The Lifecycle of Plastic

07.01.2021

The linear lifecycle of plastic consists of five steps. It starts from raw material and ends in waste disposal. This is the case when plastic is not being recycled in a correct manner. When plastic is recycled the cycle will no longer be a straight line but an actual cycle where the waste material is used again to make new material and new products.

Both lifecycles are shown in the figures below. Figure 1 shows the plastic lifecycle when the plastic is sorted in mixed waste. In Finland mixed waste is burned for energy recovery. Some might say that energy recovery is an environmentally friendly way for waste disposal, since we get energy from it after all. Hate to break it to you, but it's sadly the third worst option for plastic waste right after landfill and burning without energy recovery. The most environmentally friendly way to use plastic is to avoid it whenever possible and recycle all plastic in a correct manner. Figure 2 shows the lifecycle when plastic waste is recycled, like the plastic ending up in our bin.

              Figure 1. Plastic lifecycle if the plastic ends up in mixed waste.

             Figure 2. Plastic lifecycle when the plastic is recycled

All the steps of the chains cause emissions, and each step affects the environment and society in different ways. Yes, there seems to be more steps in the lifecycle of recycled plastic, but the total carbon release is smaller. In the following paragraphs the steps are explained more in detail.

Raw material

The raw material for plastic is conventionally oil. Oil is a non-renewable source and is formed of fossils when they are exposed to high pressure over millions of years. The resources are limited and the oil use should be reduced in every parts of the economy. Oil is a carbon sink, in other words it stores carbon. This means that the carbon will be released when the oil is being extracted. Also, the transport will release carbon dioxide into the atmosphere.

Manufacturing

There are many different processes when manufacturing plastic. The effect manufacturing has on the environment is that it releases carbon dioxide and other pollutants. The usage of materials and chemicals in the process is also a burden to the environment. The usage of energy and materials should be more efficient. It's important to note that manufacturing exists in both above-mentioned lifecycles and if the plastic is being recycled the manufacturing amounts will increase. However, the carbon dioxide emissions are lower for the second cycle since the plastic has a longer lifetime and the step of extracting raw material is being left out of the cycle.

Usage

If you look around, you can find plastic in almost everything: food packaging, clothing, toys, furniture, cosmetics, electronics... Plastic is a versatile and affordable material, with many brilliant properties. For example, it's great for maximizing the storage life of food products and minimizing food waste that way. However, one bad property is that the material will not biodegrade because of its polymeric structure. This leads to consequences if plastic ends up in nature. Plastic pollution causes eutrophication of waters and plastic particles accumulate in food chains. Therefore, it's important that the plastic ends up in waste management and not in nature.

Mixed waste

Mixed waste consists of the materials that you can burn. Mixed waste should be used only for materials that can't be recycled. Non-recycling plastic materials are for example PVC, polystyrene and foam plastic.

Energy recovery

In Finland all mixed waste is being burnt and the heat is recovered as energy. However, this step releases all the carbon in the material into the atmosphere, which speeds up global warming.

Plastic waste

Plastic packages can be collected in plastic waste recycling. Sadly, this is not so straight forward as it seems. Many packages can include different materials, which aren't suitable for plastic recycling. These materials are PVC and some biodegradable plastics. One should always be careful when using bioplastics, since most of them aren't suitable for composting nor plastic recycling, so they have to be sorted as mixed waste. Many packages also include other materials with plastic, such as aluminium or paper, and if they can't be separated at sorting the package can't be recycled.

Refinery

Plastic waste is turned into granules in a refinery. The process consists of mechanical treatments. In the future chemical treatments will become more common. This recovery will however affect the environment in the same manner as the manufacturing factories.

Granules

The product of the recovery is often granules which look like small plastic pearls. The granules will work as the new raw material for the factories producing plastic products. The granules become new plastic products through different kinds of mechanical processes. The most common processes are injection moulding, blow moulding and extrusion.

Recycled plastic products

Now we have again a plastic product but now it is done from recycled materials. This doesn't however mean that the plastic couldn't be recycled again. A plastic product made from thermoplastic can be recycled a dozen times.

The plastic lifecycles are being showed in REDI during 4.1. until 17.1. You can walk the path of the plastic and get a concrete picture of how your plastic waste can be recycled and how you can take part in circular economy.

References

Material Economics (2019). Industrial Transformation 2050 - Pathways to Net-Zero Emissions from EU Heavy Industry. https://materialeconomics.com/latest-updates/industrial-transformation-2050

Suomen Uusiomuovi Oy. (2020). Household Packaging Recycling. https://www.uusiomuovi.fi/fin/in_english/household_packaging_recycling/

HSY. (2020). Mixed Waste. https://www.hsy.fi/en/waste-and-recycling/lajitteluohjeet/mixed-waste/

Anne Ali-Hokka, Joel Kanerva, Eetu Pietarinen. (2019). Muovin lyhyt elämä. Read 20.12.2020. https://yle.fi/uutiset/3-11062711