Clean energy journalism for a cooler tomorrow

Now Form Energy is using its battery tech to clean up iron and steel

The energy storage startup is adapting its iron-air battery technology to make low-carbon iron, a key input for decarbonizing the steel industry.
By Julian Spector

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(Form Energy)

Form Energy launched in 2017 to tackle one of the biggest problems hindering the clean energy transition: how to cheaply store renewable energy for days on end. In developing its iron-air battery, though, the company stumbled on a potential breakthrough for another notorious climate challenge: cleaning up the iron and steel industries.

Form designed a novel battery that stores clean energy by converting rust into pure iron, and discharges electricity by oxidizing or rusting the iron again. The company now is building out a commercial-scale factory in West Virginia to start mass-producing these novel batteries by the end of the year. But Form’s early-stage R&D engineers started thinking about how to decarbonize the iron that goes into those batteries, and realized the charging mechanics helped out there too: They could prepare iron using electricity rather than high heat and fossil fuels.

Last month, Form’s clean iron proposal was one of 13 projects selected to receive funding from the Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E). Now the team has $1 million to take the technology from benchtop scale to the next level. In short, one of the most ambitious energy storage innovators has entered the colorful and dynamic field of clean iron and steel technologies.

We found a cheaper, more scalable, more efficient process for producing green iron,” co-founder and CEO Mateo Jaramillo told Canary Media. We know that it has a chance to create a ton of value, so we’re going to pursue it.”

Steel production generates approximately 9 percent of global carbon emissions, and much of that comes from the preparation of iron ores as an input. That’s because the furnaces that turn iron into steel can’t take the stuff in the form that comes out of the ground.

Iron has a high affinity for oxygen. Over the four billion years or so the iron has been in the Earth’s crust, it has turned to iron oxide or hydroxide,” said P. Chris Pistorius, a metallurgical researcher who co-directs the Center for Iron and Steelmaking Research at Carnegie Mellon University. To make this material useful for iron or steel applications, it needs to be reduced by removing the oxygen, which yields metallic iron.

Traditionally, steel companies have prepared iron by putting ores in a scorching hot blast furnace with limestone and a purified coal called coke. More recently, some steel companies have switched to another method, called direct reduced iron (DRI): flowing fossil gas over iron pellets in a towering shaft furnace at extremely high temperatures, causing reactions that pull out the oxygen and leave metallic iron, also called sponge iron. It’s efficient both from the point of view of energy use and cost,” Pistorius said. But both systems depend on carbon for heat and to catalyze the necessary transformation, and the resulting greenhouse gas emissions are a big problem for the climate.

Green steel techniques remain in their infancy, but several strategies for cleaning up this essential industry are gaining traction. Steelmaking in electric arc furnaces is already a common practice — in the U.S., these furnaces are in widespread commercial use, primarily because they’re good at recycling steel scrap. Reducing the carbon emissions from these types of furnaces is not technically hard to do — it’s simply a matter of running them on clean electricity. Cleaning up the precursor iron production has proved more challenging.

One of the most promising pathways for mitigating the steel industry’s carbon emissions involves running DRI facilities with clean hydrogen instead of fossil gas; hydrogen can also pull away the oxygen atoms from ores. Then the green iron can feed electric arc furnaces powered by clean electricity, producing green steel.

So far, only the Hybrit plant in Sweden has implemented DRI with hydrogen, but the Biden administration recently awarded two $500 million grants to construct hydrogen-based iron plants in the U.S. The price tag for such facilities runs in the billions of dollars, and they ultimately depend on high-volume clean hydrogen production, which doesn’t yet exist.

Other pathways receiving funding from the ARPA-E grants take radically different approaches, like using lasers or microwave-powered kilns to heat the iron. More similar to Form’s proposal is the electrowinning” technique from startup Electra, which zaps dissolved iron ores to produce plates of solid metal.

Unlike Electra, Form didn’t launch with the goal of producing green iron. Form’s core product is a grid battery that uses powdered iron for the anode and runs the reduction and oxidation reactions back and forth to charge and discharge. The saying goes that if you wield a hammer, everything looks like a nail; Form’s engineers store energy by reducing iron, so they saw green iron production as another opportunity to apply their energy storage technique.

Energy storage is effectively all around us. Iron mines are just discharged piles of iron, if you will,” Jaramillo said. We saw the challenge of the green steel industry as what they need to do is charge the oxides.’”

With that insight, the Form team engineered a system that places powdered iron ore in a low-temperature alkaline solution; adding an electrical current produces powdered metallic iron. This process can be run continuously and at high efficiency, Jaramillo said, and has a strong shot of competing on cost with conventional furnace operations. But furnaces entail a minimum investment in the billions of dollars; Form’s electrolytic technique could be easier to deploy because it can be scaled up in smaller increments.

Any electrically driven iron production will still be energy intensive, due to the fundamental chemical task at hand.

The main electricity consumption is breaking the bonds between iron and oxygen. That’s a fixed baseline that you can’t get below,” Pistorius said. Pistorius surveyed the leading pathways for green steel and found they all clock in at between 3 and 4 megawatt-hours per metric ton of steel produced. A European low-temperature alkaline electrolysis process called Siderwin, which shares some key attributes with Form’s new approach, hits the lower end of that energy-use range.

To compete with fossil-fueled iron reduction, the cost of electricity will have to be very low — something like 3 cents per kilowatt-hour, well below the current U.S. average, Pistorius said. And to actually slash emissions, the electricity itself has to be clean.

Form is very much aware of these dynamics, and is designing its iron electrolysis to integrate directly with variable renewable generation, the company told Canary Media. It also chose a low-resistance cell architecture that the company believes will reduce energy consumption relative to the historic baseline of alkaline electrolysis techniques. Given those factors, Form aims to compete on cost with blast furnaces, even if it has to buy electricity at today’s prevailing industrial rates. 

That cost-competitiveness is something Form still has to prove. But whereas traditional ironmaking has matured over centuries, the newer electrochemical iron producers have lots of room for improvement. And their costs will decline as ever-cheaper renewables flood into the power system. They’re not alone in that: The whole green hydrogen industry is banking on increasingly cheap clean electricity, since that’s the major cost input for it too. Renewables are continuing to get bigger and cheaper; it’s just a question of how cheap they’ll be by the time the green iron techniques are ready for prime time.

Julian Spector is a senior reporter at Canary Media. He reports on batteries, long-duration energy storage, low-carbon hydrogen and clean energy breakthroughs around the world.