Direct ethanol solid oxide fuel cells: The case of PT anodes

Abstract

The limitation of fossil fuels deposits and the detrimental effects of their combustion emissions on the environment make it necessary to develop alternative technologies, such as fuel cells and use the renewable and environmentally-friendly liquid fuels such as ethanol. The latter has been recognized as a suitable "clean" fuel for electricity generation in fuel cells and particularly in solid oxide fuel cells (SOFCs) with numerous advantages [1, 2]. Solid oxide fuel cells constitute a high temperature energy conversion technology, with the highest efficiency among all the types of fuel cells, which is unattainable from all conventional thermal engines. Moreover, their multi-fuel capability allows the utilization of various kinds of hydrocarbon related species via internal and/or via simple external reforming [3]. In the present work, an YSZ electrochemical reactor directly fed by a mixture of ethanol/water operated as a solid oxide fuel cell has been investigated. The SOFC performance has been tested over Pt anode slectrocatalyst at temperatures ranging from 550oC to 700oC. The inlet partial pressure of ethanol was kept at 5.4 kPa, while for the water 7.0 kPa. The total flow rate of the feed stream was kept constant at 23.5 ml/min. According to the experimental results, it was found that the open circuit voltage of the cell was approximately 1.0 V, while under closed circuit conditions and relatively lower temperature (550-600oC) the cell voltage dropped initially rapidly with a consequent increment of the current density, due to higher activation over-potential on Pt. which is most probably resulted from the big particle size of Pt. It can also be found that there was an obvious decrease of cell voltage along with the current density in the ohmic polarization range. This could be attributed to the low operation temperature. Under the investigated conditions, the maximum power density was 1 8 mW/cm2 at 70 mA/cm2 and at 700oC.