To further advance sustainability in the aluminium industry, it is important to understand where the energy for the production comes from.
Here, the difference between the production of primary aluminium and the extraction of secondary aluminium through recycling is significant.
But how is aluminium extracted in the first place?
Primary aluminium is extracted from the raw material bauxite. For this purpose, the bauxite is first heated in a sodium hydroxide solution. Aluminium hydroxide is formed. Aluminium oxide obtained through further process steps is finally processed into aluminium by the electrolysis, more precisely the melt flow electrolysis. However, the electrolysis and the preceding processing of the raw material consume energy.
How high is the energy consumption?
It is difficult to determine the exact energy level required for the production of aluminium. Current studies from the year 2020 assume at least 14,237 kWh of electricity and 62 mN³ of natural gas per ton of aluminium produced in the electrolysis process (source: "Aluminium - Information on Sustainability," German Federal Institute for Geosciences and Natural Resources).
However, it is important to consider how big the CO₂ footprint of production is in this process. This value is highly dependent on the energy sources used.
The CO₂ footprint of aluminium
If we assume the global average, a large part of the energy is still obtained from fossil fuels. For example, about 55 % of the energy comes from coal. However, 30% is already obtained from hydropower. This puts aluminium in a very good position compared with other metals.
The CO₂ footprint varies greatly from country to country. On average, aluminium has a footprint of 17 kilograms of CO₂ per kilogram of aluminium produced. This is a very good value compared to other raw materials. However, even more CO₂ can be saved by recycling aluminium. In Europe, for example, 1 kilogram of recycled aluminium currently requires just 0.5 kg of CO₂ in production.
Aluminum as a sustainable resource
The results show that aluminium is a good resource for a CO₂-neutral future. Aluminium already offers a good energy balance, but more focus will be needed on secondary aluminium in the future. However, the progressive expansion and use of renewable energies, also in industry, show a positive trend and aluminium is an ideal resource for a sustainable industry due to its good recyclability.