A critical factor in designing flow batteries is the selected chemistry. The two electrolytes can contain different chemicals, but today the most widely used setup has vanadium in different oxidation states.
[pdf] Form Energy will develop a long-duration energy storage system that takes advantage of the low cost and high abundance of sulfur in a water-based solution. Previous MIT research demonstrated that aqueous sulfur flow batteries represent the lowest chemical cost among rechargeable batteries.
[pdf] Gham Power together with its partners Practical Action and Swanbarton have officially been awarded a project by United Nations Industrial Development Organization (UNIDO) to install one of the largest energy storage systems in Nepal, with a total battery capacity of 4MWh.
[pdf] 
