The reasons why wind turbines end up in the waste vary. This could be due to construction defects, already obsolete turbine technology or loss of performance. The result is always the same – the wind turbine has to be removed.
The wind turbine operator – legally bound to dismantle and dispose of the plant – has two options: they can remove the turbines and reinstall them in another country or dispose of them.
This is the problem that a research project by the Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut (WKI), seeks to tackle: the team led by Peter Meinlschmidt has successfully developed a recycling technique that enables wind-power rotor blades to be dismantled into their individual components so that balsa wood and plastic foam can be recovered.
“With our project, we have demonstrated that the large quantities of balsa wood used in wind-power rotor blades can be further utilised,” explains Meinlschmidt, Project Leader at the Fraunhofer WKI. “This creates a vast potential for, amongst others, the recycling industry.”
The innovative aspect of the approach lies in the fact that the usable sections containing the balsa wood are separated during dismantling of the rotor blade at its original location. This enables the separate processing and high-quality recycling of the materials.
New insulation and building materials
Wind power turbines are producing more and more sustainable electricity. But recycling the rotor blades involves considerable effort and expense due to their highly robust fibreglass-reinforced plastic skin. This is why rotor blades have usually been incinerated up until now.
However, incineration is problematic because the fibre-reinforced plastics form clumps in the incinerator when heat is applied, potentially causing blockages and damage in conventional waste incineration plants. What’s more, large quantities of valuable raw materials are lost.
The main aim of the research project was therefore not just to develop an innovative recycling technique for recovering balsa wood and plastic foam from the rotor blades.
It also aimed to develop innovative processes for utilising the recycled materials to produce new and improved insulation and building materials.
The real innovation of the recycling process is the ultra-lightweight wood-fibre insulation mats made from balsa wood, which have densities of below 20 kg/m3. Mats with these kinds of densities have not previously been available on the market. The reduced density is combined with significantly better insulation.
This results in advantages over insulation materials made from polystyrene or special insulation materials, such as extruded polystyrene foam (XPS) or expanded polystyrene (EPS). The wood-fibre insulation mats can be utilised in construction as between-rafter insulation and as solid insulation boards.
A further new product is extruded decking boards made from wood polymer composites (WPC), which have not been produced from balsa wood up until now. The balsa wood makes the boards both lighter and stronger than the standard WPC decking boards currently available.
“One advantage of the new recycling procedure is that rotor blades are no longer incinerated – during which valuable raw materials are lost in large quantities – but are instead exploited as a ‘material source’ for new products. With our recycling approach, we offer solution possibilities for the disposal problem and simultaneously demonstrate innovative utilisation opportunities for the recovered balsa wood,” says Project Leader Peter Meinlschmidt, summing up the project’s achievements.
Sustainability through the utilisation of renewable raw materials has formed the focus at the Fraunhofer WKI for more than 70 years. With the new, innovative recycling technique, Peter Meinlschmidt’s team has demonstrated that the recovery of secondary raw materials for high-value reutilisation is an important step in recycling the large-scale composite components in rotor blades.The development of novel building and insulation materials gives green energy a holistic perspective.