Life Cycle Assessment

A life cycle assessment (LCA) is an analysis of the potential environmental impacts of a product throughout its lifetime. The LCA process can be divided into four main stages:

1. Extraction and processing of raw materials

2. Manufacturing and packaging

3. Product use

4. Product disposal

These stages help us compare the environmental impacts of different products.

Stages of an LCA

Extracting and processing

Extracting resources from nature can harm the environment. For example, it can deplete limited resources like crude oil and ores, or damage habitats through mining, deforestation, or quarrying.

Extracting and processing these raw materials requires a lot of energy. This can indirectly damage the environment through the release of pollutants.


There are three main environmental problems with the manufacturing and packaging of products:

  • Using up land for factories
  • Releasing pollutants due to the use of machines
  • Producing waste during the manufacturing process

Product use

The environmental impact of a product during its use depends on the type of product. For example, a reusable bag, used hundreds of times, will have less impact on the environment compared to a single-use bag.

Product disposal

The disposal of a product affects the environment in various ways, such as:

  • Using up space at landfill sites
  • Transportation to landfill sites releasing emissions
  • Potential leakage of chemicals into the environment
  • Emission of pollutants when burning waste

It’s also important to consider whether any or all of the products can be recycled.

Comparative LCA’s

We can use comparative LCA’s to compare the environmental impact of two different products at different stages. For example, let’s compare plastic bags and paper bags.

Plastic bagPaper bag
Raw materialsMade from crude oil, a finite resource. Requires fractional distillation to separate the oil, which requires a large amount of energy.Made from recycled paper or trees. Making paper reduces the number of animal habitats and requires more energy than recycling paper.

However, it still requires less energy than making plastics.
ManufactureHydrocarbons from fractional distillation are cracked (to form alkenes) and undergo polymerisation (to make plastics).Producing paper bags is more expensive because pulping requires a large amount of energy.

It also releases pollutants and generates a lot of waste.
UsePlastic bags are stronger, so they can be reused many times.Most paper bags are single-use.
DisposalCan be recycled, but the process is expensive and polluting.

Plastic bags are non-biodegradable, so they take up space in landfills, or end up harming animals.
Biodegradable, non-toxic and recyclable.

Criticisms of LCA’s

Making products often involves many different stages, so it can be challenging to quantify each individual stage. However, sometimes it is possible to measure the values for each stage accurately. For example, accurately measuring the energy required to extract and process a product.

However, even with quantifiable data, assessing the environmental harm of each stage is still difficult. Also, this process is not completely objective, and different people carrying out the LCA may have varying judgements of the effects at each stage.