Our vanadium redox batteries (VRB®) store energy in liquid electrolyte in a patented process based on the reduction and oxidation of ionic forms of the element vanadium. This is a nearly infinitely repeatable process that is safe, reliable, non-toxic, and can be almost 100% recycled at end-of-life, dramatically improving economic and environmental benefits compared to other lead-acid and lithium based systems.
At the heart of the system are cell stacks, which are each comprised of proprietary ion-exchange membranes, electrodes and flow channels for the electrolyte. External to the cell stacks are is the electrolyte stored in tanks. The electrolyte is circulated through the cell stacks under low pressure. When a charge is applied the resulting electrochemical reaction changes the valence of the vanadium ions in the solution, which can be stored nearly indefinitely. When discharging, the reaction reverses and current is discharged to the connected loads.
The power rating (in kilowatts, kW, or megawatts, MW) of a VRB-ESS® is determined by the number of cell stack power modules installed, while the system's energy capacity is determined by the volume of electrolyte contained in the storage tanks (in kilowatt-hours, kWh, or megawatt-hours, MWh). Adding modules gives more power handling capacity; adding tanks gives more hours of energy storage. The result is a system that has low marginal cost for additional energy capacity, and which can be engineered to precisely fit customers’ requirements.
VRB-ESS can respond to grid conditions within ½ cycle, providing frequency and voltage support in real time, while simultaneously serving longer-duration energy needs.
Benefits
· Virtually unlimited cycle life at full-rated depth of discharge
· Electrolyte that never wears out and is recyclable
· Proven high availability with low-cost operation and maintenance
· Inherently safe design with no risk of fire from sudden, unintended release of stored energy
· Accurate, real-time state of charge measurement
· Ability to transition between grid-connected and microgrid-isolated modes of operation