Flaming cauldrons of molten metal have long been the primary venues for steel production. But blast furnaces require a lot of coal, which means greenhouse gas pollution. In fact, worldwide, steelmaking is responsible for 5 percent of annual emissions.
But scientists working on a way to harvest oxygen from the iron oxide in lunar soil for future moon bases realized that they happened on a better way to make steel here on Earth. The trick? Produce steel the way we make aluminum: use electricity rather than flame. [Antoine Allanore, Lan Yin and Donald R. Sadoway, A new anode material for oxygen evolution in molten oxide electrolysis, in Nature]
To make steel the old-fashioned way, you blast iron ore with heat and purify the resulting molten metal with oxygen. The process removes carbon from the steel, but produces carbon dioxide. Making a ton of steel releases roughly two tons of CO2—and the world uses a lot of steel in cars, buildings and other infrastructure.
The new method involves passing a current through a molten pool of iron oxide, which drives off the originally sought-after oxygen. The by-product is steel. And depending on the source of the electricity, the process could be nearly CO2-free. Which, as far as the atmosphere is concerned, would be very cool.
[The above text is a transcript of this podcast.]
[Scientific American is part of Nature Publishing Group.]