Dr. Niels Bredemeyer

Dr. Niels Bredemeyer, Dr. Nils Tenhumberg

ThyssenKrupp Industrial Solutions AG

Gregor Polcyn, Peter Toros

ThyssenKrupp Uhde Chlorine Engineers

New concept for large scale Redox-Flow-Systems


A lot of different energy storage technologies with different advantages and challenges are under discussion. Compared to other storage systems that can be built on a large scale, Redox-Flow-Systems exhibit a quite high efficiency. In these systems power and capacity can be designed separately to suit the demand of different applications and locations.

ThyssenKrupp Uhde Chlorine Engineers (TKUCE) as a part of the ThyssenKrupp Industrial Solutions AG (TKIS) is one of the world leading engineering companies for different electrolysis technologies. Thus, TKUCE has a width competence in electrochemistry and the engineering and construction of large scale electrochemical systems. 

For the above mentioned reasons TKIS is currently developing a Redox-Flow-System that can be scaled to an industrial size like e. g. chlor-alkali electrolysis systems. The main challenge is the reduction of the investments without decreasing the system efficiency. Besides optimized manufacturing this can only be obtained by a real scale-up of the system, meaning not only a simple numbering-up of the cells but also a scale-up of the active cell area. The aim of TKIS is to develop cells with an active membrane area of around 2.5 m², similar to other electrolysis technologies.

Cell design concept

To achieve high power density of a single cell an electrode with a high surface area per geometric area is needed. Thus, three dimensional highly porous electrodes like carbon felts are widely applied and the electrolytes flow through the electrode from the bottom to the top. At the same time the state-of-charge (SoC) of the electrolytes changes in the same direction as well, meaning that the SoC at the top of the cell is different from the bottom. This leads to the fact that each component of the cell (membrane, felt and bipolarplate) stays in contact with an over the height gradually changing electrolyte.

While this fact might not be a big problem for smaller cells, it is a challenge for the design of large Redox-Flow-Cells. Furthermore, the pressure drop within the cell increases with increasing the height of the cell and might lead to safety and efficiency issues.

To circumvent these challenges as well as challenges with the flow distribution in large cells, TKIS developed a new cell concept. We will present the actual cell design concept and will show the latest results from the current state of development.