Pathways towards full use of hydrogen as reductant and fuel

Abstract

The transition to a green steel making is a journey over decades that involves many technologies and pathways, in most scenarios with the use of hydrogen − both as reductant and as fuel − as the endgame. The paper describes a general pathway to decarbonisation including increased energy efficiency, use of low carbon fuels, carbon capture, and use of clean hydrogen as reductant and fuel. The possibilities for developing a greener blast furnace process as a short-term solution, is discussed. Combinations like direct reduced iron production with carbon capture using a gasified waste or biomass, could be a mid-term solution at some steel mills. Dependent on location-specific conditions some technologies, like use of hydrogen as fuel in reheating, is coming into use already now, whilst in other areas in near- and mid-term there will be intermediate solutions applied. Development of hydrogen production technologies is briefly described. Challenges for the transition are found not only within the steel industry itself, but also, e.g., in supply of renewable power and suitable iron ores. Moreover, potential supply chain integrations and impact of geographical dislocations are discussed. Overall, it is important to apply an integrated approach with clear milestones for the chosen pathway, where existing assets like blast furnaces are transformed into a lower carbon footprint operation applying technologies that also can be used in the subsequent transition, e.g., use of coke oven gas for producing direct reduced iron that is charged into blast furnaces where carbon capture is applied, or changing into more energy-efficient combustion systems that are ready for use of hydrogen when viably available.