Air-Iron Battery by Form Energy will last for days

Form Energy ​’s 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.

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 novel design based on rusting and de-rusting iron is not an obvious darling for the titans of climate finance. 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.

Canary Media

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.


I don’t understand the hang up on multi day storage. Lithium-ion is perfectly capable of multi day storage. It’s all just energy in and energy out.

The real benefit - assuming the marketing isn’t just hype but reasonably close to reality - is the cost. This type of energy storage is claimed to be significantly less expensive than lithium-ion. It certainly seems to be more environmentally friendly, as the chemicals used are iron, oxygen (taken directly from the air) and water. That should be significantly less damaging than lithium extraction and processing.

It certainly sounds promising.