Fast large-scale current oscillations in SOFCs with intermediate fuel utilisation

Abstract

Abstract In the push towards renewable energy technology fuel cells are set to replace many conventional means of power generation. Their efficiency and cleanliness compared to internal combustion engines is undisputed, however widespread adoption has yet to occur on a global scale. Two of the key issues affecting their mass adoption are their cost and their long-term stability. Whilst long-term testing has proven fuel cells a worthy competitor in the energy market, there are still reports in the literature of degradation caused by a number of different phenomena. In particular, most long-term testing focusses on intermediate fuel utilisation whereas many applications require high fuel utilisations. It is known that at high fuel utilisations several degradation mechanisms may come into play, sometimes resulting in agglomeration, cracking, decreased power output, and electrical oscillations. In this paper, current oscillations are reported in a solid oxide fuel cell under intermediate fuel utilisation which places it firmly in the applicable region for standard operation. Thus it is incumbent on fuel cell researchers to understand and control this unwanted behaviour in order to ensure long-term stability of a fuel cell stack. A prototype model is used here to explore potential causes using first principles.