Closer scrutiny by NGO Centre for Science and Environment, however, shows the process is not quite as CO2 emission-free as claimed
Early in May, researchers at the Massachusetts Institute of Technology (MIT) announced the discovery of a new method of producing steel that is free of CO2 emissions. The process, known as molten oxide electrolysis (MOE), was initially employed to generate oxygen. The product generated was oxygen and, astonishingly, steel.
Given the emission-intensive nature of conventional steel production, this announcement by material chemist Donald Sadoway and fellow researchers at MIT brought some hope to the industry. The report on the study details the working of MOE, a process which uses electricity as a means of breaking down iron oxide (key raw material) into its metal form and releasing oxygen. Very pure steel was produced as an unintentional by-product of the process, without any CO2 generation.
Conventional steel-making route involves heating iron oxide in a furnace along with coke at temperatures ranging from 900°C to 1,300°C and producing hot metal with impurities such as carbon and trace amounts of sulphur, and huge amounts of CO2. MOE (see 'Molten oxide electrolysis' process), however, works at 1,600°C, produces pure carbon-free steel and zero CO2 emission. Like any other electrolysis process, MOE consists of two oppositely charged plates—electrodes—immersed in a solution containing iron oxide along with other metal oxides—electrolyte. Electricity is passed through these electrodes into the electrolyte and the end product is molten iron, which collects on the negatively charged electrode and oxygen is released from the positive electrode. Since the purpose of the study, funded by the National Aeronautics and Space Administration (NASA), was to generate oxygen using lunar soil to be used in possible future human bases on the moon, the process was performed on lunar-like soil, rich in iron oxide, extracted from the Meteor Crater in Arizona.