Stock Photo - 11 December 2020, Baden-Wuerttemberg, Stuttgart: Walter Schoefer (l-r), managing director of Stuttgart Airport, Winfried Hermann (Bündnis 90/Die Grünen), Minister of Transport of Baden-Wuerttemberg and HY4 project manager Josef Kallo, are looking at a new version of the hydrogen fuel cell aircraft HY4 of the company H2Fly at Stuttgart Airport. The aircraft was the first four-seater passenger aircraft in the world that was powered only by hydrogen fuel cells and a battery. After the maiden flight in 2016, the aircraft has now been further developed and a new version has been presented. Photo: Christoph Schmidt/dpa. - Stuttgart/Baden-Wuerttemberg/Germany