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Efficiency improved for small wind turbines, the kind you could use at home

People who want to generate electricity for their own consumption using wind power need a powerful, small wind turbine. Researchers at the Fraunhofer Institute for Applied Polymer Research IAP, in collaboration with the BBF Group, have developed a lightweight rotor that is specifically designed for operation in regions with low wind speeds. The first prototypes have been delivered. These systems enable private households, businesses, or disaster relief organizations to set up a decentralized energy supply and use renewable energy efficiently.

Small wind turbine in lightweight design: Optimization of aerodynamics and the manufacturing process enables a new wind turbine to achieve up to 450 rpm and generate an output of 2,500 W. [Credit: Photo courtesy of Fraunhofer Institute for Applied Polymer Research IAP]

 

 

 

 

The newly developed wind turbines start moving even in a light breeze. Wind tunnel tests show the rotor begins to turn at a wind speed of 2.7 m/sec -- a key requirement for the efficient use of wind power in regions with low wind conditions. The starting speed for comparable systems is 4 m/sec.

Weak wind, high efficiency
"Our goal is to use the power of the wind as effectively as possible to generate electrical energy," says Marcello Ambrosio, head of Simulation and Design in the Polymer Materials and Composite PYCO research division at Fraunhofer IAP in Germany. The lightweight construction experts at the Wildau site are taking a holistic approach to the development of the wind turbine. "We have optimized the aerodynamic design and the manufacturing process," says Ambrosio.

The result: The wind turbine achieves up to 450 rpm. With an output of 2,500 Watts at a wind speed of 10 m/sec, this unit is on average 83% more powerful than comparable systems on the market. Overall, the system achieves an efficiency of 53%.

"Physically, a maximum of 59 percent is possible," says Ambrosio, classifying the measurement data from the wind tunnel test. Raul Comesana, managing director of the BBF Group, adds, "Efficient small wind turbines make an important contribution to an independent energy supply. As a project developer and construction company in the Berlin-Brandenburg region, we demonstrate with this project how end consumers and businesses can design decentralized energy generation individually and sustainably."

Customized lightweight construction: Optimized design, manufacturing
The rotor blades of the small wind turbine are constructed from two shells in a lightweight design. They are made of fiber composite materials. Compared to conventional designs, which are constructed with a foam core, the newly developed components are hollow inside. This construction method reduces the overall weight up to 35%. Fiber composites are produced by precisely laying fiber strips in a mold, which is then hardened using resins or other plastics to form a component.

Ambrosio and his team specially designed the mold for the rotor blades. The scientists use an industrial 3D printer that can print objects up to 2 x 2 m in size. A modern automated-fiber-placement system handles the placement of the fiber strips in the mold. This automated method ensures high quality, reduces overlaps compared to manual placement, and allows for smaller component dimensions.

A special laminate structure also ensures the rotor withstands strong winds. "We designed the individual layers of the composite material so that the rotor blades can flex elastically in a storm and turn out of the wind," says Ambrosio. This automatically reduces the rotation speed of the turbine and protects it from overload. Complicated control technology and elaborate mechanics can thus be avoided.

Five prototypes of the small wind turbine were recently delivered to the BBF Group to be installed at various locations. With this approach, the researchers and their development partner aim to find out how the position and height of the system affect performance. The next steps include further optimization of the rotors and the development of lightweight structures made of monomaterial (meaning chemically identical materials) instead of composite materials. Such components are easier to recycle and help improve the environmental balance of lightweight solutions.

Source: Fraunhofer Institute for Applied Polymer Research IAP

Published October 2025

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