Iron and steel production is a cornerstone of modern infrastructure and industry, but it comes at a steep environmental cost.
According to UNSW expert Professor Yansong Shen, current iron and steelmaking methods contribute approximately 7 to 9 per cent of global carbon dioxide emissions, making this sector one of the largest industrial polluters in the world.
As demand for these essential materials continues to grow with urbanisation and development, finding more environmentally friendly and economically feasible production methods is critical for combating climate change.
Professor Shen, who leads the UNSW SCOPE Lab for Green Metals (SCoPE), is at the forefront of research aimed at transforming iron and steel manufacturing to cut emissions while maintaining the supply and quality critical to global markets.
“Steel underpins almost all the structures and machines that we use every day, and demand for these metals is expected to persist well into the future,” he explained.
“An iron-and-steel-making plant lasts for decades, so when you build one you are actually locking in the level of greenhouse gas emissions for many years into the future.”
Traditional steelmaking primarily relies on smelting iron ore in blast furnaces powered by coke, a carbon-intensive fuel made from coal.
The molten iron is then refined into steel in basic oxygen or electric arc furnaces.
This coal-dependent process generates significant CO₂ emissions, which Professor Shen identifies as the main hurdle in decarbonising the sector.
“If we want truly green metals, fixing this ironmaking step, which is coal-based, is the main challenge,” he states.
Several emerging technologies offer pathways to greener iron and steel.
One promising approach is hydrogen-based direct reduced iron (H-DRI) combined with electric arc furnaces powered by renewable electricity.
This method uses green hydrogen to reduce iron ore without carbon emissions, potentially cutting emissions by 80-90 per cent.
However, the widespread adoption of H-DRI hinges on affordable, reliable access to high-grade iron ore, green hydrogen, and renewable energy — all currently limited by cost and infrastructure constraints.
Another widely accessible green steel option is recycling scrap steel in electric arc furnaces powered by renewable energy.
This method can reduce emissions nearly to zero but is constrained by the availability of quality scrap metal, particularly in fast-growing regions requiring large volumes of new steel.
A frontier technology under exploration is iron ore electrolysis, where renewable electricity splits iron ore directly into iron and oxygen, eliminating carbon fuels entirely.
While this could enable zero-emission ironmaking, commercial-scale feasibility remains in the early experimental phase.
Closer to practical application, Professor Shen’s team is developing the Renewable Injectant and Sustainable Burden (RISBTM) technology, which upgrades existing blast furnaces by substituting some carbon inputs with renewable materials and capturing some residual CO₂ emissions for storage or industrial use.
“The RISB technology allows steelmakers to decarbonise existing sites without a complete rebuild,” he notes.
This approach offers a viable pathway for substantial emissions reduction in current large-scale plants at lower cost than full replacements.
Explaining the research approach, Professor Shen said: “The best way to develop new technologies for heavy industries is to use a step-by-step R&D method that starts with safe and low-cost computer simulations to test and refine ideas, followed by lab experiments to confirm the results, and finally large-scale plant tests to show the technology works in practice.
“We call this approach NLP, meaning we do numerical experiments, lab experiments, and then plant tests.
“This is much more efficient than the old trial-and-error method, which is expensive and often misses the best designs.”
The benefits of greener iron and steel extend beyond climate goals.
Reducing reliance on coal and fossil fuels cuts industrial pollution, improving air quality and community health near manufacturing sites.
Economically, green steel development can create new industries and high-value manufacturing jobs, especially in regions rich in renewable energy resources like outback Australia.
This transition promises to diversify economies beyond raw exports and build expertise and intellectual property in clean industrial technologies.
However, significant challenges remain.
Most green steel technologies are at pilot scale and must be scaled up to meet global demand. Production costs for green hydrogen and renewable energy remain higher than fossil fuels, making green steel currently 20 to 50 per cent more expensive.
Availability of scrap metal feedstock also limits recycling capacity.
“We know that steelmaking is the world’s biggest industrial CO₂ polluter. Producing just this one metal alone causes up to 9 per cent of global emissions,” Professor Shen warned.
He emphasised the urgency: “So that is why it is so important to find viable solutions to the problem as fast as we possibly can, to produce greener versions of quality iron and steel that also maintain the levels of supply needed for the global market.
“That’s the only practical pathway for change.”
The race to green steel technologies is now a critical front in the fight against climate change and for sustainable industrial development.
