Abstract
A fuel cell battery based on concentric cylindrical air and hydrogen electrodes has been developed. The cylindrical geometry allows the use of high pressures and large pressure variations of hydrogen gas while the air pressure is atmospheric. A fuel cell battery unit contains a 250 liters internal hydrogen storage. Metal hydride material is used as a storage and material is packed into the cylindrical hydrogen electrode together with an effective water cooling heat exchanger.
The electrolyte used in the system is a specific alkaline gel which is not circulated. The gel electrolyte has the same advantage as polymer electrolyte (PEM) as it is not leaking but on the other hand it has the advantage that it tolerates big differences between water evaporating and water generation due to expanding or shrinking of the gel. This means that no humidity control of the air is needed.
A fuel cell battery system is provided with an effective carbon dioxide filter which can be regenerated at low temperature 60-75°C. The outlet air flow from the fuel cell is warm enough to regenerate the filter.
The fuel cell batteries have been demonstrated in boat applications as a power source of outboard electric motor and in a light electric city car application.