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As of: 04/14/2023 4:17 p.m
Driving a car in a climate-neutral manner is possible, for example, with electricity from renewable energies. But what is forgotten is that tons of CO2 are already produced during the production of a car. How can this be changed?
On-site visit in Landshut, Lower Bavaria: BMW operates a light metal casting plant here. The Munich carmaker produces all the important aluminum parts for its vehicles itself. For example, the cylinder head for its series with six-cylinder engines. Almost 40 kilograms of liquid aluminum are required for such a head. A robotic arm swings an oversized spoon over the molded sand mold. Then the spoon tilts and the light metal, heated to 780 degrees, flows into the mould. Four minutes later, the cylinder head is finished and the robotic arm picks up the cooled component again.
One employee monitors three casting stations. On weekdays, like the rest of the plant, they are in operation around the clock in three shifts. This one job alone gives an idea of how energy-intensive the production of a car is. In order to melt the aluminum and to be able to further process it for all kinds of cast parts in the car, it has to be heated to up to 900 degrees. So far, this has only been possible with natural gas. This alone produces enormous amounts of carbon dioxide.
Recycling helps to save CO2
But the production of the light metal itself is also very CO2-intensive. In order to reduce the large emissions, BMW relies on recycling. Two-thirds of the metal is recycled material. The remaining third comes from Dubai. The supplier there produces it exclusively with solar power.
Compared to conventional production, this saves considerable amounts of the carbon dioxide responsible for global warming. But doesn’t this positive effect fizzle out again if the metal produced with “green” energy then has to be transported thousands of kilometers to Landshut?
Martin Bednarz sees no problem with this. The expert for green production processes at the Technical University of Ingolstadt refers to the “particularly energy-intensive aluminum production”. That’s why it “makes a lot of sense to produce the material on site with green electricity. Of course, the transport then has an additional impact, but that is proportionally weighted much less than the production energy,” says Bednarz.
emissions in the supply chain
From next year, BMW wants to have large parts of its aluminum manufactured with even less CO2 emissions. In Canada, with hydroelectric power and a new process developed by supplier Rio Tinto. According to BMW, this saves 70 percent CO2 compared to conventional production. An important step towards climate protection for the executive floor of the car manufacturer.
You also have to keep an eye on the production and recycling of a car, says board member Joachim Post, who heads purchasing and the supplier network. “It’s just not enough to just look at the use phase of a vehicle and a drive alone. CO2 emissions in the supply chain are very important to us.” BMW has set itself an ambitious goal: “In the supply chain plus the usage phase, i.e. over the entire lifetime of a vehicle, they want to reduce CO2 emissions by 40 percent by 2030 compared to 2019”.
According to the Munich carmaker, it is on schedule. But 40 percent less also means that every car still produces tons of CO2. New construction methods could make this problem at least a little smaller.
Car parts from the 3D printer
Thomas Binder at the Technical University of Ingolstadt is researching how this could work. The construction specialist is experimenting with 3D printers. He has already made rims there, for example. The special thing about it: The 3D printer makes it possible to build many large and small cavities into the rim. The wheel carriers feature three-dimensional honeycomb and lattice structures.
This saves material and energy and ultimately reduces the emission of greenhouse gases, says Huber: in production, but also in the use phase, since the mass to be moved is smaller. And even with recycling, the energy consumption is later reduced.
“With a racing rim that weighs around 13 kilograms, this technology has enabled us to save two to three kilograms.” If you transfer this to all components of the vehicle, “then there are savings of ten to 20 percent,” calculates Huber. However, he makes his calculation with one caveat: “Assuming we can solve the problem with the strength of our printed aluminum parts.”
Because the workpieces from the printer are still not as stable and unbreakable under extreme loads as those that are produced using the casting process. However, Binder is confident that a solution will be found. “We just have to get the alloy right.” In other words, changing the aluminum mixture so that even in printed form it can withstand the extreme forces that occur when driving a car without damaging the metal.
Hoping for a circular economy
In the foyer of BMW’s research and innovation center in the north of Munich there is a black E-Mini – a special edition convertible of which only 999 will be built. The small car is also an eye-catcher for the BMW workforce during the lunch break. Employees keep stopping and looking at the vehicle from all sides. The rims too: In this small series, they are made of 100 percent recycled aluminum. Actually only a very small step towards less CO2 in car production.
Still groundbreaking for BMW board member Post. The company’s goal is “to establish the circular economy within the automotive industry”. Steel, aluminium, glass and plastic are to be recycled in high quality in the future. The company wants to increase the proportion of secondary material in a BMW from the current 30 to 50 percent. “The raw materials for our vehicles of tomorrow are already on the road today,” says Post, describing his company’s concept, without naming a date when this should be implemented.
Probably decades to go until CO2-neutral production
For Bednarz, the expert for green production in Ingolstadt, there is no question that there is still a long way to go before the car will be produced without CO2 emissions. While the CO2-neutral operation of a car “is relatively easy to do”, it will probably take decades to manufacture.
“It will take gigantic efforts to make the production processes of steel, aluminum and plastics completely CO2-neutral.” Incidentally, this does not only apply to the automotive industry. The production of vehicles for public transport faces the same problems.