We’ve all heard of silicone and probably used it around our house, but is silicone eco friendly? How does it shape up from an environmentally friendly viewpoint?
To answer the question of eco-friendliness, many aspects need to be taken into consideration.
Things including, but not limited to: where do the raw materials come from, how long does it last, is it biodegradable, is it recyclable? Then there’s the whole weighing it up against another product that could potentially do the same job.
It’s not easy, but it’s important. So let’s take a look at how eco-friendly silicone is, starting with what it is and how it’s made before moving on to what happens at the end of a silicone product life and how it impacts the environment.
What is silicone?
Silicone is a synthetic material that is derived from silica sand. It’s not quite a plastic but neither is it a full type of rubber. Silicone sits somewhere in between these two.
Silicone products have been around in the commercial world since the 1940s but have been growing even more in popularity in recent years thanks to the surge against plastic use. You can now find all sorts of products, large and small, made from silicone.
Homeware products, such as toothbrushes (don’t forget your eco-friendly toothpaste), food containers, kitchen utensils, water bottles and parts of reusable coffee cups are all now available in silicone.
There are also the commercial uses to silicone, such as the sealant used in and around homes, medical devices, bodily implants, insulators, lubricants and a huge market for electronic components and computer chips, which has surged since the 1990s.
Have you ever wondered where Silicon Valley in California gets its name from?
Properties of silicone
The modern world is now hugely reliant on the material, and it’s the unique properties of silicone that makes it so widespread.
Generally speaking, silicone rubber is:
- Non-reactive with other chemicals and substances
- Low toxicity and hypoallergenic
- Very stable
- Resistant to extreme environments and temperatures without altering state – silicone operates in exactly the same way in at -55oC environment as it does in a 300oC environment
- Resistant to bacteria
- Water resistant
It’s due to these sought-after properties that silicone has become so popular.
It may be extremely useful in the commercial world but how environmentally friendly is silicone? It kind of looks, feels and acts like plastic, but can we categorically say silicone is an eco-friendly choice or is it bad for the environment?
What is silicone made of?
The most commonly rolled out answer is that silicone is made from sand and oyxgen. And that’s true, sand is certainly a main constituent of silicone and it’s chemically made up of a silicon-oxygen backbone, but it’s a little more complex than just sand and oxygen.
Let’s start from the beginning.
The first raw ingredient that kicks off the silicone making process is quartz, or more specifically quartz sand, sometimes known as silica sand.
Quartz is a natural mineral composed of the two most common elements in the earth’s crust: silicon and oxygen. These two chemical elements happen to like each other very much and combine readily to form quartz (silicon dioxide), making it in turn one of the most common minerals in the earth’s crust, comprising an estimated 35% of all rocks.
Over time these rocks get weathered down by wind and water to the granules we know as sand. Sand is a general term and can be made from many different rock types that have been weathered down to a granular particle less than 2mm in size. The sand you find at the beach is likely to be made up from a majority of quartz sand! A quartz or silica sand, is simply sand that has a high content of silicon dioxide.
The quartz sand used to make silicone is most commonly surface-mined in open sand pit operations all over the world: from Asia and Australia, to Europe, Africa and America. And the international sand trade is big business.
Incredibly, after water, sand is the raw material that the world consumes in the greatest quantity. Sand goes into just about everything in the building world, including concrete and all glass. Our whole cities are more of less built on the back of sand.
In 2017, the international sand trade was worth $4.5 billion. Exact data on sand extraction rates and volumes is hard to source, but estimates but the overall extraction in the region of 50 billion tonnes per year – enough to blanket the whole UK.
However, it’s not just silica sand that silicone is made of.
To make silicone as flexible, durable and as ubiquitous as it is, it needs something else: hydrocarbons.
Hydrocarbons are the most widely used organic compound on Earth. They are, and have been, incredibly useful for mankind over the last 200 years or so thanks to the energy they provide, powering almost all of our recent technological advancements. Unfortunately for the environment, they haven’t been such good news.
The most common place hydrocarbons are sourced from is non-renewable fossil fuels, such as crude oil, coal and gas.
So yes, silicone is made from silica sand (which provides the silicon and oxygen), but also hydrocarbons by way of fossil fuels. A little more on this below.
How is silicone made?
It would be easier if silicon existed in nature in its pure form. However, because silicon atoms bind so readily with oxygen, finding silicon on its own in the earth’s crust is impossible.
This is where quartz sand (made up of silicon and oxygen) comes in. To get to the silicon, large volumes of quartz sand is heated to extremely high temperatures (in excess of 1800oC).
It’s at this point where hydrocarbons, such as coal, are added. The carbon from the coal (or another carbon source) reacts with the oxygen, and we all know what carbon (C) plus oxygen (O2) equals – carbon dioxide (CO2). What’s left is then a liquid-like, molten-hot silicon mixture.
The mixture undergoes several more processes of combination, heating, distillation and polymerisation, before you end up with a silicone compound (sometimes known as silicone rubber). Once you get silicone rubber, it can then be moulded and coloured into almost any shape and size and the final product is set.
Just to be clear on the terms as some are very similar but distinct:
- Silica = silicon dioxide which is most commonly found in nature as quartz. Silica is the major constituent of sand.
- Silicon = a naturally occurring chemical element that you can find in the periodic table. Silicon binds with oxygen to form silica (silicon dioxide)
- Silicone = a synthetic material made up of silica sand which is heated and reacted with a hydrocarbon source.
Is silicone eco-friendly or is it bad for the environment?
So, the big question on silicone’s environmental impact – is silicone eco friendly?
Unfortunately, it’s not easy to answer and silicone sits in a grey area of eco-friendliness. Clearly when compared to a fully compostable or recyclable material, silicone isn’t perfect.
To start with silicone is a synthetic, manufactured material. Although it comes from a natural occurring sand mineral, it has to be fairly heavily processed and changed chemically with the aid of fossil fuel hydrocarbons, which certainly isn’t eco-friendly.
There’s also the issue of the silica sand extraction. Although abundant around the world, sand is not an infinite material nor considered to be naturally renewable. This may seem strange but don’t forget, the weathering process, although constant, is a geological process that operates over thousands and even hundreds of thousands of years. It’s illogical to consider this renewable.
Sand is also being extracted at a phenomenal rate. Intensively extracting sand from any ecological site, whether it’s farmland, forests or by the seafront, can and will have significant impacts on the environment.
Although silicone has the benefit of being primarily based on a natural mineral, it differs to fully natural products, such as cork, which grows on trees and can be stripped off without causing damage. Cork can then be used in its natural form without any alteration or chemical additions, whilst the bark cork regrows on the trees and absorbs carbon dioxide.
The main benefit of silicone to the environment comes from its extreme durability and non-toxicity – a silicone product should be highly reusable.
This allows a silicone product to be kept for many years, even decades, which in itself will stop you from needing to buy a new product which will limit other resource use and extraction. The best option seems to be keeping the silicone product for as long as you possible can before getting rid, which also comes with an environmental impact as you’ll see below.
Is silicone recyclable?
Technically speaking, yes silicone is recyclable.
But it’s recyclable with a difficulty similar to the likes of single-use coffee cups, coffee capsules and pringles tubes. When recycling silicone it’s not as simple as putting it in the correct coloured bin.
Silicone requires processing at a specialist recycling treatment facility. Few companies seem to deal with recycling silicone, which makes it difficult for the everyday person at home. And we all know what happens when something is too difficult or troublesome – for most it doesn’t get done, meaning waste such silicone ends up in landfill.
TerraCycle is one of few companies in the UK who help recycle all those difficult items that won’t be collected by local councils. This isn’t a free service though. You have to purchase a box which you fill up over the course of a few months, even years, and then send off (which is free) to TerraCycle to process. Some companies who sell silicone products may also offer a take-back scheme which might be easier to organise.
Once silicone does make its way to a recycling facility it can be processed down into a secondary material. Unfortunately, silicone isn’t infinitely recyclable, like glass for example which is considered a sustainable material. When broken down, the best that can be done is to create silicone oils. It’s not possible to get back to the silicone rubber that used to make the product being recycled, so no new silicone spatula or microchip unfortunately.
Silicone oils tend to be used in the manufacturing and car industry as lubricants, in coolants, refrigerants and other industrial uses.
Is silicone biodegradable?
Ok, this one is a little easier to answer. No, silicone is not biodegradable.
Silicone is incredibly durable, non-reactive and persistent in extreme environments, meaning it will not naturally biodegrade – not likely in our lifetime anyway.
You might have thought differently seeing as silicone is made using natural materials, but because it is chemically altered and manufactured to contain the properties it has, it’s precisely this which stops it from decomposing in nature.
What happens to silicone in the environment then? Well, it just stays there.
The fact that silicone won’t breakdown easily is also a hidden benefit. It means that it won’t break down into smaller pieces in the way that plastic breaks down into microplastics and leaches into the environment. As we’ve learnt, silicone is non-toxic so even if it does find its way into nature, which of course is far from ideal, it won’t cause any environmental impacts to the ecosystem.
The flip side of this is that silicone can stay in the environment for hundreds of years without much of anything happening. It will very slowly oxidise and become less flexible and more brittle.
Wrap up on silicone sustainability
The most obvious issue with silicone comes when the product is no longer needed.
Silicone is not biodegradable and is not widely recycled. This drastically limits the options for consumers of an eco-friendly disposal.
If silicone does end up in the environment or in the ocean, it won’t breakdown and cause any harmful environmental issues. The only issue with this is that it shouldn’t be there in the first place.
With all that in mind, silicone is a good alternative to the likes of plastic but don’t think that it is a saviour product for the environment.
There are a number of environmentally red flags within the production and disposal that don’t make silicone eco-friendly. The main hope is that the infrastructure behind silicone recycling improves, so that it’s more accessible and easier option for the consumer.
Hopefully this in-depth look has given you a better insight into the world of silicone for you to make your own judgement call on how eco-friendly silicone is.
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