60-Second Earth

Moon Base Work Yields Clean Steel Process

A new method to make steel using electricity rather than flame could produce virtually no carbon emissions. David Biello reports

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.

—David Biello

[The above text is a transcript of this podcast.]

[Scientific American is part of Nature Publishing Group.]

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