Liquid hydrogen takes up 4 times as much space as kerosene to deliver the same energy. So planes would need massive fuel tanks – either the planes would have to be bigger, causing more drag and reducing performance, and/or there would have to be fewer passengers.
Storage for liquid hydrogen on a scale for long-haul flight has not yet been developed, as it needs to be at an extremely low temperatures (-253C) in a complex vacuum tank with venting systems.
Hydrogen combustion, although not producing CO2, produces water vapour, which has a global warming effect at high altitudes, and NOx, another greenhouse gas.
Hydrogen fuel cells would power electric engines, which can’t power airplane take-offs.
Currently hydrogen is mostly produced from methane, another fossil fuel, in a process that releases CO2. Producing from water by electrolysis is inefficient and requires even more energy and cost to convert the hydrogen gas to liquid.
Overall hydrogen is a future possibility, but a long way from a foreseeable reality, and very expensive. Smaller planes up to 20 passengers are in the pipeline, but production of larger planes is at least 15 years away, plus another 15 years to achieve fleet penetration.
Bristol airport has no plans to make provision for hydrogen powered aircraft. It is planning for 99% of its passengers flying in and out on big jets, so will not be able to cater for small hydrogen powered planes which may be in operation in the next decade.