Hydrogen-Powered Aircraft

Hydrogen as Aviation Fuel

Hydrogen has the highest energy content per kilogram of any fuel — approximately 33.3 kWh/kg, roughly 2.8× the energy density of jet-A1 by weight. A hydrogen aircraft therefore needs less mass of fuel for the same energy, partially compensating for hydrogen's very low volumetric density.

There are two ways to use hydrogen in aircraft: combustion (burning hydrogen in a modified gas turbine instead of kerosene) or fuel cells (electrochemically reacting hydrogen with oxygen to generate electricity for electric motors). Both produce water vapour rather than CO2 as the primary exhaust — but they are not entirely emissions-free; high-temperature hydrogen combustion still produces NOx, and water vapour at altitude contributes to contrail formation.

Airbus ZEROe Programme

Airbus unveiled three ZEROe concept aircraft in September 2020, all targeting entry into service around 2035:

• Turbofan concept: 200-passenger aircraft with range up to 3,500 km; modified gas turbine running on liquid hydrogen
• Turboprop concept: ~100-passenger regional aircraft; range up to 1,800 km; potentially viable for European short-haul
• Blended Wing Body concept: 200-passenger; radical fuselage shape distributes hydrogen storage more efficiently

Airbus has since focused on the turbofan and turboprop concepts. Ground tests of a modified CFM LEAP-A engine running on hydrogen combustion began in 2023 at a Toulouse test facility.

Storage Challenges

Liquid hydrogen (LH2) must be stored at −253°C; requires heavily insulated cryogenic tanks that add significant weight. The volumetric disadvantage is severe: LH2 achieves ~2.8 kWh/L versus ~9 kWh/L for jet fuel, meaning hydrogen tanks must be roughly 4× larger for the same energy. Conventional underwing or belly tanks cannot accommodate the volume — fuselage-integrated aft or dorsal tanks are proposed, reducing passenger capacity. LH2 also slowly evaporates even from insulated tanks, requiring rapid turnarounds to minimise losses.

Infrastructure Requirements

Airport infrastructure is the biggest near-term barrier. Liquid hydrogen requires dedicated production or delivery facilities, cryogenic storage tanks, new refuelling vehicles and procedures, and trained maintenance staff. The Hydrogen Council estimates retrofitting a single major European hub airport could cost €2–5 billion, limiting initial routes to those between hydrogen-capable hubs.

Timeline

vs SAF

Most analysts conclude that SAF will dominate decarbonisation through 2040, with hydrogen becoming important for new aircraft entering service from 2035 onwards — particularly on short-haul routes where range limits and infrastructure rollout are most manageable.