operating at 200 degrees C. A simulation model developed for the integrated reformer-HT-PEMFC system shows that significant amount of excess heat is available at 700 degrees C. Using this excess heat, an integrated reformer-HT-LT-PEMFC power unit is designed which produces 15 kW of electrical power at an overall efficiency of 41% and a thermal efficiency of 80%. Since it has an integrated aqueous ethanol reformer, the fuel for the power unit can be stored in liquid form which makes it ideal for stand-alone power unit applications. (C) 2013 Elsevier Ltd. All rights reserved.