First successful drone flights powered by liquid hydrogen in Netherlands
The Royal Netherlands Aerospace Centre (NLR) has completed its first successful test flights of a drone powered by liquid hydrogen, marking a step toward sustainable aviation, the organization said.
The HYDRA II drone flew several minutes over NLR’s Marknesse site using liquid hydrogen as an energy carrier. The drone’s hybrid system supplied electricity to its electric motors via a fuel cell, supplemented by a battery for additional thrust.
Joost Vreeken, NLR program leader for “Unmanned & Autonomous,” explained, “For drones, hydrogen is most useful for long-distance flights. A VTOL, vertical take-off and landing aircraft, initially uses batteries during vertical lift because that phase requires high power. It then transitions to horizontal flight, where hydrogen is ideal. This trial focused on demonstrating the technology during a short hover flight.”
The use of hydrogen in aviation is gaining attention as airlines seek to reduce emissions and find alternatives to kerosene. Drones offer an ideal test platform due to their small size, manageable complexity, and relatively low cost.
NLR previously flew the HYDRA I drone in 2019 on gaseous hydrogen. The HYDRA II stores liquid hydrogen in a vacuum-insulated aluminum tank developed with a partner. The tank gradually releases hydrogen gas to a fuel cell, generating electricity. Sensors and heating elements maintain a steady hydrogen flow to the fuel cell.
Tineke van der Veen, CEO of NLR, said, “If produced sustainably, hydrogen can reduce the impact of fossil fuels on the climate. Water vapor is the only emission from the drone. Many parties in the Netherlands and abroad are working to bring commercial applications of this technology to success.”
Similar efforts are underway abroad. In 2023, German company H2fly, with Slovenian aircraft manufacturer Pipistrel, conducted a liquid hydrogen test flight.
Hydrogen, the lightest and most common element, becomes liquid below -252.77°C. The HYDRA II uses it as an energy carrier in a fuel cell, producing electricity and heat with water vapor as the only emission.
Hydrogen handling requires strict safety procedures because it is highly flammable and requires low ignition energy. NLR said it is not inherently more dangerous than other fuels when properly managed.
