The floating elements are produced here at the Fraunhofer WKI using balsa-wood foam encased in natural-fiber-reinforced bioplastics. The balsa wood is derived from scrapped wind-turbine rotor blades. For the outer shell, we use a bio-based polymer on the basis of itaconic acid and increase the strength by means of flax fibers. The flax fibers are grown in Europe and exhibit excellent mechanical properties.
Thanks to the intelligent design of the floats, the plants are watered passively. In order to achieve the shape necessary for this purpose, we are testing production by means of vacuum infusion. This technology is used in industry to manufacture complex components from conventional fiber-composite plastic. The focus of our development is on adapting the bio-based polymer for this established manufacturing process. This concerns, amongst other things, the viscosity and the processing time as well as the formulation with different reactive diluents.
Starting in August 2021, seven floating islands will be created in the Bleichenfleet between the two bridges Michaelisbrücke and Ellerntorbrücke. They will be technically tested over the course of one year and will then continue to be used to revitalize the canals. The design and evaluation of the biotopes is being carried out with the support of the environmental organizations BUND Hamburg and NABU Hamburg.
The floating islands can improve the quality of both air and life in the city. Appropriate planting will provide food, reproduction and refuge biotopes for fish, birds, insects and other small creatures in high-density urban areas.
The project also serves society in a much broader context: The floating islands illustrate the performance capabilities of modern bio-materials. As eye-catching exhibits in public spaces, they emphasize that materials made from renewable raw resources can now meet the most stringent requirements and can be manufactured on an industrial scale. The project is therefore contributing towards raising awareness regarding sustainable material solutions and ensuring that they are used more routinely in product development in the future.
Simultaneously, we are creating a possibility for recycling discarded wind-turbine rotor blades. Their core consists of lightweight balsa wood. When the rotor blade has reached the end of its life, the balsa wood accumulates in large quantities as waste. At present, there are very few material recycling options.
With the floating islands, new utilization possibilities arise for bodies of water as areas for experience and recreation. This could be interesting for the tourism, gastronomy and event sectors.
Companies that produce, process or utilize lightweight materials are provided with a new opportunity for the use of bio-based high-performance materials, thereby improving their eco-balance and market position.
For operators of wind turbines, a new recycling perspective is being opened up: The balsa wood from discarded rotor blades is being transformed from a waste material into a valuable raw material.