Introduction

Redox flow batteries are excellently suited for intermediate storing of electricity in hybrid PV and wind mini-grids and grid connected applications like in buildings. With their advantageous properties, they present a promising alternative to conventional battery-based storage units or also hydrogen storage via combined electrolyser and fuel cells. Particularly the so-called all-vanadium redox flow battery (VRFB) features essential advantages compared to conventional electric storage units: Separation of the conversion and storage units, high electric efficiency, good cycling stability and thus long lifetime, and no degradation effects in the electrolyte arising from cross-contamination via the membrane.

Image 1: Principle of a vanadium redox flow battery

Within the European project MESSIB, potential of the all-vanadium redox flow battery is investigated, starting from system concepts for different applications, cell and stack design, fluid simulations, component development and construction, development and implementation of optimised operating control strategies within a “smart redox flow control”, stack and system characterisation as well as simulation of these storage units. The final result will be the installation in the “solarhaus” in Freiburg to show the advantages of the MESS technology.

Image 2: Overview of the system integration into „solarhaus“ in Freiburg

Design, characterisation and operation strategies of 1 KW all-vanadium redox flow battery