There is more than one way to make green steel

Steelmakers around the world hope to decarbonise by changing the way they pluck oxygen from iron-oxide ores. This is done using either carbon monoxide (CO) derived indirectly from coke in a blast furnace, or by “direct reduction” with syngas, a mixture of CO and hydrogen.Both create carbon dioxide, a greenhouse gas. As a consequence, steelmaking is reckoned responsible for about 9% of man-made greenhouse-gas emissions. A widespread aspiration is thus to introduce direct reduction by hydrogen alone. The only by-product of such a reaction would be water (or rather, steam).