Effect of pressure on internal reforming in SOFC

The increasing demand for electrical energy requires the development of power plants with high efficiencies and low emissions. Hybrid power plants consisting of an SOFC system coupled with a gas turbine promise to fulfil both requirements reaching electrical efficiencies above 60% [1]. They can also be used for a large range of applications from several 10 kW to multiple MW and can use natural gas from the existing grid. The German Aerospace Center (DLR) is aiming at the demonstration of the stable operation of a hybrid power plant in the 50 kW class in which the SOFC will be operated at elevated pressures. For the realisation of the power plant the effects of pressure on SOFC has to be understood, therefore the behaviour of SOFC at pressures ranging from 1 to 8 bar with varying fuel gas composition (H2/N2 mixture and reformate gases with different methane content) and different temperatures was examined experimentally in a specially designed setup [2]. Current-voltage characteristics and gas analysis at the anode were performed to examine the influence of pressure on OCV, power density at constant voltage and constant current as well as on gas composition at the cell for different fuels. Power density increases of up to 70% were found. Simulations were used to better understand the experimentally obtained results