CO2 electrolysis instead of coal

Coal is being phased out – this is the only way to achieve Germany’s climate targets. However, the fossil fuel is also the basis for important basic chemicals. New solutions are needed. CO₂ electrolysis is one of them.

Lignite from the Rhineland region is not only used to generate electricity, it is also used to produce important basic chemicals such as carbon monoxide (CO), with which the chemical industry produces synthetic materials and acetic acid. Since lignite will soon be phased out, new, climate-friendly sources of this gas must be developed. Researchers at Jülich’s Institute of Energy and Climate Research (IEK-9) have cleared an important hurdle to help a promising technology reach a breakthrough: CO₂ electrolysis.

It converts climate-damaging CO₂ directly into pure carbon monoxide. “Without further processing, the carbon monoxide can then be used for many applications,” explains Maximilian Quentmeier, doctoral researcher at IEK-9. Together with his supervisor Bernhard Schmid and other colleagues, he developed a design for a CO₂ electrolysis plant in which the individual cells are arranged in a so-called cell stack. It is known from other electrolysis technologies that such a design can be scaled up well for industrial use.

The stack achieves an efficiency of 30 per cent in laboratory tests – which are not yet tuned for efficiency. “For this type of process, which even takes place at below 100 degrees Celsius, this is already a very promising value,” says the institute’s director, Prof. Rüdiger-A. Eichel. Plus: if such a system is operated with electricity from renewable energies, it operates in a climate-neutral manner. “If you withdraw the carbon dioxide from the atmosphere, for example using direct air capture, or from biogas plants, the technology is even potentially climate-negative,” explains Bernhard Schmid.

The work is part of the structural change project iNEW, which aims to advance the creation and safeguarding of jobs in the Rhineland region. With the help of CO₂ electrolysis, industrial companies in the region could provide carbon monoxide as a basic chemical on a decentralized basis without having to transport the toxic and highly flammable gas at great expense. Until then, the researchers aim to further improve, among other things, the efficiency of their cell stack.