Clean Technology Business Review has declared Siemens' wind turbine rotor blade the winner of the �Innovation in Renewable Energy' Award.

Clean Technology Business Review has declared Siemens' wind turbine rotor blade the winner of the �Innovation in Renewable Energy' award.

The product was selected from four nominations shortlisted for the award.

The award recognizes what is claimed to be the world's longest wind turbine rotor blade. The blade is almost as big as the wingspan of an Airbus A380.

The 246ft rotor covers 18,600m2, the area of two and a half soccer fields. The tips of the blades move at up to 80m per second, or 290kmph.

The huge rotor was made possible by special technologies that enable Siemens to make strong yet lightweight structures; the blade weighs 20% lighter than the conventional ones.

The rotor swept area is essential for the annual energy yield of the turbine. One SWT-6.0-154 wind turbine can generate about 25 million kWh annually at a typical offshore site having 8.5m/s mean wind speed.

The blade is manufactured from glass fiber-reinforced epoxy resin and balsa wood using the patented integral blade process. It has no seams or glued joints and no adhesive, all of which saves weight.

The gigantic rotor, which measures 154m, has been designed to withstand huge air masses, as it would be hit by the energy of 200 tons of air per second when the wind blows at a speed of 10m per second.