Found yourself staring at a pile of mismatching containers and lids in your bottom kitchen drawer? Now, you are on your way to the store to get a new set. One of the criteria for choosing a new container is its impact on the environment: for example, whether it can be recycled or how sustainable the materials are. This article helps you answer these questions.
Types of food containers
Here, we describe the life cycle assessment (LCA) of four different types of food-storage containers. We focus on their impact on climate change, water use, and land use. By comparing the four containers, we give you an idea of how to make a more sustainable choice when it comes to food storage.
The container types we analyse are based on the popular food storage options available in IKEA. The types are one-litre glass and plastic containers with two choices of lid for each: plastic or wooden for glass containers, and plastic or silicone for plastic containers.
We assess the life cycle of a container ‘from cradle to grave’, meaning we include everything that needs to happen for the container to come into existence, serve its purpose, and eventually, perish. There are three environmental impact categories, which appear most relevant to the life cycle of this product: climate change, water use, and land use. That is why we focus our attention on what these indicators tell us about the sustainability of food-storage containers.
The first step of any LCA is to define a ‘functional unit’, or simply put, decide on what exactly we are going to measure that our product is used for. Food containers contain food, so we are sticking with that. We assume a container is used for a year. Since all four containers are the same volume and, therefore, can hold the same amount of food, it is easy to compare one to another.
The most and least sustainable options
Here is what the life cycle of a container involves. First, of course, the production: sourcing of raw materials, making the plastics, moulding them into rectangular shapes etc. Once the product is made, it needs to be transported to a shop where you might buy it. In our case, that shop is IKEA. We also assume that all the production and retail takes place in Europe.
Thankfully, all these containers are dishwasher-safe, so we assume you will wash yours in the dishwasher around 3-4 times a week. After a year of regular use, you dispose of your container. After analysing the data available to us and calculating the environmental impact of every step of the process, we are ready to pass judgement on which container you should go for.
The chart above shows the contribution of different containers to climate change, water use, and land use relative to the highest contributor. As such, out of the four types, the one that has the worst impact on climate change is the glass container with a plastic lid. While the glass container with a wooden lid contributes most to the water use and the land use indicators.
If you wanted to purchase a new food container, the most sustainable option in terms of climate change would be a plastic one with a plastic lid. Although it does lose to the plastic container with a silicone lid in the land use category.
Where the impact is hidden
In order to see why glass containers have the heaviest environmental impact, we look into the different stages of production of a glass container with a wooden lid.
Water consumption is the highest at the use stage due to all the washing-up you have to do. Moreover, unlike all the other parts, the wooden lid cannot go into the dishwasher. You have to wash it by hand, which requires five times more water, as a dishwasher uses water more efficiently. However, when it comes to climate change and land use, the production stage of the container’s life cycle is clearly the most impactful.
If the land use impact likely comes from harvesting wood for the lid, the climate change impact source is not so easily traced back. So, we investigate it in more detail. The figure below shows us that the production of glass has the highest impact on global warming, even higher than that of transport.
Additionally, glass containers have a higher transport impact than plastic because they are heavier, and therefore, take up a higher proportion of load in trucks used for transporting goods.
Some Raw Numbers
Comparisons aside, here is how much CO2 your plastic or glass container emits over its life cycle if you use it for a year. The highest emitter – a glass container with a plastic lid – emits 2.81 kg of CO2.
To put this number into perspective, you can compare it to driving your petrol fuelled car for a little over 20 km or buying 23 avocados. The lowest impact comes from a plastic container with a plastic lid and amounts to 1.63 kg of CO2.
A big assumption in our LCA has been that a container, once purchased, is only used for one year. That is likely untrue, and theoretically both a glass and a plastic container could be used for a decade or even longer. In that case, a container’s yearly environmental footprint can be divided by the number of use years. Since plastic gets stained by foods, whilst glass is more likely to break, it would then be difficult to estimate whether the glass or the plastic container has a longer lifetime.
When looking into the end-of-life (waste processing) stage of the containers’ life cycles, we have found out that the glass containers are not recyclable. That is because they are made of Pyrex glass - a specially reinforced form of glass that can withstand high temperatures. So the glass containers are oven safe, but they need to be incinerated when disposed of. As for the plastic containers, a fraction of the waste can be recycled.
In conclusion, go ahead and buy plastic containers instead of glass ones if you have to, but even better – keep using your existing ones or shop second-hand!