A vanadium/cerium redox flow battery is used with two external circuits to ensure a chemical discharge of the electrolytes to maintain on optimum state-of-charge of the battery even in the case of electricity overproduction.

A first reactor is dedicated to hydrogen production whilst the second is dedicated to oxygen evolution.

In the first reactor, the Vanadium(II) solution in sulfuric acid is passed over a catalyst made of Mo2C to generate hydrogen under pressure.

In the second reactor, theCerium (IV) solution in sulfuric acid is apssed over a catalyst made of RuO2 to generate oxygen.

The theory underlying these electrochemical reactions on a floating catalyst will be discussed. Experiments on a 10 kWh scale will be presented.

In addition, we shall present our experience at coupling a 50 kW alkaline electrolyser with a 200kW Vanadium redox flow battery to run a service station for electric vehicles and hydrogen fuel cell cars.