An Update on Carbon Fiber Recycling – Continuous Fibers No Less

#composites, #sustainability, #recycling, #recycledfiber, #carbonfiber

I have talked about how difficult it is to recycle composites – especially those with traditional thermoset resins – and getting back something like the virgin fiber in continuous strands.  While it is still hard to do, and most composite waste is just going to landfills at present, I have seen a few instances where researchers in R&D and some industrial organizations have been able to develop processes that can reclaim nearly virgin carbon fiber in either unidirectional tow form or original fabric from things like hydrogen pressure vessels, junk auto parts, the carbon fiber parts of used wind turbine blades, and other carbon fiber composite end of life pieces and parts. 

I have talked quite a bit about what the consortium of Composite Recycling, Fiberloop, Beneteau and others have done in the EU to reclaim both the fiber and resin from end of life boat hulls, and also the Composite Recycling / Fiberloop machines intended to recycle the fiberglass and resin from end of life wind turbine blades, but to date I do not believe that these folks have demonstrated using their process to reclaim continuous filament carbon fiber – it is all chopped into about 4-5” pieces before it goes into their process.  I’m certain that they are going to work on that in the future, as soon as their respective organizations are able to tackle the huge problem they face today.  They’ve got enough on their plates today as it is. 

So, let’s move on to look at what’s presently going on in the continuous carbon fiber reclamation space – at least at the R&D and demonstration phase of development (Technology Readiness Level 4-5 and potentially leaning toward 6-7).  The lead pic in this post is from an April 2022 Composites World article about the National Composites Centre in the UK.  This is the UK’s center of excellence in composites, and they worked with industrial partners B&M Longsworth and Cygnet Texkimp, both of which are also based in the UK.  What these folks have been able to do is to reclaim continuous carbon fiber from a hydrogen pressure vessel in an effort to lower the cost of manufacturing pressure vessels for the coming hydrogen economy.  They apparently used high temperature steam in a pressurized chamber that is cycled from low to high.  This essentially melts the resin during the high pressure swing and washes it away in the low pressure swing.  At least that’s how B&M describes it. 

B&M had developed this process for cleaning polymers off of metals some time ago, but just recently realized that they could do the same with carbon fiber based composites.  And the good thing about this is that it doesn’t matter what the resin is, it apparently comes off well using this process, and leaves behind nearly pristine carbon fibers.  B&M calls this process DEECOM which is sort of short for decompression, alluding to the pressure swing process that they use.  They do not say whether or not they are able to reclaim any of the resin, but it doesn’t take too much of an imagination to think that since they have effectively dissolved the resin in the high temperature steam within the pressure vessel they ought to be able to recover some hydrocarbons that should be useful. 

And, in a recent update in February of 2024, B&M with the National Composites Centre announced that they had successfully reclaimed carbon fiber from a used hydrogen storage COPV (Composite Overwrapped Pressure Vessel) and reused them to make a new one.

I’ve also talked in the past about the goings on at NREL in this regard where they developed an entirely plant-based resin system that has nearly the same mechanical properties as aerospace epoxies and is inherently recyclable and reusable.  They made a 9 meter long wind turbine blade out of this stuff, and along the way perfected the process for removing the plant-based resin and ending up with pristine fibers, both glass and carbon. 

Recently, these same researchers at NREL have gone a step further with their plant-based resin on carbon fibers.  Previously, they had used a methanolysis-like technique, which is a type of solvolysis, to remove epoxy resins including their PECAN resin from carbon fibers.  In a fairly recent news article from NREL (Feb. 27, 2024) they announced that they had successfully been able to thermoform their carbon fiber with plant-based epoxy into whatever shape they needed. 

Apparently the PECAN plant based epoxy that was developed by NREL for the wind turbine industry can act a bit like a thermoplastic and be thermoformed.  While there are several details that were left out of the article I read, like if the material had been pre-treated with a methanolysis process before thermoforming or not, and if it was truly made using the NREL PECAN resin, they still were able to take their material and thermoform it with complex curvature into new parts.

And in one more effort that I need to highlight in this post, a German Institute, Fraunhofer EMI, has developed and demonstrated a local pyrolysis process for reclaiming continuous carbon fiber from a carbon fiber wound structure – like a hydrogen storage COPV.  I saw this first reported in an April article in Composites World (4/28/2025) where the researchers at Fraunhofer used high power lasers to spot decompose the resin in a cured part and reclaim the carbon fiber completely intact.  And the carbon fiber that they reclaimed was nearly pristine in its mechanical properties.

The laser is pointed at the little red spot that you see on the part to the right and the released and clean carbon fiber tow is being spooled up on the left side in this picture.  While this is just a lab demonstration at this point, they were apparently very successful in their efforts.  What the high power lasers allowed them to do is to control the temperature of the laser pyrolysis to more than 300°C where the resin begins to break down and less than 600°C which is where carbon fiber begins to get damaged.

This process was developed specifically for the hydrogen economy because by using this process they can reclaim all of the fiber from a hydrogen storage COPV and reuse it directly to make a new one.  As you can see from the picture of their process, this process can easily be automated, and has the potential to operate at a high rate.

There are two reasons that this development is significant.  First, it is a potentially completely automatic and rapid process, so it is already nearly ready for industrial use at a fairly large scale.  The other reason that this is important is that with current regulations for hydrogen storage tanks, the tanks must be retired long before the composite overwrap has come to the end of its useful life.  So, this will significantly lower the costs for hydrogen long term and gives hydrogen a fighting chance to overtake petroleum as the transportation fuel of choice.  And, as a side benefit, the reclamation of the carbon fiber ready for reuse uses less than a fifth of the energy that it takes to make new fiber.  A win-win in anyone’s book.

This project was funded by the German Federal Ministry for Economic Affairs and Climate Action.  The project, named DigiTain, is going to run until the end of 2025, so the researchers at Fraunhofer are diligently working on making the process more energy efficient while improving the quality of the reclaimed fibers.  My guess is that this has a good chance of becoming a fairly standard process in a fairly short span of years and should be ready for the high volume of hydrogen gas storage COPVs that will be coming out of Europe’s transition to hydrogen for transportation fuel.  So these hydrogen storage tanks for transportation have a fighting chance to not end up like the used wind turbine blades in Texas. 

That’s about it for this week.  As always, I hope everyone that reads these posts enjoys them as much as I enjoy writing them.  I will post this first on my website – www.nedpatton.com – and then on LinkedIn.  And if anyone wants to provide comments to this, I welcome them with open arms.  Comments, criticisms, etc. are all quite welcome.  I really do want to engage in a conversation with all of you about composites because we can learn so much from each other as long as we share our own perspectives.  And that is especially true of the companies and research institutions that I mention in these posts.  The more we communicate the message the better we will be able to effect the changes in the industry that are needed. 

My second book, which should be out in the fall, is a roadmap to a circular and sustainable business model for the industry which I hope that at least at some level the industry will follow.  Only time will tell.  Since my publisher and I have finally come to agreement about the title for my next book, our daughter has been kind enough to put together a draft of the cover of the book.  I’ve included that at the end of this post as promised.  Let me know whether or not you like the cover.  Hopefully people will like it enough and will be interested enough in composites sustainability that they will buy it.  And of course I hope that they read it and get engaged.  We need all the help we can get. 

Finally, I still need to plug my first book, so here’s the plug.  The book pretty much covers the watershed in composites, starting with a brief history of composites, then introducing the Periodic Table and why Carbon is such an important and interesting element.  The book was published and made available last August and is available both on Amazon and from McFarland Books – my publisher.  However, the best place to get one is to go to my website and buy one.  I will send you a signed copy for the same price you would get charged on Amazon for an unsigned one, except that I have to charge for shipping.  Anyway, here’s the link to get your signed copy:  https://www.nedpatton.com/product-page/the-string-and-glue-of-our-world-signed-copy.  And as usual, here’s a picture of the book.