Vanadium redox (redox flow) batteries (“VRB”) are large scale storage batteries that are ideal for intermittent power sources such as wind and solar. They can be scaled to very large sizes, they have long lives with little maintenance and they can provide power very quickly. The technology is well established and commercial units are available for home and industrial use.
A vanadium redox battery consists of an assembly of power cells in which the two vanadium based electrolytes are separated by a proton exchange membrane. The two half-cells are additionally connected to storage tanks and pumps so that very large volumes of the electrolytes can be circulated through the cell to generate power. Similar to the PEM fuel cell, the bi polar plates in a vanadium redox battery are made out of graphite. It is estimated that 300 tonnes of graphite are required for every mW/hr of VRB capacity.
There are an increasing number of manufacturers and examples of vanadium redox battery installations. Use of these batteries is price sensitive and will increase as costs come down with higher volumes.