A test facility for the conversion of carbon dioxide (CO2) from the air into solid carbon is being built at Karlsruhe Institute of Technology (KIT).

The facility will be the world’s first container-scale facility of its kind to convert CO2 contained in ambient air into highly pure carbon black powder that can be used as a resource in industry.

The research project, scheduled for a duration of three years, is funded by €1.5m by the Federal Ministry for Economic Affairs and Energy.

INERATEC GmbH, a spinoff of KIT, and Climeworks, a spinoff of ETH Zurich are partners of the project.

“Our project approach consists of removing CO2 from the atmosphere and converting it into carbon black, i.e. highly pure carbon in powder form,” said Professor Thomas Wetzel of the Institute of Thermal Process Engineering and Head of the KALLA Karlsruhe Liquid Metal Laboratory of the Institute for Thermal Energy Technology and Safety.

“In this way, a hazardous greenhouse gas will be converted into a raw material for high-tech applications. Carbon black can be used in electronics, printing, or construction.”

The test facility to be set up within the NECOC research project will combine the following process steps: By means of an absorber, CO2 is first captured from ambient air (direct air capture, DAC). 

Together with renewable hydrogen, it is the converted into methane and water in a microstructured reactor. The methane produced serves as a carbon carrier in the downstream process and is passed into a bubble reactor filled with liquid tin.

In the ascending methane bubbles, a pyrolysis reaction takes place, by means of which methane is decomposed into its constituents. These are, on the one hand, hydrogen, that is directly fed back to methanation and, one the other hand, solid carbon in the form of microgranular powder, i.e. carbon black.

All process steps have already been studied and developed up to the laboratory scale by the researchers involved.

“We know the individual modules well,” said Dr Benjamin Dietrich, Project Coordinator of NECOC.

“However, they have never been realised together in an integrated facility so far. This is the first time worldwide. Skilful integration of the process modules and correct process conduct will be decisive for the energy efficiency of the process and the quality of the carbon black product.”

“Solid carbon is far less difficult to handle than CO2 and can even be used as a resource. So far, carbon black has been produced mainly from fossil petroleum. That is why our process represents a technological approach for a sustainable future in several respects.”

Future extensions of the facility are planned to increase the performance per container and to enable parallel operation of many facilities.