A life cycle assessment (LCA) is comprehensive scientific examination of the environmental and economic effects of a product at every stage of its existence, from production to disposal and beyond. It looks at the impacts of the 'product system', including:

• the mining and extraction of raw materials;
• fabrication;
• transportation;
• use;
• recycling/ disposal;
• energy and ancillary material supplies.

A typical LCA exercise will comprise:

• goal and scope definition to describe the application covered, the reasons for the study, target audience and a detailed technical description of the "product system”
• life cycle inventory analysis which is the compilation and quantification of the environmental inputs and outputs for the product system throughout its life cycle
• life cycle impact assessment to understand and evaluate the size and significance of the potential environmental impacts of the product system
• interpretation or the conclusions and recommendations from the findings of the life cycle inventory analysis and impact assessment in line with the defined goal and scope.

Life cycle assessment is used by the aluminium industry to assess and stimulate environmental improvement in production processes and product development. The review of life cycle assessment environmental aspects in production processes can also lead to improvements in the production processes themselves.

Aluminium industry life cycle assessment

A life cycle assessment of aluminium has to look far beyond the production processes of:

• bauxite mining, the first step in aluminium production;
• production of alumina where aluminium oxide, the raw material for primary aluminium production, is refined from bauxite;
• production of primary aluminium using electrolysis.

A life cycle assessment of aluminium also covers the impacts and benefits of the material throughout the lifespan of the different aluminium products including their reuse and recycling. Other steps in the aluminium life cycle therefore include:

• semi-fabrication encompassing several industrial processes for the production of rolled products, extrusions, wire, tubes, forgings and castings;
• product manufacture where aluminium is processed into finished products;
• the use phase is often the most significant in life cycle assessments. For example, for a car the use phase accounts for more than 80% of total CO₂ emissions. In this phase aluminium can bring substantial savings;
• recycling and re-use in new products. The use of recycled aluminium further decreases energy consumption and greenhouse gas emissions compared to those resulting from primary aluminium production. This adds further value to the basic reductions already achieved by aluminium use per se - such as in transportation applications.

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