Steel production is responsible for approximately 7–9% of global CO₂ emissions — one of the largest industrial contributors to climate change. Decarbonising the steel sector is therefore one of the most consequential sustainability challenges in manufacturing.
A proven solution is already deployed at scale: secondary steel — produced from scrap in an electric arc furnace (EAF) — saves 1.4 tonnes of CO₂ and 75% of energy per tonne compared to primary steel from iron ore. This post examines the numbers behind this claim, the process that delivers it, and what it means for India’s steel sector.
| Metric | Primary Steel (BF-BOF) | Secondary Steel (EAF from Scrap) |
| CO₂ per tonne produced | ~2.0 tonnes CO₂ | ~0.6 tonnes CO₂ |
| CO₂ saving | — | 1.4 tonnes CO₂ per tonne (70% less) |
| Energy per tonne | ~20 GJ | ~5 GJ (75% less) |
| Iron ore required | Yes — mined and sintered | None |
| Coking coal required | Yes — converted to coke | None |
| Key CO₂ source | Ore reduction chemistry (unavoidable) | Grid electricity (falling with renewables) |
| Decarbonisation pathway | Green H₂ reduction (future) | Already deployed — scales with scrap |
The blast furnace route: where primary steel’s carbon comes from
Primary steel production via the blast furnace-basic oxygen furnace (BF-BOF) route is one of the most carbon-intensive industrial processes in the global economy.
The carbon emission is not primarily from energy consumption — it is from chemistry. Iron ore (iron oxide — Fe₂O₃) must be chemically reduced to metallic iron (Fe). This reduction requires a reducing agent. In the blast furnace, that reducing agent is carbon — in the form of coke derived from coking coal.
The reduction reaction produces CO₂ as a direct chemical byproduct: the carbon from the coke bonds with the oxygen stripped from the iron oxide, forming CO₂. This is not an inefficiency to be engineered away — it is the chemistry of the process. As long as iron ore is the input and carbon is the reductant, CO₂ is a necessary output.
This is why green hydrogen is being explored as a future reductant for primary steelmaking — hydrogen produces water rather than CO₂ when it reduces iron oxide. But hydrogen-based steelmaking is not yet commercially deployed at scale. It is a future option.
The present option is the electric arc furnace — which sidesteps the ore reduction chemistry entirely.
The electric arc furnace: why it avoids primary steel’s carbon
The electric arc furnace’s carbon advantage is structural, not incremental. It comes from what the EAF does not do:
No iron ore: The EAF’s input is steel scrap — already metallic iron. The ore reduction chemistry — and the CO₂ it produces — is bypassed entirely.
No coking coal: The EAF uses electricity, not combustion, as its energy source. No coke, no coking ovens, no coking coal supply chain.
No blast furnace: The 1,500°C blast furnace operation — with its continuous combustion and its associated CO₂ — does not exist in the EAF route.
The EAF melts scrap directly using high-voltage electrical arcs, refines the molten metal to specification, and produces steel output that meets the same IS-grade standards as blast furnace steel for the vast majority of construction, industrial, and manufacturing applications.
The CO₂ the EAF does produce comes from the electricity it consumes — and as India’s electricity grid incorporates more renewable energy, this residual carbon footprint will fall further.
| Factor | India’s Secondary Steel Opportunity |
| Steel consumption | One of world’s largest — growing to 300MT target by 2030 |
| Scrap generation | Growing with infrastructure ageing, end-of-life vehicles, demolitions |
| EAF expansion | Government and industry actively promoting EAF capacity growth |
| CO₂ saving potential | 1.4T CO₂ avoided per tonne shifted from BF-BOF to EAF-scrap route |
| Import substitution | Reduced iron ore and coking coal imports as scrap share grows |
The decarbonisation pathway that does not need a breakthrough
Steel decarbonisation conversations in India and globally tend to focus on emerging technologies — green hydrogen direct reduction, carbon capture and storage, novel smelting processes. These are genuinely important long-term pathways.
But the secondary steel route — EAF from scrap — is not a long-term pathway. It is a present-day, commercially deployed, fully proven technology that delivers significant CO₂ savings with every tonne produced.
The constraint is not technology. The constraint is scrap supply and EAF processing capacity. As India’s scrap generation grows — with the ageing of its infrastructure stock, industrial equipment, and vehicle fleet — and as EAF capacity expands, the potential CO₂ saving from secondary steel scales proportionally.
Every tonne of steel produced from scrap instead of ore is 1.4 tonnes of CO₂ that never happens. At India’s scale of steel consumption and growth, the cumulative climate impact of building secondary steel processing capacity is substantial — and it starts now, with the technology and the scrap that already exist.
Conclusion
Secondary steel from scrap saves 1.4 tonnes of CO₂ per tonne vs blast furnace primary steel — a measured difference, not a projection. The saving comes from eliminating ore reduction chemistry: no iron ore, no coking coal, no blast furnace combustion. The electric arc furnace route uses 75% less energy — running on electricity that can be increasingly sourced from renewables. India is among the world’s largest steel consumers and a major scrap generator — the secondary steel opportunity is structurally significant. Steel decarbonisation via secondary steel does not require breakthrough technology — the process exists, the scrap exists, the market exists. Every tonne from scrap is 1.4 tonnes of CO₂ that never happened.
FAQs
Why does secondary steel produce less CO₂ than primary steel?
Secondary steel is made from recycled scrap, eliminating the need to reduce iron ore using coking coal. This avoids one of the largest sources of emissions in traditional steelmaking.
What is an electric arc furnace?
An electric arc furnace melts recycled steel scrap using electricity instead of relying on blast furnace processes. It is widely used for producing secondary steel.
Does secondary steel meet the same quality standards?
Yes. When produced under appropriate quality controls, secondary steel can meet the same applicable IS-grade specifications required for construction, manufacturing, and industrial applications.
Why is steel recycling important for India?
India’s growing infrastructure, automotive sector, and industrial base generate increasing volumes of recyclable steel scrap. Recovering and processing this material helps improve resource efficiency while reducing emissions.
Can secondary steel help achieve decarbonisation goals?
Secondary steel is already contributing to lower industrial emissions by reducing energy use and avoiding carbon-intensive ore reduction processes. Expanding recycling infrastructure can further strengthen these environmental benefits.