Life Cycle Assessment and RecyclingAQA GCSE Chemistry: Revision notes

A life cycle assessment is a systematic method used to evaluate the environmental impact of a product or process throughout its entire life. LCAs examine four key stages:

1. Extracting and processing raw materials – obtaining materials from the Earth and preparing them for use
2. Manufacturing and packaging – converting materials into finished products and preparing them for transport
3. Use and operation – the period when consumers use the product
4. Disposal at end of life – what happens when the product can no longer be used (landfill, recycling, incineration)

Each stage consumes energy and resources, and may generate waste or emissions. By assessing all four stages together, LCAs provide a complete picture of a product's environmental footprint rather than just focusing on one stage.

LCAs can be used to compare the environmental impact of different products or processes across all stages of their life. This allows manufacturers and consumers to make more informed choices about which option is more sustainable.

For example, LCAs can be used to compare:

• Paper bags versus plastic bags for shopping
• Recycled aluminium versus newly extracted aluminium
• Different manufacturing methods for the same product
• Packaging materials with different environmental costs

By calculating the total environmental cost (energy used, emissions produced, waste generated) across all four stages, LCAs reveal which product has the lowest overall impact. This is important because a product that appears 'green' at one stage may have hidden environmental costs at another – for instance, a product that produces no waste during use might require enormous amounts of energy to manufacture.

Although LCAs are valuable tools, they have significant limitations that mean they cannot provide a complete picture of environmental impact:

Difficult to quantify impacts:

• Some environmental effects cannot be easily measured in numbers, such as:
  • Loss of biodiversity – destruction of habitats and species
  • Visual pollution – ugliness of landscapes or industrial facilities
  • Noise pollution – disturbance from machinery or traffic
  • Water pollution – impacts on aquatic ecosystems
  • Habitat destruction – loss of natural environments

Requiring value judgements: Because these impacts are hard to measure scientifically, LCAs require value judgements – subjective decisions about how important each impact is. Different people may weigh these factors differently. For example, is protecting a rare ecosystem more or less important than reducing carbon emissions? Different organisations may give different answers.

This means that LCAs can be biased depending on who conducts them and what they choose to prioritise. Results may vary significantly between different LCA studies of the same product.

Recycling metals provides significant environmental and economic benefits:

Conserves finite ore supplies:

• Metal ores are naturally occurring minerals that contain metals – these are non-renewable resources
• Recycling metals means we rely less on mining new ores from the Earth
• This extends the availability of ore deposits for future generations

Uses less energy than extraction:

• Extracting metals from ores (through mining, crushing, and processing) requires enormous amounts of energy
• Recycling metals requires much less energy because the metal is already pure and refined – it only needs remelting
• Lower energy use means fewer carbon emissions and lower fuel costs

Reduces waste to landfill:

• Metal waste that is not recycled must be disposed of in landfills
• Landfills create environmental problems: they take up space, can leak harmful substances, and many are now full
• Recycling diverts metals away from landfills, reducing environmental damage and freeing landfill space for waste that cannot be recycled

Economic benefit:

• Recycling metals is often profitable because metal scrap has market value
• This incentivises collection and recycling schemes

Not all metals are equally valuable to recycle. Aluminium is particularly valuable to recycle because of its exceptional energy requirements for extraction.

Why aluminium recycling is especially important:

Other metals valuable to recycle:

• Copper – high value because of energy-intensive extraction
• Steel – used extensively so recycling saves substantial resources
• Lead – toxic, so recycling prevents environmental contamination

Metals less urgently recycled:

• Some metals have lower energy extraction costs, so recycling them saves less energy (though it still has benefits)

The key principle is: the more energy required to extract a metal from ore, the more energy is saved by recycling it, and the more valuable that recycling becomes.