Technology: high-tech steel for sustainability
Steel and aluminum turn green
Steel production Mercedes
© press-inform – the press office
In the automotive industry, a lot is currently revolving around electromobility. But at least not everything, because in addition to models, driver assistance and drives of the future, car manufacturers and the supplier industry are fighting to reduce their own CO2 emissions to a minimum. Steel and aluminum in particular are of central importance.
The reason why the two types of metal are so much in focus is obvious. Around one-fifth of an electric vehicle consists of steel, because in addition to the body, numerous chassis parts and components are made of the heavy metal. The situation is no different with aluminum, because wherever weight is to be saved and other lightweight materials are either technically unusable or too expensive, the light metal is processed in automobile construction. The problem is not so much the materials themselves, but the large amount of energy used, because the production of one ton of steel in the blast furnace generates around two tons of CO2 on average. This can be significantly reduced if, instead of coke-based production, direct reduction and electric steel processes are combined. In the natural gas-based direct reduction process, carbon monoxide and hydrogen release the oxygen from the iron ore.
Steel and aluminum turn green
In the electric arc furnace, the reduced iron is smelted together with residual metals to form steel of the desired quality. If green hydrogen and other renewable energies are now used to operate the furnace instead of natural gas, as was the case in the past, emissions can be significantly reduced. “Mercedes-Benz is working with all its partners on the decarbonization of the steel supply chain in order to promote the sustainable transformation of the automotive industry,” explains Gunnar Güthenke, who is responsible for purchasing at Mercedes and almost CO2-free steel in our vehicles.” By the end of the decade, Mercedes wants to process more than 200,000 tons of CO2-reduced steel from its various suppliers in the production of new models – extremely positive for the energy balance of the vehicle.
First, the new production methods will be used in Europe and especially in Germany; but are then to be rolled out to the other production facilities in Asia and the United States. By the end of the decade, the star brand wants to at least halve the average CO2 emissions per vehicle in the new car fleet compared to 2020. But steel alone is not enough, because the situation is very similar with aluminum. Together with the company Hydro, Mercedes is working on saving large amounts of energy and thus CO2 here as well. Hydro is bringing the low-CO2 light metal with a proportion of at least a quarter of old components into the first structural cast components for body shells this year. The components manufactured in this way have a footprint of 2.8 kilograms of CO2 per kilogram of aluminum. “We are thus reducing the CO2 footprint of aluminum by almost 70 percent compared to the European average,” explains Mercedes Board Member for Production Markus Schäfer. “Our EQS and EQE are among the first models to be equipped with the more sustainable material.”
Mercedes is not the only automaker fighting for every gram of CO2. As the main supplier to Volkswagen, Salzgitter AG wants to use steel in a much more energy-efficient manner than before. By 2033, 95 percent of CO2 emissions are to be saved in steel production. The first models with the green steel will be on the international markets from the end of 2025. In contrast to the widespread production of pig iron using carbon-based blast furnaces, Salzgitter AG intends to use a new process to produce steel using green hydrogen and renewable energies. For this purpose, hydrogen electrolysers, direct reduction plants and electric furnaces are being built in Salzgitter.
BMW is also working flat out to use green steel and green aluminum in its future models. Two thirds of the aluminum used in the Landshut foundry comes from a specially created recycling circuit, of which almost two thirds come from the foundry’s own system. By 2030, BMW wants to reduce the vehicle’s CO2 emissions over the entire life cycle, including supply chain, production and customer use, by at least 40 percent compared to 2019. But the BMW Group can also go a few sizes smaller. Those who opt for the electric Mini Cabrio can now order an aluminum rim made entirely of reused aluminum. The aluminum rim of the Mini Cooper was developed in cooperation with rim manufacturer Ronal.
Ford relies on the most modern production methods in its newly opened Cologne Electrification Center. More than 2,000 tons of CO2 and more than 2,600 MWh of electrical energy are to be saved per year through energy-efficient solutions. By 2030, Ford aims to purchase at least 10 percent of aluminum and steel that produces zero carbon emissions in extraction and processing. Sue Slaughter, Ford Purchasing Manager Supply Chain Sustainability: “Improvements within our supply chain are critical. With the use of climate-neutral steel, we will take a significant step towards reducing the CO2 footprint of our vehicles.” The Hyundai Group also wants to become more sustainable in its production and recently introduced new guidelines for its suppliers to reduce their greenhouse gas emissions in the vehicle production of models of the Hyundai, Kia and Genesis brands and to support them towards carbon neutrality. Gradually, Koreans’ steel production will transition to green steel by 2030, reducing carbon emissions by a third.