Kiel scientists develop rotor blades for small wind turbines from natural fibers

A research team from the Kiel University of Applied Sciences (HAW Kiel) is developing a process together with Nuebold Yachtbau GmbH that can reduce the expensive production of rotor blades for small wind turbines for energy supply. Instead of manufacturing them from glass and carbon fiber-reinforced plastics, which also have to be disposed of laboriously later, the Kiel scientists use natural fibers as the base material.

The use of composite materials made of glass and carbon fiber for rotor blade construction is not particularly ecological. The dismantling of older wind turbines in the coming years will produce a large amount of waste. Tens of thousands of tons are already produced annually – a disposal problem. Steel and concrete are less of an issue. Around 85 percent of them can be reused, say the scientists.

The composite materials used in the rotor blades, which provide the necessary stability and flexibility so that the wind turbines can withstand the loads permanently, are particularly problematic.

Material tests and prototype creation

In the run-up to the project, the researchers, together with Nuebold Yachtbau GmbH, have been working on how glass fiber composites can be replaced by natural fibers. The boatbuilder produced various samples from flax fibers and tested them for stability and load-bearing capacity. This is still done without considering the special properties of flax fibers, explains Jaron Nübold, managing director of the company.

The investigations have now been intensified as part of the project. First, suitable natural fiber materials will be examined more closely. These include flax, balsa wood, and Paulownia, a type of bluebell tree. The natural fibers will be tested for their load-bearing capacity. The researchers will then develop the structure and shape of the rotor blades using computer simulations, which will then be translated into initial models. These models will then be tested in the HAW Kiel wind tunnel, and initial full-size prototypes will be created. This includes load tests, such as bending, according to the DIN standard for wind turbines. A small wind turbine with a rotor area smaller than 200 m² will then be assembled with the rotor blades made of natural fibers, according to the scientists' plan.

“We want to show that sustainable rotor blades made of flax fibers and other renewable raw materials can meet all technical requirements and thus make a real contribution to even more sustainable wind energy,” explains project leader Prof. Dr.-Ing. Sten Böhme of HAW Kiel.

The project started on October 1, 2025, and has a duration of two years. It is funded by the Gesellschaft für Energie- und Klimaschutz Schleswig-Holstein (EKSH), which supports the research work with 175,000 euros.

(olb)