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Siemens has produced 75-meter rotor blades for wind turbines

Siemens has produced the world’s longest rotor blades for wind turbines. Measuring 75 meters in length, the blades are almost as big as the wingspan of an Airbus A380. Beginning this fall, the B75 rotor blades will be installed into a prototype six-megawatt offshore wind power system in Denmark’s Østerild test station.

As it moves, each rotor covers 18,600 square meters, which is the size of two and a half soccer fields. The tips of the blades move at up to 80 meters per second, or 290 km/h (180 mph). The huge rotor was made possible by special technologies that enable Siemens to make extremely strong yet lightweight structures.

The B75 blade is the world’s largest fiberglass component cast in one piece. Click to enlarge.

To produce the B75 rotor blade, Siemens uses the patented IntegralBlade process, in which the entire blade is poured as a single piece made of glass fiber-reinforced epoxy resin and balsa wood. As a result, the blade has neither seams nor bonded joints and is extremely robust. The gigantic rotor, which measures 154 meters, has to withstand huge air masses, as it is hit by the energy of 200 tons of air per second when the wind blows at a speed of 10 meters per second.

Due to another patented process, QuantumBlade, the rotor blade weighs 20% less than conventionally produced blades. As a result, the nacelles, towers, and foundations can be made lighter as well, which reduces the facility’s cost. 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.

Siemens has been manufacturing wind power plants for the past 30 years. The size and output of the associated technology has steadily grown during this time. Whereas the first wind turbines generated 30 kW and had five-meter-long rotor blades, the latest turbines can produce 6 MW of power. The first two six-megawatt turbines from Siemens (equipped with standard 60-meter rotor blades) are now being installed and tested at the Gunfleet Sands wind farm off England’s south coast. Over the next several years, the Danish energy supplier Dong plans to install 300 gearless Siemens wind turbines off the British coast. These turbines will be equipped with the new record-breaking rotor blades.



As I gather from the Siemens site, transportability over land is becoming an issue with these blades. For offshore turbines, this is no problem and they're already thinking about 20 MW turbines with 200 m rotors. For onshore turbines, we could be close to the practical size limit.


Offshore units could be built on ships near or at the final installation sites. Such factory/installing ships could travel around the world and install huge wind turbines in many places. On board family quarters could be made available.

Wind turbines have progressed by more than 300 times in the last 30 years or so and will progress more in the next 10 to 30 years. Very large units may produce electric at the same price as polluting coal fired power plants, specially when installed at sites with very high quality winds.

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