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No magic wand: electrolysis for carbon-free metals manufacture
21/1/2026
8 min read
Feature
Development of carbon-free manufacture of iron, steel and aluminium are some of the most challenging aspects of the energy transition. There is no single solution and a broad range of options are being investigated. Key technology initiatives are underway using electrolysis. New Energy World Features Editor Brian Davis reports.
There are two potential ways to separate iron from the oxygen in iron ore – traditionally using chemical reductants such as hydrogen or carbon (coal/coke) in a blast furnace, or using electrolysis to reduce the iron ore to iron.
A conventional blast furnace uses coke and limestone to reduce iron ore at high temperature, and emits a vast volume of carbon monoxide (CO). Iron ore is sintered or pelletised and mixed with coke and limestone (flux) to remove impurities (gangue) to form slag which floats on the iron. Hot air at about 1,000°C blows into the furnace, igniting the coke to produce intense heat and CO. As the material descends, the iron ore is reduced from iron oxides to metallic iron. The molten iron and slag collect at the bottom of the furnace, where they are drained off periodically (tapped) from separate openings. The iron is then cast into ‘pigs’ or transferred for steelmaking. A blast furnace typically produces 1.8 tonnes of CO2 for every tonne of steel made.
Electrolysis
By comparison, in one high temperature electrolysis technique the iron ore is dissolved in a solvent of silicon dioxide (SiO2) and calcium oxide (CaO) at 1,600°C, and an electric current passed through. Negatively charged oxygen ions migrate to the anode, and oxygen bubbles off. While positively charged iron ions migrate to the cathode where they are reduced to pure iron. If the electricity comes from renewable sources (or nuclear), the iron produced is carbon-free without CO2 emissions.