Aerospace giant Airbus has unveiled plans for what it hailed as the first commercial zero-emission aircraft.
It said its hydrogen-fuelled passenger planes could be in service by 2035.
Airbus chief executive Guillaume Faury said the three ZEROe concept designs marked “a historic moment” for commercial aviation sector”.
The use of hydrogen had “the potential to significantly reduce aviation’s climate impact”, he added.
The concept of emissions-free aviation relies heavily on finding ways to produce large quantities of hydrogen from renewable or low-carbon sources.
Most large scale production at the moment relies on fossil fuels, particularly methane, and is not considered to be low carbon.
Analysts point out that it is not the first time that hydrogen has been touted as the saviour of modern air travel..
Its use in aviation goes back to the days of airships in the early 20th Century, but the Hindenburg disaster in 1937 brought that era to an end.