Airbus said on Friday it is delaying plans to develop a hydrogen-powered commercial aircraft by the middle of next decade, citing slower than expected developments in technology.

Environmental groups argue hydrogen would still come at an environmental cost because of the energy used to produce it

Airbus SE said that one of its most ambitious projects for future propulsion — using hydrogen to power an aircraft — is progressing slower than planned because of the technological hurdles involved, dealing a setback to the industry’s efforts to clean up air travel.

Airbus acknowledged on Friday that progress on developing an aeroplane operating on hydrogen was slower than expected, but said it was not reviewing its approach to decarbonising aviation.