A Fuel Cell Power Supply for Long Duration Balloon Flights Using Stored Cryogens

Abstract

Large balloon launched cosmic ray experiments can require up to 1.8 kW of power for the duration of the mission. Present day battery packs, which have a mass of 550 kg, limit the mission time for such experiments to less than 60 hours. Long duration polar balloon missions require a power supply that can deliver power at the rate of 1.5 to 2 kW for a period of time from 10 to 21 days. A hydrogen-oxygen fuel cell is an attractive option for a power supply because 20.6 kg (291 liters) of hydrogen and 165 kg (144 liters) of oxygen can provide the 1.42 kW of power for a 18 day mission at a fuel cell efficiency of 80 percent. If the water produced by the oxidation of the hydrogen in the fuel cell can be dumped during the mission, the required ballast needed for the mission can be reduced by almost 190 kg. The waste heat from the fuel cell can be used to preheat the fuel and oxidizer before they enter the fuel cell. The remainder of the waste heat must be transferred away from the balloon by radiation. This report describes a fuel cell power supply configuration.