Hydrogen fuel cell four-seater passenger plane takes to the air

The HY4 fuel cell zero-emission aircraft rolls over the runway at the airport in Stuttgart, southern Germany, during its presentation on September 29, 2016. The German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR) presented the four-passenger aircraft powered solely by a hydrogen fuel cell battery system.
Christoph Schmidt / dpa / AFP