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Blades for rooftop wind turbine manufactured with Biotex flax

News International-French

4 Mar 2014

Composites Evolution’s Biotex flax has been used to manufacture natural fibre reinforced blades for a rooftop wind turbine at the University of Stuttgart.

The blades were conceived, designed and manufactured by the SWE (Endowed Chair of Wind Energy) at the University, the team having found that Biotex Flax reinforcement’s unique twistless technology gave them the performance characteristics that they were looking for.

SWE’s research is focused on improving the reliability of turbines whilst reducing the production costs of wind energy. It started design in 2011, with the aim of constructing new rotor blades for the university’s 1kW rooftop wind turbine. After a trip to “The Eden Project” in the UK, the team wanted to familiarise themselves with natural fibres and contacted Composites Evolution to test the performance of its Biotex materials.
Along with a range of other materials, the fibres were tested with different resins to validate their performance characteristics. SWE found that Composites Evolution’s Biotex Flax correlated best with the performance they expected and it felt they had a good data basis to make a lightweight and stiff natural fibre blade.

The blade, consisting of Biotex Flax 2x2 twill 400gsm as the main shell and Biotex Flax unidirectional 275gsm used for the blade’s belt and root, was built in two halves. Both were hand-laminated and then vacuum-bagged in two female moulds. The two separate halves were then joined using Momentive’s RIM 235 epoxy resin.

Once completed the blades were assembled onto the rooftop turbine for performance tests. SWE plans to use the blades in further tests focusing on their strength performance compared to blades constructed from other materials. A fourth blade was embedded with strain gauges and the team will be comparing the results to standard carbon and glass blades.