http://news.bbc.co.uk/2/hi/science/nature/1248068.stm

It looks a bit like a cross between a balsa-wood helicopter and a
kite, but Professor Bryan Roberts hopes this odd-looking craft will help meet
future energy needs. A counter-balance is attached on each single-blade rotor.
His gyromill, as he calls it, is actually a flying wind turbine. It uses its
rotors to climb into the sky and then lies back in the wind as those same rotors
generate electricity.

Thanks to UltraSport