Life Cycle Assessment (AQA GCSE Chemistry)

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

Lifecycle assessment

Diagram showing the four stages in a life-cycle assessment

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

Manufacturing

• 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

Use

• 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

• The disposal of outdated products has an impact on the environment which may include: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

How is a lifecycle assessment carried out?

• 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

Lifecycle Assessment

Lifecycle assessment (LCA)

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

A life cycle assessment 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 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