The Four Stages of Life Cycle Assessment Revision Notes | GCSE AQA Higher Chemistry

1. Why Life Cycle Assessment Matters

Every product you use - from your phone to your trainers - leaves an environmental footprint. But here's the catch: most of that impact happens before you even buy it.

Life Cycle Assessment (LCA) is like creating an environmental CV for products. It tracks every stage from 'cradle to grave' - revealing hidden costs that don't appear on the price tag.

Companies use LCA to spot the biggest environmental problems in their supply chains. This helps them make smarter choices - like switching to renewable energy or using recycled materials.

2. Stage 1: Raw Material Extraction and Processing

Everything starts with raw materials. Your smartphone contains over 60 different elements - from lithium in Bolivia to rare earth metals in China. Getting these materials out of the ground creates the first wave of environmental impact.

This stage includes mining ores, drilling for oil, cutting down trees, and processing these materials into usable forms. Think copper ore becoming copper wire, or crude oil becoming plastic pellets.

The environmental costs here are massive: habitat destruction from mining, CO₂ emissions from processing plants, and water pollution from chemical treatments. For aluminium, this stage accounts for 60% of its total environmental impact.

3. Stage 2: Manufacturing and Packaging

Raw materials now get transformed into the actual product. This stage covers everything that happens in factories: melting, moulding, assembling, quality testing, and wrapping the final product.

Manufacturing is energy-intensive. Factories need electricity for machines, heat for chemical reactions, and power for assembly lines. The packaging adds another layer - cardboard boxes, plastic wrapping, and foam padding all have their own environmental footprints.

Here's where transport between stages matters too. Components might travel thousands of miles between different factories before final assembly. A car's parts typically visit 5-10 different countries during manufacturing.

4. Stage 3: Use and Operation

This is the stage you see - when you actually use the product. But the environmental impact varies wildly depending on what the product does.

For a washing machine, this stage dominates the environmental impact. Over 10 years, it uses far more energy washing clothes than was needed to manufacture it. The same applies to cars, fridges, and computers.

But for a plastic bag or disposable cup, the use stage has almost zero impact - you use it once and throw it away. The environmental cost was front-loaded in manufacturing.

Worked example: Comparing Environmental Impact During Use Stage

A washing machine uses 2 kWh of electricity per wash cycle. If used 3 times per week for 10 years, calculate the total energy consumption during the use stage.

1. Energy per week = 2 kWh × 3 cycles = 6 kWh — Multiply energy per cycle by cycles per week
2. Energy per year = 6 kWh × 52 weeks = 312 kWh — 52 weeks in a year
3. Total energy = 312 kWh × 10 years = 3,120 kWh — This is about 20 times the energy used to manufacture it

Answer: 3,120 kWh over the 10-year lifespan

5. Stage 4: Disposal and End of Life

Eventually, every product reaches the end of its useful life. What happens next determines the final environmental impact - and whether valuable materials get recovered or lost forever.

The disposal stage includes collection, transport to waste facilities, and final treatment. Products might get recycled (materials recovered), incinerated (energy recovered), or sent to landfill (no recovery).

Smart disposal can actually reduce the overall environmental impact. Recycling aluminium cans saves 95% of the energy compared to making new aluminium from ore. But poor disposal - like electronic waste in landfills - can leak toxic materials into soil and water.

6. Putting It All Together: LCA in Action

LCA reveals surprising truths about environmental impact. Paper bags seem more eco-friendly than plastic bags, but Some LCAs show plastic bags can have a lower carbon footprint in manufacturing and transport, but this depends on the assumptions made and does not include every environmental issue such as pollution.

The power of LCA is comparing alternatives. Should a company use recycled plastic or biodegradable plastic? Should they manufacture locally or import from cheaper factories? LCA provides the data to make evidence-based decisions.

7. Exam Technique: Mastering LCA Questions

LCA questions test your ability to identify stages and evaluate environmental impacts. Examiners love asking you to compare different materials or suggest improvements to reduce environmental impact.

Common exam mistakes include forgetting the use stage for products like cars (where it dominates) or assuming recycling is always better without considering the energy costs of the recycling process itself.

A full life cycle assessment considers raw material extraction, manufacturing and packaging, use, and disposal. Transport and distribution can occur between every one of these stages, so transport must be counted throughout the product's life rather than being treated as a one-off detail.