Form Energy wins $450M to rust iron for multiday energy storage

The long-duration storage startup is on a fundraising tear as it validates its iron-air battery technology and scouts locations for a U.S. factory.

A rusty metal surface that is dark red and blue
(Jimmy Ofisia/Unsplash)
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Form Energys effort to commercialize multiday clean energy storage got a major boost from a $450 million fundraise Tuesday.

The Series E round, which brought in a staggering sum for an unconventional grid-storage hardware startup, will carry Form out of its current precommercial state. The company, which produces iron-air batteries, will double its staff headcount from its current level of 326 as it plows through the validation and testing required to sell a warrantied product. Simultaneously, Form is finalizing the location for its first commercial factory, which will begin manufacturing batteries in the U.S. within two years, CEO and co-founder Mateo Jaramillo told Canary Media.

We expect to be generating meaningful revenue in 2025,” said Jaramillo, who led Tesla’s energy-storage business before leaving in 2016 to tackle the challenge of multiday energy storage.

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The business proposition at Form is essentially to rebut the tired critique of renewable energy — that the sun doesn’t always shine and the wind doesn’t always blow. If Form’s battery works like it’s supposed to, it will store renewable energy so cheaply that a power plant can deliver emissions-free energy around the clock for days on end. That could create a viable alternative to fossil-fueled plants for ensuring a 24/7 supply of reliable electricity as the grid decarbonizes.

a large industrial facility comprising many white rectangular metal boxes
An artist's rendering of Form Energy's long-duration storage technology (Form Energy)

Lithium-ion batteries are used for nearly all new grid-storage installations today, but they cannot cost-effectively store energy for more than a few hours. Long-duration energy storage that can deliver power for days represents a fundamentally new type of product.

We’re trying to zag while everybody is zigging,” Jaramillo explained.

Energy-storage investors tend to avoid anything with a whiff of newness about it. A novel design based on rusting and de-rusting iron is not an obvious darling for the titans of climate finance. But Form is graduating out of the venture-capital space and drawing growth equity from some massive institutions. TPG Rise Climate, a $7.3-billion fund run by veteran private equity firm TPG, led this round, joined by Singapore’s GIC and the Canada Pension Plan Investment Board.

Since its last fundraise — $200 million, scarcely a year ago — Form completed the design of the battery it will soon ship to customers. It is currently making this battery on a pilot manufacturing line for internal validation purposes. The forthcoming factory will take that production design and manufacture it at high volume.

Form scouted 100 possible sites across 16 states and narrowed its search to three states. Key criteria include great logistics, land availability and a strong labor pool, Jaramillo said. 

While the search for a factory site wraps up, a whole wing of the company is running tests to validate the product and make it bankable.” Form needs to gather enough data to convince someone to warranty the device, which is necessary for customers to secure low-cost financing to purchase it.

Bankability is the threshold that we have to achieve for being able to deploy energy-storage systems at large scale,” Jaramillo said. 

The startup modeled its reliability testing on processes the automotive industry uses to ensure vehicles and all their components are safe enough to put on the road. To oversee this effort, Form hired Paul Hanson, who previously managed validation at Tesla and Bentley. His team is running iron-air batteries through high-temperature endurance trials, temperature shocks, excessive humidity and other scenarios.

As it sprints to market, Form is managing its testing push, ongoing technological improvement, factory buildout and commercial negotiations more or less simultaneously. In theory, that means that when Form completes its validation tasks, it can quickly push out warrantied products to customers.

It all happens in parallel; we don’t have time to do things sequentially,” Jaramillo said. Our partners are all with us on this parallel journey together.”

The first field deployment — a 1-megawatt/150-megawatt-hour pilot for Minnesota utility Great River Energy — was scheduled for late 2023. Site preparation is underway, Jaramillo said, but completion is now expected in 2024. Form is also working with utility Georgia Power on installing iron-air batteries, but that project is still navigating the regulatory process.

Julian Spector is senior reporter at Canary Media.