Thermodynamic and economic analysis of a steam reformer-solid oxide fuel cell system fed by natural gas and ethanol

In the present work, ethanol and methane are compared as candidate fuels for solid oxide fuel cells (SOFCs). The thermodynamic analysis of both alternatives was undertaken considering that a SOFC stack operates by being fed by the equilibrium products of the steam reforming of each raw fuel. The comparison was made at atmospheric total pressure assuming low reforming factors (steam/fuel feed ratios) and SOFC operation in the temperature range of 800 to 1200 K. All operation conditions have been selected so that carbon deposition in the SOFC anode is thermodynamically impossible. Results were obtained in terms of the maximum theoretical electromotive force and the thermodynamic efficiency of total energy conversion. It was found that both fuels exhibit similar thermodynamic behavior when fed in a SOFC stack, and some qualitative advantages with respect to ethanol are discussed.