Life cycle assessments and reducing use of resources

What is a life cycle assessment (LCA)?

A method used to assess the environmental impact of a product over its entire lifetime, from raw materials to disposal.

What are the four main stages of an LCA?

• Raw material extraction – Obtaining resources from the Earth.

• Manufacturing and processing – Converting raw materials into a product.

• Use and operation – The product’s impact while being used.

• Disposal – How the product is dealt with at the end of its life (landfill, recycling, etc.).

What are the environmental impacts of extracting raw materials?

Uses energy and depletes finite resources.

• Causes pollution (e.g., mining damages habitats).

What are the environmental impacts of manufacturing and processing?

Requires energy and produces waste.

• Some processes release harmful gases (e.g., CO₂ from factories).

What are the environmental impacts of product use?

Some products release pollutants (e.g., car emissions).

• Energy consumption (e.g., electrical appliances).

• Some products (e.g., reusable bottles) have low impact in this stage.

What are the environmental impacts of disposal?

Landfill takes up space and may cause pollution.

• Incineration releases CO₂ but can generate energy.

• Recycling reduces waste but requires energy.

How does an LCA help compare products?

It allows scientists to determine which product has a lower environmental impact.

Why are some LCAs not fully reliable?

Some stages are difficult to quantify (e.g., estimating pollution levels), and LCAs can be biased if companies manipulate data for marketing.

Compare the LCA of a plastic bag vs. a paper bag.

Stage	Plastic Bag	Paper Bag

Raw Material

Crude oil (finite resource)

Trees (renewable but deforestation)

Manufacturing

Requires energy, produces waste

Uses lots of energy and water

Use

Reused many times

Often used once

Disposal

Non-biodegradable, landfill issues

Biodegradable, decomposes faster

✅ Plastic bags may be better overall if reused multiple times, despite their impact on disposal.

Why is it important to reduce resource use?

To conserve finite resources (e.g., metals, fossil fuels).

• To reduce pollution and waste.

• To lower energy consumption and environmental impact.

What are the three key ways to reduce resource use?

Reduce, Reuse, Recycle

How does reducing help sustainability?

Using fewer raw materials reduces extraction and lowers energy use in manufacturing.

How does reusing help sustainability?

Extends a product’s life, meaning fewer new items need to be made. Example: Refilling glass bottles instead of making new ones.

How does recycling help sustainability?

Converts waste materials into new products.

• Uses less energy than producing new materials.

• Reduces landfill waste.

How is glass recycled?

Sorted by colour.

• Crushed and melted.

• Remoulded into new glass products.

How are metals recycled?

Separated from other waste.

• Melted and reshaped into new products.

eg. some scrap steel can be added to iron from a blast furnace to reduce the amount of iron that needs to be extracted from the ore

What are the challenges of recycling metals?

Sorting different metals can be difficult.

• Removing impurities takes time and energy.

How does recycling aluminium compare to extracting it?

Recycling aluminium uses 95% less energy than extracting it from bauxite!

What are alternative materials to reduce metal and plastic use?

Biodegradable plastics (e.g., made from cornstarch).

• Composite materials (e.g., carbon fibre instead of metal).