The Steel Industry's Decarbonisation Problem Is Harder Than It Looks
Steel production is responsible for approximately eight percent of global carbon dioxide emissions, making it the largest single industrial source of greenhouse gas emissions and one of the most technically challenging sectors to decarbonise because the carbon in blast furnace steelmaking serves a chemical function rather than merely a thermal one. The coke and coal that blast furnaces consume are not simply fuels providing the high temperatures that iron ore smelting requires but chemical reducing agents whose carbon atoms bond with the oxygen in iron oxide ore to produce metallic iron and carbon dioxide as reaction products. Any replacement technology for blast furnace steelmaking must therefore provide both the thermal energy that the process requires and the chemical reducing function that removes oxygen from iron oxide, and the choice of reducing agent or alternative electrochemical mechanism defines the decarbonisation pathway's technical requirements and commercial economics. The hydrogen-based direct reduced iron route, in which green hydrogen replaces the coal-derived syngas used in conventional DRI shaft furnaces to reduce iron ore pellets to metallic iron that electric arc furnaces then melt into steel, is the decarbonisation pathway that has attracted the most investment and policy support and that Stegra's Boden, Sweden plant, described as the world's first full-scale green steel plant producing two and a half million tonnes per year using hydrogen-based DRI combined with downstream EAF steelmaking with its April 2026 construction announcement, represents. The commercial limitation of the hydrogen DRI route is its dependence on green hydrogen whose production at the scale that global steel decarbonisation requires would consume a substantial fraction of the renewable electricity capacity that energy transition planning is also committing to grid decarbonisation, industrial heat electrification, and other uses.
Molten oxide electrolysis is the alternative electrochemical steelmaking approach that eliminates the need for a reducing agent entirely by using electricity to drive the direct decomposition of iron oxide into metallic iron and oxygen through an electrolytic process that operates at the temperatures where iron oxide is molten. The MOE cell applies an electrical current between an anode and a cathode immersed in a molten iron oxide bath, depositing liquid metallic iron at the cathode and releasing oxygen gas at the anode in a process whose only inputs are iron ore and electricity and whose only outputs are liquid steel and oxygen. The elimination of both the reducing agent and the intermediate steps of producing, storing, and distributing green hydrogen creates a direct electricity-to-steel conversion whose simplicity and operational integration advantages over the hydrogen DRI route are the commercial proposition that Boston Metal has built its commercial development strategy around.
Boston Metal and the MOE Commercial Programme
Boston Metal is the MIT spinout company whose molten oxide electrolysis technology has attracted over $400 million in investment from ArcelorMittal's XCarb Innovation Fund, Microsoft's Climate Innovation Fund, BHP Ventures, Aramco Ventures, Breakthrough Energy Ventures, and Baillie Gifford, creating the capitalisation that its commercial development programme requires. Its Series C round of $262 million closed in 2023 with the strategic investor participation that signals the major steel and mining companies' assessment of MOE as a credible commercial pathway rather than a speculative laboratory concept. Boston Metal's commercial development sequence has separated its near-term revenue path from its steel MOE programme by commercialising MOE for high-value metals production at its Brazilian subsidiary Infinium Metals, where the same electrolytic principle applied to niobium, chromium, and other high-value alloying metals produces commercially attractive returns from smaller-scale MOE cells that demonstrate the technology's commercial operability before steel-scale deployment. The inert anode technology that is the critical enabling component for steel-scale MOE, whose anode must resist the highly corrosive molten oxide bath at temperatures above 1600 degrees Celsius without dissolving or introducing impurities into the metal product, is the primary engineering challenge whose solution at production scale is the technical milestone that its steel commercialisation programme depends on.
Electra is the Colorado company whose electrochemical iron production approach differs from MOE in operating at much lower temperatures using an aqueous acidic electrolyte rather than a molten oxide bath. Electra's electrowinning process dissolves iron ore into an acidic solution at temperatures below 60 degrees Celsius, electrolytically deposits pure iron metal from the solution onto cathode plates, and produces the solid iron product that electric arc furnaces convert to steel. The low-temperature operation eliminates the extreme materials challenges of the molten oxide environment and allows the use of renewable electricity directly without the high-temperature thermal management that MOE requires. Electra's $186 million Series B funding round co-led by Capricorn Investment Group and Temasek Holdings in 2025, with participation from BHP, Rio Tinto, Roy Hill, and Nucor, demonstrates the iron and steel industry's commercial interest in the electrowinning pathway as an alternative route to the hydrogen DRI approach that the same companies are also investing in.
The Commercial Case and Energy Intensity
Both MOE and electrowinning convert renewable electricity into iron metal without carbon emissions, but their energy intensities differ significantly. MOE's high-temperature operation requires substantial electrical energy for both the electrolytic decomposition and the thermal maintenance of the molten bath, creating an energy intensity that the process's direct conversion efficiency partially offsets. Electrowinning's low-temperature operation has lower thermal energy requirements but requires the acidic leaching and solution management steps that add process complexity and chemical inputs. The comparative economics of MOE, electrowinning, and hydrogen DRI for green steel production depend critically on the cost of renewable electricity in the producing region, the capital cost of the production facility per tonne of annual capacity, and the premium that green steel buyers will pay above conventional steel prices, whose combination determines the investment return that commercial deployment can achieve at current technology costs and steel market conditions.
Top 10 Companies in Electrochemical and Green Steelmaking Technology Globally
- Boston Metal: US MOE steelmaking company with $400 million raised and ArcelorMittal, BHP, and Microsoft investment; its Brazil high-value metals commercialisation and its pilot MOE steel plant outside Boston create the most commercially advanced molten oxide electrolysis programme targeting green steel without green hydrogen.
- Electra: US electrochemical iron production company with $186 million Series B and BHP, Rio Tinto, Nucor, and Temasek investment; its low-temperature electrowinning process and its Colorado demonstration plant create the aqueous electrolytic iron production approach whose lower operating temperature reduces the materials engineering challenges of molten oxide systems.
- Stegra (H2 Green Steel): Swedish green steel company with its Boden plant announced April 2026 producing 2.5 million tonnes per year of hydrogen-based DRI and EAF steel; its renewable electricity and green hydrogen integration and its EU Innovation Fund support create the largest commercial green steel plant demonstrating the hydrogen DRI pathway that MOE and electrowinning compete with.
- ArcelorMittal (XCarb): Luxembourg steel company with Boston Metal investment through its XCarb Innovation Fund and its own DRI-EAF green steel investments; its global steel market position and its multi-pathway green steel investment strategy create the incumbent steel company's hedge across competing decarbonisation technologies.
- SIDERWIN: EU-funded research project developing alkaline iron electrowinning for green steel; its low-temperature alkaline electrolyte approach and its European steel research consortium create the academic-industrial programme that is developing the electrochemical iron production science that commercial developers like Electra are applying.
- Tenova: Italian steelmaking technology company with DRI and EAF technology for green steel production; its Energiron DRI technology and its electric arc furnace engineering create the established steelmaking technology supplier whose process expertise serves the green steel plants that hydrogen DRI and EAF investment is building.
- Midrex Technologies: US DRI technology company with hydrogen-compatible shaft furnace technology for green steel production; its installed base of DRI plants being converted to hydrogen-ready operation and its licensing model create the dominant DRI technology licensor whose commercial position in the hydrogen DRI pathway differs from the electrochemical approaches.
- thyssenkrupp Steel (tkH2Steel): German steel company with its direct reduction plant at Duisburg producing hydrogen-based DRI for its electric arc furnaces; its 2024 production of the first hydrogen-DRI steel in Germany and its decarbonisation investment create the incumbent European steel producer's commercial hydrogen DRI deployment.
- POSCO: South Korean steel company with HyREX hydrogen reduction technology for green steel and MOE research investment; its HyREX fluidised bed hydrogen reduction process and its green steel commercial roadmap create the Asian steel company's proprietary electrochemical and hydrogen-based decarbonisation technology development.
- voestalpine: Austrian steel company with its greentec steel programme replacing blast furnaces with electric arc furnaces and evaluating hydrogen DRI; its Linz plant EAF transition and its Austrian green steel commercial programme create the European integrated steel company whose operational decarbonisation demonstrates the EAF transition economics that MOE and electrowinning must compete with.