The Solar Impulse 2 aircraft flew 42000 km without a single drop of fuel. Apart from setting up a record, the adventure’s primary aim was to demonstrate and present a tangible limit to which clean energy can be used. Unfortunately, considering current technology, solar-powered flights can not replace fossil fuels-driven flights in any way. The aircraft would have to be gigantic and it would be very slow. Bio-fuels is the way forward for a cleaner aviation industry. Unmanned solar planes similar to the solar impulse 2 can, however, be of use for research purposes in the upper atmosphere.