11.04.4 Life Cycle Assessment

Syllabus

- Life cycle assessments (LCAs) are carried out to assess the environmental impact of products in each of these stages:

1. extracting and processing raw materials
2. manufacturing and packaging
3. use and operation during its lifetime
4. disposal at the end of its useful life, including transport and distribution at each stage.

Use of water, resources, energy sources and production of some wastes can be fairly easily quantified.
Allocating numerical values to pollutant effects is less straightforward and requires value judgements, so LCA is not a purely objective process.
Selective or abbreviated LCAs can be devised to evaluate a product but these can be misused to reach pre-determined conclusions, eg in support of claims for advertising purposes.
Students should be able to carry out simple comparative LCAs for shopping bags made from plastic and paper.

What does this mean?

Carrying out an LCA

This is new and environmentally-based.

So it's likely to appear somewhere on the exams most years.

If we tried to carry out an LCA for Paper bags v Plastic bags we should assess the impact of making the object across all LCA Stages.

We may be surprised that a paper bag has a worse LCA rating than a quality plastic bag.

What does it even mean?

Well, if we only used quality plastic bags and used them many times before disposing of them by recycling then we should use them rather than paper bags.

But real-life means that this may not happen.

So, we may be better off with paper bags anyway - especially if we move towards making them with renewable energy rather than fossil fuels.

Problems with LCAs

In the real world it is easy to quantify:

Use of water
Use of resources
Amount of energy used
How much waste is produced

But it is not easy to quantify the effects of pollutants because we can’t be sure what the overall total effect will be.

And This means we have to use value judgments - which differ from person to person and are, therefore, unreliable.

LCAs use facts mixed with judgments - making them unreliable too.

Selective or abbreviated LCAs

If a paper bag manufacturer wanted to advertise their product, they might use a selective/abbreviated LCA – which only shows some of the impacts of the product on the environment.

Should we take any notice of these?

They might “approximate” the raw material processing impact and use a value judgement to make it seem less than it is.

So can they be trusted?

Unless an LCA has been peer-reviewed by an independent group we should beware that it may have been misused to reach a pre-determined conclusion - one that suits the manufacturer.

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