Swiss aviation pioneer Bertrand Piccard is developing a plane powered by green liquid hydrogen after a much-hyped flight in 2015 that used sunlight to travel around the world. The new project, called Climate Impulse, aims to circle the globe in 2028 in a lightweight two-seater that runs on super-cooled liquid hydrogen, which its makers say could revolutionize sustainable air travel. (AP video by Mustakim Hasnath)