The following paragraphs are not an admission that anything discussed in them is prior art or part of the knowledge of persons skilled in the art.
Fuel cells provide a source of electrical power that can be used for a variety of different purposes. Fuel cells are commonly configured into stacks that generate useful voltages. Fuel cell stacks require a number of auxiliary components in order to function efficiently, e.g., conduits, valves, pumps, compressors and the like for delivering process gases; humidifiers for humidifying processed gases; control equipment. These additional components are commonly referred to as “balance of plant” or BOP.
To make a fuel cell stack readily useable for a variety of applications, fuel cell stacks are sometimes packaged with the associated balance of plants components to form a fuel cell power module. Such power modules can be integrated to the extent that they require no more than connections to necessary reactant supplies (e.g., hydrogen and air), and possibly a coolant (water, although sometimes air again is used as a coolant), and additionally electrical connections for the electricity generated by the fuel cell power module.
It has been proposed to use fuel cell power modules as backup power supplies. Such backup power supplies may be deployed at installations that require a high degree of integrity in their power supply and/or may be located in remote areas where a standard electricity power supply is not reliable. For example, remote transmitting towers for various functions often require backup power supplies.
In order to provide the necessary level of reliability, it is common to provide two or more power modules together. For example, sometimes three power modules are provided, with the intent that two would be sufficient to provide the necessary power and the third power module then acts as a further backup, in case one of the other two power modules fails.