A Cleaner Way to Make Steel

Every year, global steel manufacturing produces more than a billion tons of carbon dioxide, a major greenhouse gas that contributes to global warming. Donald Sadoway, a professor of materials science and engineering, is hoping to make that ancient history, with a steel-manufacturing process that does not emit carbon dioxide.

Steel, which is iron that contains a minute amount of carbon for strength, is currently produced in two steps. First, iron ore and distilled coal are heated in a furnace, a process that produces carbon dioxide and an impure form of liquid iron. Then oxygen gas is passed through the molten iron in a second furnace to remove excess carbon and other impurities, creating steel and additional carbon dioxide. In Sadoway's process, material derived from iron ore is placed in a special container along with a solvent. Two electrodes are immersed in the solvent bath, and an electrical current is passed through the iron. Oxygen gas, which can be harnessed and marketed, forms at one electrode, and pure liquid iron is produced at the other. Later, a small amount of carbon is added to the iron.

Sadoway's prototype container is about the size of a coffee cup, but with a 2003 Innovation Grant from the Deshpande Center for Technological Innovation, he is scaling it up to the size of a 19-liter bucket. The final prototype will need to accommodate tons of iron ore, but industry representatives are already interested. Faced with the possibility of steep environmental taxes, a leading European steel company put Sadoway's method on its short list of alternative processes. If the method becomes commercially viable for steel, Sadoway says, it could be useful in producing other metals, such as titanium. "I'm taking on the whole periodic table," he says.