Stealthy storage contender Form Energy reveals secret formula: Iron and air

And it raised another $200 million to get to market.

  • Link copied to clipboard

Form Energy finally lifted the veil of secrecy over its technology that purports to store clean electricity for days on end.

The startup revealed Thursday that it is building iron-air batteries, a technology that has been studied for decades but never commercialized for grid storage. The announcement coincided with a profile in the Wall Street Journal and a $200 million Series D raise led by global steel and mining giant ArcelorMittal.

Subscribe to receive Canary's latest news

We felt that we had made enough progress that it was relevant to talk about,” Form CEO Mateo Jaramillo told Canary Media Thursday.

The company had filed for the patents it needed to secure its intellectual property, he added. And when news broke that a steel company, which sources massive amounts of iron, was taking a stake in Form, some people probably could have connected the dots.

The revelation ended a period of speculation about Form, launched as a sort of energy storage supergroup in 2017. Jaramillo built Tesla’s energy storage business before joining forces with MIT battery expert Yet-Ming Chiang. Along with co-founders Billy Woodford, Ted Wiley and Marco Ferrara, they systematically examined every material that stores electricity to see if it could reach very low costs for very long durations. 

Lithium-ion batteries cost-effectively store power for several hours today, making them useful for shifting solar production into the evening hours. Other startups liberally claim the long-duration moniker for durations of six hours, eight hours, 12 hours, or whatever else they offer. 

Form wants to store clean power and deliver it over 100 hours or more, which would constitute a whole new type of power plant. Jaramillo describes it as competing with gas plants, not batteries.

After all the buildup, iron isn’t the most dramatic substance to reveal. But that’s kind of the point, Jaramillo said.

Boring is what scales,” he explained. We can’t be infatuated with exotic things for [their own sake]. We can only be concerned with and working on relevant technologies with relevant timeframes.”

Now the question is whether Form’s iron-air battery can succeed where similar efforts have failed to achieve the stunning low costs necessary to deliver that vision. And will there be a market for it, if that happens?

Help from a defunct storage venture

The iron-air” system stores energy via reversible rusting.” In discharge mode, the battery pulls in oxygen from the air to make the iron rusty. Running the process in reverse releases oxygen and returns the iron to its pre-rusty state, while charging the system. 

The Department of Energy funded research on this concept by Westinghouse in the 1970s, Jaramillo said. But it didn’t work for commercial needs at the time. Form looked at the challenge afresh in its search for cheap storage materials.

That long history raises the question of why nobody figured out how to make it work after all those years, a charge that applies to long-simmering rival technologies like vanadium flow batteries. 

But Jaramillo frames this scientific pedigree as a positive.

If we had invented the chemistry itself from scratch, that’s a much longer timeline,” he said. What we’re doing is optimizing a technology that had never been commercialized before.”

Form got a boost in that effort a year ago when it bought all the patents and assets of defunct zinc-air battery company Fluidic Energy. Billionaire Patrick Soon-Shiong bought that company in 2018, renamed it NantEnergy, and then quietly shut it down. 

The zinc-air battery was deployed by the thousands, largely in remote, solar-powered microgrids around the world. But its operating profile didn’t find a niche in the broader storage market, and not even $220 million raised or a billionaire’s backing could save it. 

That doesn’t sound like the most auspicious place to find a breakthrough technology. But among the scraps, Form found what Jaramillo called the world’s best air cathode,” honed by Fluidic scientists over a decade. Form no longer needed to wait for its internal effort to reinvent the wheel; it could merge the well-honed cathode with its iron anode.

It saved us a chunk of time and really reduced the risk,” he said.

Abundant iron

The active ingredients, iron and oxygen, are cheap and abundant enough to supply a global long-duration storage boom, Jaramillo argues.

Crucially, Form’s battery doesn’t require complicated transformations of iron in order to function.

The entire steel industry knows [iron] extremely well and is able to provide the kind of thing we need in our battery,” Jaramillo noted. We can scale what we’re doing very quickly.”

Iron flow battery company ESS makes a similar argument about its key ingredient. That company, going public via merger with a special-purpose acquisition company, builds batteries capable of providing 12 hours of storage. Both ESS and Form received investment from Breakthrough Energy Ventures, backed by billionaires including Bill Gates. Those choices now look like a bet on different configurations of iron.

Scarce market opportunities

But Form still needs to install its first project, for Minnesota utility Great River Energy in 2023 (it’s on track, Jaramillo said). Then it needs to figure out manufacturing and how to get to market. 

The latter will involve developing projects and supplying batteries to other power producers, Jaramillo said. Form recently hired RJ Johnson, who led storage development at renewables juggernaut NextEra Energy Resources and later ran Tesla’s energy business.

The new $200 million fundraise will support manufacturing and project development. 

It’s really to go after the market that is materializing very quickly,” Jaramillo said.

That market remains a point that needs to be proven. Since nothing like Form’s product has been deployed thus far, there is no track record of how it fits into the grid ecosystem or how it competes against more familiar power plants. The company literally built new grid modeling tools to show potential customers how to think about Form’s storage.

The market currently supports short-duration storage, almost all of it lithium-ion. Storage developer Cody Hill noted on Twitter that developers face steeply diminishing returns for storage beyond four hours of duration. 

That’s the kind of market Jaramillo insists is materializing faster than many people expect. He has a stable of highly trained MIT energy modelers to support that claim. It’s too early to know if their prognostications are correct, but Form has copious investor dollars to spend proving the thesis.

But Form isn’t planning for today’s market. It’s planning for a grid state where ample renewable generation regularly creates huge surpluses and long droughts of energy. A 100-hour battery can arbitrage between the two.

(Article image courtesy of Form Energy)

Julian Spector is an editor at Canary Media and reports on the rise of clean energy. He worked at Greentech Media for nearly five years, and before that he reported for CityLab at The Atlantic.