Good for the environment, but difficult to dispose of: Wind turbines last an average of twenty years before they need to be replaced. However, recycling old equipment can be difficult. The rotor blades, in particular, pose a problem due to their material composition of fibre-reinforced plastics. Other plastic-based waste, such as car trunk lids and smaller parts, e.g. from healthcare and pharmaceutical applications or electrical and electronic applications, cannot currently be recycled or are difficult to recycle.
A new research project at the IKK (Institute of Plastics and Circular Economy) of Leibniz University Hannover (LUH) in cooperation with KraussMaffei Extrusion (Laatzen) intends to solve this problem. The project was launched on 1 July 2023. Led by Prof. Dr.-Ing. Hans-Josef Endres, the researchers aim to develop a new process to recycle industrial waste from technical plastic components, i.e. from fibre-reinforced plastics and plastic-based material composites. The Ministry of Science and Culture of Lower Saxony (MWK) is funding the ReKon project with approximately 550,000 euros provided over a period of two years.
The idea behind the project is that recycled plastics should be reused in the industry sector they came from (closed-loop recycling). This way, a trunk lid could later become a trunk lid again, or at least another part of a car. “The quality of a product increases with the highest possible degree of purity and a low level of input contamination. The pre-treatment steps of sorting, separation, washing and cleaning therefore play a decisive role”, says Professor Endres. The benefits of having the original part manufacturer take care of recycling are obvious: The exact composition of the plastic and its components is known, making sorting much easier. In addition, distances are short, avoiding long transports with high CO2 emissions. Ultimately, future generations of components will also be designed to be easier to recycle. This helps conserving valuable raw materials.
At the moment, there are several ways to recycle plastics: Chemical and, more recently, solvent-based processes are increasingly being used. At the IKK, Professor Endres’ team is relying on established, but far from perfected, mechanical recycling methods. In comparison, these mechanical recycling processes use significantly less energy and resources. The principle is simple and can be applied to other raw materials such as textiles: The first step is to shred the plastic waste. The resulting material is then melted in an extruder at high pressure and high temperatures, cleaned and finally processed into a type of granulate. This recyclate – fine grains of plastic – then forms the basis of new components that can be reused elsewhere.
The new research project focuses on components that combine different plastics and other materials in such a way that they cannot be separated using the recycling technologies currently available on an industrial scale. These are mainly fibre-reinforced plastics from rotor blades, composites from the pharmaceutical sector, electronic waste as well as automotive shredder residue, which despite its high plastic content is currently not considered recyclable and is mostly incinerated.
The amount of industrial plastic waste will continue to increase in the future. For example, a new car now contains more than 300 kilograms of plastic, and the EU has set ambitious recycling targets for future generations of vehicles in its recent end-of-life vehicles directive. The number of wind turbines that will need to be overhauled in the next few years is also increasing. A 2022 study conducted by the German Environment Agency (UBA) predicts that up to 430,000 tonnes of glass fibre-reinforced plastics will be produced from rotor blades alone by 2040.
Prof. Dr.-Ing. Hans-Josef Endres
Institute of Plastics and Circular Economy at Leibniz University Hannover
Tel. +49 511 762 13302
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