NASA is developing a plane that makes flying more environmentally friendly. The X-Plane is an experimental all-electric aircraft. Instead of fuel-powered engines (引擎), the X-Plane gets its power from batteries. The aircraft is also quieter than fuel-powered planes, as its electric components (部件) change the way it sounds. It has 14 electric motors (发动机) and propellers (螺旋桨), allowing it to fly more efficiently (有效率地). It will begin testing next year.