The Cambridge Energy Storage Project in Cambridge, Minnesota will be the first commercial deployment of iron-air battery technology. Developed by startup company Form Energy, the battery system will provide 1.5 MW and 150 MWh of multi-day energy storage.
Iron-air batteries are based on the principle of reversible rusting. When discharging, the battery releases energy by breathing in oxygen from the air and converting iron metal to rust. When charging, the battery takes up electrical current that converts rust back into iron and breathes out oxygen.
An individual iron-air battery module is about the size of a washer/dryer set and contains about 50 individual cells filled with a water-based, non-flammable electrolyte. For a utility-scale system like that being built in Cambridge, modules are grouped together in enclosures and hundreds of enclosures grouped together in megawatt-scale power blocks. A one-megawatt low-density system would take up about half an acre of land. High-density systems would be capable of producing more than 3 MW per acre.
The technology has lower costs compared to lithium-ion battery technology but may be best suited as complementary with it since lithium-ion is primarily used for short-duration energy storage while air-iron can store energy for several days.
The system is expected to be operational by late 2025. Great River Energy, the operator of the system, plans to conduct a multi-year study to evaluate the system’s performance and potential for broader development.
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Minnesota co-op breaks ground on multi-day energy storage project
Photo courtesy of Form Energy.
Earth Wise is a production of WAMC Northeast Public Radio
