Remarkably, the 75-meter-long (246-ft) blades consist of a single component made from epoxy resin and balsa reinforced with glass fiber, cast in a gigantic mold using a process Siemens has cunningly named IntegralBlade.
Initially, three B75 blades will be put to use in a prototype 6-MW offshore turbine at Denmark's national test center at Østerild. The sweep of the completed turbine will cover 18,600 sq m (200,200 sq ft) and the tips of the blades will move at 290 km/h (180 mph) at full lick. At a wind speed of 10 m/s (19.4 knots), the turbine will be hit by 200 tons (181 metric tonnes) of air every second.
The blade length of 75 m is not a kick-in-the-pants off the wingspan of an Airbus A380 (at 79.75 m or 261.6 ft), meaning that in a Y-position, the airliner could easily pass within the 154-meter (505-ft) sweep's radius above the blades (spatially at least. In practice this isn't recommended).
Siemens has already seen 6-MW turbines installed at the UK's Gunfleet Sands wind farm, albeit with 60-m (197-ft) blades. Thanks to a process Siemens has branded "QuantumBlade," it claims the B75s weigh four fifths of conventional blades. "The weight reduction is achieved by using specially designed blade profiles that are also shaped in a way that delivers maximum rotor performance at a range of different wind speeds," the company says.