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

Diagram illustrating the life cycle of products, starting from extraction of raw materials, transitioning through manufacturing and usage phases, and ending in 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 the raw materials requires a lot of energy. This can indirectly damage the environment through the release of pollutants.


There are three main environmental problems associated 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 releases 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 LCAs

We can use comparative LCAs 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 has a significant environmental impact 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’s possible to accurately measure the values for each stage. For example, accurately measuring the energy required to extract and process a product.

Even with quantifiable data, assessing the environmental harm of each stage is still difficult. Also, this process is not entirely objective. Different individuals conducting the LCA might have varied judgments of the effects at each stage.

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