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Matthias Köpf, Rohrdorf
When Helmut Leibinger opens the metal flap with the lever, the small window allows a view like a bubbling volcano. The clinker is actually already being cooled here again after the 80 meter long steel tube had pushed the limestone towards the 20 meter long burner flame by constantly rotating it. The temperature in the furnace is almost 1500 degrees, and this deep rumbling already suggests that a lot of energy is burned here. But that alone would not be the reason why cement production is considered the climate killer par excellence. Because more than two-thirds of the carbon dioxide does not arise during heating, but escapes from the limestone, which has formed over millions of years from deposited sea creatures. When burning a ton of clinker, which later binds the concrete, almost 800 kilograms of CO₂ are released, says Mike Edelmann. Here in Rohrdorf, they recently answered the question of how to avoid as much as possible by generating electricity from waste heat and practically no longer burning coal, instead using scrap tires and production residues from the plastics industry, among other things. In the meantime, however, they are asking themselves another question: “How clean is the CO₂?”