Tbilisi Flow Battery

Electrical grid operators and utilities alike have taken note of the promise of flow batteries to provide long-term reliability and many more daily hours of usage than other battery storage options, such as lithium-ion or lead acid batteries.

Flow batteries can discharge up to 10 hours at a stretch, whereas most other commercial battery types are designed to discharge for one or two hours at a time. The role of flow batteries in utility applications is foreseen mostly as a buffer between the available energy from the electric grid and difficult-to-predict electricity demands.

The main difference between flow batteries and other rechargeable battery types is that the aqueous electrolyte solution usually found in other batteries is not stored in the cells around the positive electrode and negative electrode. Instead, the active materials are stored in exterior tanks and pumped toward a flow cell membrane and power stack.

Whereas lithium-ion batteries can deliver big amounts of energy in a short period of time (1 to 2 hours), flow batteries have much less power density. That means they are better at delivering a consistent amount of less energy over a longer period of time (up to 10 hours).

There are different types of flow batteries out there, from polysulfide redox, hybrid, to organic, as well as a long list of electrochemical reaction couplings (including zinc-bromine and iron-chromium), though none have reached the performance, efficiency, or cost levels needed for wide scale adoption - yet.