Aluminium and ecology


Producing aluminium through the Hall-Héroult process consumes huge amounts of energy (but: the produced aluminium is now hugely cheaper than it was before this process existed). Typically, 13.5 MWh are needed to produce 1 metric ton of aluminium, with an average global yield of 50%.. A typical aluminium-producing plant needs +/- 600 MW per hour, which is half of what can generate an average nuclear energy station.

Each year, 38 million tons of aluminium are produced through the world, implying the rejection into the atmosphere of some 38 million tons of CO2 (without taking into account the CO2 rejected during the production of the electricity needed for producing the aluminium). But these fact have to be viewed in a global perspective. These rejections only represent 0.5-0.8 percentage of all these caused every year by the human activity. If I use 1 litre of petrol, I already reject 2.3 Kg of CO2.

There are other negative effects of this production: the rejection of tetrafluoromethan and of hexafluoroethan, the noxiousness of which is not yet fully measured. But it is estimated that these gasses are at least 10.000 times more absorbent of the infrared than CO2. The production of one ton of aluminium provokes the rejection of 1 kg of these gasses (together)..

But... when discussing about ecological matters, one must always take care to view the complete picture, the global "profit & loss" account. One must also mention the positive aspects on our lives of the usage of aluminium.

First of all, do not forget that aluminium is 3 times lighter than steel, with a a maximal yield strength that is often higher than steel. The use of aluminium in nearly all domains of public and private transportation has allowed huge energy savings all over the world in these domains. Just try to imagine what air transportation would have been without aluminium and other light metals...

It should also be remembered that aluminum can be recycled almost indefinitely. It suffices to re-melt it, which consumes only 95% of the energy that was needed to produce it.