In the ReduCO2 project, the two UAS are jointly developing a catalytic cell that enables the chemical reduction of carbon dioxide (CO₂) to ethanol with the help of electricity. Ethanol is an important raw material in the chemical industry and in turn produces CO₂ when burned. Therefore, the project creates a cycle for reusing CO₂ and thus contributes to climate protection and energy transition.

The project leaders, Prof. Raimund Förg (DIT) and Prof. Dr. Martin Kammler (OTH Regensburg), envisage several application scenarios for their development: from large-scale industrial use to a small device installed on private chimneys, everything is possible. “It really just depends on what the market wants,” says Förg. “The technology itself is almost infinitely scalable.”

And his colleague Martin Kammler adds: “Producing ethanol is only the first step in our project. We want to develop the technology further to convert carbon dioxide into long-chain carbon compounds that are also needed in the chemical industry. These substances can then be, for instance, processed into plastics – thus removing carbon dioxide from the system altogether.” 

Should the solution to our CO₂ problem really be that simple?

Of course it isn't, otherwise every chimney would have been equipped with a carbon dioxide catalyst long ago. Researchers have been working on the idea since the 1980s, but no one has yet made the breakthrough. “So far, the process is simply not efficient and specific enough,” explains Förg. “However, transferring findings from basic research to industrial scale is the core competence of universities of applied sciences.”

The close connection between UAS and industry also helps. As in many projects, several companies are on board as partners for ReduCO2, including well-known manufacturers of semiconductors and process equipment for the solar cell industry as well as a company involved in the electrosynthesis of raw materials.

Nanostructures are the key

The fact that the chemical reduction of CO₂ to ethanol is being researched again today is due to advances in nanotechnology – because nanostructured surfaces can help kick-start the reaction. “Nanostructures give a surface completely different properties,” Kammler explains. “This makes the catalyst more selective and efficient.”

Förg and Kammler are also focusing on nanostructures in their project. The team first replicates the most promising nano-surfaces of other research groups. Based on the results, they then look for the ideal combination of materials. However, they need also to solve one particular problem: Hitherto, the nanostructures are far too unstable. Depending on their composition, they only last a few days or even hours, which means that the technology is not quite ready yet to be used under real conditions.

The ReduCO2 team is therefore primarily looking for material combinations that stabilise the catalyst. Currently, the most promising approach is a mixture of multilayer graphene and metallic nanostructures that protrude from the surface like spikes. Förg admits that this combination has a negative impact on efficiency, but it is much more durable. “It's a bit like comparing a Formula 1 car and a VW Golf: the racing car may go faster, but the Golf lasts 15 years.”

Finding the ideal nano-surface is therefore only one aspect of the project, adds Kammler: “We have to keep the entire process in mind so that we can provide a marketable solution in the end.” For a successful transfer of the technology to industrial application, other questions are also important, such as: How will the CO₂ get into the device and the ethanol out? And where is the electricity that drives the reaction supposed to come from?

When it comes to new technologies, this is often the question that divides opinion. But the project leaders and their colleague Prof. Dr. Alfred Lechner – who initiated the project at the OTH Regensburg and led it until he retired in 2022 – are optimistic on this point as well: firstly, generating electricity from renewable energy sources is becoming easier and easier, they say, thus making it more readily available. And secondly, the conventional processes in the chemical industry also require large amounts of energy, but in the form of fossil fuels.

Climate protection can be economically worthwhile

Besides, Kammler and Förg have another important argument on their side: “There are studies that prove that our technology is going to be more economical than conventional chemical manufacturing processes using fossil raw materials,” says Kammler. “This is partly due to our cells producing a pure end product, whereas in other manufacturing processes two-thirds of the costs incur just for separating the end products.”

So, the ReduCO2 project seems to be on the road to success, and that is partly due to the commitment of the industrial partners. Some of them “get fully involved”, says Förg, because they are interested in the entire process or the final product. Others are more interested in certain details such as the production of the nanostructures. But all of them are noticeably willing to help the project reach a successful conclusion.

In the remaining time until September 2024, the project team aims to solve the stability problems and to find ways to regenerate the catalyst cells. The final project goal is a demonstrator that shows feasibility, is scalable, and describes the manufacturing process for the cells. “Afterwards, the catalyst can directly be implemented and brought to market by interested companies,” says Raimund Förg. In that case, the technology would finally have made the much-needed leap from Formula 1 car to VW Golf – and could actively contribute to climate protection and energy transition.