Steel can be produced through several technology routes, each with different emissions profiles, energy needs, and product-control advantages. This article compares modern scrap-based EAF, natural-gas DRI–EAF, hydrogen DRI–EAF, and iron-ore briquettes used in blast-furnace supply chains, using BF–BOF as the benchmark (International Energy Agency [IEA], 2020; Vogl, Åhman, & Nilsson, 2018).

white storage tanks against a blue sky

Benchmark: BF–BOF

BF–BOF (blast furnace–basic oxygen furnace) is the classic ore-to-steel route. A widely used reference point is:

• Emissions: commonly around ~2.2 tCO₂ per tonne of crude steel (varies by plant efficiency and electricity mix)
• Energy: on the order of ~15 GJ per tonne of liquid steel
  (IEA, 2020)

Comparison table: BF–BOF as the baseline

Sources: IEA (2020); Vogl et al. (2018); Hasanbeigi, Arens, & Price (2014); Mathieson (2025).

Industrial production line of Iron ore pellets in metallurgical factory

Understanding energy exposure and costs

Different routes concentrate costs in different places:

• BF–BOF: energy and reduction chemistry are embedded in coal and coke use.
• Scrap-EAF: electricity and scrap quality are the main drivers.
• Gas DRI–EAF: natural gas, DR-grade pellets, and electricity all matter.
• Hydrogen DRI–EAF: electricity dominates because hydrogen is typically produced via electrolysis.
  (IEA, 2020; Fischedick et al., 2014)

Because energy prices, feedstock availability, and carbon policies vary widely by region, outcomes differ by site and market (Rootzén & Johnsson, 2016).

Electricity exposure by route

Electricity use provides a clear view of operational sensitivity for EAF-based routes:

• Scrap-EAF: commonly on the order of ~0.35–0.60 MWh per tonne of steel
• Natural gas DRI–EAF: often ~0.45–0.80 MWh per tonne, with additional gas energy used in the DRI plant
• Hydrogen DRI–EAF: substantially higher electricity use because electrolysis dominates total energy demand; one assessment estimates ~3.48 MWh per tonne of liquid steel
  (Vogl et al., 2018; IEA, 2020)

Hydrogen DRI–EAF: what it is and why it is future-proof

Hydrogen DRI–EAF is widely regarded as the most future-proof option for new, ore-based primary steel capacity aiming at near-zero emissions. It replaces carbon in the iron-reduction chemistry with hydrogen, producing water rather than CO₂ (IEA, 2020; Vogl et al., 2018).

Step 1: Hydrogen production (electrolysis)

Low-carbon hydrogen is commonly produced by splitting water using electricity:

2H₂O → 2H₂ + O₂
(Vogl et al., 2018)

Inputs: water, electricity, electrolyser
Outputs: hydrogen (to the DRI plant) and oxygen (byproduct)

Step 2: Ironmaking in the DRI plant

Hydrogen removes oxygen from iron ore to produce metallic iron. The solid product is direct reduced iron (DRI). Steel is not produced at this stage (IEA, 2020).

A simplified reaction for hematite is:

Fe₂O₃ + 3H₂ → 2Fe + 3H₂O
(IEA, 2020; Vogl et al., 2018)

Key clarification:
The 2Fe represents metallic iron. In practice, this iron exits the reactor as DRI, a porous solid mainly composed of iron. The oxygen leaves the ore as water vapor, not CO₂.

Step 3: Steelmaking in the EAF

DRI is melted and refined in an electric arc furnace. Chemistry is adjusted with controlled additions of carbon and alloying elements to meet steel grade specifications (IEA, 2020).

Inputs: DRI (often blended with scrap), electricity, fluxes, small carbon/alloy additions
Outputs: liquid steel, slag, off-gas and dust

Benefits beyond CO₂

• Product quality: DRI provides a cleaner and more consistent iron unit than mixed scrap, supporting tighter chemistry control and higher-grade steels (Daehn et al., 2017; Hasanbeigi et al., 2014).
• Operational control: EAF-based routes offer faster start-up, flexible output, and fewer large process units.
• Transition options: Incremental measures—such as iron-ore briquettes in blast-furnace supply chains—can deliver near-term reductions where legacy assets continue to operate (Mathieson, 2025).

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Definitions

• BF–BOF: blast furnace followed by basic oxygen furnace; traditional ore-to-steel route.
• EAF: electric arc furnace; melts scrap and/or DRI using electricity.
• DRI: direct reduced iron; solid iron produced by reducing iron ore before melting.
• Hydrogen DRI: DRI produced using hydrogen as the reducing gas.
• Electrolysis: process that uses electricity to split water into hydrogen and oxygen.
• DR-grade pellets: iron ore pellets optimized for direct reduction performance.

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References (APA)

Daehn, K. E., Cabrera Serrenho, A., & Allwood, J. M. (2017). How will copper contamination constrain future global steel recycling? Environmental Science & Technology, 51(11), 6599–6606. https://doi.org/10.1021/acs.est.7b00997

Fischedick, M., Marzinkowski, J., Winzer, P., & Weigel, M. (2014). Techno-economic evaluation of innovative steel production technologies. Journal of Cleaner Production, 84, 563–580. https://doi.org/10.1016/j.jclepro.2014.05.063

Hasanbeigi, A., Arens, M., & Price, L. (2014). Alternative emerging ironmaking technologies for energy-efficiency and CO₂ emissions reduction: A technical review. Renewable and Sustainable Energy Reviews, 33, 645–658. https://doi.org/10.1016/j.rser.2014.02.031

International Energy Agency. (2020). Iron and steel technology roadmap: Towards more sustainable steelmaking. IEA.

Mathieson, J. G. (2025). A feed-flexible blast furnace strategy to place the steel industry on an accelerated path toward net-zero CO₂ emissions. Journal of Sustainable Metallurgy.

Rootzén, J., & Johnsson, F. (2016). Managing the costs of CO₂ abatement in the steel industry. Energy Policy, 98, 459–469. https://doi.org/10.1016/j.enpol.2016.09.026

Vogl, V., Åhman, M., & Nilsson, L. J. (2018). Assessment of hydrogen direct reduction for fossil-free steelmaking. Journal of Cleaner Production, 203, 736–745. https://doi.org/10.1016/j.jclepro.2018.08.279

Mathieson, J. G. (2025). A feed-flexible blast furnace strategy to place the steel industry on an accelerated path toward net-zero CO₂ emissions. Journal of Sustainable Metallurgy.

Rootzén, J., & Johnsson, F. (2016). Managing the costs of CO₂ abatement in the steel industry. Energy Policy, 98, 459–469. https://doi.org/10.1016/j.enpol.2016.09.026

Vale. (2021, September 9). Vale announces “green briquette” capable of reducing CO₂ emissions of steelmaking clients by up to 10% [Press release].

Vogl, V., Åhman, M., & Nilsson, L. J. (2018). Assessment of hydrogen direct reduction for fossil-free steelmaking. Journal of Cleaner Production, 203, 736–745. https://doi.org/10.1016/j.jclepro.2018.08.279