“The energy used for primary production is embodied, to a large extent, in the metal and, consequently, in the building too. Today’s buildings and their contents therefore present large “urban mines” of around 400 million tonnes of aluminium metal that can be extracted and recycled by future generations through the use of only 5% of the originally used energy, not just once but repeatedly."
Aluminium is extensively employed in buildings, but it does not remain permanently in place. Buildings are remodeled periodically, and even deconstructed, thereby freeing the aluminium for recycling. Therefore, it is not inaccurate to regard this aluminium as “urban ore” and cities as “urban mines”.
The aluminium is embodied in such items as exterior surfaces, counters, appliances, and electronics. In highly-developed countries, aluminium in buildings of all types amounts to between 120 and 200 kg per person. Globally, it is estimated that buildings and their contents contain some 400 million tonnes of aluminium, which can be extracted and reused by future generations time after time, requiring only about 5% of the energy originally used to extract and process aluminium from more traditional geologic sources.
Aluminium recycling thus not only represents good urban housekeeping, it provides major energy benefits today and tomorrow.”
Professor Thomas E. Graedel, Yale School of Forestry and Environmental Science