Iron. It's the material of the industrial revolution, and it's dirty stuff to make.
Researchers at MIT, however, say they have come up with a way to produce the metal without generating carbon dioxide or other pollutants. In the experimental process, an electric current is passed through a vat of liquid iron oxide, which then gets transformed into iron and oxygen.
"What sets molten oxide electrolysis apart from other metal-producing technologies is that it is totally carbon-free and hence generates no carbon dioxide gases -- only oxygen," said Lawrence W. Kavanagh, AISI vice president of manufacturing and technology in a prepared statement.
Another potential advantage is that manufacturers are familiar with the electrolysis process: this is similar to how aluminum gets made.