Application of regenerative fuel cells for space energy storage: a comparison to battery systems

A major advantage of regenerative fuel cells compared with battery systems arises from the decoupling of their rated power and their capacity, which determines the storage system. The mass of battery systems is related to the energy stored, whereas the masses of regenerative fuel cell systems are mainly determined by their rated power. On the other hand, average power and total energy are not independent variables, since they are correlated by the period of discharge of the electrochemical cells. Thus a comparison of the different approaches to storage can be given, by evaluating system masses as a function of power requirement and period of discharge. Since space power applications are considered, the charging and discharging periods can be expressed in terms of orbit altitudes.