The choice for hydrogen and bromine
From all different chemistries that theoretically could be used to design a flow battery, Elestor has selected hydrogen and bromine as active materials. This leads to several advantages.
The choice for hydrogen and bromine is purely driven by Elestor’s mission to build a storage system with the lowest possible storage costs per kWh. While taking full advantage of the typical flow battery features, this mission cannot be accomplished without an inexpensive chemistry.
Hydrogen and bromine are abundantly available on a global scale. The supply is not restricted to geographical availability, and cannot be dominated by a small group of suppliers (unlike Lithium, Cobalt and Vanadium).
The above factors add up to very low-priced active materials. Not only for today, but for decades to come, when large volumes are required for high volume production of hydrogen bromine flow batteries.
Another advantage of selecting hydrogen and bromine is that these enable a high power density [W/m2] as well as a high energy density [kWh/m3], both contributing to the reduction of storage costs per kWh.
Below image depicts Elestor’s electrochemical cell configuration:
The heart of all Elestor’s storage systems is the cell stack. This stack consists of a number of individual electrochemical cells as shown above, connected in series.
Each membrane in this stack is on one side in contact with the electrolyte circuit, an aqueous solution of HBr and Br2, and on the other side with a hydrogen (H2) gas circuit. Both active materials circulate in a closed loop along their own respective side of the cell. The electrolyte (HBr/Br2 solution) and hydrogen (H2) circuits are separated by a proton-conductive membrane.
Nothing goes in or out… except electricity!
Since the chemical reaction of Elestor’s storage systems is 100% reversible, its storage capacity [kWh] remains unchanged during the lifetime. While (dis)charging, the active materials are only used, not consumed, and in fact only the chemical composition of the electrolyte reservoir and the pressure of the hydrogen tank changes during the (dis)charge process.
Consequently, once a storage system has been installed and the individual reservoirs have been filled, there is no need to access the reservoirs anymore:
The chemicals remain in the system without the need for human intervention, inherently ruling out risks related to human error if handled improperly.
Elestor’s storage systems are 100% self-contained, and nothing goes in our out… except electricity!