New panes from recycled car windows for the Audi Q4 e-tron

Together with its partner companies, Audi is taking on the challenge of establishing a closed material cycle¹  for car glass as part of a one-year pilot project. Recycling damaged class into new windowpanes saves not only resources, but also energy and water in window manufacturing. Audi hopes to use car windows produced that way in Audi Q4 e-tron model production – the only cycle of its kind thus far.

In Audi’s pilot project, irreparably damaged car windows first go to Reiling, where the old windows are broken into small pieces and processed. The objective: to reintroduce car glazing into plate glass production. “Until now, recycled material has mostly been turned into beverage bottles,” explains Daniel Rottwinkel, Plant Manager at Reiling. And that is precisely where the joint pilot project starts: namely, recycling damaged glass back to its original quality for car windows. In order to be able to produce recyclable material from old glass, the company meticulously sorts out non-glass materials like the PVB plastic layer (polyvinyl butyral) in the glass, window edgings, metals, and wires. The elimination process is carried out using magnets, non-ferrous metal separators, extraction units, and electro-optical sorting units.

In the next recycling step after Reiling has processed the glass recyclate and removed all the waste materials it can, Saint-Gobain Glass turns it into plate glass on its float line in Herzogenrath, Germany. That means roughly 3 x 6 meter (10 x 20 feet) rectangles, from which the affiliated company Saint-Gobain Sekurit makes automotive glazing in a subsequent process. One requirement for the final base glass product: the purest and most homogeneous glass recyclate possible.

Along with the shards, Saint-Gobain also mixes the recyclate with basic glass components that do not come from automotive sources, like quartz sand, sodium carbonate, and chalk, at a ratio of 30-50 percent. “For us, this cycle of making new car windows out of defective ones is an important step toward producing automotive glass in a way that conserves resources and energy,” says Markus Obdenbusch, production manager in charge of the Saint-Gobain float at the Herzogenrath site. 

“We’re just starting to look at glass as a recyclate, so we anticipate that there will be more potential for improvement,” Obdenbusch says. Beyond the pilot project with Audi, Saint Gobain plans to put up to 30,000 tons of shards into production in Herzogenrath within the next three years, which will in turn save energy and reduces carbon emissions. That will mean that the company will emit up to 75 tons less CO₂ from a typical day’s tonnage. Consumption of water, which otherwise would have been used in the production of new glass, will also be reduced.

The three partner companies have decided to put the process to an initial one-year test so that they can learn about material quality, stability, and costs. If glass can be recycled in an economical and ecologically meaningful way, the resulting car windows will be used in the Audi Q4 e-tron series.

The pilot project is one example of how Audi and its partner companies are working to move materials – of which a great many are needed – into intelligent cycles. The goal is to use secondary materials wherever that is technically possible and economically sensible to do so in order to shape value chains more sustainably and conserve resources.