Professor plans flying power station

The real thing would be 10 times as big

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.

The plan is to send clusters of these vehicles 4.5 kilometres (14,700 feet) up into the jet stream to create a sort of flying power station.

Professor Roberts, from the University of Western Sydney, has spent 20 years proving the concept and is now ready to put it into practice. He wants to build the first station near Woomera in South Australia

The professor believes gyromills will prove to be a cheaper and more flexible method of electricity generation than traditional wind turbines.

A tether would bring down the generated electricity

By operating in the jet stream - the near-constant "river" of fast-moving air high above the Earth - the gyromills can escape the more turbulent winds found at ground level and which require a robust and expensive design for traditional turbines.

Each of the Professor's gyromills would be tethered to the ground.

"The cable connecting it to the ground can draw energy from the ground and use that energy to power the machine as a helicopter," Dr Roberts told the BBC TV science programme Tomorrow's World. "Then, when it gets to altitude, the gyromill's motor can be switched to a generator and energy is pushed back down the cable to the ground."

Professor Roberts has been chasing his dream since 1979

Professor Roberts has been working on the gyromill idea since 1979. The design has gone through many phases, and prototypes have been flown successfully in wind tunnels and in the sky. The professor says it is now time to scale up.

"There would be a cluster of these things in the sky - like a range of kites at an altitude of approximately four kilometres. The power station would cover an area about 20 kilometres (12 miles) in diameter.

"To bring them down, you'd simply winch them in - or you could fly them down. In the best winds in Australia, the gyromills can stay up six days out of seven."

But Professor Roberts will have to convince the aviation authorities that his project is a safe one. Aircraft would have to be kept well clear of the gyromills and their trailing cables.

The power station would cover an area 20 km in diameter