Journey of the world’s longest wind turbine rotor blade through Denmark

A crucial factor affecting the energy yield of a wind turbine, besides air density and wind speed, is the rotor swept area over which the wind flows. This swept area, in turn, is determined by the length of the rotor blades. The industry trend is clearly heading in the direction of longer and longer rotor blades. The Siemens rotor consisting of three 75-meter rotor blades has a diameter of 154 meters and covers a surface area of approximately 18,600 square meters, equal to about two and a half soccer fields. The Siemens 6 megawatt wind turbine will generate about 65% more energy using the 75-meter rotor blade compared with the Siemens 3.6 Megawatt bestseller using the earlier blade with a length of 58 meter.

Dong Energy ordered a total of 300 6-megawatt wind turbines featuring the record rotor measuring 154 meters in length. These wind turbines are to be installed in wind power plants off the British coast between 2014 and 2017.

Needs the power of 680 horses

Transporting the world’s longest rotor blade, at 75 meters, is not only technically or logistically challenging but also an impressive feat of the truck’s driver. The vehicle is 85 meters long, five meters wide and four meters high.

Loaded and ready to go

The world’s longest rotor blade is loaded onto a special transport vehicle in the port of Esbjerg. Measuring 75 meters in length, the Siemens B75 rotor blade weighs about 25 tons, which is equal to the weight of four bull elephants. Loading required precision, working with exceptional accuracy and a good eye from all those involved.

Weight is the key

The weight of rotor blades is a critically important factor. Thanks to the patented IntegralBlade process, Siemens is capable of producing especially light rotor blades. Heavy rotor blades are exposed to higher loads and necessitate sturdier nacelles, towers and foundations. Consequently, the combination of intelligent design and low weight has a positive effect on the power generating costs of wind turbines.

Maximum speed: 67 km/h

The world’s longest rotor blade is escorted by two accompanying vehicles on the 320-kilometer route from Esbjerg to Østerild, travelling at a maximum speed of up to 67 kilometers per hour, even though the transport vehicle is not always able to drive so quickly.

Stable and yet relatively light

Once installed in a wind turbine, the 154-meter rotor must withstand huge air masses. At wind speeds of ten meters per second, it captures the energy of 200 tons of air every second. Siemens’ patented QuantumBlade technology assures that the rotor blade is up to 20% lighter than rotor blades produced with conventional methods.

Traffic circles pose a challenge

The route included 9 roundabouts, through which the special transport vehicle, with a total length of more than 80 meters, had to maneuver. To negotiate the curves, the wheels of the rear trailer also had to be precisely steered.

Close to the destination

The rotor blade has almost completed the 320-kilometer trip across Denmark. In the Danish town of Østerild, three of these 75-meter-long rotor blades, the longest in the world, will be installed in a 6-megawatt wind turbine in the next few weeks. The new technology is then tested to determine what benefits and advantages it actually provides.

More information at http://www.energy.siemens.com/

Photos: Siemens AG

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