[Portions of this article first appeared in Industry Insights at grpsinc.com]
In the fall of 2021, The Wall Street Journal wrote a piece on Form Energy, a self-described “American technology and manufacturing company,” who claimed they’d made a “breakthrough in long-duration batteries” that were poised to offer a complementary alternative to lithium-ion (LIB) storage for renewable energy grid projects. Their investors, including a who’s-who of technology innovators like Bill Gates and Jeff Bezos, are banking on Form’s ability to build, “the kind of battery that could enable a fully reliable, clean and affordable electric grid year-round.” That’s how Form’s CEO, former Tesla Powerwall developer, Mateo Jaramillo described their technology in a recent email interview for this story.
Four years later, we’re about to find out if Form’s Iron Air technology lives up to the hype because their high-volume manufacturing facility, known as Form Factory 1, is producing their “grid-scale” storage solution in anticipation of their first U.S. battery storage system. Construction on Form Factory 1 began in Weirton, West Virginia in May of 2023. The half million s.f. facility was completed just over a year later, and Form is now about to deploy its first multi-day Iron Air battery installation.
Their investors now include GE Vernova, MIT’s Engine Ventures, and Energy Impact Partners, according to reporting in Engineering News-Record. A spokesperson for Form Energy also named T. Rowe Price as a major investor, saying that they “led our recent Series F round” of capital investments.
Form’s initial commercial Iron Air installation is a pilot project with Minnesota’s Great River Energy expected to go online in summer 2025. Form Factory 1 is deploying its first large-scale package as part of the 1.5MW project, and three more Form storage systems, two 10MW projects for Xcel Energy and a 15MW facility for Georgia Power are projected for 2026 online dates. They have now executed contracts with Dominion Energy, the California Energy Commission, and NYSERDA, as well.
The company’s largest installation, planned for a converted paper & pulp mill in Lincoln, Maine, is due to start construction in 2027. At 8,500MWh, it is expected to be “the largest battery project by energy storage capacity in the world,” according to the Form spokesperson interviewed via email, and is expected to be online in 2028.
What is an Iron Air Battery?
Before delving into how Iron Air battery technology works, it’s worthwhile to remember, first, how LIB technology works, since it is the current king of the renewable energy hill.
A Refresher on Lithium-Ion Battery Technology
Lithium-ion batteries store and release energy by shuttling lithium ions between two electrodes – anode and cathode – through an electrolyte. The process is almost identical to that of traditional lead acid batteries with two key exceptions: Lithium provides a longer lifespan and is considered more reliable than the pack of batteries in your junk drawer. Their high energy density, efficiency, and perceived long cycle life make LIBs the most popular option for storing energy. This is the same technology that is used in EVs, cell phones, and a plethora of chargeable electronic devices.
LIB technology has proven scalable, and at the grid scale, has been a successful storage solution for intermittent renewable energy, making it the storage system of choice for renewables like solar and wind energy.
However, according to Form Energy, “Lithium-ion batteries are currently only capable of cost-effectively storing 4-8 hours of energy. To enable a fully reliable electric gid, we’ll need technologies capable of cost-effectively storing energy at longer durations.” Form Energy’s spokesperson also spoke to the scarcity of Lithium and its vulnerability to supply chain risks.
Plus, that LIB high energy density does come with risk, especially at scale. Thermal runaway is the term used to describe the chain-reaction-like combustion that occurs on the rare occasion that a lithium-ion array catches fire. Thermal runaway is considered so dangerous, due to both its toxicity and extreme temperatures, that the International Association of Fire Chiefs “strongly advises” that no firefighter enter an LIB facility fire location. A power station fire at Moss Landing in Monterey, California in January of 2025 decimated what was “the largest battery storage facility of its kind in the world.”
Iron Air Battery Technology Explained
At its simplest, Iron Air technology operates on a concept Form Energy calls “reversible rusting.”
The cycle is deceptively simple:
- When the Iron Air battery is discharging its energy, the battery “breathes in” oxygen and converts its iron metal (stored inside the battery in a form of iron powder) to rust
- When the battery is charging, the application of an electrical current converts the rust back into iron as the battery “exhales” oxygen
"When a building rusts or a bridge rusts, it is very slowly discharging [energy]," Jaramillo explained. Form's batteries can reverse the rusting process with the addition of electric current, turning rust back to iron and releasing oxygen. When the energy is needed, the battery takes in oxygen, rusting the iron and releasing some energy.
"What we have done is build a device that takes that reaction and harnesses it and lets us manufacture that battery and deploy it in very large volumes," Jaramillo told Newsweek in late 2024.
While critics may decry Iron Air’s size – about the size of a standard washer/dryer set in the U.S., containing stacks of about 30, meter-tall cells, while lithium-ion technology can be much smaller – no one is trying to put Iron Air into cars or smartphones. These batteries are designed to store for multiple days instead of hours, and to discharge large quantities of energy at grid scale.
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Plus, Iron Air batteries are reportedly significantly less expensive to produce and operate. Targeting an average cost of $20 per KWh at scale, this emerging technology offers a significant increase in storage duration, and the base conductive material, iron, is “abundant, nontoxic, and nonflammable,” unlike the chain-reaction thermal runaway combustion of an LIB, for one tenth its cost, per Form’s spokesperson.
“Form Energy is committed to delivering energy storage solutions that ensure safety and long-term reliability for customers and communities, they continued. “Unlike other battery chemistries, such as lithium-ion battery chemistries, Form Energy’s iron-air battery does not undergo thermal runaway.”
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According to Form, their Iron Air technology prevents thermal runaway by use of a water-based electrolyte and a stable reaction process. The battery’s UL9450A safety test, conducted in 2024, was completed successfully, with no flame or thermal event propagation.
These are just a few reasons why Form Energy sees Iron Air technology as an all-round energy solution that moves beyond renewables, able to “store energy from any power source to ensure grid reliability, resiliency, and security.”
How Form Energy Is Helping a Steel Town Retool for a Green Future
Weirton, West Virginia (population18,386) was once a bustling industrial town housing one of the largest steel mills in the world, Weirton Steel. At its peak in 1942, Weirton employed more than 12,000 people. But slower steel production, industry consolidation, and economic pressures reduced operations to the point that only about 900 employees remained in 2023.
As West Virginia Public Radio contributor and daughter of a Weirton Steel employee, Ella Jennings, put it, “It was a place where people always reminisced about the past, because there wasn’t much to look forward to in the present.”
Located just six miles from Cumberland, the town had lost over 10,000 residents as steel production slowed. The company declared bankruptcy, restructured multiple times, went public, was acquired by Cleveland Cliffs, and laid off more than one-third of its remaining 900 employees. Weirton’s Basic Oxygen Plant, or BOP, was demolished in 2019.
One of the reasons Form Energy chose Weirton as the site of Form Factory 1 was the chance to restore economic opportunity in the region. According to Form, the company plans to invest as much as $760 million As of this writing, the facility employs 400 people, according to CEO Jaramillo.
“Form Factory 1 is an example of the manufacturing renaissance that’s possible for America’s future and is already actively emerging across the country. The 550,000 square foot facility was built in just about a year, demonstrating that large-scale, advanced manufacturing can be achieved rapidly and at high volumes right here in the U.S. … By 2028, it will expand to around 850,000 square feet, support more than 750 employees, and have a production capacity of at least 500 megawatts of batteries per year. Situated on the historic site of the former Weirton Steel mill, a cornerstone of America’s industrial past, Form Factory 1 is showing firsthand that America’s greatest manufacturing epoch isn’t behind us – it’s unfolding now.”
According to local reporting in 2024, Weirton’s former owners, Cleveland Cliffs, are now building a new electrical distribution transformer production plant to help maintain, modernize, and adapt the U.S. energy grid. And an economic impact study conducted by the West Virginia University Bureau of Business and Economic Research found that while the company will directly employ 750 people, another 3,356 workers are needed to work in adjacent “supplier industries.” The study expects the net employment result to be about 4,106 new jobs by 2029.
For those in the renewable energy industry, and the energy industry as a whole, Iron Air battery storage systems could prove to be the missing link in the expansion and modernization of the U.S. power grid, and a key player in future manufacturing jobs. Whether they live up to being a tool that helps move toward cleaner power grids and transmission remains to be seen.
