NASA and the Comparative Aircraft Flight Efficiency (CAFE) Foundation have announced the Green Flight Challenge, which offers up to $1.5 million for an aircraft that can average at least 100 mph on a 200-mile flight while achieving greater than 200 passenger miles per gallon.

Technology innovations might include bio-fueled propulsion, breakthroughs in batteries, motors, fuel-cells and ultra-capacitors that enable electric-powered flight, advanced high lift technologies for very short takeoff and landing distances, ultra-quiet propellers, enhanced structural efficiency by advances in material science and nanotechnology and safety features such as vehicle parachutes and air bags.