Technological watch

As part of the THINKTANK Industrial Resource Strategies, researchers at the Karlsruhe Institute of Technology (KIT) have been working with Audi for a good six months on the pilot project “Chemical Recycling of plastics from automotive manufacturing.” After the completion of the project, it is clear that the is both technically feasible and environmentally and financially promising.
New Pilot Project
Fuel tanks, airbag covers, or radiator grilles – many components in cars are made of plastics. They need to meet stringent safety, heat resistance, and quality requirements. This is why plastic automotive components that are subject to particularly high levels of stress can, to date, only be manufactured from materials of virgin material quality, which usually do not achieve.
Additionally, mixed plastic waste is often not available for mechanical recycling. For this reason, the THINKTANK Industrial Resource Strategies at the Karlsruhe Institute of Technology (KIT) launched a pilot project for chemical recycling together with Audi at the end of 2020. Within the scope of the project, tests were carried out to determine the extent to which mixed automotive plastic fractions can be fed back into a resource-friendly cycle via Chemical Recycling.
Under the leadership of Prof. Dr. Dieter Stapf from the KIT Institute of Technical Chemistry and Dr. Rebekka Volk from the KIT Institute of Industrial Management and Industrial Production (IIP), scientists investigated the technical feasibility of the process as well as its cost-effectiveness and its impact on the environment.
Waste to Automotive Manufacturing
The results show that chemical recycling can be used to process the mixed plastic waste from automotive manufacturing into pyrolysis oil, which can replace petroleum as a chemical raw material. This means materials made from it exhibit the same high quality as virgin materials. This means that plastics made from pyrolysis oil can be reused in automotive manufacturing to produce plastic components that are subject to high levels of stress. Audi is one of the first automakers to test this recycling method in a pilot project with automotive plastic waste. Audi intends to intensify its research together with its partner KIT. As such, the partners plan to test its industrialization potential in a follow-on project. This would allow fossil resources to be used for longer and reduce the use of additional fossil resources.
“An initial assessment shows that chemical recycling may be superior to energy recovery from both a financial and environmental perspective. We are comparing this process with energy recovery, as this is the current recovery route for the automotive plastic waste we analyzed. An initial comparison of the figures shows that the costs for chemical recycling are on par with the prices that have to be paid for energy recovery. Furthermore, chemical recycling offers the opportunity to recycle much of the carbon and reuse it in the production of new plastic components,” explains Dr. Rebekka Volk from IIP. As a result, carbon dioxide emissions from chemical recycling are significantly lower than from the current energy recovery process – which benefits the climate.
Complementing mechanical recycling, pyrolysis also converts mixed waste plastics and composites into a liquid chemical feedstock while separating out unwanted constituents. After a purification step, this pyrolysis oil can be processed into new plastic using conventional industrial processes, thus replacing primary raw materials from fossil energy sources, such as petroleum. This conserves resources and energy.
Sustainable Production of Automotive Components
The aim of the “Chemical Recycling of plastics from the automotive industry” pilot project was to test intelligent cycles for plastics by means of chemical recycling and to evaluate this method as a supplement to mechanical recycling and as a substitute for energy recovery. Now that the research has proven its technical feasibility, Audi intends to scale up the process together with its partners. “We want to establish intelligent cycles in our supply chains and use resources efficiently,” says Marco Philippi, head of procurement strategy at Audi.
“Chemical Recycling harbors tremendous potential in this regard, because if plastic components can be manufactured from pyrolysis oil instead of petroleum without any loss of quality, it would be possible to significantly increase the percentage of sustainably manufactured components in cars. Over the long term, this process may also play a role in end-of-life vehicle recycling.”