AI-rewritten: This is a summary of an article from MIT Technology Review, rewritten by AI (Qwen, running locally) to make it easier to read. The facts come from the original article – read it for the full story.

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Form Energy is developing iron-based batteries designed to store energy for up to 100 hours, addressing the need for long-duration storage that lithium-ion systems currently lack. While lithium-ion batteries are popular due to their light weight and high energy density, they rely on expensive metals and typically cannot store power longer than four to six hours. Form’s technology uses a process it calls "reversible rusting," where iron metal converts to rust during discharge to release electrons, and returns to its metallic state when charged.

The company is scaling production at its West Virginia factory to meet commercial demands. Its first project, a 150 megawatt-hour system for Minnesota utility Great River Energy, is scheduled to go online in 2027. Additionally, Form has signed a major deal with Xcel Energy to provide 30 gigawatt-hours of storage for a new Google data center, expected to operate between 2028 and 2031. These installations aim to balance supply and demand during extreme weather events like heat waves or deep freezes.

Form’s goal is to achieve a cost of $20 per kilowatt-hour, making its systems competitive with natural gas alternatives. Although the company has not disclosed current costs, it notes that its existing production capacity of 2 gigawatt-hours per year is far below the 80 gigawatt-hours promised through agreements. To bridge this gap, Form secured new financing in August, bringing total funding to over $2 billion alongside state and federal grants. The technology requires significant space, with each installation needing an acre for every two to three megawatts of capacity.