Hydrogen-powered cars are set to become an increasingly common sight on UK roads by the 2020s as new models are announced and infrastructure investment plans revealed.
Leading motoring manufacturers such as Toyota, Honda, Audi and Volkswagen are all developing new models, while a handful of Hyundai vehicles are already available in the UK.
The fuel cells in hydrogen cars generate electricity by combining hydrogen, stored in high-pressure tanks, and oxygen. Only water is emitted from the exhaust.