Vanadium redox flow batteries for the storage of electricity produced in wind turbines

In this work, accelerated degradation charge‐discharge tests have been applied to compare the performance of a bench‐scale vanadium redox flow battery (VRFB), when charged under galvanostatic conditions and under the highly variable conditions of current produced by wind turbines. Wind speed patterns applied for the VRFB charge were obtained during 3 representative days in winter, in Ciudad Real (Spain). The accumulated and delivered charge capacities and the different efficiencies (coulombic, voltage, and energy) were analyzed during 3 charge and discharge cycles. The conversion of the different vanadium species during the charge‐discharge cycles indicated that the operation mode had a strong influence on the performance of the VRFB and helped to explain the charge profiles obtained. Although, similar efficiencies and charge/discharge capacities were found, the VRFB operated in wind‐charging mode performs slightly worse than the VFRB operated in galvanostatic mode. Increased crossover of vanadium species in the negative electrolyte compartment explains the differences found. Nevertheless, it can be concluded that this type of technology seems to be promising for the storage of electricity produced by wind turbines