<aside> ℹ️ Here you will read about:

• What the usual composition of steel is.
• Why steel is a carbon-intensive material.
• What the potential decarbonisation pathways for the industry are, and which pathways have the largest impact in emission reductions. </aside>

Table of content

<aside> <img src="/icons/info-alternate_gray.svg" alt="/icons/info-alternate_gray.svg" width="40px" /> Steel is an alloy of iron (Fe) and carbon (C), with a carbon content ranging up to 2% [39].

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<aside> <img src="/icons/city_gray.svg" alt="/icons/city_gray.svg" width="40px" /> Steel is an integral part of buildings and infrastructure due to its mechanical properties.

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<aside> <img src="/icons/upload_gray.svg" alt="/icons/upload_gray.svg" width="40px" /> Steel production globally accounts for 7% of annual greenhouse gas emissions.

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3.2. Steel

Steel is an alloy of iron (Fe) and carbon (C), with a carbon content ranging up to 2% [39]. Steel can also contain different amounts of other elements, depending on the properties needed for a particular use.

Steel is an integral part of buildings and infrastructure due to its mechanical properties. Its production globally accounts for 7% of annual greenhouse gas emissions [40].

Steel is a crucial material in our society, as it makes up infrastructure such as buildings. However, massive steel production poses a problem, since it is a very carbon-intensive industry, meaning that its production traditionally releases a lot of CO2 to the atmosphere (between 1.4 and 2.3 tonnes of CO2 per ton of steel, depending on the production route [41]).

<aside> ⚠️ Steel production in 2021 released between 1.4 and 2.3 tonnes of CO2 per ton of steel

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In the IEA Net Zero Scenario, steel production emissions need to decrease to 1 ton of CO2 per ton of steel by 2030, to be able to reach net-zero in 2050. To achieve that, we need to understand how steel is produced currently and the different decarbonisation pathways that exist.

3.2.1. Overview of standard production process

Raw materials

To produce steel, you need two main elements: iron (Fe) and carbon (C).

Iron can be obtained from iron ore, which is the natural mineral aggregation. The ore contains iron in an oxide form, meaning that to be able to use iron, the first thing needed is to remove the oxygen (via a chemical reaction called reduction).

<aside> 🪨 Iron oxide: Fe3O2

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<aside> 🔥 Reduction of iron ore into iron

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<aside> 🔥 Fe3O2 + 2 CO —> 3 Fe + 2 CO2

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<aside> <img src="/icons/science_blue.svg" alt="/icons/science_blue.svg" width="40px" /> Steel production

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<aside> <img src="/icons/science_blue.svg" alt="/icons/science_blue.svg" width="40px" /> Fe + C —> FeC

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How to produce steel