Energy storage startup Form Energy has raised $750 million to expand production in West Virginia, signaling strong momentum behind long-duration batteries as electricity demand climbs.
The company's iron-air batteries are designed to supply power for up to 100 hours, far beyond the short-duration systems common in today's grid. That makes them especially relevant for balancing renewable energy, which is taking a larger share of new power generation in the United States.
Form Energy's approach uses iron-based chemistry instead of materials such as lithium, cobalt, and nickel. During discharge, the system converts iron into rust; when recharged, it reverses the process. This design aims to support large-scale storage with a more accessible material base.
The company has already attracted major customers, including Google, Crusoe, Xcel Energy, and FuturEnergy Ireland. Its commercial backlog now stands at about 80 gigawatt-hours, reflecting rising interest in storage solutions for data centers and grid reliability.
Form says about 80% of its materials come from the U.S., with the rest sourced from Europe and Asia. The Series G round was led by T. Rowe Price with participation from several major investors across climate, technology, and infrastructure-focused funds.
As long-duration storage moves closer to scale, it could help shape a more flexible and resilient energy system for the next phase of electrification.
