In this study, the balance of plant (BOP) of an ethanol-fueled SOFC is analyzed using the GCTool software package developed by Argonne National Laboratory (ANL). The effects of the excess air ratio and fuel utilization on the electric and heat efficiencies of the SOFC are systematically examined for two reforming methods (steam reforming and auto-thermal reforming) and two flow sheets (BOP A and BOP B). In BOP A, the cathode off-gas is passed directly to the afterburner together with the unreacted fuel, and the hot flue gas exiting the burner is then used to provide the thermal energy required for the ethanol reforming process. In BOP B, the cathode off-gas is passed through a heat exchanger in order to heat the ethanol fuel prior to the reforming process, and is then flowed into the burner with the unreacted fuel. The results show that given an SOFC inlet temperature of 650 degrees C, a fuel utilization of 70.2% and excess air ratios of 4, 6 and 7, respectively, the overall system efficiency is equal to 74.9%, 72.3% and 71.0%. In general, the results presented in this study provide a useful starting point for the design and development of practical ethanol-fueled SOFC test systems. (C) 2011 Elsevier Ltd. All rights reserved.