Form Energy

Its iron-air cells run on reversible rusting, oxidising iron with air from the atmosphere to discharge and converting the rust back to iron to charge, using materials so cheap the company claims a cost per kilowatt-hour a fraction of lithium-ion's. That makes multi-day storage viable, the duration Jaramillo argues is where batteries stop shaving peaks and start replacing thermal power plants. The company manufactures at Form Factory 1, a 550,000 square-foot plant in Weirton, West Virginia built on a former tin mill site, now in production with more than 450 people on site; a September 9, 2026 technician hiring sprint is filling day and night shifts as output ramps. The first commercial system, a 1.5 MW / 150 MWh project with Great River Energy in Cambridge, Minnesota, is still unfinished: Great River Energy's May 2026 integrated resource plan said structures and balance of plant were substantially complete, remaining modules were still awaited, and commercial operation is targeted by the end of 2026. A July 2026 independent site visit found the pad still mostly empty after the initial late-2025 enclosure install. Demand is now driven as much by AI data centers as by utilities. Form has more than 80 GWh of commercial projects under agreement, including a 300 MW / 30 GWh system with Google and Xcel Energy that Xcel calls the largest battery project by energy capacity ever announced, a 12 GWh capacity agreement with Crusoe for AI data centers starting in 2027, and its first deployment outside the US, a 1 GWh project with FuturEnergy Ireland. A separate 85 MW / 8.5 GWh project at a former mill in Lincoln, Maine, backed by nearly $150M in DOE grid-resilience funds, is slated to start construction in 2028. Form has raised more than $2B, including a $750M Series G led by T. Rowe Price that closed in August 2026 (a down round at about $1.75B pre-money), added Wes Sloan (ex-Panasonic Energy Nevada) as COO and Navneet Govil as CFO, has picked JPMorgan and Jefferies to lead its IPO, and plans to go public in 2027. Jaramillo has said the company expects its first meaningful revenues in 2026 and that factory output is allocated into late 2028 or 2029.

formenergy.com↗Updated Sep 15, 2026

1. Aug 122026

   Form Energy raises $750M Series G to scale battery output

   Form Energy said on August 12 it closed a $750 million Series G led by T. Rowe Price, with participation from Sequoia Capital, Janus Henderson, Franklin Templeton, GE Vernova, Coatue and other existing and new investors, taking the company's total funding raised to more than $2 billion. The round funds continued manufacturing scale-up of Form's 100-hour iron-air batteries at its Weirton, West Virginia factory, where a nearly 300,000 square-foot expansion is already under construction, and follows the company's disclosure that its commercial order book has more than tripled to over 80 GWh on demand from AI data center operators including Google and Crusoe.

   TechCrunch ↗FinSMEs ↗

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  Iron-Air Multi-Day Battery

  A grid storage system built from modules the size of a washing machine, each filled with iron electrodes and a water-based alkaline electrolyte. Discharging oxidises the iron with oxygen drawn from the air; charging reverses the reaction and turns the rust back into metallic iron. Because the active materials are iron, water and air, the cost per kilowatt-hour is a small fraction of lithium-ion's, which is what makes 100-hour duration economic. Systems are assembled into multi-acre installations sized from megawatts to hundreds of megawatts.

Employees

~1,000 company-wide

(West Virginia, Massachusetts and California); more than 450 at Form Factory 1 in Weirton

Est. annual revenue

Not disclosed

CEO Mateo Jaramillo said Form expects its first meaningful revenues in 2026 as the Minnesota pilot finishes and factory shipments begin, against an 80+ GWh order book whose large deliveries run from 2027 through 2029.

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Storage duration

100 hours at rated power

roughly 25x a standard 4-hour lithium-ion system

Commercial pipeline

80+ GWh of projects under agreement, more than tripled from ~20 GWh in 2025; reconfirmed as of the August 2026 Series G raise. Factory output is allocated into late 2028 or 2029

First international deployment

Ballynahone Energy Storage

10 MW / 1 GWh iron-air project with FuturEnergy Ireland in County Donegal, targeted online 2029

Largest single project

300 MW / 30 GWh with Google and Xcel Energy - the largest battery project by energy capacity announced worldwide

Total funding raised

Over $2B, including a $750M Series G closed in August 2026, the final private round expected before a 2027 IPO

Series G valuation

About $1.75B pre-money, down from about $3B pre-money in the October 2024 Series F - a down round even as the commercial order book more than tripled. No later valuation has been published.

Form Factory 1

550,000 sq ft in Weirton, West Virginia, in production with more than 450 people on site; nearly 300,000 sq ft expansion under construction toward ~850,000 sq ft

2028 manufacturing target

500 MW / 50 GWh of annual capacity across 1M+ sq ft; current output already allocated into late 2028 or 2029

Utility and data-center customers

Google/Xcel

(300 MW / 30 GWh), Crusoe (12 GWh), FuturEnergy Ireland (10 MW / 1 GWh), Great River Energy (1.5 MW / 150 MWh, COD targeted end-2026), Georgia Power (15 MW / 1.5 GWh), Dominion Energy (8.94 MW Darbytown pilot), Lincoln Maine / Power Up New England (85 MW / 8.5 GWh, construction 2028), NYSERDA, California Energy Commission

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Lincoln, Maine project

85 MW / 8,500 MWh at the former Lincoln Paper and Tissue mill; construction targeted 2028; nearly $150M in DOE grid-resilience funds; sized to power about 65,000 households

Latest debt facility

$270 million closed 21 Sept 2026

(revolver plus Section 45X tax-credit advance). Accordion can raise total credit under the facility to $1 billion; that ceiling is not committed drawn funding. Barclays lead; Citi, Jefferies, JPMorgan, RBC, Societe Generale, Stifel, Wells Fargo in syndicate.

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Cambridge EIA-860M status (August 2026)

Plant 2038 generator BA1: status U, under construction <=50% complete; batteries; 1 MW nameplate; planned December 2027. Not operating.

Darbytown iron-air pilot

Not operating

August 2026 EIA-860M has no battery generator at Darbytown plant 7212 (four gas turbines only, OP). Form Energy share is 4.94 MW / 494 MWh beside 4 MW Eos; late-2026 target not met as of this inventory.

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Form Factory 1 (homepage)

Homepage now says a one-million-square-foot Weirton plant employing over 500 people, versus earlier 550,000 sq ft / more than 450 language.

How past announced dates turned out.

$2.1Bdisclosed across 5 rounds with a stated amount