Lightweight rotor for low wind speeds

15.10.2025

Source: E & M powernews

The Fraunhofer IAP has developed a rotor for small wind turbines specifically for low-wind regions. The target groups: Households, businesses and disaster relief teams.

Researchers at the Fraunhofer Institute for Applied Polymer Research (IAP) have joined forces with the BBF Group to develop a lightweight rotor that is specially designed to work reliably even at low wind speeds. The first five prototypes have now been delivered, according to a statement from the Fraunhofer Institute. They will now be set up at various locations in order to analyze the effects of position and height. In the future, the researchers plan to develop lightweight components made of mono-material in order to improve recyclability and further optimize the environmental balance.

According to the Fraunhofer IAP, the newly developed wind turbine starts moving at a wind speed of just 2.7 meters per second. Comparable systems require an average of four meters per second, they say. The low start-up speed is a key prerequisite for ensuring that small wind turbines can also be operated economically in regions with weak winds.

On average 83 percent more powerful than comparable systems

"Our aim is to harness the power of the wind as effectively as possible to generate electrical energy," says Marcello Ambrosio. The aim is to enable private households, small businesses and disaster relief teams to generate energy more independently in future. The team in Wildau, Brandenburg, has optimized the aerodynamic design of the rotor blades and at the same time further developed the production technology, says the Head of Simulation and Design in the Polymer Materials and Composites PYCO department at the Fraunhofer IAP. Tests in the wind tunnel have shown speeds of up to 450 revolutions per minute. At a wind speed of ten meters per second, the system achieves an output of 2.5 kW and is therefore on average 83 percent more powerful than comparable systems on the market. The researchers put the efficiency at 53 percent. According to Ambrosio, a maximum of 59 percent is physically achievable.

Raul Comesana, Managing Director of the BBF Group, emphasizes the practical benefits of small decentralized systems. "As a project developer and construction company in the Berlin-Brandenburg region, we are using this project to show how end consumers and businesses can design decentralized energy generation individually and sustainably," he says.

According to the Fraunhofer IAP, the rotor blades of the turbine consist of two lightweight, hollow shells made of fiber composite material. In contrast to conventional designs with a foam core, this construction method reduces the weight by up to 35 percent. The mold for the components was produced using an industrial 3D printer, which can produce objects up to two meters in size. The fiber strips are inserted automatically using an automated fiber placement system, which increases dimensional accuracy and reduces overlaps.

A special laminate structure ensures that the rotor blades turn elastically out of the wind in strong winds, thus automatically reducing the speed of rotation. This eliminates the need for complex control technology.

Author: Fritz Wilhelm