If you analyse the life cycle of a cow, you notice it starts of with a calf growing inside a cow. The calf is born, either as a cow or bull. This then carries on and on, but what happens to the life cycle of raw materials like crude oil? As the planet evolves, we can see the increase use of materials like crude oil, is not being used in a completely sustainable way. As a result, we are first hand experiencing the damages such as pollution and climate change. We are responsible for this, and so to make processes and our use of finite resources more sustainable, we can do life cycle assessments, which is what we will be exploring today.

• We will look over the module of a life cycle assessment, this will also include the different stages in some depth.
• After, we will explore two examples of a life cycle assessment: plastic bags and paper bags.
• Finally, we will explore the limitations of life cycle assessments.

Life cycle assessment model

Life cycle assessments enable multiple industries, business and government departments and agencies to explore their impact on the environment. This includes exploring the assessments to introduce new policies and products. They target four main areas:

1. Sourcing and processing raw materials.
2. Producing the product and any packaging that comes alongside it.
3. Reusing the product and how it is maintained.
4. Discarding the product after it can no longer be used.

In these four main areas, the amount of energy required is assessed and any transport that is required. To carry out the assessment, the energy and material input and outputs are listed alongside the energy required for it. The environmental impact is then assessed based on the input and output. Finally, the results are analysed to decide, whether the product is right, if any materials need to be changed, or if a better process is required.

Now, you may be thinking, how is this a life cycle? This is because the aim of this assessment is to track the moment from when raw materials are extracted from the environment to the point where they are returned to the environment. How they are put back in the environment, however, does not necessarily mean they will be in the same format that they were extracted in. For example, if we are using water from a dam or a river in our process when returning the water if there is waterborne water, this still means that the raw material has been returned to the environment.

In the next section, we will go into the four steps in more depth.

Life cycle assessment stages

1. Extracting materials

The initial step of the life cycle assessment is to gather all the raw materials that we will be using to make the product or service. We must remember to include the impact that they have on the environment. If for a product we need to use trees and therefore, causing deforestation, we must include that habitats are being damaged.

2. Manufacturing

Manufacturing includes how exactly we will make the product, such as the energy required for machines. In addition, it also includes the environmental impact if we are required to transport machinery, or clear land to build factories.

3. Usage and re-usage of the product

The third section that is assessed is the use and re-use of the product. For this particular section, several things are assessed including; how much energy is required for it to be used, if energy is required to maintain the product and any energy required to repair the product to be re-used. It not only includes the energy production, but also the impact of the product. We can see this if we look at a car, where petrol and diesel cars produce carbon emissions, so we need to record this. Whereas, if you look at a wooden spoon, energy is not required to maintain it, and it does not produce any emissions.

4. Waste production

The main factor of this section is how we dispose of the product. Some products have to be broken down instead of just being thrown away and this requires energy, after it is broken down they can be thrown away, if it is not made from biodegradable material, landfill sites will be required. Another factor that may also be considered is whether parts of the product can be recycled or if it can all be recycled, either way, energy is required.

As you can see there is much thought, time and money required for a life assessment to take place. But we must carry out these types of assessments to build a sustainable future where our finite resources are protected.

Life cycle assessment examples

A good example that we can look at is paper bags versus plastic bags. We’re going to go through all four steps of our life cycle assessment:

Extracting raw materials

Plastic bags require crude oil. Crude oil is a finite product and to get what we need from crude oil and for crude oil to be extracted, a vast amount of energy is required.

For paper bags, the raw materials we require are usually from trees, but we can also use recycled paper. To process the trees to make paper, the energy required is more than if we used recycling paper. Nevertheless, it is still substantially less than the energy required for plastic bags.

In terms of extracting raw materials, we can see that in this particular stage, plastic bags require a lot of energy compared to paper bags.

Manufacturing

Going on to the manufacturing state of the assessment, we firstly know for the plastic bags, the raw material of crude oil needs to be processed, this includes fractional distillation, cracking and polymerisation. Crude oil does not produce much waste and is relatively cheap to manufacture.

On the other hand, the assessment of paper bags is quite different. To produce paper from trees requires a lot of energy. Firstly, the paper must be pulped, chemicals like sulphur dioxide are added and there is a considerable amount of waste.

In this stage of the assessment, we can see that producing plastic bags looks like a more viable and environmentally friendlier option.

Usage and re-usage of the product

It is safe to say that plastic bags are pretty reusable. Most of these bags produced today are made to withstand a substantial amount of weight, so individuals can use the bag over and over again for whatever they require. This can especially be seen in the UK since it became law, that you have to purchase a carrier bag and that they are no longer free.

Now, if we look at paper bags, there is a stark difference. They are not as durable as plastic bags; they can easily be destroyed by rain. These two factors alone allow us to determine that in terms of usage, plastic bags are much better.

Waste production

Finally, we have come to the last factor that needs to be assessed, how the different bags are disposed of and the waste that is produced. If we first look at plastic bags, we will know that they can be recycled, but this can cost a lot of money and also produces pollution. Furthermore, if they are not recycled they tend to end up in landfills which take up land, and they just stay there because they are not made from biodegradable material.

On the other hand, paper can be recycled, but as mentioned before this can be expensive. Alternatively, even if they are not recycled, the material is biodegradable and will not take up land space.

So for this particular part of the assessment, paper bags look like a better choice as they are made from biodegradable material and can also be recycled.

Overall conclusion:

When going over all four factors of the assessment, plastic bags look like the better option. A key reason is that they can be reused multiple times and this knocks on how much waste is produced, how much raw material is needed and the energy for manufacturing. However, if plastic bags are not being reused, then it may not be the better option and paper bags would be a better choice. So, in conclusion, there are positives and negatives to both options, but usage is definitely a heavy determining factor.

Limitations of life cycle assessment

As you can see, there are a wide variety of factors that go into a life cycle assessment, and quite frequently the results and conclusions from the assessment can be debatable. One factor that can be particularly seen is the environmental impact. If these recorded impacts are made by firms that are sponsoring the assessment it cannot be determined whether the report is completely unbiased as an independent body has not initiated the assessment, this is our first limitation.

If we then look at how we assessed how particular processes are being impactful, the question arises as to how far this can go. Does this mean we can look at the assessment locally, regionally or even internationally, especially as we can see matters such as climate change are affecting the entire planet, not just one specific area, this is our second limitation.

Furthermore, in all four areas, we are not evaluating issues such as costs or the performance of different stages. This is especially important as findings from these types of assessments may be publicised and used for positive advertising. So, it could be said to make this study more reliable, peer review could be used to check the validity.

Our final limitation can be seen in how we quantify the inputs and outputs of the assessment. We must remember, that for some information we do not yet have the required data, so we may need to use estimates and assumptions, which can sometimes be close to the real figure and sometimes very distant.