Development of boron-based hydrogen and fuel cell system for small unmanned aerial vehicle

A hydrogen generation system utilizing sodium borohydride solution and a 200 W fuel cell system were developed for powering a small custom-designed and manufactured unmanned aerial vehicle. A complete hydrogen generation system having a special cobalt-base catalyst, was able to produce 5.4 L/min of hydrogen in an 11 cm3 reactor volume with durability of more than 10 cycle. This flow rate of hydrogen was enough to feed 50-cell fuel cell system to produce 218 W power (24.5 VDC and 8.9 A current). Hydrogen generation system mainly consisted of peristaltic pump to feed fuel, reaction chamber for catalyst, reaction product cooling, gas/water separation tank and flow control units. Fuel cell system had air cooling and air-breathing cathode providing air for the reaction. Hydrogen fed through porous gas diffusion layer structure and humidity of the membrane electrode assemblies were controlled by dead-end operation algorithm. The weight of the whole system was 7.5 kg including UAV. The energy density of power system (fuel cell, hydrogen generation system and fuel) is measured as 325 Wh/kg which is about two fold of lithium-ion energy density of this particular application.