Material Insights · Understanding the Material World

Steel plant energy recovery: Impact and additionality

Real cuts in CO2, water and dust, with a coal catch

What this tab covers The impact and additionality lens: direct emission cuts, side benefits for water and air, and the risk of prolonging the life of a polluting host plant.

Abatement per plant is large and measurable, with real water and dust benefits. But it optimises a coal-based route that the sector needs to leave.

Direct Scope 1 and Scope 2 abatement

Favourable

A CDQ unit displaces an oil-fired boiler of the same output. CTCN and the vendor both put this at about 18 t CO2 per hour for a 100 t/h unit, about 0.18 t CO2 per tonne of coke (calculated, oil baseline; lower against a gas or renewable grid). The 2023 Turkish TRT study reported about 10.9 t CO2 avoided per hour, but that implies about 2 kg CO2 per kWh generated (calculated), several times a normal grid factor, so it is not relied on here. Sinter cooler recovery cuts about 19.9 kg CO2 per tonne of sinter, about 117,000 t a year for a 5.9 Mt/y plant (calculated). Japanese technology could cut Indian steel CO2 by 13 Mt a year, on a 2015 JISF estimate. Global average steel energy intensity fell to 20.95 GJ/t in 2024, from about 50 GJ/t in the 1960s.149111213

CDQ avoided CO2 about 0.18 t CO2/t coke (calculated, oil baseline)1112 Sinter recovery CO2 19.9 kg CO2/t sinter4 India potential, Japanese tech 13 Mt CO2/y9

Water and air synergy

Favourable

CDQ removes the quench water entirely. Wet quenching uses about 0.6 m3 per tonne of coke and sends a dusty steam plume into the air. Dust falls from about 300 to 400 g to under 3 g per tonne of coke. Two Chinese CDQ systems were credited with saving almost 4 million t of water. Coke also comes out drier and stronger, with moisture of 0.1 to 0.3% against 2 to 5%. Dry slag granulation would save the roughly 1,000 litres of water per tonne used in wet granulation.2711

Wet quench water about 0.6 m3/t coke (CDQ: none)2 Quench dust 300-400 g/t (wet) vs under 3 g/t (CDQ)2 Wet slag granulation water about 1,000 L/t slag7 Water saved, two CDQ systems (China) almost 4 million t11

Avoided lock-in

Unfavourable

This is the weak point for an impact investor. Every rupee spent on CDQ or TRT improves the economics of the blast furnace route, which still depends on coking coal. It can delay a switch to scrap-based or hydrogen-based steel. The case is strongest for plants already built and running for many years, and where coke ovens will keep supplying a furnace that later moves to partial hydrogen or carbon capture.

Sources

  1. Energy use in the steel industry World Steel Association (worldsteel), 2025
  2. Dry cooling of coke (practitioner article, second-hand) IspatGuru (Satyendra Kumar Sarna)
  3. Sinter plant heat recovery (power generation from sinter cooler waste heat) UNFCCC Climate Technology Centre and Network (CTCN)
  4. Dry slag granulation CSIRO
  5. Japan steel industry's contribution to energy saving (K. Fujimoto, JISF, 2nd CJK Cooperation Dialogue) Japan Economic Foundation / Japan Iron and Steel Federation, 2015
  6. Coke dry quenching for iron and steel sector UNFCCC Climate Technology Centre and Network (CTCN)
  7. Coke Dry Quenching (CDQ) technology sheet (vendor claims) Nippon Steel Engineering, via JASE-W (Japanese Business Alliance for Smart Energy Worldwide), 2018
  8. Performance, exergy, and environmental analysis of blast furnace top pressure turbine in an iron-steel factory (Albayrak, Ergun and Yildiz), Periodicals of Engineering and Natural Sciences 11(4) International University of Sarajevo (peer-reviewed journal), 2023