Form Energy’s iron-air battery operates by driving a rusting reaction forward and backward electrochemically.
Photographer: Cayce Clifford for Bloomberg Green
Why Rust Is the Future of Very Cheap Batteries
The clean energy transition will require a carbon-free grid, and a lot of batteries. Form Energy is betting rust can help.
When Billy Woodford and his friends set out to build a new kind of battery that could replace a coal plant, their breakthrough technology took inspiration from the disposable hand-warming sacks that spectators use at football stadiums. The battery’s key ingredient: rust.
Woodford’s startup, Form Energy Inc., went into business in 2017 with a clear and ambitious goal. The battery needed to soak up renewable energy during the day and release it at night, and to keep running after sunset and on windless days. A lithium-ion battery, like those in EVs and smartphones, would work, but no utility can afford to run that type of battery on the grid for more than a few hours. Utilities need one that will also be cheap enough to deploy for 100 hours or more. “You can have pretty much any battery do any duration on the grid,” says Mateo Jaramillo, who worked at Tesla Inc. before co-founding Form and is today its chief executive officer. (Woodford is chief technology officer.) “It always comes down to cost.”