AQA GCSE Chemistry

Revision Notes

10.2.1 Life Cycle Assessment

Test Yourself

Total Environmental Impact

  • A life cycle assessment (LCA) is an analysis of the overall environmental impact that a product may have throughout its lifetime
  • The cycle is broken down into four main stages which are:
    • Raw Materials
    • Manufacture
    • Usage
    • Disposal

Life Cycle Assessment - Flow Diagram, IGCSE & GCSE Chemistry revision notes

Diagram showing the four stages in a life-cycle assessment

  • 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

  • Manufacturing 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
    • Production of waste

  • 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)
  • The disposal of outdated products has an impact on the environment which may include:
    • Using up space at landfill sites
    • Whether the product or its parts can be recycled

  • 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

Exam Tip

Be careful if you are provided with a life cycle assessment which is abbreviated when evaluating a product as they do not give the complete picture. They are often used in advertising campaigns to support claims to highlight the benefits to the environment of a product without explaining the negative environmental impact it may have.

Lifecycle Assessment of Shopping Bags

Example

An LCA can be carried out on plastic and paper shopping bags.

10-2-1-lca-for-plastic-and-paper-bags-new

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 thus 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 then the argument for using plastic bags is less favourable

Exam Tip

You could be asked to carry out a comparative LCA for shopping bags made from paper or plastic. For each stage of the life cycle that you are given information about, make a comparison of all the materials and explain why one material is better than another for the environment.

Give a conclusion to state which material you think would have the least environmental impact overall during its lifespan and justify this with some reasons.

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