The bench test data will aid further research using a lighter fuel cell and a larger UAV platform. The NRL wants to develop a long-endurance, persistent surveillance UAV able to operate from 8h to 24h. Its researchers have concluded that batteries cannot deliver the power needed but fuel cells will.

“Fuel cells are improving, we couldn’t have done this two years ago. We are shooting for specific energies exceeding 1,000Wh/kg,” says Naval Research Laboratory’s (NRL) chemistry division head of alternative energy section and Spider-Lion programme manager Karen Swider-Lyons.

The Spider-Lion uses a water-cooled Protonex Technology 100W fuel cell.

While not efficient enough to deliver the NRL’s specific energy goal of 1,000Wh/kg plus it uses water to cool it, which Swider-Lyons says enables a higher power output.

The fuel cell was developed at NRL using commercial hardware and Protonex’s fuel-cell stack and components.