Carbon Fiber, often touted as the ‘Miracle Material’, is stronger than steel, aluminium & even titanium, but still lighter than them. Resulting from their light weight & high strength, Carbon Fiber is used as a high-performance material in modern Formula 1 cars, Wind turbines & Aircrafts.
As of 2021, 114k tons of Carbon Fiber was sold with wind & aerospace contributing to ~25% & ~15% of the sales respectively. The global demand is set to grow to 180k tons by 2026 at 9.6% CAGR, set to outdo a supply of 125k tons. The Carbon Fiber market is valued at around $4.5 Billion as of 2021 and is set to grow to approximately $7Billion by 2030, driven largely by price increase and slight production increase.
But this miracle material is quite energy intensive to produce. As per estimates from the North American Forest Foundation, plastic takes 87.5 MJ/KG of production on average, steel from iron takes 37.5 MJ/KG, while Carbon Fiber uses about 240 MJ/KG of production!
Therefore, the combination of high energy intensity required to produce Carbon Fiber, and the excess demand, will create a market vacuum for a replacement to virgin Carbon Fiber (vCF). While there are no materials that could act as direct replacement, the large inflow of CF waste will make recycled Carbon Fiber (rCF) a strong contender, if the recovered fibres’ physical properties are not damaged.
Recycling of Carbon Fiber –
Recycling of Carbon Fiber is dependent on the type of waste available. Generally, CF waste comes in 2 major forms –
- Production scrap (cut offs of CF sheets during manufacturing) – It is estimated that ~30% of CF is wasted during the production. In 2021, they made up 45% (25k tons) of total CF waste generated.
- End of life (EOL) waste (products with Carbon Fiber that have reached the end of their usage cycle). Generally, these are products with multiple materials and called Carbon Fiber Reinforced Polymers (CFRP). In 2021, they made up the remaining 55% (31k tons) of total CF waste generated. But with the first wave of composite materials (composite structures from 10-20 years ago) coming to EOL in the coming decade, the share of EOL waste is expected to reach 85% by 2040.
In 2021, about 56k tons of carbon fiber waste was generated. This is close to half the amount of carbon fiber manufactured that year. By 2024, CF waste grew by 34% to 75k tons. It is forecasted that by 2040, 210k tons of CF waste will be produced!
As of 2024, it is estimated that about 10k tons of carbon fiber will be recycled across the various recycling methods, growing at a CAGR of 115% from just 1k ton in 2021.
The following are the major types of recycling carbon fiber:
- Mechanical recycling –
Mechanical recycling of CF is grinding CF waste into coarse pieces under 10mm. This can further be used in moulding new products. While this is the cheapest method of recycling, the output’s physical properties are likely equivalent to Glass Fiber. Therefore, it is considered as downcycling. As a result of this, they are priced around 10-20% of the price of vCF at $4-8 per kg. These are usually used as fillers in mouldings to make various products like sport bats, surf boards, bicycle skeletons etc.
About 60% of the 10k ton of CF expected to be recycled in 2024 will be done through mechanical recycling.
- Thermal recycling –
Thermal recycling is the process of burning resins in CFRPs to recover CF. These recovered fibers retain a tensile strength 50-85% compared to vCF. But the process can be energy intensive. Depending on the efficiency of the process, thermally recycled CF costs between $10-13 per kg. High quality recovered fibers have been piloted to make non-critical automotive parts, like car bumpers, while low quality recovered fibers are used in moulding automotive equipment like dashboards.
About 30% of the 10k ton of CF expected to be recycled in 2024 will be done through thermal recycling.
- Chemical recycling –
Chemical recycling is dissolution of the epoxy resin binding multiple layers of carbon fiber with chemical solvents. It is the most promising recycling solution as it retains 90+% of the tensile strength & other physical properties of vCF. But the use of harmful chemicals in the recycling process makes it very expensive & makes the process more complicated from a safety perspective. As a result of the high property retention, chemically recycled CF costs about 50% of vCF at around $20 per kg. As a general rule, recycled CF is not expected to cost more than 50% of vCF.
About 10% of the 10k ton of CF expected to be recycled in 2024 will be done through chemical recycling.
Current challenges in Carbon Fiber recycling –
Although we’ve observed a strong upturn from 115% CAGR growth in CF recycling over the past 3 years, the CF recycling landscape is still in its nascency with a 13% recycling rate. The market is made up of many small recyclers & some large scale vCF manufacturers getting into the recycling landscape. There is still sometime before consolidation happens within the sector. With research still happening on commercialization ‘true recycling’ of carbon fiber, the success of recycling CF would become a reality upon solving the following challenges –
Collection: Collection of CF waste (largely EOL waste) requires setting up specific collection networks. While the biggest consumers of CF today, wind blades & airplanes have robust collect networks for EOL products, the challenge is in the separation of CF from the other materials in the composites.
Scalability of recycling methods: Chemical recycling is the ideal recovery method because of the physical properties of the fiber. There are companies that are able to recover long continuous fibers with 95+% of the physical properties of vCF, but there are no industrial scale chemical recycling units. Creation of CF recycling plants that can independently breakeven is the crucial challenge facing the industry. In addition, the output of chemical and thermal recycling are multiple singular fibers. The true strength of carbon fiber comes from the stacking of multiple singular fibers. Therefore, unidirectional realignment of the recovered fibers that can be rewoven is a key aspect of recycling carbon fiber that has not been focused by a lot of players.
End-use: Recycling of CF is dependent on the way rCF can be used. As rCF inherently carries the length of its original product (as EOL waste) or its cut off (as production scrap), its length is limited, while vCF could theoretically be ‘endless’. Therefore, the resulting rCF has to be matched with new product designs depending on the available length of the rCF and required design length, ideally on a case by case basis. Therefore, figuring out upcycling possibilities remains a key challenge. Various F1 teams have already piloted the usage of rCF in their cars. Some companies have already created a closed loop for reusing CF from H2 storage tanks in the production of newer tanks. While this is likely a proof of concept, the economic scalability for end uses is a critical barrier for successful recycling of CF.
Regulations: Unlike vehicle tyres, or more recently clothes, there are no specific mandates for the disposal of CF making it challenging to source EOL waste. In addition, the move to recycle CF is largely driven by GHG emission targets by the EU rather than specific material recycling targets.
Eco-Design: A critical part of recycling is product design. Using patterns & cuts that preserve the length for the fibers and ease separation from other materials in the composite are the most effective methods to improve recyclability of CFRPs. An innovative method in ‘eco-design’ is using recyclable epoxy resins that bind together sheets of vCF. This has already been piloted by Siemens Gamesa for their recyclable wind blades.
Future Outlook:
Recycling Carbon Fiber is crucial not only to increase the life of one of the most energy intensive materials that we humans produce, but it is also a key lever to scale Hydrogen energy & making aviation greener.
The growing popularity of Hydrogen fuel in renewables is well established. But there is a critical problem of storage, as most metals are heavy (have a lot of deadweight) and cannot withstand the high pressure in which Hydrogen is stored. Further, steel specifically tends to brittle on contact with pressurized Hydrogen. Carbon Fiber makes the ideal replacement for metals and glass fiber in storage containers (Type 5 Hydrogen tanks). This push is set to make H2 storage the biggest consumer of Carbon Fiber between 2040 and 2050.
In the aviation industry, the usage of composites has gone up from less than 10% in the 1990s to about 50% in modern aircrafts, mainly for weight reduction. The reduction in weight has a direct impact on the fuel efficiency and therefore the GHG emissions from the industry.
While still in its infancy, this sector is a must watch for Aerospace & renewable energy companies within the EU to reduce their carbon footprint in the next 20-25 years. The recycling of carbon fiber could make this miracle material a super miracle material making it greener & cheaper.