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Life Cycle Assessments


What is a Life Cycle Assessment?

A Life Cycle Assessment (LCA) examines the

environmental and human impacts of a product across

its entire lifespan.

LCAs consider the use of resources (e.g. water, energy

input or output) and the environmental impact of each

stage in the life of a product.

The stages in the life of a product include:

making the material for the product

manufacturing the product

using the product

disposing or recycling the product.


Stages considered in an LCA


Sorting activity


Comparing different materials

The ability of different materials to perform the same job can

be compared by carrying out a Life Cycle Assessment (LCA).

This allows companies to make the most

environmentally friendly decisions about

the items they produce.

The waste production and use of water,

resources and energy can easily

be measured.

Measuring the effect of pollution, however, is

not straightforward. It is a subjective process

that requires assigning numerical values to the

different effects of pollution.


LCA of a carrier bag


Plastic or paper?

starting

resources used

waste

production

global warming

one polyethene

plastic bag

one paper

bagassessment

factor

energy usage

water consumption

non-renewable renewable

8 g 50 g

4 kg CO2 eq

730 kJ 1680 kJ

1.80 litres

14 kg CO2 eq

4.60 litres

Compare the LCA’s of a paper bag and a plastic bag.

Which bag would you choose?


Interpreting LCA data

Which is more important:

using renewable resources

or reducing greenhouse

gas emission?

Which type of bag is more environmentally

friendly: polyethene plastic bags, or paper bags?

From the data given, it seems that

plastic bags win the argument– is this

what you expected?

It is important to remember that

both materials use up energy

and release CO2.

How could you improve the LCA of a paper bag?


Recycling products

PET is what everyday drinks

bottles are made out of.

As they consist purely of

PET, it is possible for

the used bottles to be

manufactured into a

new product.

Reusing recycled materials reduces energy consumption and

greenhouse gas emissions during manufacturing processes.

For example, reusing plastic

bottles reduces the need to

manufacture new polymers.


Recycling PET bottles

Collection - Through recycling schemes, such as your

local recycling collection.

Sorting - The PET plastic must then be separated from

other materials.

Recycling and reuse of PET bottles is a multi-step process

that involves:

Downsizing – The plastic is crushed into flakes and

cleaned to remove food particles and other impurities.

Manufacture of the new product.

New products that are made from recycled PET include:

soap bottles, soft drink bottles and plastic film.


Biodegradable plastics are increasingly being used in

carrier bags, bin bags and food packaging.

One of the problems with traditional plastics is that they do

not break down when thrown away.

Biodegradable plastics are

plastics that can be broken down.

They are converted into carbon

dioxide, water and minerals by

microorganisms.

Biodegradable plastics, such as polylactide, are plant-

based polymers. They are often made from starch that has

been modified to become more stable.

What are biodegradable plastics?


How is biodegradable plastic made?


Biodegradable or non-biodegradable?

starting resources

used

global warming

non-

biodegradablebiodegradable

assessment

factor

disposal

non-renewable renewable

moderate

incineration, landfill,

recycling

high

incineration, landfill,

recycling, composting

The table below compares data for non-biodegradable

plastic with biodegradable plastic.

Time is required to allow plants to grow for the production

of biodegradable products.


Trusting Life Cycle Assessments

How do you know a Life Cycle Assessment is accurate?

Increasing attention towards environmentally friendly products

puts a new demand on companies and manufacturers.

The subjective nature of LCA’s mean that companies can use abbreviated

assessments. These are selective

towards specific factors, in order to

reach the desired outcome.

LCA’s are used to justify the manufacture of products and support environmental

claims that are beneficial to sales.


Can life cycle assessments be biased?

Think about the following example:

Alternatively, if multiple hand

towels are used per person?

LCA’s for paper towels and an electric hand dryer were carried

out and compared.

What would be the outcome if the

company assumed only one paper

towel is used per person?

It would be more beneficial to the paper towel company if the

LCA assumed only one paper towel is used per person.


What can businesses

and individuals do to

reduce the amount of

waste they produce?

Dealing with waste is

important, but there are

many issues involved:

If more products are made from biodegradable plastics,

how will the management of landfill sites change?

Dealing with waste

How many products could be made from recycled and

biodegradable plastic?

What will happen to closed landfill sites in the future?


How is waste plastic disposed?


Landfill – pros and cons


Incineration – pros and cons


Recycling – pros and cons


Disposing plastics


Electricity generation schemes

Some waste products can be used to generate electricity.

The methane can be captured and

burned to produce electricity.

An example is the biogas methane.

This is produced from organic

matter such as plant and animal

waste at farms and landfill sites.

The electricity produced is renewable, and improves the life

cycle assessment of a process by reducing the amount of

waste product.


Glossary


Multiple-choice quiz

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