Crediting aluminium recycling in LCA by demand or by disposal
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- Frees, N. Int J Life Cycle Assess (2008) 13: 212. doi:10.1065/lca2007.06.348
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Background, Aim and Scope
By using recycled aluminium or by disposing used aluminium products for recycling, it is normal LCA practice to give a credit for the avoided production of primary or recycled aluminium. Lately, consequential approaches have been suggested to qualify and quantify this credit in terms of market mechanisms. Depending on supply, demand and price elasticity of primary products and scrap products, a mixed share of primary and recycled material may be credited. Aluminium, having high energy consumption for its primary production and low energy consumption for recycling, is very sensitive concerning whether production of primary or recycled aluminium is avoided. This paper includes presentations of aluminium products which are typically made from primary and from recycled aluminium. This is essential concerning which production may be avoided. Examples of market mechanism parameters of aluminium for consequential LCA are given.
A survey of aluminium products manufacturing is made to determine which products are made from primary and which from recycled aluminium. To estimate the price elasticity, statistics of supply and prices of primary aluminium and aluminium scrap are compiled and papers concerning supply, demand and price elasticity of aluminium are summarised. The parameters are suggested for performing consequential LCA.
The available amount of aluminium scrap covers only approx. 30–40% of the demand for aluminium, and hence approx. 60–70% of the demand is inevitably made from primary aluminium. Open loop recycled aluminium is primarily used for casting alloys, but closed loop recycling exists, for example, for aluminium cans. The open loop market for low-alloyed aluminium sheets and profiles is primarily covered by primary aluminium. It is therefore of no use to demand recycled aluminium of these qualities, but if the products are recycled after use, they should be credited for the avoided production.
The supply price elasticity of aluminium scrap is estimated to be rather inelastic, and the avoided production will hence primarily be of primary aluminium. This is in contradiction to a default recommendation for consequential LCA saying that a 50/50 share of primary and recycled material is avoided by recycling most materials.
An important conclusion of the paper is that, given the inelastic price elasticity of aluminium scrap, it is production of primary aluminium which is avoided by recycling. This conclusion is actually in agreement with the traditional systems expansion, which has been put under question by consequential LCA. Because primary aluminium is avoided by recycling, a credit of avoided production of primary aluminium should be given when a used product is recycled. Hence, a credit should not be given when demanding recycled aluminium, or aluminium with a certain recycled content.
Recommendations and Perspectives
It is recommended that aluminium is considered price inelastic in consequential LCA, and that avoided production of primary aluminium is credited when recycling a used aluminium product. Avoiding primary material by recycling has great perspectives for aluminium with its high energy consumption for primary production and low energy consumption for recycling.