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Life Cycle Assessments

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Life Cycle Assessments Revision

Life Cycle Assessments 

To live more sustainably, societies need to understand the impact that products and services have on the environment. To do this, people can use life cycle assessments. Life cycle assessments can be compared to one another to help us choose more sustainable products, such as using paper bags over plastic ones. These assessments will have issues however, such as subjective judgements on the scale of a products impact. 

What is a Life Cycle Assessment?

Life cycle assessments (LCAs) aim to help us understand the environmental impacts of the various products and services that people use in their everyday lives. The assessments consider a products whole life cycle, from raw materials extraction, to eventual disposal. The stages considered are; extraction of raw materials, the processing of these raw materials, product distribution, product use and operation, and disposal.

  • Materials Extraction: To produce a product, the raw materials used for its production must first be extracted. This extraction can have a range of environmental impacts. Extraction of materials can often require mining operations which will destroy the environment around them. Extraction operations also have their own associated carbon emissions


  • Materials Processing and Manufacturing: In this stage, raw materials are taken to factories and are processed into useful products. The processes used to manufacture products may produce large volumes of carbon emissions as well as other chemical or material waste. This waste must be disposed of and can be harmful to people and the environment


  • Distribution of Products: After products have been manufactured, they must be distributed for use and sale. This stage mainly produces carbon emissions as a result of transportation


  • Use and Operation: Certain products, such as motor vehicles, will produce carbon emissions during their operation. Electrical goods that need power will also create emissions indirectly by driving demand for fossil fuel consumption in power generation. Other products, such as food and drink or cleaning products and cosmetics may produce waste in the forms of packaging and chemical waste.


  • Disposal: Finally, once product has reached the end of its useful life it must be disposed of. This can be done in a number of ways including, recycling, incineration, and landfill. Disposal methods such as recycling and incineration can produce carbon emissions as a result of the need to power these processes. Incineration can also produce other harmful gaseous pollutants. Landfills can release toxic pollutants into the environment, particularly into sources of natural water such as ground water. 

There are of course other considerations at every stage of a products life, and specific LCAs can be incredibly comprehensive. For example, when considering both raw materials extracting and product disposal, the renewability and biodegradability of the materials used must be considered.

By comparing the life cycle assessments of different products it is possible to compare the environmental impacts of different processes as well as the products themselves. 

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Comparing LCAs: Plastic and Paper Bags

When people go shopping, they need to carry what they have bought. For a long time this has primarily been done using plastic shopping bags. Though cheap and easy to produce, these bags are not very environmentally friendly. In recent years, it has become common for shops to provide paper shopping bags instead. We can see which has a lower impact on the environment by comparing their LCAs.

Life Cycle State Plastic Bags Paper Bags
Raw Materials Extraction

 Plastic bags are produced from compounds found in crude oil

Crude oil is non-renewable.

Extraction produces carbon emissions

Paper is produced from trees

Trees are a renewable resource.

Harvesting trees can damage natural environments. Process produces carbon emissions

Manufacturing  Produced in factories. Leads to carbon emissions from manufacturing. Produced in factories. Leads to carbon emissions from manufacturing. 
Distribution  Distributed by traditional shipping (e.g. lorries). This again produces carbon emissions. Distributed by traditional shipping (e.g. lorries). This again produces carbon emissions
Use  Often used once before disposal. Generates more waste. Often used once before disposal. Generates more waste. 

Plastic is non-biodegradable and therefore will take a very long time to break down in landfill. 

Plastic bags are non-recyclable so can’t be used to produce new bags or other products. 

Paper is bio-degradable and will breakdown quickly in the environment. 

Paper bags are recyclable and can be used to create new plastic bags or other paper products.

We can see that, for many of the middle steps, (manufacturing, distribution, and use), the LCAs of the products are the same. Most products are distributed in similar ways, using existing supply chains that produce large amounts of carbon emissions and the use of plastic and paper bags is often very similar. However, the difference in the materials used impacts the first and last stages of these products lives. 

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Issues With LCAs

LCAs can be useful to help us understand how a product impacts the environment, but they are not without their problems. Accounting for all other ways in which a product might impact the environment is an incredibly difficult task. Some impacts are easy to see, such as environmental destruction from mining or carbon emissions from transportation.

Some however are more difficult to assess. For example, when impacts become indirect it becomes difficult to assess where to draw the line between environmental impacts resulting from the products and other separate impacts.

It is also difficult to numerically assess some environmental impacts. Often times people will need to make value judgements on the scale and severity of an impact, and this will always be subjective.

Finally, LCAs can be manipulated to produce desired assessments. This can be done by deliberately judging impacts to be less severe or by leaving out all but the direct impacts of a product.  

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Life Cycle Assessments Example Questions

Any two from:

  • Materials Extraction
  • Manufacturing
  • Distribution
  • Use of Operation
  • Disposal
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Some impacts on the environment are difficult to quantify. 


Sometimes it will be necessary to make value judgements about an impact meaning that LCAs can be subjective.


LCAs can be manipulated to produce desired outcomes by selectively ignoring certain impacts.

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Can be broken down naturally in the environment.

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