Passengers with a low-cost airline could be served water created as a waste product from hydrogen batteries under plans for a zero-emissions fuel system.
Budget airline easyJet made the claim as it unveiled designs for a hybrid plane which could be trialled this year.
The concept would involve storing a hydrogen fuel cell in the aircraft's hold. Energy captured as the brakes are deployed during landing would then power the jet when it is on the ground, similar to the kinetic energy recovery system used in Formula One.
Ian Davies, easyJet's head of engineering, said the water produced as a waste product from the batteries would be discarded or reused.
Asked whether it would be served to passengers, he replied: "I think we could reuse the water. It's absolutely pure. Why would we throw water away when it's absolutely pure?"
Mr Davies said it could be used for drinking and flushing toilets.
He added: "This is potentially the freshest, cleanest water."
EasyJet estimates around 4 per cent of its fuel consumption is used when its aircraft are taxiing. It hopes hybrid planes could save around 50,000 tonnes of fuel for its fleet each year. This is equivalent to $US25 million-$US35 million ($A35 million-$A49 million).
The system is being developed in partnership with Cranfield University in Bedfordshire.
Mr Davies, speaking in Venice at the launch of easyJet's latest base, said: "The hybrid plane concept is both a vision of the future and a challenge to our partners and suppliers to continue to push the boundaries towards reducing our carbon emissions."
EasyJet hopes to launch the hybrid plane within the next decade.
