Pilot project with potential

Green power requires new technologies. This not only concerns the expansion of renewables but also storage of power generated from renewable energy sources. With this in mind, RWE is working on different storage solutions, including a redox flow pilot project named Panta.rhei which will be set up in the former Fuel Cell Pavilion at the RWE Campus. The project will involve 30 redox flow modules offering a total capacity of 130 kW. The unit’s peak electrical output will be slightly higher at 240 kW.

The project team is not starting from scratch. A number of studies and findings on redox flow technology exist which see a huge potential in the future. After all, batteries are essential to a successful energy transition: They can temporarily store green power and thus balance intermittent generation.

How do redox flow batteries work?

The basic principle of a redox flow battery is always the same: Two containers contain different liquids, namely the electrolytes. These are connected via two stacks which exchange ions between the two electrolytes with the help of an electric current. One side is chemically reduced, the other side oxidized. The process was the inspiration for the name. If the reaction is reversed, the ions flow back again and produce electricity. 

High capacity, (still) high costs

The advantage of redox flow batteries is that power and capacity can be scaled independently of each other. Moreover, this technology ages much more slowly than conventional batteries. The amount of power delivered by the battery depends on the size of the stacks. Depending on the size of the tanks, up to several gigawatt hours of electricity from renewables can be stored.
For the time being, the individual modules as well as production capacities are still too small resulting in a relatively high price for the power stored. But that can change quickly, as we have seen with lithium-ion batteries. Growing demand could lead to lower prices and a significant increase in production capacities.