Life Cycle Assessment (AQA GCSE Combined Science: Synergy: Physical Sciences): Revision Note

Life cycle assessment

• A life cycle assessment (LCA) is an analysis of the overall environmental impact that a product may have throughout its lifetime

• The assessment considers the environmental impact of the materials used and the energy resources needed at each of four main stages:

  1. Extracting and processing raw materials

  2. Manufacturing and packaging

  3. Use and operation during its lifetime

  4. Disposal at the end of its useful life

• Transport and distribution is also considered at each stage

Extracting and processing raw materials

• Obtaining the necessary raw materials has an impact on the environment, which may include:

  • Using up limited resources such as ores and crude oil

  • Damaging habitats through deforestation or mining

  • Energy resources used in extraction and transport to processing facilities

Manufacturing and packaging

• Manufacturing and packaging processes also have an impact on the environment, which may include:

  • Using up land for factories

  • The use of fossil-fuelled machines for production and transport

  • Energy and materials used in packaging production

  • Production of waste

Use and operation during its lifetime

• Usage of a product may also affect the environment, although it depends on the type of product

• For example, a wooden desk has very little impact whereas a car will have a significant impact (air pollution)

Disposal at the end of its useful life

• The disposal of products at the end of their useful life has an impact on the environment, which may include:

  • Using up space at landfill sites

  • Whether the product or its parts can be recycled

Carrying out an LCA

• A life cycle assessment is carried out using the data of a given product and the criteria of the assessment

• Some stages are easily quantifiable, e.g. the amount of water used during manufacturing of a product or quantity of waste materials produced

• However, other stages are more difficult to allocate a numerical value to, e.g. the polluting effect of a product 

• In these cases, people can make a value judgement about their effect but this is not an objective process and different people may allocate different values, or they may be biased

• Rarely is there a perfect product with zero environmental impact, so often a compromise is made between environmental impact and economical factors

Interpreting LCA data

• An LCA can be carried out on plastic and paper shopping bags to compare their environmental impact

LCA of paper and plastic shopping bags

Conclusion

• Considering both life-cycle assessments, the plastic bag may be the better option

  • Even though they aren’t biodegradable, they do have a much longer lifespan and are less harmful than paper bags

• Much depends on the usage of the item:

  • If the paper bag is recycled then it could be more favourable to use it

  • If the plastic bag is used only once, then the argument for using plastic bags is less favourable