Lightweight Solar-Regenerative Energy Storage for High Altitude Airships

Systems and Processes Engineering Corporation (SPEC) will build and test a solar-regenerative energy storage (RES) system for high-altitude airship applications scaled to provide 160 kW-hr of energy storage with a 16-hour maximum annual discharge and 24-hour charge/discharge cycle. System design incorporates low-loss power conversion and management that maximizes power delivery efficiency and improves specific energy density. Solid-state components perform transformer operations during charge to deliver a constant voltage to the airship systems while delivering excess photovoltaic power to charge the system. A low-loss mechanical transfer switch allows the unitized fuel cell (UFC) to provide power to the airship systems at near-100% efficiency during discharge. Passive water separation components manage water content within the UFC and the gas streams to and from light-weight H2 and O2 storage tanks. A thermal management subsystem uses high-efficiency heat exchange components to remove water vapor from gas streams, heat and humidify incoming UFC gases, and minimize RES thermal emissions to internal airship volume. The complete power system will be demonstrated over solar-regenerative cycles to validate specific energy density and weight estimates for a full-scale (1600 kW-hr) RES system. Round trip energy efficiency will be measured and manufacturing requirements for production will be identified.