Power-to-X processes: Highly Efficient and Climate-Neutral

The speedy reduction of worldwide CO₂ emissions is one of the most pressing and challenging tasks of our time. There are a number of technologies which transform unavoidable CO₂ into valuable products. Scientists at the Fraunhofer IKTS in Dresden have developed reactors based on ceramics, which use CO₂ and water vapor to produce raw materials for the chemical industry.

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As one of the world’s largest economies, Germany ranks sixth worldwide in terms of CO₂ emissions. In the industrial sector alone, 188 million tons of CO₂ are produced each year. At the same time, Germany must significantly increase the share of renewable energies in its electricity supply in order to achieve its climate targets. However, these renewable energies fluctuate over time and are not unlimited. It is therefore important to use them intelligently and above all efficiently.

Various strategies are currently being pursued for the use of unavoidable CO₂ emissions, for example to produce chemical raw materials (X). For this process to be as climate-neutral as possible, the power required for it must be obtained from renewable energies – in this way climate-damaging CO₂ is used to manufacture climate-neutral products.

However, such power-to-X processes are still too inefficient because they consist of many complex individual processes. Scientists at Fraunhofer IKTS have now succeeded in developing a pilot plant – consisting of ceramic-based reactors – in which CO₂ can be converted into climate-neutral chemical raw materials. In these reactors, the individual processes are smartly coupled, and material and energy flows intensified. This increases efficiency compared to previous power-to-X processes.

Unavoidable CO₂ emissions occur in large quantities for example in the cement and lime industries. Fraunhofer IKTS uses a wide range of ceramic components and technologies to harness this CO₂. For example, ceramic filter cartridges remove dust from exhaust fumes. The CO₂ can only be filtered out by ceramic membranes after such coarse cleaning. The CO₂ thus obtained is converted into carbon monoxide at over 750 °C in a newly developed ceramic high-temperature electrolysis reactor. At the same time – and this is remarkable – hydrogen is produced from steam in the same reactor, hence the name co-electrolysis. Put together, carbon monoxide and hydrogen form synthesis gas.