So far, we know that a type of waste that might be problematic in the future (if we don’t find a way to handle it from now) is solar panels. Well, another is one from the automotive, aerospace and renewable industries: carbon and glass fiber composites (CFRP).
Currently, we find a lot of this material in wind turbine blades, hydrogen tanks, airplanes, yachts, construction, and car manufacturing. And since they’re everywhere now, it can potentially be a key waste stream worldwide.
Researchers at the University of Sydney, however, have come up with a better method to recycle the waste. Their findings are published in Composites Part B: Engineering.
Potentially problematic waste
Experts have projected that, without proper recycling, the annual accumulation of CFRP waste from aircraft and wind turbine industries alone can reach 840,300 tons by 2050. That’s the equivalent of 34 full stadiums.
“Carbon fiber composites are considered a ‘wonder’ material – they are durable, resistant to weathering and highly versatile – so much so that their use is projected to increase by at least 60 percent in the next decade alone,” Dr Hadigheh from the School of Civil Enginering said.
“But this huge growth also brings a huge increase in waste. For instance, it’s been estimated that around 500,000 tons of carbon and glass fiber composite waste from the renewable energy sector will exist by 2030,” Dr Hadigheh added.
Now, there are recycling methods and efforts already. However, they’re not that many—most of this waste currently goes to landfills or is incinerated. It’s made worse with the production of “virgin” composites. This can also lead to resource depletion and high energy input during production.
While, on the other hand, if we can fully implement numerous methods to recycle carbon fiber composite, we can significantly reduce energy use by 70% and prevent key streams of materials from going to waste.
The complicated nature of recycling the material
Recycling carbon fiber is a complex issue. The industry exists with the hope of solving problems—the goal to keep carbon fiber waste out of landfills and to fill a potential gap between carbon fiber supply and demand.
However, much of the produced carbon fiber still ends up as waste. Meanwhile, most analysts agree that annual demand for the material could surpass current annual production capacity within the next few years.
Although, it should be noted that the recycling industry is not without success either. Commercial suppliers of recycled carbon fiber (rCF) have been pointing consumers to reclaimed and repurposed material, offering a potential solution to this supply and demand gap.
Nonetheless, the rCF industry has its own challenges.
The technology to recycle carbon fiber composites has existed for some time now, as mentioned. It can also yield a product with mechanical properties very near that of virgin material.
But, composite recycling sector is still so young—in fact, it’s still in the early stages of developing markets for the materials it produces from recyclate.
Some people still prefer “virgin” composites, as they haven’t really trusted the recycled one. On the other hand, confidence in the quality of recycled fiber is actually increasing—raising future concerns about availability.
According to some experts, the current largest challenge for the industry is perhaps the concern over supply chain security.
Will the new recycling method work?
To address (and with the hope of tackling) the issue, Dr Hadigheh and Dr Yaning Wei have developed a new recycling method for carbon and glass fiber composites in a bid to prevent end-of-generation materials from going to landfill.
The researchers approach ensures increased material recovery and improved energy efficiency compared to previous methods.
According to Dr Hadigheh, the new method—which utilizes pre-treatment—doesn’t only facilitate greater breakdown. It also preserves the mechanical properties of fibers by reducing heat consumption during recycling.
Recycled fibers obtained from pre-treated CFRP retained up to 90% of their original strength, surpassing the strength of fibers recovered through thermal degradation alone by 10%.
To show how applicable their methods are, the researchers tested their discovery to recycle part of a bicycle frame and airplane scraps made of CFRP composites.
“These results not only validate the effectiveness of chemical pre-treatment but also demonstrate the improved mechanical characteristics of the recycled carbon fibers,” Dr Hadigheh said.
Better recycled carbon fiber
Previously, the team presented a detailed evaluation of 10 different carbon and glass fiber composite waste treatment systems based on economic efficiency and environmental effects, taking into consideration the type of waste material and its geographical location.
It’s just that in the new research, the team found that solvolysis could reclaim carbon fiber while delivering a high net profit. They also discovered that thermal recycling methods also provided a high economic return.
In simpler terms, solvolysis is a method whereby materials can be broken down with an application of solvent under a specific pressure and temperature. Solvolysis and electrochemical methods could lead to substantially lower CO2 emissions into the atmosphere than landfilling and incineration.
The potential to change the industry
According to the researchers, manufacturers and consumers should look beyond creating and using virgin material and develop recycled products from end-of-life streams.
Dr Wei stated that what they had discovered was a huge opportunity, not only because various modes of recycling could be cost-effective and minimally impactful on the environment.
“In an era of mounting supply chain disruptions, local recycled products can provide a more immediate product when compared to imports and create a burgeoning advanced manufacturing industry,” Dr Wei said.
The researchers added that although awareness of everyday consumer recycling is increasing, and plastic waste is in the spotlight, more people should consider recycling more construction materials before they become another unsolvable waste problem.
Other than this research, Dr Hadigheh’s team is developing methods for the recycling of composite material. Moreover, they’ve also recently patented a machine to precisely align recycled carbon fibers, so that they can be repurposed.
The future for carbon fiber recycling is not hopeless
Even though it sounds rather grim for now, things are looking up. For one, the quality of rCF being produced has been shown, in some cases, to be on par with virgin fiber—this will convince the ones preferring virgin fiber to switch to the recycled one.
For example, LG Carbon Fibre, which reclaims carbon fibers using pyrolysis, says its fiber typically retains at least 90% of its tensile strength with no change in modulus.
Some experts say that looking ahead, the challenge is all about getting the cost down to a level comparable to that of other materials such as aluminum. Other than that, compressing the wait time.
Big changes, especially when it comes to something relatively new like carbon fiber recycling, often happen in small steps. The young sector does need to push forward, slowly but surely, but perceptions about the material are beginning to change and have changed in some areas.
Furthermore, the quality of fiber has been proven and processes continue to evolve. With how awareness of the necessity to recycle carbon fiber is getting higher, and more players are getting involved, combined with new findings from the University of Sydney and perhaps other scientists in the future, we can potentially prevent carbon fiber waste to be a major problem.
So, let’s give it time and let’s remain optimistic about the future.
Sources
https://www.compositesworld.com/articles/the-state-of-recycled-carbon-fiber
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