Carbon fibre is a material growing in popularity throughout the advanced world.
It’s a super light and super strong material, making it a go-to for all sorts of commercial ventures, including green businesses. Car manufacturing, racing bikes, wind turbines, planes and building infrastructure all make use of carbon fibre.
With it now being used so often, a good question many are asking is how sustainable is carbon fibre?
Luckily, we’ve been doing the research for you, so let’s find out if it’s sustainable or if carbon fibre is bad for the environment.
Background on carbon fibre
Carbon fibres have been available for more than 150 years. However, their high strength-to-weight and stiffness-to-weight ratios have only been attained in the last half-century or so due to manufacturing process advances.
Joseph Swan invented them in 1860. In 1879, Thomas Edison (of light bulb notoriety) burned cotton strands at high temperatures and superheated them into an all-carbon-fibre strand.
In 1958, more high-performance varieties such as pan-based carbon fibres were invented.
Even though they were inefficient, these fibres comprised about 20% carbon and had low structural strength properties. However, their strong potential was recognized in 1963 when a new production method was found at a British research facility. You can find more carbon fibre history here.
Although it’s clear that carbon fibre isn’t a new material, what is new is the sheer scale of demand. It’s the huge demand that’s causing greater concerns for the environment.
What is carbon fibre?
Carbon fibre, sometimes referred to as graphite fibre, is a synthetic polymer. It’s made from continuous chains of carbon atoms bonded together.
The characteristics of carbon fibre products are similar to those of steel, and the weight is almost equal to that of plastic.
In recent years, carbon fibre has been used to replace steel in certain applications. This is for a couple of reasons. Carbon fibre is much lighter than steel and it has a higher weight to strength ratio. So, using it to replace steel in products such as cars and planes makes sense.
Carbon fibre gets its characteristics and strength from the way it’s made. Let’s have a look to see the environmental impact of carbon fibre production.
How is it made?
Carbon fibre is formed from thin, robust crystalline carbon filaments. It gains serious strength when the strands are twisted together to form a type of fabric, or tow.
These carbon filaments are often combined with another materials, such as plastic polymer resin to create a carbon fibre composite.
The fibres themselves are usually produce from polyacrylonitrile (PAN). This is a fossil-fuel based polymer and part of the acrylic resins.
As explained in this 2022 study, the creation of a carbon fibre requires a series of thermosetting, carbonisation and treatment steps. Once the fibre is produced, the composites can be created via some form of molding.
Carbon fibre environmetal footprint
But what’s the environmental cost behind this carbon fibre production?
Carbon fibre is very energy intensive to produce.
PAN is a synthetic thermoplastic and has undergone polymerisation itself. So, even before you start to think about making carbon fibres, the precursor already has a high carbon footprint. The industrial process of thermosetting and treatment add to the environmental cost.
The embodied energy of carbon fibre is thought to be at least 10 times that of glass and 3 times that of polyester resin. Compared to stainless steel, carbon fibre has 40% more embodied energy! If you’re wondering, embodied energy is the total amount of energy used to produce a material.
It’s fair to say that no, carbon fibre is not environmentally friendly.
Is carbon fibre sustainable?
The high energy costs associated with the creation of carbon fibre is where most of the environmental damage is caused.
Recycling and reusing carbon fibres will certainly save a big energy cost, but it has a big cost in itself – a financial one. Being a composite, they are inherently difficult to recycle.
If carbon fibre isn’t recycled, the world could have another major waste problem on its hands.
In 2017, the Green Alliance charity published a report where it stated that carbon fibre composites could cause serious issues in the future when it comes to waste.
When you think of the uses you can see why it might become a problem. Cars might have a realistic shelf life of 15 years before the enter the waste stream. Planes have a longer life of roughly 25 years.
However, the good news is that EU End of Life Vehicle regulations state that cars have to be collected with 85% of materials being recycled or reused.
This is important as this 2022 report predicted that the most promising route for decreasing the environmental impact of carbon fibre polymers is through the recycling and recovery of fibres.
At present, carbon fibre is not sustainable, but with advancements in technology and recovery, we could see this improved.
How to recycle carbon fibre?
Yes carbon fibre can be recycled. The process is just difficult and expensive to do so.
Unlike the major environmental benefits that come with the infinitely recyclable stainless steel and aluminium, carbon fibre can’t be melted down. This is because the carbon fibres are mixed with other materials.
One way to recycle carbon fibre is through a chemical process where the binding polymers are dissolved, leaving the wanted carbon fibres behind. Although not in as good quality as before and not suitable for use in cars and planes. Not yet anyway.
Not only does this process sound expensive, the use of strong, corrosive chemicals sounds environmentally costly.
Companies are hard at work to reduce the cost and increase the effectiveness of carbon fibre recycling, so there is a glimmer of hope for the future.
Uses of Carbon fibre
Carbon fibres are typically used in applications that need low weight and high rigidity.
You can find carbon fibre used in many different industries.
Aerospace was among the first sectors to embrace carbon fibre because of its durability and lighter weight. And they’ve definitely made effective use of it.
The aircraft sector is responsible for 30% usage of carbon fibre production. It can be found in everything from spaceships and airplanes to gliders and helicopters.
Carbon fibre was quickly adopted as a raw material in the automobile industry.
It was originally used in Formula 1 and NASCAR cars due to its strength-to-weight ratio, which aided in producing speedy cars. Due to its slick, high-tech appearance, the material has also gained popularity in the construction of high-end automobiles.
The use of carbon fibre has advanced significantly since the 1800s.
Earlier used for lamps in navy ships, it’s now used in anything from drones and missiles to tent poles and helmets. Its primary advantages for the army are its durability and lighter nature, which allows for simpler transportation and energy savings.
Another area where carbon fibre has achieved great progress in recent years is in the medical field.
It appears transparent on X-ray pictures, leading to its application in various X-ray and photographic devices. It’s also used in prosthetic limbs, making them sturdy, lightweight, easy to wear and use.
Carbon fibre is widely used in sports equipment due to its strength and light weight.
It’s used in various sports gear such as tennis rackets, hockey sticks, golf clubs, bicycles, and rowing boat shells. Even protective gear and clothes are made of carbon fibre, including racing sports shoes and helmets.
Advantages of carbon fibre
Carbon fibre is used for various purposes because of its unique qualities.
- Toughness and Strength: Carbon fibres are hard, powerful, and long-lasting, which is why they are used for several commercial purposes.
- Weight: Despite its strength, carbon fibre is very light. It has an incredible strength-to-weight ratio and is significantly lighter than steel and aluminum, so it’s an excellent choice if you’re looking for a lighter alternative.
- Stress resistance: Carbon fibre ends are less likely to wear and strain. It will not rot or disintegrate even in adverse conditions.
- Corrosion resistance: It is also resistant to corrosive conditions. The material is suitable for usage in chemically rich industries and environments where other materials are subject to corrosion.
- Flexibility: Working with carbon fibre is quite easy. It is a soft material that can be easily transformed into a wide variety of objects, making it ideal for complicated shapes and elaborate designs.
Can bio-based materials be used in fibre production?
Scientists are looking for at a sustainable bio-based alternative to PAN (the initial material in carbon fibre production). One good option is lignin.
Lignin is a natural resource found in most land-based plant cell walls. It’s a common material used for bioplastics.
Lignin-based fibres follow roughly the same procedure as PAN but without the initial heavy energy outlay associated with fossil fuels. Lignin is also a renewable resource, which will reduce the environment cost of fibre production.
Wrap up on carbon fibre sustainability
Carbon fibre, like any other material requiring a lengthy and intensive production process from a fossil fuel source, will impact the environment negatively. Currently, carbon fibre production is not sustainable. In fact, in terms of embodied energy it’s a lot worse than the materials it’s replacing (which are already energy intensive!)
If carbon carbon fibre is to become sustainable, a lot of research and work is needed to streamline the process and bring energy costs down. You then have the big problem of recovering carbon fibre after it’s been used rather than seeing it go to waste.
However, there is hope.
More work is being put in to recovering and recycling carbon fibres in a more cost effective way. Even commercial industries, like Formula One, plan on becoming carbon neutral by 2050, so we hope to see advancements here.
Read more about material sustainability here…
Ben is the Creator and Editor of Tiny Eco Home Life. I write and publish information about more sustainable, environmentally friendly living in and around the home.
Alongside this website, I love spending time in the natural world, living a simple life and spending time with my young family (Murphy the dog!) I round up my thoughts and recent blogs on the Eco Life Newsletter.