MIT spinout Boston Metal has powered up its electricity driven steel production reactor and made over a ton of metal in a crucial step toward commercializing its process. With clean electricity, the process could make steel with zero CO2 emissions.
According to the World Steel Association, steel production releases almost twice its weight in carbon dioxide (CO2) pollution. Specifically, it says, for every one metric tonne of the metal produced, 1.92 metric tonnes of the greenhouse gas is released. That accounts for between seven and nine percent of global CO2 emissions.
This is because in the ore found in nature, iron is bound to oxygen, creating iron oxide, more commonly known as rust. To begin its journey into steel, the ore is placed into blast furnaces where a type of coal known as coke is burned. Carbon monoxide from the burning coke combines with the oxygen to strip it away, purifying the iron for use as steel but also forming the planet warming greenhouse gas, carbon dioxide.
Joining other efforts to decarbonize the steel-production process such as those using hydrogen to refine iron ore, Boston Metal has pioneered a process known as molten oxide electrolysis (MOE).
This method of producing the metal involves combining iron ore with an electrolyte in a reactor and then using electricity instead of coke to heat the mix to about 1,600 °C (2,900 °F). Doing so causes electrons to split the bonds in the iron ore to purify it while outputting only oxygen. Not a single molecule of carbon dioxide is released during the process.
If the electricity that drives the reaction is provided via a clean method such as wind or solar, then the molten metal that results would be completely carbon neutral.
The key to the success of the recent test that led to the creation of a ton of molten metal is Boston Metal's inert anode which can drive the electrical process in the reactor without degrading. To scale the process, multiple anodes are required, and the recent output of the Woburn, Massachusetts-based factory proves that such a multi-anode approach is effective.
“We are the only company with a direct and scalable approach to more efficient and clean steelmaking, and I can now say that tonnage steel is flowing from our multi-inert anode MOE cell,” said Tadeu Carneiro, CEO of Boston Metal. “With this milestone, we are taking a major step forward in making green steel a reality and we’re doing it right here in the US, demonstrating the critical innovation that can enhance domestic manufacturing.”
Because the current reactor can only make about a ton or two of material per month, the company plans to build an even larger demonstration plant set to come online in 2026 and begin operations a year later. Ultimately, Boston Metal hopes to license its green production process to other steel manufacturers.
You can watch the molten metal flow from Boston Metal's test plant in the following video.
Sources: GlobeNewswire; Boston Metal; MIT Technology Review
Mr. Google says, "The average steel smelter output varies widely depending on the type of smelter and its capacity, with electric arc furnaces (EAFs) typically producing around 1.5 million tonnes per year and mini-mills ranging from 50,000 to 3,000,000 tons per year. "