Bodywork: bauxite and the recycling rate
Bauxite contains up to 25 percent aluminum and is currently the only ore that is mined for the commercial production of aluminum. It is found primarily around the equator at a relatively shallow depth, under stones and clay which need to be dug up. Mining and processing change the landscape, affect the diversity of species and the water quality, and can also lead to soil erosion. To minimize the environmental impact, the mining company can replant cleared vegetation immediately after the bauxite mining. Volkswagen has obligated its direct suppliers to maintain sustainability standards such as protection of the environment and is working to enforce these standards right up until the last link of the supply chain.
To obtain pure, so-called primary aluminum from bauxite, the bauxite is melted down so the aluminum can be separated from the other components. This chemical process is called molten-salt electrolysis. The liquid aluminum is collected in troughs and sucked out.
Aluminum has a relatively low density of 2.7 grams per cubic centimeter and is easy to work. Alloys with magnesium or silicon also give it a higher strength – thus making it ideally suited for bodyworks. The rolled plates and components that Audi, for example, sources from its suppliers are about 40 percent lighter than their steel equivalents. This makes the car lighter overall and thus reduces fuel consumption. The rule of thumb is that when a vehicle with a gasoline engine “slims down” by 100 kilos, it uses 0.32 liters less fuel per 100 kilometers driven.
Challenge and approach
High energy consumption
From bauxite to the finished components, aluminum production consumes a lot of energy: each kilogram of aluminum requires around 15 kilowatt-hours of energy. A vehicle from the Volkswagen Group contains on average 140 kg of aluminum. If these 140 kilograms consisted entirely of primary aluminum, the production would involve an energy expenditure of 2,100 kilowatt-hours. With that amount of power, you could charge a smartphone almost 700,000 times, run an energy-saving lamp for more than 21 years – or send an e-Golf on a journey longer than the distance between Lisbon and Vladivostok.
A high recycling rate
Assorted aluminum scrap can theoretically be recycled infinitely often – and, in the process, consumes 95 percent less energy than that required for primary aluminum production. That’s why Volkswagen is working in cooperation with its suppliers to collect the aluminum scraps from their own pressing plants and feed it back into the cycle. This reduces the CO₂ emissions resulting from production. The Group’s aluminum foundries also use secondary raw materials to a large extent – at the foundry in Kassel this is already 100 percent. Since 2013, Audi has also been a member of the international Aluminium Stewardship Initiative, which is dedicated to the responsible production of aluminum and has defined minimum standards across the entire supply chain: from the original bauxite mining to the mills and right on up to the individual components themselves.