This work presents a simulative energy efficiency analysis performed on fuel processor PEM fuel cell systems, considering ethanol as fuel and steam reforming or autothermal reforming as processes to produce hydrogen. System analysis was performed on conventional configuration, where a classic reforming reactor is followed by a conventional CO clean-up section, constituted by water gas shift and preferential CO oxidation reactors, and on innovative configuration, where the reforming unit is coupled with an innovative highly selective hydrogen membrane. Steam to ethanol and oxygen to ethanol inlet ratios and reforming temperature are screened to identify the conditions that maximize global system efficiency. Pressure and sweep gas to ethanol inlet ratio are also considered as operative parameters in the membrane-based systems. A comparison with the results obtained when crude-ethanol is employed as fuel is also presented and discussed. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.