Decarbonisation Technology - November 2022

Near- and long-term options for decarbonising steel production Longer-term solutions to decarbonise the steel industry are not sustainable today, but steelmakers can take affordable short-term steps towards decarbonisation

Joachim von Schéele Linde

T he steel industry ranks amongst the top three CO₂ emitters from the industrial segment. Consequently, the pressure to decarbonise steelmaking has led many producers to set carbon-neutral goals over the 2030- 2050 timeframe. But how are those goals to be achieved? Based on the individual preconditions, it is important to develop and deploy roadmaps that include both near-term actions and, in parallel, longer-term activities broken down as measurable milestones. The transition of the industry, which is the aggregated result of the actions of each individual plant, is a journey that will span decades. In 2021, world steel production reached 1,950 million tonnes (Mt), with a supply of iron for that steelmaking being 1,354 Mt of iron from blast furnaces and 119 Mt of direct reduced iron (DRI), most of the latter produced using natural gas as reductant. Additionally, some 750 Mt of scrap were charged. Steel is the most recycled material in the world, and the first step to achieving sustainability and decarbonisation is to maximise the degree of recycling. Between the years 2000 and 2010, world steel production grew by more than 700 Mt/a, predominantly in China, where today more than half of the world’s steel production takes place. This is resulting in a massive increase in availability of scrap for years to come. Clearly, this will have a very positive impact on the carbon footprint of the steel industry, as the increase in scrap supply will be larger than the growth of steel production. However, for the next decades, most of the raw material for steel production will remain pig iron.

While electrification is the direct route to decarbonise many processes, several processes in steel production are extremely difficult to electrify – these include processes for iron ore reduction, as well as heating processes which use large-scale high-temperature combustion in a steel mill. For such processes, the main options include use of oxyfuel combustion to achieve increased energy efficiency, introduction of low-carbon fuels, and carbon capture. Ultimately, the use of clean hydrogen as a reductant as well as a fuel source is the endgame that steelmakers will adopt when a viable supply of hydrogen becomes available. Accordingly, there is a general pathway to decarbonisation:  Increase energy efficiency, e.g., by using oxyfuel combustion  Use of low-carbon fuels  Carbon capture  Use of clean hydrogen as reductant and fuel Over the next decades, a large transition will take place, but it will take time and involve multiple solutions – some more incremental in their nature, some more disruptive – and the pace will be different in different parts of the world. The drive from the market to produce steel with a low carbon footprint and availability of a viable supply of clean energy are two important factors. Figure 1 is an attempt to summarise the expected general development over the coming decades. A greener blast furnace Integrated steel mills, which produce steel from iron ore, account for 70% of global steel production but emit almost 90% of CO₂