This article is part of our special series "The Tough Stuff: Decarbonizing steel, cement and chemicals." Read more.

Electrowinning’ could help win the race to clean up dirty steel

Startup Electra wants to replace blast furnaces with battery-like systems that use acid solution and clean electricity to pull pure iron out of low-grade ores.
By Jeff St. John

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workers in industrial factory
Workers at startup Electra’s pilot facility, which uses electricity and acid to process iron ores and extract pure iron for use in steelmaking (Electra)

For the past 150 years, steelmaking has been a big, hot business centered around enormous blast furnaces that burn metallurgical coal to melt iron. Those furnaces are the chief driver of the industry’s enormous carbon footprint; it’s responsible for 7 to 9 percent of human-caused global greenhouse gas emissions.

But Sandeep Nijhawan and Quoc Pham, co-founders of Electra, see a far different future for the steel industry. Instead of massive blast furnaces, Electra uses electrochemical devices similar to batteries that can produce pure iron at temperatures well below the boiling point.

These devices can be laid out in modular fashion at many different sites instead of consolidated at a handful of huge ones, giving the industry a new option for making iron for steelmaking without spending billions of dollars on a massive new factory in one go.

We are a clean iron company,” said Nijhawan, CEO of the Boulder, Colorado–based startup. We don’t make steel — we make iron to make steel.” But 90 percent of emissions from steel are from the refinement process for iron,” he said, and that’s where 90 percent of the energy is consumed.”

The traditional way to make steel is to use fossil fuels to heat furnaces to 1,600 degrees Celsius to smelt iron; 70 percent of the world’s steel is still produced this way. Most companies working to produce green steel plan to use hydrogen to process iron.

Electra, instead, dissolves iron ores into an aqueous solution, then zaps that solution with electricity to separate and collect pure iron molecules while removing impurities. No fossil fuels or hydrogen required.

This process is known as electrowinning, and it’s already being used to produce significant amounts of other critical metals such as copper, nickel and zinc. But Electra says it has developed a system that uses electrowinning to pull pure iron from iron ores, including those that are too impure to cost-effectively process via other commercial-scale means.

The company’s pilot tests have shown it can produce plates of pure iron. These are ready to be fed into electric arc furnaces — a well-developed alternative to blast furnaces that today are used mostly to turn scrap steel into new steel. Electric arc furnaces already produce steel with far lower carbon emissions than blast furnaces, and emissions would be reduced further by using electricity from zero-carbon sources. Feed iron made via Electra’s carbon-free process into low-carbon electric arc furnaces, and you’ll have a dramatically cleaner way to make steel.

A year ago, Electra raised $85 million to carry out its plans. Its backers include not just climatetech investors like Bill Gates–founded Breakthrough Energy Ventures, Amazon, Temasek and S2G Ventures, but also Nucor, the biggest steelmaker in the U.S., which exclusively uses electric arc furnaces.

When paired with Nucor’s [electric arc furnace] technology, Electra’s green iron presents a unique opportunity to dramatically decarbonize our own operations and those of the steelmaking industry at large,” Nucor says.

How Electra stacks up against other pathways to green iron and green steel

There’s good reason to believe that electrowinning offers a viable pathway for green steel, said Dan Steingart, a professor of chemical metallurgy at Columbia University who served as Electra’s chief scientist in 20212022 and is now a technical adviser to the company. In particular, it offers key advantages compared to the other methods now being pursued, he said.

One alternative method, which Steingart described as the heir apparent” to today’s steel industry, is the direct reduction of iron via hydrogen. DRI using fossil gas already produces about 10 to 15 percent of the iron used in steelmaking in the world today, he said. Converting from using fossil gas to using hydrogen is a nontrivial” effort, he said, but it’s the most straightforward drop-in” replacement. DRI is at the core of the biggest green-steel projects in the world, such as the H2 Green Steel and Hybrit plants in Sweden.

But the hydrogen DRI process poses challenges for the companies investing billions of dollars to bring it to commercial scale. The most obvious is the need for low- or zero-carbon hydrogen, which is currently in short supply and expensive. Using hydrogen in lieu of fossil gas to produce direct reduced iron can more than double the cost, Steingart said. It can also be difficult for a hydrogen-fueled DRI process to effectively use lower-grade iron ores as inputs, he said, which could add to the challenge of supplying the steel industry with the iron it needs.

The second alternative method for producing green steel is molten oxide electrolysis, or MOE, which involves using electric currents to heat iron ore to around 1,600 degrees Celsius to drive chemical reactions. MOE eliminates the need for hydrogen by electrifying the process of converting iron ore into iron suitable for steelmaking. MIT spinout Boston Metal is pursuing MOE, and it landed $262 million in September to scale up its first projects targeting the niche markets for higher-value metals such as niobium.

It’s a very clever process,” Steingart said of MOE — but he cautioned that it also has drawbacks. To be zero-carbon, MOE needs to use 100 percent zero-carbon electricity. But because the electrolytic reaction in MOE requires molten metal to be kept at temperatures at least as high as those reached in blast furnaces, intermittent renewables are not a great fit. If the process freezes, it takes a very long time to restart it,” he said.

Electrowinning, by contrast, can be done at far lower temperatures — about 60 degrees Celsius for Electra, approximately the temperature of a cup of hot coffee. We needed to set up a process that works at low temperature…because we need to integrate renewables,” Nijhawan said.

Electra’s process can also be stopped and started, rather than needing to maintain a constant supply of energy to prevent molten metal from hardening, the CEO said. That means that it can run when wind and solar power are available and stop when they aren’t, rather than relying on a source of zero-carbon energy that can be provided continuously.

Cracking the code for electrowinning iron 

Electra is not the only company trying to achieve a scalable and cost-effective approach to electrowinning iron. A research effort in Europe called Siderwin has explored an electrowinning process that uses an alkaline electrolyte, as opposed to Electra’s acid-based process. Fortescue, the Australian iron mining giant that also has a multibillion-dollar clean-energy and green hydrogen business, announced in March that it has successfully produced pure iron using an electrolysis process developed in its labs — and the way the company describes it sounds a lot like electrowinning.

Electrowinning — the process of reducing metallic ores to the metals — has been around for hundreds of years,” said Travis Lowder, a project manager at the U.S. Department of Energy’s National Renewable Energy Laboratory.

We’ve industrialized electrolytic processes, especially for aluminum — but we haven’t done so for iron-making, although there’s been research around this for quite a while,” he said. But now that even steelmakers recognize the need to decarbonize, you’re getting more conversation around, What can the process do for us?’”

However, iron ores are far harder to process via electrolysis than copper, nickel, zinc and other metals commonly refined via electrowinning.

There are two primary reasons for this, said Pham, the Electra co-founder who now serves as chief technology officer. The first is that iron oxide — the primary form of iron ore — is very, very slow to dissolve in acid. Even with a concentrated acid, you can spend weeks — or even years — to get a solution.” The second, and related, problem is that once dissolved, the iron ions tend to crash out” of a solution before all the impurities the process is meant to remove are gone.

These barriers almost ended Electra’s work before it began, Pham said. I thought it would be the shortest-lived startup I ever started.”

The answer that Electra came up with is kind of our secret sauce,” he said, although some details are available via the company’s patents. We found a very simple, elegant way to alter” the matter state of the iron ore by decreasing the amount of time it takes to dissolve it and honing the process to deal with the most difficult impurities.”

That innovation has also made it possible for Electra to work with far lower-grade iron ores than can be used for steelmaking today, Nijhawan said. We wanted to solve for a very major constraint in the steel industry — that we’ve been running out of high grades of ore that can directly go into steelmaking processes.” Nucor highlighted Electra’s ability to use low-cost, abundant ores, which are commonly treated as waste today” as a factor in its decision to invest in the company.

The shortage of high-grade iron ores also presents a major hurdle to scaling up hydrogen DRI processes, Nijhawan noted. That’s because, unlike blast furnaces, DRI processes can’t add fluxes” to the mix— materials that interact with iron ore to draw out impurities. Instead, with DRI, the impurities in the iron ore are actually getting concentrated with the iron.”

A 2022 report from the Institute for Energy Economics and Financial Analysis states that a lack of high-quality ore could hinder a faster switch to DRI technology this decade as well as delaying longer-term targets to significantly ramp up DRI operations to reach net-zero emissions targets by 2050.”

Electra’s process, by contrast, can use both lower-grade iron ores suitable for blast furnaces and ores with impurities that currently bar them from being used for steelmaking altogether, Nijhawan said. Those include mine tailings and ores mined but left unused. The only reason we call it waste is because they have more impurities than [steelmakers] want for commercial grade,” he noted.

Cutting costs and charging toward commercialization

It was very clear to us from the beginning that we have to invent a process that’s not only sustainable and green, but can be economic without any subsidies,” Nijhawan said.

Electra also aims to eliminate the need for the green-steel industry to charge a green premium,” or a higher price than its legacy competitors charge for standard products.

Nijhawan sees opportunities for Electra to cut not just the cost of making green iron but also the cost of building the facilities to produce it. Today, iron ore and energy are responsible for about three-quarters of steelmaking costs. But the colossal costs of building new large-scale facilities — DRI plants, green hydrogen systems and supply chains, and mining operations that can provide the higher-quality ore required for the hydrogen DRI process — are also a daunting barrier.

Electra’s technology skirts the need for enormous capital investments — at least in its early stages. It’s an electrochemical system,” Nijhawan said. The way we build capacity and scale is the same way you build capacity of an EV pack.”

This modular approach could allow the steel industry to avoid sinking gigantic amounts of money into huge, one-off facilities, he said. That’s a vital consideration in a highly cost-competitive global industry.

Steingart, whose research has focused on battery chemistries, also highlighted the similarity between EV batteries and Electra’s process. The power plant in a classic Corvette is an enormous V8 that you feed gasoline into,” he said. In a modern Tesla, the actual power plant is 10,000 lipstick-container-sized cells that are working in concert to give you more efficient power than what that Corvette could ever give you.”

We’re asking to do the same thing with iron,” he said. Today, you have a big blast furnace. How do you beat that with a billion smaller efforts?” 

There are certainly technical challenges to scaling up an alternative production method, Steingart acknowledged. But there’s not a fusion-like scientific question,” he said.

By the end of this year, Electra expects to have built its first module capable of producing what Nijhawan called industrial-scale plates of iron.” That process works almost identically to how copper and zinc electrowinning systems work today, he said. The pure metal ions adhere to a plate. Those plates are removed by cranes, and metal — about 100 kilograms per plate — is stripped and collected for shipment to electric arc furnaces.

Electra’s total funding to date is enough to move ahead on this plan, according to Nijhawan. In fact, the $85 million capital raise last year was more capital than what we needed,” he said. I had a hunch the capital markets were going to tighten. We took that buffer to be prepared for that eventuality.”

This is a capital-intensive business, of course,” he said. As soon as we can reduce the next level of risk, we go get more capital.”

Nijhawan noted that current government policies meant to drive the decarbonization of the steel industry don’t offer the same support for novel methods like Electra’s as they do for the hydrogen DRI processes now seeing the largest private-sector investment. Namely, both the U.S. and the European Union have created significant incentives for producing low- to zero-carbon hydrogen and capturing carbon from industrial processes.

But if I do not use hydrogen, or produce carbon emissions, I do not get a tax credit,” he said. Specifically, Electra is not eligible for the tax credits for clean hydrogen and carbon capture created by last year’s Inflation Reduction Act.

Nijhawan noted that other federal programs, such as the Department of Energy’s industrial-decarbonization demonstration grant program and the low-interest loans on offer from DOE’s Loan Programs Office, could help fill that gap.

Still, the federal tax credits for hydrogen production and carbon capture will put Electra in the position of competing against steel that doesn’t have any carbon penalty to it,” he said, using an incumbent process that’s 150 years old, with fully depreciated plants.”

In that light, partnerships like Electra’s work with Nucor may provide the clearest view of how its approach to green iron production will scale up to compete with blast furnaces.

As Leon Topalian, president and CEO of Nucor, said in a December statement on its investment in Electra, Just as Nucor changed the face of the steel industry 53 years ago with our first electric arc furnace, successfully developing and scaling up a zero-carbon iron product is the type of transformative technology that could change the steel industry as we know it.”

Jeff St. John is director of news and special projects at Canary Media. He covers innovative grid technologies, rooftop solar and batteries, clean hydrogen, EV charging and more.