Steel made with electricity offers great potential for large carbon emission reductions
Producing iron is an energy-intensive operation because it involves separating iron from oxygen, which are tightly bound in naturally occurring minerals. At the same time, steel – an alloy of iron and carbon – plays a vital role in building the backbone of our energy infrastructure, from tools and engines to large-sized equipment. This cycle of producing steel and leveraging it into energy infrastructure feeds into itself, leading to both an increase in energy availability and the continuous growth of steel-based infrastructure.
Towards carbon-neutral steel manufacturing
Historically, the process of making steel from ores has relied entirely on energy from burning coal, a method that releases CO2 into the atmosphere – and a practice that the EU-funded SIDERWIN project sought to change. To this end, it developed an R&D pilot at ArcelorMittal R&D campus’ site in Maizières-lès-Metz (France)to validate the technology at TRL 6. SIDERWIN’s approach differed from traditional iron production methods in the step where iron oxide is reduced to metallic iron. In traditional steelmaking, this reduction occurs in a blast furnace through a process that involves high temperatures and carbon (usually in the form of coke). This process generates a significant amount of CO2 as a by-product. SIDERWIN eliminated the need for coke and the production of CO2 associated with the chemical reduction in a blast furnace. “Our approach entails the use of an electrochemical process for the reduction step. This process involves passing an electric current through iron oxide in the presence of an electrolyte to directly convert it into metallic iron and oxygen gas, without involving high temperatures or carbon,” notes project coordinator Valentine Weber. What’s more, given that SIDERWIN’s process is powered by electricity, it offered the flexibility to use renewable energy sources, such as wind or solar power. This shift from a thermal and carbon-intensive process to an electrochemical one, potentially powered by clean energy, made it possible to produce iron with an even smaller environmental impact. “Our goal was to achieve carbon-neutral steel production by utilising electricity that is nearly 100 % free from carbon,” highlights Weber. SIDERWIN also explored how iron oxides generated as by-products from other industrial processes, such as the waste from the aluminium industry’s Bayer process, could serve as raw materials.
Drastic emission reductions and significant cost savings
“By using electricity, it is possible to cut the carbon footprint of steel coil by 60 % in the near term and up to 74 % with a fully decarbonised electricity supply,” states Weber. “Moreover, SIDERWIN technology could provide exceptional flexibility capacity to the European power grid, of up to 39 GW.” This adaptability not only helped balance the power system but also reduced the need for peak-load energy sources. “The flexibility of the SIDERWIN system can prevent around 6 million tonnes of direct CO2 emissions annually at European level by replacing peak-load energy sources,” notes Weber.
Keywords
SIDERWIN, electricity, steel production, iron oxide, CO2 emissions, energy-intensive industries, process industries
