Using CO2 and “green” energy to produce specialty chemicals

EVONIK and Siemens have launched the second phase of their joint research project Rheticus, in which they are developing a process that uses carbon dioxide (CO₂) and renewable energy to produce specialty chemicals and could reduce CO₂ emissions.

Rheticus launched in January 2018. The first phase, Rheticus I, focussed on developing a technically-feasible basis for artificial photosynthesis using a bioreactor and electrolysers. In artificial photosynthesis chemical and biological steps are combined allowing energy to be used to produce chemicals from CO₂ and water.

Siemens and Evonik are each contributing core competencies – electrolysis and biotechnology – to this process.

In Rheticus II, they will combine previously separate plants in a test facility that will use carbon dioxide (CO₂) and renewable energy to produce specialty chemicals. The facility will be located at Evonik’s site in Marl, Germany.

The test plant will use CO₂, water, energy from renewable sources, and bacteria to produce specialty chemicals.

Siemens

In the first step CO₂ and water will be converted into carbon monoxide (CO) and hydrogen (H₂) in electrolysers, using electricity from renewable sources. Siemens developed the world’s first CO₂ electrolyser – comprising ten cells with a total surface area of electrodes of 3,000 cm² – which it is contributing to the project. Siemens’ fully automated CO₂ electrolyser was integrated into a container in Q2.

In the next step of the process, special microorganisms in a bioreactor are used to convert CO into specialty chemicals. The bacteria in the test facility are to produce butanol and hexanol that will be used for research purposes. Both chemicals are already produced at the Marl site and are chemical feedstocks used in products such as specialty plastics and food supplements.

The synthesis module came on stream at Evonik in Q1, and at its heart is an 8 m high stainless-steel bioreactor with a capacity of 2,000 L. Microorganisms in the bioreactor will work continuously provided with the main nutrients H₂ and CO.  

The process has the potential to produce other specialty chemicals, by employing different strains of bacteria and conditions.

The companies will combine the electrolyser and bioreactor in the “coming months”.. Additionally, a unit is being constructed that will process liquid from the bioreactor into pure chemicals.

Once Rheticus II is successfully completed, Evonik and Siemens will have a unique technology platform which can produce useful, energy-rich substances such as specialty chemicals and artificial fuels from CO₂ using a flexible, modular process.

Launched on 10 October, Rheticus II is expected to run until 2021, with the test facility expected to begin operating in early 2020.

The project will receive €3.5m (US$3.89m) in funding from Germany’s Federal Ministry of Education and Research.

Thomas Haas, who is responsible for the Rheticus project at Evonik, said: “The innovative technology used for Rheticus has the potential to contribute to the success of Germany's energy transition.”

“In the future, this platform could be installed anywhere CO₂ is available — for example, at power plants or biogas plants.”

Karl-Josef Kuhn, leading the Power-to-X (Power2X) research at Siemens, said: We are developing a flexible system that can provide answers to various questions raised by the energy transition.”

“We are making it possible to store renewable energy by converting it into useful substances such as specialty chemicals or fuel. We are also contributing to the stability of the grid because production is so flexible that we can respond to fluctuations in power supply.”

Power2X refers to technologies that convert electricity from renewable sources into physical energy stores, energy carriers, and energy-intensive chemical products. The energy can then be used in fuels or plastics and chemical products. The Power2X project is funded by the German Federal Ministry of Education and Research and involves a consortium of research institutions, industrial companies, and civil society bodies. Evonik and Siemens are both taking part in the project, which aims to find ways of using energy from renewable sources.