Due to its special properties, aluminium is a key material in vehicle construction - and it is increasingly gaining in importance. We introduce the light metal: its characteristics, extraction and processing, its use in our vehicles and our aluminium strategy.
Aluminium: The element
Aluminium is a light metal that is used in various fields due to its properties - high electrical and thermal conductivity, low density, high strength-to-weight ratio. It is a very soft metal that is relatively easy to process by casting, forming, machining, welding or soldering.
Occurrence, extraction, production
Aluminium is the third most common element and the most common metal in the earth's crust and, on top of that, the most widely used light metal. Due to its reactive character, it is only found in bound form, for instance as oxide, hydroxide or silicate. The only economically important aluminium ore for further processing into aluminium is bauxite. The red rock was formed from the weathering of various, mostly magmatic rocks and consists of various aluminium oxide and hydroxide compounds such as gibbsite, boehmite and diaspore.
The largest mining areas for aluminium-bearing soils are located in Australia, Brazil, Guinea and China. Deposits for bauxite are mostly shallow and close to the surface. The deposits can be found two to ten meters below the earth's surface. Due to the storage conditions, bauxite is mainly extracted in opencast mining. Usually, the removed layers of earth are then backfilled for recultivation.
From bauxite to primary aluminium
The bauxite is first ground and mixed with caustic soda. In this first step, the aluminium hydroxide compounds contained in the ore are split off, separated from foreign substances and subsequently burned to aluminium oxide.
In order to break down the aluminium oxide into its components, it is then dissolved in a cryolite melt and subjected to a high direct electrical current. This causes liquid aluminium to settle at the bottom of the electrolysis furnace. The oxygen combines with the graphite of the anode to form carbon dioxide. The process of electrochemical fused-salt electrolysis is very energy-intensive.
On average, 15 megawatt hours of electricity are required for one tonne of primary aluminium. That's about as much as an average household consumes in four years.
Aluminium: Use in the vehicle and in the battery cell
Usage
Aluminium is increasingly replacing steel in vehicle construction, in particular because of its lightness. The reduced overall weight improves the energy efficiency in the use of the vehicle. This reduces carbon dioxide emissions. In the case of electric vehicles, the lower weight increases the range. The amount of aluminium used in our vehicles varies depending on the vehicle model. In the entry segment, for instance, it is about 360 kilograms, with only about 10 percent accounted for by the body.
Another advantage of using aluminium for the body is its formability. In the event of an impact, the energy can be better dissipated.
Due to its properties, aluminium is also used in batteries - on average it is 90 kilograms per battery. 50 kilograms protect the battery as a housing, and cell blocks are made from another 40 kilograms.
Recycling
Aluminium is infinitely recyclable. Even today, 130-year-old aluminium is still in circulation. The recycling of aluminium is worthwhile, as it requires only five percent of the energy that is needed for initial extraction. In order to minimise impurities that are introduced via the aluminium scrap, a certain amount of primary-produced aluminium is added during remelting. The sorted separation of aluminium scrap is therefore an important prerequisite for high-quality secondary aluminium.
Our way to decarbonisation and a sustainable aluminium supply chains
CO₂ reduced Aluminium
Depending on the model, the use of aluminium in vehicles accounts for on average more than 20 percent of the total CO₂ footprint. The reason for this is the high energy consumption for the production of this light metal. Accordingly, the greatest potential for CO₂ savings lies in using green electricity in the production of aluminium. It has already been agreed with our Tier 1 suppliers for battery housings that they must use green electricity for production and may also only use aluminium produced with green electricity. Gradually, aluminium is to be completely replaced by green aluminium.
Use of secondary aluminium
We are increasingly using recycled aluminium. The use of so-called secondary aluminium saves up to 90 percent of the energy requirement compared to the production of primary aluminium. Together with suppliers, aluminium alloys are developed that meet the high requirements and at the same time allow for a high use of recycled aluminium.
Our standards
We are committed to a responsible supply of aluminium and rely on the application of recognized standards and robust certificates.
Mercedes-Benz is also a member of the Initiative for Responsible Mining Assurance (IRMA), which promotes cross-commodity standards for industrial mining. As part of IRMA, we have launched a research-driven project to develop mine site assessment procedures that increase and ensure the involvement of affected local communities before, during and after mine site assessment.
For a sustainable aluminum supply chain, Mercedes-Benz relies on a comprehensive approach: to protect our environment and resources, we are systematically increasing the proportion of recycled aluminum in our supply chain. At the same time, when sourcing so-called primary aluminum, the company is committed to the socially responsible and environmentally sound mining of the raw material bauxite, which is needed to produce the material. Mining of the raw material is attracting criticism, especially in Guinea, due to social and ecological aspects and the consequences for the local population. Bauxite is therefore one of the potential raw materials of risk that Mercedes-Benz is examining more closely with respect to human rights risks.
One of the salient risk areas prioritized in our assessment for aluminium is Community and Indigenous Rights with a particular regional focus on the Brazilian Amazon and Guinea. In order take joint responsibility for the entirety of the aluminium value chain, Mercedes-Benz closely works together with aluminium supplier Hydro. Both companies partner up to reduce the carbon footprint of aluminium and are committed to involving indigenous and traditional communities in the process.
This article was last updated in June 2024.
