US space agency NASA is hosting a competition to find the fuel efficient aircraft of the future. Five teams will compete in the 2011 Green Flight Challenge to bag $1.65 million (£1m) in prize money.
The planes can be electric, biofuel or hybrid powered. To win, an aircraft must fly 200 miles in less than two hours and use less than one gallon of fuel per occupant, or the equivalent in electricity.
The Google-sponsored event will take place at the Charles M. Schulz Sonoma County Airport in Santa Rosa, USA next week.