Scientists test German waste ash to absorb CO2 for construction use
Researchers are investigating if 6 million tonnes of annual incineration residue can be turned into road and concrete materials.
Germany produces approximately 6 million tonnes of ash from municipal waste incineration every year, according to a report by the Times of India. Scientists are now testing if this residue can absorb carbon dioxide (CO2) and be used for road construction and concrete production.
The research project involves TH Köln (Cologne University of Applied Sciences) and RWTH Aachen University. They are studying carbonation, a chemical process where minerals in processed ash absorb and permanently bind CO2.
The initiative is part of the KARMA project, which focuses on the carbonation of waste-incineration ash. The project is led by the Bergischer Abfallwirtschaftsverband (BAV) and has secured more than one million euros in funding until mid-2028.
Researchers are comparing two methods: wet carbonation, which uses water for higher absorption but requires more energy, and a method using limited moisture that forms a surface layer. Axel Wellendorf of TH Köln said both approaches have different advantages and disadvantages.
A technical test facility is being set up at the Leppe waste disposal centre near Lindlar to move the research beyond laboratory settings. The facility will be operated by BAV using processed ash supplied by refer GmbH.
The project aims to see if the carbonated ash can replace sand or gravel in roads or act as a binder in concrete. Using this residue could reduce the need for energy-intensive extraction of conventional construction materials.