The world’s largest wind turbine, for the time being, is the E-126 from Enercon GmbH. The unit sports a 126-m rotor, about 413 ft, and is said to be a more sophisticated version of the earlier E-112 which was rated at 6 MW. The company erected the turbine in Emden, Germany and will be testing several storage systems along with it. The first prototype was installed November 2007 and the second about September 2008. Oddly, the E-126 is also rated at 6 MW, but some say will produce 7 MW or 20 million kWh/year.
The rotor will turn at a leisurely 12 rpm, a speed thought to be of little concern to birds. The turbines are equipped with several unusual features such as a spoiler on each blade extending to the hub, and a precast concrete base. The elevated hub height and blade profile are expected to surpass the performance of the E-112. In addition the E-126 has no gearbox so the generator is directly driven by the turbine. The generator is housed in the widest part of the nacelle.
The size of E-126 components presents several challenges. For example, crew sizes are twice that needed for a 2-MW installation, and each blade is so large is has to be assembled from two sections on location. Each assembled blade takes 1.5 days to attach to the hub. In addition, the rotor and 140-ton stator of the generator are each hoisted separately because of their weight.
Also, the design uses an inverter instead of a synchronous generator. That is, a controller converts the fluctuating ac current generated into ac synchronous to the grid. And instead of a cut off speed for protection in high wind, the unit pitches its blades away from the wind to continue generating although at a lower rate. A wind farm of 11 E126 turbines is under construction in Belgium. Company literature mentioned no costs.
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