Wednesday, February 27, 2013

How much energy is used to make a new aluminium can and a recycled aluminium can?

Good information on the internet can be quite tricky to find and also often it is difficult to verify the information with regards to the energy used to make a new aluminium can. I decided to focus on the following information which references the CSIRO because if the reference is correct, the information is likely to be better.

CSIRO calculate that the embodied energy (all the energy used to make the material) for aluminium is 211 GJ per tonne... Read More

Based on the CSIRO calculation of 211GJ per tonne, where a tonne is 1,000kgs, this gives us 211MJ per kg. The next step is to use the figure from 2005 (www.aluminium-cans.com.au) where an aluminium can weighs 14.7g giving us 68.03 cans per kilogram. Thus the amount of energy to create a single new can is 3.101MJ.

A common unit of measure for costing electricity is kWh. MJ or mega joule is an amount of energy, whereas kWh is the amount of energy used over an hour. One joule per second is one watt. To determine the energy used to make a single can we take 3.101MJ and use the energy over an hour. There are 3,600 seconds in one hour. Thus 3.101MJ/3600s gives us 861Wh of energy usage or 0.861kWh.

This is a good figure because we can now plug that figure into the Energy Cost Calculator which shows if we used this energy in one hour at domestic rates, the cost per can for the energy would be 22 cents. Of course an aluminium smelter wouldn’t pay this type of money. I don’t know what they pay but it would be at a considerable discount.

The next figures of interest is that in 2005 71.3% of cans were recycled and it only costs 5% of the energy to create a can from recycled material as it does to create a new can. Thus if only using recycled cans the cost of energy at retail rates would be 1.1 cents. If using 28.7% new cans and 71.3% of recycled cans which means at domestic electricity prices the average cost of electricity to produce at can would be around 7.1 cents. I can only guess the rate aluminium smelters pay for their electricity, but I suspect it would be in the order of half to a quarter of what a consumer would pay. Thus an average can would cost perhaps 2-3 cents to create.

In summary the energy used to manufacture a new can is around 861Wh and the energy to make a can from recycled cans would be around 43Wh.

I hope others find this information interesting.

- Kelvin Eldridge
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