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Life Cycle Assessment

Worksheet Overview

QUESTION 1 of 10

If we want to improve the environment, we need to choose products that are sustainable. The trouble is that there are lots of things to think about when making that decision. Life Cycle Analysis is a way of making sure that we don't miss out anything important when making sustainability decisions.

Let's take an example that shows how simple decisions can turn out to be quite complex. What's the best material to make shopping bags- paper or plastic?

When we do a Life Cycle Analysis (or LCA for short), there are four stages in the life of a product that we have to think about;

  1. Extracting and processing the raw materials.
  2. Manufacturing the product and its packaging.
  3. Using the product during its lifetime.
  4. Disposing of the product at the end of its life.

At each stage in the LCA, we need to think what resources (especially energy) are used, and whether they are renewable or non-renewable. We also need to think about what waste products are produced, and the effects of disposing of them. To see how this works, let's think about the LCA for paper and plastic bags.

Raw materials:

Paper bags are made of wood. Wood is renewable, but large quantities of water and energy are needed to turn wood into paper.

Plastic bags are made from processing crude oil. Oil is a non-renewable resource.

Manufacturing the product:

Turning paper into bags uses quite a lot of resources, because of the need to glue the bag together.

Turning plastic sheet into bags is relatively easy, since the joins can be made by melting small amounts of the plastic.

Use:

Paper bags can normally only be used a few times before they become damaged.

Plastic bags are stronger than paper, so can be used many times.

Disposal:

Paper biodegrades easily, and can normally be recycled.

Plastic can sometimes be recycled. If plastic is not recycled, it does not biodegrade.

Conclusion:

Which material is better depends on how people will use the bags. If they re-use shopping bags, and recycle the plastic at the end, plastic shopping bags are more sustainable than paper bags. If they forget to do either of these things, than paper bags are more sustainable than plastic bags.

LCA doesn't automatically tell us which product is "better", though it does highlight which factors make a difference.

Reuse or recycle?

At the end of a product's life, we can either reuse the product, or recycle the materials in the product.

"Bags for life" are an example of a product being reused, as are refillable water bottles.

Recycling is when we break an object back into its materials, and then make a new product out of them.

Recycling is usually more sustainable than making new materials from scratch. To make new iron, we need to quarry iron ore from the ground, then heat it to extract the iron. This requires a lot more energy than melting an existing iron product down. However, recycling requires a lot of work to transport and sort products so that they can be processed into fresh materials.

The problem with a lot of environmental issues is that we need to think about lots of factors. Life cycle analysis gives us a tool to do this.

 

What does LCA mean?

Lightly Charged Anions

Low Carbon Alternatives

Life Cycle Analysis

Lifetime Carbon Allowance

Match these examples of parts of Life Cycle Analysis with stages of LCA.

Column A

Column B

Extracting and processing raw materials
Glass bottles are heavier than plastic bottles, so...
Manufacturing the product
Glass is made of sand, limestone and salt, heated ...
Using the product
Glass is formed into bottle shapes at about 1100 &...
Disposing of the product
Glass bottles can be washed and reused many times....

Match these materials with the key factors affecting their manufacture

Column A

Column B

Paper
Use of water and chemicals to make wood pulp
Plastic
Use of hydrocarbons from crude oil
Metal
Mining and heating of ores

Here are some data on the carbon footprints for the manufacture of different types of cup.

Type of cup Carbon footprint for manufacture (g CO2)
Disposable paper cup 18
Thin plastic cup 70
Thick plastic cup 170
Reusable metal cup 180

How many times would you have to reuse a thin plastic cup for it to have a smaller carbon footprint than a paper cup?

Here are some data on the carbon footprints for the manufacture of different types of cup.

Type of cup Carbon footprint for manufacture (g CO2)
Disposable paper cup 18
Thin plastic cup 70
Thick plastic cup 170
Reusable metal cup 180

The people who collected these data said that "This table proves that reusable cups are more sustainable than disposable cups. Are they right? Pick an answer and a reason.

A company makes two types of trainers. Standard trainers are made from new materials, eco trainers are made from recycled materials.

This table shows the energy required in MJ for each stage of the life cycle.

  Standard trainers Eco trainers
Manufacture of materials 1.4 0.1
Manufacture of trainers 3.5 1.1
Disposal 0.7 0.7

Which stage of the life cycle is missing from this table?

Distribution

Use

Recycling

A company makes two types of trainers. Standard trainers are made from new materials, eco trainers are made from recycled materials.

This table shows the energy required in MJ for each stage of the life cycle.

  Standard trainers Eco trainers
Manufacture of materials 1.4 0.1
Manufacture of trainers 3.5 1.1
Disposal 0.7 0.7

At which stage is the biggest percentage energy saving made? (Take the standard trainers as a baseline.)

Manufacture of materials

Manufacture of trainers

Disposal

Which of these activities are examples of reuse, and which are examples of recycling?

 ReuseRecycling
Refilling empty bottles
Making new bottles out of old glass
Using an old yogurt pot to grow seeds
Making a plastic ruler out of old yogurt pots

Which metal is more likely to be recycled? (Clue: think about how they are obtained.)

aluminium

iron

A company makes two types of trainers. Standard trainers are made from new materials, eco trainers are made from recycled materials.

This table shows the energy required in MJ for each stage of the life cycle.

  Standard trainers Eco trainers
Manufacture of materials 1.4 0.1
Manufacture of trainers 3.5 1.1
Disposal 0.7 0.7

What is the total energy saving for a pair of eco trainers, compared with standard trainers?

aluminium

iron

  • Question 1

What does LCA mean?

CORRECT ANSWER
Life Cycle Analysis
EDDIE SAYS
The point of LCA is to analyse all the environmental impacts of a product, to make sure we don't miss anything important.
  • Question 2

Match these examples of parts of Life Cycle Analysis with stages of LCA.

CORRECT ANSWER

Column A

Column B

Extracting and processing raw mat...
Glass is made of sand, limestone ...
Manufacturing the product
Glass is formed into bottle shape...
Using the product
Glass bottles are heavier than pl...
Disposing of the product
Glass bottles can be washed and r...
EDDIE SAYS
If you have to write an LCA for a product, start with the headings; treat them as paragraphs, so that you don't miss out any important points.
  • Question 3

Match these materials with the key factors affecting their manufacture

CORRECT ANSWER

Column A

Column B

Paper
Use of water and chemicals to mak...
Plastic
Use of hydrocarbons from crude oi...
Metal
Mining and heating of ores
EDDIE SAYS
Life cycle analysis questions often depend a bit on general knowledge; you will need to remember how different materials are produced, so you can identify the key issues for that material.
  • Question 4

Here are some data on the carbon footprints for the manufacture of different types of cup.

Type of cup Carbon footprint for manufacture (g CO2)
Disposable paper cup 18
Thin plastic cup 70
Thick plastic cup 170
Reusable metal cup 180

How many times would you have to reuse a thin plastic cup for it to have a smaller carbon footprint than a paper cup?

CORRECT ANSWER
4
EDDIE SAYS
70 ÷ 18 = 3.89, but we can't use a cup a fraction of a time, so we have to round up to 4. Even if the answer had been 3.21, we would still round up, not down.
  • Question 5

Here are some data on the carbon footprints for the manufacture of different types of cup.

Type of cup Carbon footprint for manufacture (g CO2)
Disposable paper cup 18
Thin plastic cup 70
Thick plastic cup 170
Reusable metal cup 180

The people who collected these data said that "This table proves that reusable cups are more sustainable than disposable cups. Are they right? Pick an answer and a reason.

CORRECT ANSWER
EDDIE SAYS
The point of LCA is to consider everything, not just one stage. Reusing cups reduces the impact of manufacture, as we saw in the last question, but creates other issues, like washing the cups when they are dirty.
  • Question 6

A company makes two types of trainers. Standard trainers are made from new materials, eco trainers are made from recycled materials.

This table shows the energy required in MJ for each stage of the life cycle.

  Standard trainers Eco trainers
Manufacture of materials 1.4 0.1
Manufacture of trainers 3.5 1.1
Disposal 0.7 0.7

Which stage of the life cycle is missing from this table?

CORRECT ANSWER
Use
EDDIE SAYS
"Use" is the stage that is missing- probably because trainers don't use any energy while they are being worn. "Distribution" normally gets included with manufacture (it's before the trainers are being used).
  • Question 7

A company makes two types of trainers. Standard trainers are made from new materials, eco trainers are made from recycled materials.

This table shows the energy required in MJ for each stage of the life cycle.

  Standard trainers Eco trainers
Manufacture of materials 1.4 0.1
Manufacture of trainers 3.5 1.1
Disposal 0.7 0.7

At which stage is the biggest percentage energy saving made? (Take the standard trainers as a baseline.)

CORRECT ANSWER
Manufacture of materials
EDDIE SAYS
The saving at the materials manufacture stage is 1.3 MJ, so the percentage is 1.3 ÷ 1.4 x 100 % = 93 %. The same calculation for making the actual trainers gives a saving of 2.4 ÷ 3.5 x 100 % = 69 %. Disposal works the same for both types of trainer, so there is no saving there.
  • Question 8

Which of these activities are examples of reuse, and which are examples of recycling?

CORRECT ANSWER
 ReuseRecycling
Refilling empty bottles
Making new bottles out of old glass
Using an old yogurt pot to grow seeds
Making a plastic ruler out of old yogurt pots
EDDIE SAYS
If we reuse the object (even if it's for a different purpose), it counts as reuse. If we only save the materials (but melt them down, or break them apart), this is recycling. Reuse is normally more sustainable than recycling, because we do less work to the object.
  • Question 9

Which metal is more likely to be recycled? (Clue: think about how they are obtained.)

CORRECT ANSWER
aluminium
EDDIE SAYS
Aluminium is extracted from its ore by electrolysis, which uses huge amounts of energy. Iron is extracted by heating its ore with carbon, which is relatively easy. Because of this, aluminium is much more valuable than iron, so is more likely to be recycled.
  • Question 10

A company makes two types of trainers. Standard trainers are made from new materials, eco trainers are made from recycled materials.

This table shows the energy required in MJ for each stage of the life cycle.

  Standard trainers Eco trainers
Manufacture of materials 1.4 0.1
Manufacture of trainers 3.5 1.1
Disposal 0.7 0.7

What is the total energy saving for a pair of eco trainers, compared with standard trainers?

CORRECT ANSWER
EDDIE SAYS
The total energy in the lifecycle of the standard trainers is 5.6 MJ. The total energy in the life cycles of the eco trainers is 1.9 MJ. The difference is 3.7 MJ.
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