The present invention relates generally to the field of fuel cells, particularly to solid oxide fuel fells.
Fuel cells are electrochemical devices which can convert energy stored in fuels to electrical energy with high efficiencies. High temperature fuel cell systems, such as solid oxide fuel cell (SOFC) systems and molten carbonate fuel cell (MCFC) systems, require significant heat-up times to reach normal operating (steady state) temperature and significant cool down for safe shutdown. In start up times, a power source must be provided to drive components which are used during the heat-up. For example, electric heaters or blowers for air supplied to catalytic reactors must be powered. Normally, the power supply for these start up components is either the grid or a distributed generator such as an internal combustion engine fueled by diesel or gasoline fuel. In some cases a battery supply, previously charged by a battery charger powered by the grid may also be utilized. However, this methodology is inefficient. Furthermore, during the significant heat up time for system start up and cool down time for shutdown, a stored anode purge gas is used to prevent anode oxidation when steam reformed fuel is not available. The anode purge gas is stored within the system and replenished periodically based on usage rates. The purge gas storage container takes up valuable space in the system.