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News – What`s happening in energy research

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The aim is to make smart blades as cheap to produce as the rotor blades which have been used to date.
© DLR
Smart blades
14.02.2013

The intelligent rotor blade, or “smart blade”, adapts to wind strengths. Thanks to its movable trailing edge, a slat and flaps in the rotor blade, it deflects the wind currents.
© DLR

A 50-metre rotor blade can withstand a bending moment of up to 50,000 kNm. By way of comparison: if a locomotive with a length of around 30 metres and a weight of about 100 tonnes were to be placed onto the blade, this would correspond to the maximum load at the fixing point.
© Fraunhofer IWES

Rotor blades are getting smarter

In the future, wind turbines will continue to generate power even when subjected to strong gusts of wind. Intelligent rotor blades will detect and compensate currents independently. This will minimise downtimes. Until now, manufacturers have been discouraged by the high effort. Now the Wind Energy Research Alliance is focussing on this development.

Smart blades, the intelligent rotor blades, will in future automatically react to strong gusts of wind. With the aid of laser-optical remote sensing techniques, all wind turbines will in the future be able to record the incoming wind field and draw conclusions for the best possible control strategy. In order to adapt to local wind flows, they will use movable trailing edges and slats. This will enable wind turbines to feed in power even when there are strong gusts of wind. Until now, operators have turned rotor blades away from the wind when it has become too strong.

Due to the enormous length of the current rotor blades of up to 85 metres, a wind turbine sweeps over a circumferential area of 22,670 m² while turning. By way of comparison: this almost corresponds to the area of St. Peter’s Square in Rome, which covers around 23,000 m².

Taking a development risk with the smart blades

Due to this huge area, different wind speeds occur within the contact area covered during wind gusts. During a storm, the difference within the rotor area can be 20 or 40 m/s. A general adjustment of the entire rotor blade would not be sufficient. It is not a new idea to construct rotor blades with more movable parts, which can therefore be better adapted to the wind conditions. However, until now, plant constructors have shied away from developing smart blades. The challenge here is that the rotor blades can become less reliable , more expensive, heavier and more maintenance intensive due to the active mechanisms. The aim of the research project is therefore to provide evidence of the feasibility and efficiency of smart blades. The Fraunhofer Institute for Wind Energy and Energy System Technology (IWES), the ForWind Centre for Wind Energy Research and the German Aerospace Center (DLR) are jointly working on the problem in the Wind Energy Research Alliance.

The researchers anticipate that due to the adaptability of the smart blades, the load on the rotor blade will be reduced. They want to implement an aerodynamically optimised and light design. This is intended to increase the service life of the turbine and to save material and logistics costs.

The German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety is providing 12 million euros in funds for the Wind Energy Research Alliance in the development and construction of the intelligent rotor blades. The “Smart Blades - Development and Construction of Intelligent Rotor Blades” project has a runtime of 39 months. The project is supposed to develop construction documents for the rotor blades and will then make them available to the manufacturers.

(cg)

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