At an innovative test facility in Marl, North Rhine-Westphalia, Siemens and Evonik are conducting research into the use of CO2 as an alternative raw material for the production of specialty chemicals as part of the Rheticus project. The plant is the first to combine renewable energy, electrolysis processes and fermentation. It is thereby helping the energy and chemicals sectors to come together and opening up possibilities for the chemical industry to be put on a more climate-friendly footing.

Oil from fossil sources is one of the key feedstocks used in the chemical industry. The test facility developed in the Rheticus project demonstrates how switching to sustainable alternatives can be successfully achieved by using CO2 as a raw material. The system converts the gas, utilizing water and electricity, into specialty chemicals in a two-stage process. The project extends the useful life of carbon, which is needed for the manufacture of many products, in line with the CCU concept and indicates innovative potential applications in the field of power-to-X. These in turn can also help to close the carbon cycle, working in a similar way to photosynthesis in the natural world.

Innovation: CO2-based specialty chemicals

The test facility is the first to combine the electrolysis of CO2 with subsequent fermentation. In the first step, the electrolyser splits carbon dioxide (CO2) and water into carbon monoxide (CO), hydrogen (H2) and oxygen (O2) using electricity from renewable sources. The second step takes place in a bioreactor, where special microorganisms convert the synthesis gas consisting of carbon monoxide and hydrogen into butanol and hexanol. These specialty chemicals, which can normally only be manufactured by means of expensive, multistage processes, will later serve as raw materials for the production of specialty plastics, nutritional supplements or synthetic fuels, for example. In a development project launched in May 2020 as part of the German government’s Copernicus Projects research initiative, Evonik has begun cooperating with Beiersdorf with an eye to using the products in the cosmetics industry, amongst other applications. There is also potential for further products in the future.

“The innovative technology developed in the Rheticus project has the potential to contribute towards a successful energy transition. In future, the platform could be installed anywhere CO2 is present.”

Dr Thomas Haas, responsible for the project at Evonik Creavis GmbH

Efficiency: Innovative combined facility

The test facility on the site in Marl is currently under construction, with test operations due to begin in the second half of 2020. Prior to this, in an initial phase of the project, the required CO2 electrolyser and the bioreactor were developed independently of one another by Siemens and Evonik, respectively. Germany’s Federal Ministry of Education and Research (BMBF) is providing grant funding of around 3.5 million euros to support the second phase. The first industrial plant, based on the technology developed, could produce 10,000 tonnes of hexanol and butanol each year, thereby sequestering 25,000 tonnes of CO2. It will be at least five years before such a plant could go into operation.

“We’re developing a platform that can be used to produce chemical products on a far more low-cost and eco-friendly basis than today,”

says Dr Günter Schmid, technical project lead at Siemens Gas and Power GmbH.


of CO2 could be sequestered each year when the first industrial plant is established.

Versuchsanlage in Halle

Rheticus test facility from Siemens and Evonik. © Evonik

Ausschnitt des Magazins Elements 01/2018 (Herausgeber: Evonik Industries AG)

Extract from Elements magazine 01/2018 (Publisher: Evonik Industries AG) . © Evonik

Impact: Less oil, less CO2

CO2 contained in waste gases is bound as a raw material and not emitted into the atmosphere. At the same time, the approach gives the chemical industry access to an additional source of raw materials as an alternative to fossil-based options. By making use of CO2 and combining power-to-X with microbial processes, the project serves to illustrate a way in which the chemical industry can be made more climate-friendly whilst simultaneously closing the carbon cycle. Thanks to its flexible operation, this technology will also support sector coupling and grid stabilisation.


Your Contact

Dr. Günter Schmid

technical project lead at Siemens Gas and Power GmbH

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Dr. Thomas Haas

responsible for the project at Evonik Creavis GmbH

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