In-house hydrogen fuel cell expands Naval Research Lab’s UAV use

The do-it-yourself skills of a U.S. Naval Research Laboratory team may help bring hydrogen-powered fuel cell technology to the Navy—with a little help from an unmanned aircraft vehicle. Utilizing its previously built and tested UAV—the Ion Tiger—the NRL team has created and proven out an in-house hydrogen-powered fuel cell capable of producing up to 5,000 watts.

“NRL having the know how to build their own fuel cells in house gives ONR and the U.S. Navy the understanding and tools needed for transitioning fuel cells to the fleet,” said Michele Anderson, program manager at the Office of Naval Research.

The team flew the UAV in September to test out a new fuel cell design using formed metal-foil bipolar plates. The new design save space and weight, according to the team.

Benjamen Gould, NRL’s chief scientist on the project, said the new design allowed the team to leverage the know-how of the automotive industry. “Using the plates also enabled enhanced storage capabilities and weight savings that are critical for naval unmanned system applications.”

As described by the research team, the biopolar plates are held together with titanium straps and serve as the structural backbone of the fuel cell system that provides pathways for fluid, air, hydrogen and coolant while also acting as an electrical pathway for conduction between each individual cell.

In 2013, the NRL team flew the Ion Tiger for 48 hours using the liquid hydrogen fuel. Liquid hydrogen is three times denser than 5,000 psi compressed hydrogen. According to NRL, success in flight requires developing a high quality, lightweight insulated flight dewar for the cryogenic fuel, plus matching the boil-off of the cryogenic hydrogen to the vehicle fuel consumption.

The NRL team’s ability to create components in-house also allows for low-cost modular systems for both prototype development of naval UAVs and for the scalability to a range of sizes.