WEIRTON, W.Va., July 13 — A startup founded by a former Tesla executive and an MIT professor is working on a battery technology that stores energy using iron and oxygen, through a process the company describes as reversible rusting. Form Energy, established in 2017, aims to provide long-duration energy storage for up to 100 hours at a target cost that investors say could reshape how utilities manage power during stretches of low wind or cloudy weather.
The company broke ground in 2023 on its first manufacturing facility here in Weirton, West Virginia. That plant is designed to produce 2 gigawatts of battery capacity per year.
The project is backed by a $760 million investment from a group that includes Breakthrough Energy Ventures and the U.S. Department of Energy’s Loan Programs Office.
How the iron-air battery works
The technology relies on a chemical reaction between iron and oxygen. When the battery discharges, iron rusts — turning into iron oxide. When electricity is applied to charge it, the process reverses, turning the rust back into iron and releasing oxygen.
The company says this cycle can store energy for multiple days, filling a gap left by lithium-ion batteries, which typically provide four to six hours of storage. Form Energy’s co-founders are Mateo Jaramillo, a former Tesla executive, and Yet-Ming Chiang, a professor at the Massachusetts Institute of Technology.
The two have positioned their iron-air battery as a complement to lithium-ion systems rather than a replacement.
Pilot projects with utilities
The company has signed contracts with two utilities for pilot projects. Great River Energy, based in Minnesota, and Xcel Energy, based in Colorado, are both working with Form Energy to test the technology in real-world grid conditions. These early projects are designed to demonstrate whether the battery can reliably provide multi-day backup during periods when renewable generation drops.
The encouraging part for energy planners is the target cost. Form Energy aims to deliver storage at $20 per kilowatt-hour, a figure that, if achieved, would undercut most existing long-duration storage options.
But the technology is still in its early stages, and the company has not yet disclosed whether its pilot projects are meeting that cost target. What to watch next: whether the Weirton factory ramps up to its full 2 GW annual capacity on schedule, and whether the pilot projects with Great River Energy and Xcel Energy lead to broader commercial contracts.
For now, the approach offers a measured, evidence-based path toward longer-duration energy storage — one that does not rely on lithium or cobalt, and that uses materials that are abundant and inexpensive.
Sources
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