The archive · Climate & Energy · Product decision · 2017–2026
Form Energy's iron-air battery bet: first commercial 100-hour grid deployments in 2025
MIT-born startup bet iron, water and air could store 100 hours at ~1/10th lithium-ion's cost; first commercial units hit Minnesota's grid in Oct 2025.
Form Energy
What the business is
Form Energy builds utility-scale iron-air batteries that discharge for up to 100 hours, marketed to utilities as multi-day storage plants that bridge several days without wind or sun.
How it started
The idea began at CERAWeek 2016 in Houston, where MIT materials scientist Yet-Ming Chiang and Tesla executive Mateo Jaramillo discussed the unsolved problem of storing renewable energy across windless, cloudy stretches. They co-founded Form Energy in Somerville, Massachusetts in 2017 with three other founders, targeting storage at roughly $20/kWh with multi-day discharge. By June 2023 Form had its biggest single order — Georgia Power's 15 MW/1,500 MWh system — and about 40 MW/4 GWh of utility contracts.
What happened
Form raised more than $800 million in venture capital by early 2024, then closed a $405 million round in October 2024 led by T. Rowe Price, bringing investor capital past $1.2 billion to fund its Weirton, West Virginia factory. On August 15, 2024 it broke ground with Great River Energy on its first commercial deployment: a 1.5 MW iron-air plant in Cambridge, Minnesota. In October 2025 the first production battery modules began deploying to the site, with the project expected fully operational in 2026.
How it ended up
Still scaling. First commercial units are on the ground in Minnesota, the West Virginia factory is producing, and systems in Colorado, California, New York, Georgia and Virginia were contracted — but full operation of the flagship plant and proof of the promised cost and reliability at scale are still ahead.
Background
Form Energy was co-founded in 2017 by MIT materials scientist Yet-Ming Chiang and former Tesla executive Mateo Jaramillo on a specific bet: the grid needed storage that could cover several days without wind or sun, and the winning chemistry would be the cheapest one, not the densest one. Their answer — rechargeable iron-air batteries that discharge for up to 100 hours by reversibly 'rusting' iron — targeted roughly $20 per kilowatt-hour, about a tenth of lithium-ion's cost.
The bet required becoming a manufacturer before the market existed. By June 2023 Form had won its first major order, Georgia Power's 15 MW/1,500 MWh system, and held about 40 MW/4 GWh of utility contracts. It raised over $800 million by early 2024, then added a $405 million round led by T. Rowe Price in October 2024, pushing investor funding past $1.2 billion and funding its Weirton, West Virginia factory.
The first commercial milestone came in Minnesota: on August 15, 2024, Form and Great River Energy broke ground on a 1.5 MW iron-air pilot in Cambridge, and in October 2025 the first production battery modules began deploying to the site, with full operation expected in 2026. Jaramillo framed the moment as the payoff of 'becoming a manufacturing company' — equipment, yields, quality targets and a cost trajectory.
Form is past the lab-to-product chasm but not yet proven at scale: first commercial units on the grid, a working factory, and contracted projects across six states. The open risk is execution — whether iron-air systems deliver the promised economics and 100-hour reliability in day-to-day utility operation.
What has to be true
- The wedge was cost, not energy density: iron, water and air are abundant and cheap, and weight doesn't matter for stationary grid storage, so Form could attack a price no lithium battery can reach.
- The ~$20/kWh, 100-hour target came from grid modeling showing that multi-day storage below that cost would make wind-solar mixes cost-competitive in resource-rich regions.
- Anchor utility orders (Georgia Power, Great River Energy) came before volume production, proving demand and funding the factory build-out.
- Over $1.2 billion in investor capital financed the unglamorous work — a factory, production equipment, yields and cost curves — which became the real barrier to entry.
What can be applied
Pick a chemistry whose cost floor is set by abundant materials, then target a price no incumbent can reach: the hard constraint becomes manufacturing, not market acceptance.
Aftermath
As of September 2026, Form's first commercial batteries had been deploying at Great River Energy's Cambridge, Minnesota project since October 2025, with full operation of the 1.5 MW plant expected during 2026. The company had raised over $1.2 billion from investors, run its Weirton, West Virginia factory, and contracted systems in Colorado, California, New York, Georgia and Virginia. The open questions were commercial: whether iron-air chemistry delivers promised economics and multi-day reliability at scale, and whether utilities standardize 100-hour assets.
Sources
- Power when the sun doesn't shine
- Press Release: Great River Energy, Form Energy break ground on first-of-its-kind multi-day energy storage project
- Climate solution: Form Energy secures $405M to speed development of long-awaited 100-hour battery
- Form's first 100-hour batteries are hitting the grid
spotted an error? The archive wants to know.
Your turn
You just read one. Describe what you are building, and see who is betting on the same thing.
Free account · 3 free questions · no card