Battery Technology

Multi-day storage, the pathway to a clean, reliable and secure grid

To run the grid reliably and affordably, we need new cost-effective technologies capable of storing electricity for multiple days. In pursuit of this, we have reinvented and optimized the iron-air battery for the electric grid. The active components of our iron-air battery system are some of the safest, cheapest, and most abundant materials on the planet — low-cost iron, water, and air. Iron-air batteries are the best solution to balance the multi-day variability of renewable energy due to their extremely low cost, safety, durability, and global scalability.

Our first commercial product using our iron-air technology is optimized to store electricity for 100 hours at system costs competitive with legacy power plants. This product is our first step to building a more reliable, resilient and secure electric grid: making low-cost clean energy available when and where it’s needed, even during multiple days of extreme weather, grid outages, or periods of low generation.

Form’s internal analytics predict that over the next decade, achieving Form’s cost and performance targets will unlock tens of gigawatts of demand for multi-day storage in the U.S. and accelerate the country’s trajectory towards a more reliable and resilient, clean electric grid. At such levels of deployment, Form’s technology will catalyze billions of dollars in savings to American electricity consumers.

Technology Applications
  • Firmed renewables over any weather event or season

  • Transmission capacity expansion and optimization without new wires

  • Reliability without thermal generation

  • Resilience during multi-day grid events

A Better World
  • Grid reliability and safety

  • Local economic development

  • Improved local air quality

  • Job creation through manufacturing and assembly

A Closer Look

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

Our modular, scalable multi-day storage system

Each individual battery module is about the size of a side-by-side washer/dryer set and contains a stack of approximately 50 one meter-tall cells. The cells include iron and air electrodes, the parts of the battery that enable the electrochemical reactions to store and discharge electricity. Each of these cells are filled with water-based, non-flammable electrolyte, like the electrolyte used in AA batteries.

These battery modules are grouped together in environmentally protected enclosures. Hundreds of these enclosures are grouped together in modular megawatt-scale power blocks. 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 comprises half an acre of land. Higher density configurations would achieve >3 MW/acre.

Our battery systems can be sited anywhere, even in urban areas, to meet utility-scale energy needs. Our batteries complement the function of lithium-ion batteries, allowing for an optimal balance of our technology and lithium-ion batteries to deliver the lowest-cost clean and reliable electric system year-round.

Key Advantages of Our Technology


Stores energy at less than 1/10th the cost of lithium-ion battery technology.


Pairs well with lithium-ion batteries and renewable energy resources to enable optimal energy system configurations.


Delivers 100+ hour duration required to make wind, water, and solar reliable, year round, anywhere in the world.


Can be sited anywhere for utility-scale needs.


Materials and designs with global scale needed for zero carbon economy.


No risk of thermal runaway. No heavy metals. High recyclability.