Steel production is responsible for eight percent of CO2 emissions worldwide. Are there environmentally friendly manufacturing processes? Two experts provide insights!
Our world is built on steel. From buildings and power lines to the automotive industry and ship-building to medical, office and computer technology, there is no area of our lives that does not contain steel in some form. “Steel has thousands of applications,” says Wilfried Liegard, a member of the research team at Bystronic. While steel offers many different properties, it can be as rigid as it is flexible, absorbent or resilient, easy to shape or dimensionally stable. Added to this is the fact that iron ore is almost inexhaustibly available on our planet. “Our world is built on steel, and the hunger for steel is growing,” he says.
In the last 50 years, steel production has increased about six-fold. In 2022, over 1.8 billion tons of steel were produced, according to the World Steel Association, two thirds of it in China. Steel production, therefore, has a decisive influence on achieving climate targets. Worldwide, steel production is responsible for around eight percent of CO2 emissions, while in Europe the share is four percent. In the classic manufacturing process, 1.8 metric tons of CO2 are produced concurrently with each metric ton of steel, or as Christian Leinenbach, metals expert at the Empa Research Institute and lecturer at EPFL, pointedly puts it: “It’s actually CO2 production, and iron is the useful by-product.”
As in other areas of life, pressure is growing in the steel industry to become climate neutral, but how? The magic word is fossil-free, or “green” steel – steel whose production releases as little CO2 as possible into the air. Christian Leinenbach cites several ways to achieve this. Oxygen can be removed from the ore using hydrogen instead of carbon. “The reaction with hydrogen produces not pig iron but porous granulate,” he says. This can then be processed into steel in the electric arc furnace using electricity – the energy requirement to do so is lower than that of the blast furnace. The important thing is that the electricity for the arc furnace and the production of the hydrogen must come from renewable energy sources.
As an additional means on the road to CO2-neutral steel production, Leinenbach mentions carbon capture technologies, such as those being built by the Swiss start-up Climeworks. Produced CO2 is captured here and stored in the soil, for example.
Wilfried Liegard goes even further: “In the end, the whole chain should be green, including transport,” he says. If the iron ore is mined in India, processed into pig iron in the Middle East and refined into steel in France, the transport of the material puts an additional burden on the climate. The mines would also have to become greener, for example by using electric machines to mine the ore. Last but not least, these machines would themselves have to be made of green steel.
For the research team at Bystronic, the material properties are also of particular interest. Can green steel be cut and bent in the same way as conventional steel? “Green steel is chemically and physically practically the same as fossil steel,” says Liegard. Cutting, he says, is not a problem. Bending, on the other hand, raised questions: does the green steel contain larger residues of hydrogen, for example? “We compare curves and try to conclude how the steel behaves at different pressures,” he says. Nor, he adds, can one simply speak of steel as a material. “There are about 3000 different steels,” adds Empa researcher Leinenbach. “It is a group of materials,” he says.
Substantial investment required
Nevertheless, green steel is not yet being produced in large quantities. The Swedish company SSAB is currently leading the way – but with a total production capacity of just under nine million metric tons, it is a small fish in the pond. In 2020, the steel giant China Baowu Group produced over 115 million metric tons, while Arcelor Mittal managed 78.5 million metric tons.
“The biggest challenge is scalability of production,” Liegard says. The change would require high investments, he calculates, at around one billion U.S. dollars per steel company. “We therefore expect steel to become about 30 percent more expensive” he says. Leinenbach confirms this figure, while calling it a balancing act. The auto industry, for example, would either have to let the more expensive steel flow into its pricing or use less steel. Electric cars would have a certain advantage, as they do not contain an engine block. Last but not least, recycling needs to be considered, he says. Every ton of steel already contains about thirty percent recycled steel, he says, and this figure could be improved. “We have to look at the material as a recyclable material,” Leinenbach concludes.
For more information please see www.bystronic.co.za or contact Bystronic on 010 410 0200.
