MODULAR, SCALABLE MULTI-DAY STORAGE SYSTEM
THE BATTERY CYCLE
The basic principle of operation is reversible rusting
While discharging, the battery breathes in oxygen from the air and converts iron metal to rust
While charging, the application of an electrical current converts the rust back to iron and the battery breathes out oxygen
Each individual battery is about the size of a washing machine. Each of these modules is filled with a water-based, non-flammable electrolyte, similar to the electrolyte used in AA batteries. Inside of the liquid electrolyte are stacks of between 10 and 20 meter-scale cells, which include iron electrodes and air electrodes, the parts of the battery that enable the electrochemical reactions to store and discharge electricity.
These battery modules are grouped together in modular megawatt-scale power blocks, which comprise thousands of battery modules in an environmentally protected enclosure. Depending on the system size, tens to hundreds of these power blocks will be connected to the electricity grid. For scale, in its least dense configuration, a one megawatt system requires about an acre of land. Higher density configurations can achieve >3MW/acre.