A battery that never moves does not have to be light and small.
Current batteries are designed for portability, which is irrelevant for the grid.
While batteries such as lithium-ion are optimized for size and weight, flow batteries are optimised for cost and scale.
Lithium-ion batteries rule the grid. The problem is they are not designed for it.
Their air sensitivity means they are manufactured as individual small cells to be wired together. A car battery is actually 7000+ cells. Putting them together adds cost, which means lithium-ion batteries become more expensive the bigger they get. Flow batteries are made to become less expensive per unit of energy the bigger they get.
For the grid, that just makes sense.
Flow batteries are big. NASA invented flow batteries in the 1970s, and they are the world’s largest batteries.
In a flow battery, the charge storage molecules (+, -) are dissolved in a liquid, stored in a tank, and flowed over electrodes in a separate stack when charging or discharging.
The capacity (number of molecules; duration of backup) is decoupled from the power (size of electrodes; wattage), allowing each to be independently sized. This means that the duration and wattage of flow batteries are easily tailored to the application.
You don’t pay for what you don’t need.
Why aren’t flow batteries widespread?
Though the architecture of flow batteries has existed for decades, their vanadium-based chemistry is highly corrosive. This corrosivity leads to extreme costs in every component.
Our mild, salt-water based chemistry enables our batteries to be built from inexpensive, standard industrial equipment.