GCSE Chemistry revision

Life cycle assessment

Life cycle assessment and recycling

AQA 4.10.2.1 Foundation & Higher

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A life cycle assessment (LCA) analyses the environmental impact of a product across all stages of its life, from raw material extraction to disposal.
The four main stages of an LCA are: extracting and processing raw materials, manufacturing and packaging, using the product, and disposing of it.
The goal of an LCA is not to memorise facts but to understand each stage so you can compare the environmental impact of different products.

1. Introduction AQA

A life cycle assessment (LCA) analyses the environmental impact of a product across all stages of its life, from raw material extraction to disposal.
The four main stages of an LCA are: extracting and processing raw materials, manufacturing and packaging, using the product, and disposing of it.
The goal of an LCA is not to memorise facts but to understand each stage so you can compare the environmental impact of different products.

Extracting raw materials from nature can directly damage local environments, for example by deforestation or open-cast mining.
Processing raw materials can indirectly harm the environment due to the large amounts of energy required, such as during fractional distillation of crude oil or extracting metals from their ores.
Pollutants can also be released during processing, for example when purifying extracted materials.

2. Stage 1: Extracting and Processing Raw Materials AQA

Extracting raw materials from nature can directly damage local environments, for example by deforestation or open-cast mining.
Processing raw materials can indirectly harm the environment due to the large amounts of energy required, such as during fractional distillation of crude oil or extracting metals from their ores.
Pollutants can also be released during processing, for example when purifying extracted materials.

The three main environmental concerns during manufacturing are energy use, the release of pollutants such as carbon monoxide or hydrogen chloride, and the production of waste products.
Waste products from manufacturing are sometimes used as raw materials for other processes, but are often useless and must be disposed of, adding to environmental burden.

3. Stage 2: Manufacturing and Packaging AQA

The three main environmental concerns during manufacturing are energy use, the release of pollutants such as carbon monoxide or hydrogen chloride, and the production of waste products.
Waste products from manufacturing are sometimes used as raw materials for other processes, but are often useless and must be disposed of, adding to environmental burden.

When assessing the impact of using a product, we must consider how much pollution or damage it causes during its lifetime, for example the emissions from driving a car or fertiliser runoff into waterways.
The length of time a product is used also matters — a reusable bag used thousands of times has a very different environmental impact compared to a single-use bag.

4. Stage 3: Using the Product AQA

When assessing the impact of using a product, we must consider how much pollution or damage it causes during its lifetime, for example the emissions from driving a car or fertiliser runoff into waterways.
The length of time a product is used also matters — a reusable bag used thousands of times has a very different environmental impact compared to a single-use bag.

Disposing of products in landfill takes up space that could be used by nature, and chemicals may seep out and damage surrounding ecosystems.
Burning waste (incineration) can release harmful pollutants into the atmosphere, contributing to air pollution.
The energy used to transport waste to landfill or an incinerator must also be factored into the environmental assessment.

5. Stage 4: Disposing of the Product AQA

Disposing of products in landfill takes up space that could be used by nature, and chemicals may seep out and damage surrounding ecosystems.
Burning waste (incineration) can release harmful pollutants into the atmosphere, contributing to air pollution.
The energy used to transport waste to landfill or an incinerator must also be factored into the environmental assessment.

Plastic bags are made from crude oil, a finite resource that requires energy-intensive fractional distillation, cracking of hydrocarbons, and polymerisation to produce polymers. Paper bags are made from wood, meaning trees must be cut down, reducing habitats for animals and plants, and the pulping process requires large amounts of energy and produces significant waste. In terms of use, plastic bags can generally be reused multiple times, whereas paper bags are typically single-use. For disposal, plastic bags are non-biodegradable, meaning they persist in landfill or in the wild where they can harm animals, while paper bags are biodegradable and non-toxic, making them less harmful at end of life.

6. • Case Study: Plastic Bags vs Paper Bags AQA

Plastic bags are made from crude oil, a finite resource that requires energy-intensive fractional distillation, cracking of hydrocarbons, and polymerisation to produce polymers. Paper bags are made from wood, meaning trees must be cut down, reducing habitats for animals and plants, and the pulping process requires large amounts of energy and produces significant waste. In terms of use, plastic bags can generally be reused multiple times, whereas paper bags are typically single-use. For disposal, plastic bags are non-biodegradable, meaning they persist in landfill or in the wild where they can harm animals, while paper bags are biodegradable and non-toxic, making them less harmful at end of life.

LCAs are difficult to carry out accurately because modern manufacturing involves many complex steps, making it nearly impossible to quantify every environmental impact. Even when all data is collected, it is hard to compare different types of harm — for example, weighing the production of particulates that cause lung disease against greenhouse gases that drive global warming. Because LCAs are so complex, they can be manipulated to favour a particular company, potentially being used as misleading positive advertising, and such bias is difficult to detect.

7. Limitations of Life Cycle Assessments AQA

LCAs are difficult to carry out accurately because modern manufacturing involves many complex steps, making it nearly impossible to quantify every environmental impact. Even when all data is collected, it is hard to compare different types of harm — for example, weighing the production of particulates that cause lung disease against greenhouse gases that drive global warming. Because LCAs are so complex, they can be manipulated to favour a particular company, potentially being used as misleading positive advertising, and such bias is difficult to detect.