US startup produces first ton of zero-CO2 green steel

According to the World Steel Association, smelting steel releases nearly twice as much carbon dioxide into the air as the steel itself weighs. That puts the steel industry at 7-9% of global greenhouse gas emissions, which has long been a truism. But Boston-based startup Boston Metal has been able to implement a technology to produce steel using electricity, reducing CO₂ emissions to zero.

Image source: Boston Metal

The original steelmaking technology using a non-destructible (inert) anode was developed at the Massachusetts Institute of Technology (MIT). The Boston Metal company was founded by representatives of the institute with the intention of commercializing the development and, in the long term, earning money by selling licenses for the technological process. To demonstrate the capabilities, a small reactor with one anode was created, and production technology with several anodes was tested to increase the volume of steel smelting.

In traditional smelting of iron ore, coke is added to it, which, when burned in a blast furnace, produces carbon monoxide. This gas combines with oxygen contained in the ore (as part of iron oxide) and turns into carbon dioxide, which is released into the atmosphere.

Boston Metal has developed a carbon-free method called molten oxide electrolysis (MOE). This metal production process involves mixing iron ore with an electrolyte in a reactor and then heating it to about 1,600°C using electricity instead of coke. The resulting electrons break down the bonds in the iron ore, purifying it and releasing only oxygen. No molecule of carbon dioxide is produced in the process.

Boston Metal’s single-anode inert anode plant has produced over one ton of steel using only electricity. When the electricity comes from renewable sources, MOE steelmaking is completely green in terms of greenhouse gas emissions.

Because the current reactor can only produce about one to two tons of metal per month, the company plans to build a larger-scale demonstration plant, scheduled to be operational in 2026 and begin operations in 2027. Boston Metal eventually hopes to license its clean manufacturing process to other steelmakers.