German hydrogen propulsion startup H2FLY has made aviation history with the successful completion of the world’s first crewed liquid hydrogen-powered flights at Maribor Airport in Slovenia. While the Soviets experimented with liquid hydrogen 35 years ago, H2FLY’s HY4 aircraft achieved a milestone by relying solely on liquid hydrogen for the entire flight, powered by a hydrogen fuel-cell powertrain.

The achievement marked the culmination of Project HEAVEN, an EU-funded initiative demonstrating the feasibility of using liquid hydrogen in aircraft. H2FLY’s HY4 demonstrated impressive flight capabilities, with a 10-minute test flight and a remarkable 3-hour flight using 10kg of hydrogen. With its full 24kg storage capacity, the aircraft could stay airborne for up to 8 hours.

One of the pilots, Johannes Garbino-Anton, emphasized the teamwork and perfect functionality of the technology. Notably, the lack of vibrations, noise, and carbon dioxide emissions set the aircraft apart from conventional planes. H2FLY’s propulsion system includes hydrogen storage, a 120kW fuel-cell energy converter, and an electrical engine.

While the HY4 had been flying since 2016, the summer of 2023 marked a significant breakthrough, as it operated on liquid hydrogen, offering greater energy density than gaseous hydrogen. This advancement allows for longer flight ranges without compromising payload capacity.

H2FLY’s future plans involve scaling the fuel-cell system to megawatt capacity, unlocking longer ranges and higher altitudes. A partnership with Deutsche Aircraft aims to retrofit a 30-seat Dornier 328 demonstrator with hydrogen-electric fuel cells, with test flights scheduled for 2025. H2FLY envisions a 40-seat regional plane with a 2,000km range by the end of the decade and the potential for even larger aircraft in the future.

To support the transition to hydrogen-powered aviation, refueling infrastructure is essential. H2FLY collaborated with Air Liquide, a French industrial gas supplier heavily investing in green hydrogen. The successful refueling of liquid hydrogen at a commercial airport marks a crucial milestone.

H2FLY, founded in 2015, is at the forefront of hydrogen propulsion technology, developing complete systems and individual components as needed. In 2021, the company was acquired by Joby Aviation, a California-based firm specializing in electric vertical take-off and landing vehicles (eVTOL) for air taxi services. The aviation industry’s journey toward clean-burning, hydrogen-powered flight appears promising, with liquid hydrogen offering potential as a gamechanger for commercial aviation.

By Impact Lab