Vanadium redox flow batteries (VRFBs) are fairly unique in the battery world.
They work by taking advantage of the natural properties of vanadium, a metal with four different oxidation states. But rather than using the metal in a solid state, vanadium electrolyte (a liquid solution) is used for both half-cells and the configuration is divided by a proton exchange membrane. Typically, massive tanks filled with vanadium electrolyte are connected, pumping the solution through at high volumes to charge or discharge.
This unique setup gives VRFBs a few interesting advantages for something like grid-scale energy storage:
As a result, VRFBs can be used in a variety of energy storage applications such as peak-shaving, load leveling, microgrids, wind and solar, off-grid power supplies, and uninterruptible power supplies.
VRFBs are getting more attention from utilities companies, and large battery projects have already been announced.
The most notable vanadium-flow battery is probably a 200 MW system being built on the Dalian peninsula in China, which will serve 7 million residents. Costing $500 million, it’ll be used to peak-shave approximately 8% of Dalian’s expected load by 2020. This battery system will be the world’s largest, and it will single-handedly triple China’s grid-connected battery storage capacity.
According to Chinese firm Azure International, the market projection for VRFB demand (by MW) in the top 10 countries is growing at an 80% CAGR from 2013 to 2020, ultimately culminating in more than 7,000 MW of vanadium-flow capacity needed in 2020.
This demand could be even more substantial than that if the price of vanadium electrolyte could be reduced – it makes up about 30-50% of the cost of each battery alone.