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  • Writer's pictureNed Patton

What’s Going On in the World of Glass Fiber Recycling

I thought this week I would come back to this subject because it is arguably the most difficult problem we have to solve with regard to recycling and/or reusing composites.  There is more tonnage of “fiberglass” or glass fiber composites that have already reached end of life than there is of any other composite.  That’s why I am also sort of recycling an old pic of something I posted some time ago – from a bit different perspective to give you a sense of the scale of the problem.  The piles of used fiberglass wind turbine blades in Sweetwater Texas shown in this pic is mind boggling. 

Apparently there was a company that bought up the used turbine blades from two sites in Nolan County, Texas, promising to recycle them into useful material again.  There are estimated to be over 4000 of these in two sites (this is the smaller one) and they have been sitting there since 2018.  This pic is from a piece on the local ABC station in August of 2022 that covered what Sweetwater eventually called a nuisance, since it was harboring all sorts of animals that should not have been there, and as the blades were breaking down, it was contaminating the site.  And, as it turns out, the company that bought the blades and stored them at the sites in Nolan County – Global Fiberglass Solutions – as of September 2023 is being sued by General Electric – the operator of the wind turbine farms there.  Ad it looks like from the Global Fiberglass Solutions website that they are legitimate.  I’d be curious to know if this is a case of a misunderstanding or if this is just another case of greenwashing.  In any case GE is now involved, so that battle continues……..

What this entire debacle illustrates is that there is a very large environmental problem looming just in figuring out what to do with end of life wind turbine blades.  And this problem is only going to get worse over time if we don’t focus a lot of energy (and dollars) on solving the problem of how to separate the fiber from the resin in composites. 

So now that we understand the problem, I need to tell a bad news, good news story here.  That’s why I’m focusing this week’s post on recycling used up fiberglass pieces and parts (like wind turbine blades) at the scale that it needs to be.  I had posted some time ago that there is the likelihood of as much as 50 million tons of this stuff that is going to come from just the wind turbine industry alone in the next decade or two.  That’s the bad news part.

The good news part is that there are at least two companies that have sprung up in Europe that are focused on glass fiber recycling in the marine industry.  In the past, it has been the reclamation of the more expensive and difficult to make carbon fiber that has been the focus of recycling and reclamation efforts.  This is also because traditional high temperature pyrolysis techniques don’t damage carbon fibers as much as they do glass fibers, so there was less incentive to work on glass fiber recycling. 

And, of course, the major reason that glass fiber composite recycling companies have not sprung up in the past is that the traditional pyrolysis process for separating the fiber from its matrix destroyed the resin and left fibers that were not continuous.  And these fibers had degraded mechanical properties, even significantly degraded mechanical properties in the case of higher temperature pyrolysis that works better for carbon fiber, but not as well for glass fiber.  In addition to that, if the resin is not recovered as well, the chopped glass fiber itself is a low value product so it is difficult to justify the expense of building recycling plants or recycling the fiberglass if all you get is a relatively low value product to sell.

In the past few years that has been changing, and fortunately changing rapidly.  I wrote a little bit about this a couple of weeks ago when I talked about Composites Circularity in the Marine Industry.  This is of course driven by the European marine industry and new laws in France and also in other countries in the rest of the EU that I mentioned a couple of weeks ago. 

In that vein, there are a couple of European startups in this very industry with very smart chemists that have gotten funding from some of the larger players in this industry.  These are the two companies I mentioned above that have built their business around recycling end of life fiberglass boats.  This means that they are dealing with E-Glass and polyester or vinyl ester resins.  They have not worked on carbon fiber / epoxy yet, but what they have been able to accomplish is quite the breakthrough in recycling composites and reusing the recycled materials. 

One Italian company – Korec in Bientina, Italy (Tuscany) – is working with none other than Owens Corning here in the US.  Owens Corning has taken it upon themselves to reduce their carbon footprint by 50% and using 100% renewable energy for processing by 2030.  Fairly ambitious goal. 

Korec’s patented process (US Patent Number 10,308,784) is a thermo-chemical process where they place the fiberglass part into a stainless steel chamber, remove all of the air from the chamber – especially the oxygen –and replace it with CO2.  Then they raise the temperature in the chamber to between 350 and 550 degrees C, hold it for 3 to 5 hours.  When they extract the hot gas from the chamber, all of the resin has been depolymerized and is contained (dissolved actually) in the gas.  The resin is then condensed out of the gas and you get back a liquid that can be used directly as an additive in your next resin batch.  So, they have come up with a technique that retains the higher value resin nearly intact. 

They claim to recover nearly 100% of the glass fiber and nearly 85% of the resin using this process.  The patent that covers this process was issued in 2015, and they worked on perfecting the process until 2019.  That’s when they began to scale the process up.  They opened up their first industrial scale plant in March of 2021 intending to process a minimum of 500 metric tons of material per year.  That’s a really good start.

Another company in the French speaking part of Switzerland – Composite Recycling – has also developed a process along the same lines as Korec where they use another proprietary pyrolysis process in the absence of oxygen to depolymerize the resin from waste glass fiber composite materials and recover quite a bit of the resin in the form of what they call “pyrolysis oil”.  While they do not disclose on their website any more about their process, we can safely assume that it is most probably very similar to what the Italians are up to.  The one thing that Composites Recycling has done to increase their ability to facilitate the market is to bring their fiberglass recycling process to the site of the recyclable composite materials – as in at a wind turbine blade dump – rather than having used wind turbine blades shipped to a central recycling facility.  They have been able to fit their entire glass fiber composite recycling process equipment along with all of the chemistry required in a 40’ ISO container.  In the case of the blades in Sweetwater Texas this means that Composites Recycling could bring 10 or 20 of these machines in their 40’ containers right to the site where the turbine blades are stacked. 

As I mentioned the development of these two pyrolysis processes was primarily driven by the European boat industry.  That industry has been keenly aware of the problem that they have encountered – mostly political – in the fact that fiberglass boats that are at the end of their useful life are starting to cause fairly significant and more importantly very visible degradation to the local marine environment.  Europeans are far more acutely aware of ocean pollution than are quite a few of the other developed nations – including the US.  They also have more coast line per capita than the US, and the major population centers are primarily along the coasts.  Along with the European sensitivity to the beauty of nature, and their overall environmental consciousness, this has become a very visible problem.  So, they have been actively doing something about it because of the political will of the people of Europe.  European politicians also need to get elected.  So, since the populus of Europe is ahead of most other developed parts of the world in this respect, their politicians pay attention and do something about it. 

Here in the US, there are several efforts ongoing to scale up primarily higher temperature pyrolysis processes to retrieve the glass fiber from the waste fiberglass.  One of these is being scaled up by a company in Tennessee called Carbon Rivers.  Their process is what they call a multi-stage pyrolysis that apparently avoids the degradation of the mechanical properties of the glass fiber.  What they end up with is a product that can be used directly as a reinforcement in new discontinuous glass fiber composites that retain what they call “virgin-like” properties which apparently means properties very much like new fiber.  Once they have the fiber reclaimed from the waste composite, they mix it with some desirable polymer – presumably thermoplastic – and produce a pellet product that can be directly molded into things like automotive door panels or other discontinuous glass fiber thermoplastic composites.  They do not, however, recover any of the resin. 

TPI Composites Inc. of Scottsdale has also announced that they have moved into the second phase of their wind turbine blade recycling and recycled glass fiber yarn developments using technology co-developed with the University of Tennessee in Knoxville.  This second phase of the work is scaling up using industrial textile manufacturing equipment and methods to develop a recycled glass yarn that may eventually compete with new glass fiber yarn tows (  This work is also being supported by the Oak Ridge National Laboratory (ORNL) with Dr. Uday Vaidya of ORNL which is also the CTO for the Institute for Advanced Composites Innovation (IACMI).  Their process again uses a high temperature pyrolysis technique that does not recover the resin component, but it does leave the glass fiber in a good enough product form that it can compete on a mechanical properties basis with new fiber and new yarn. 

To my knowledge the two companies in Europe that are focused on recycling end of life fiberglass boat hulls are the only two that recover significant quantities of the resin during the recycling process.  And to date, no company has figured out how to take epoxies apart and still save the resin to enable it to be used to make new epoxies.  There is a technique called “solvolysis” that uses strong acids to break down the epoxy in carbon / epoxy composites, but what is left is not usable as resin.  The fiber ends up being in pretty good shape, but this technique ends up with a lot of hazardous waste that needs to be disposed of safely.   Bottom line – we’re not there yet. 

That’s about it for this week.  I hope everyone that reads these posts enjoys them as much as I enjoy writing them.  As usual I will post this first on my website – – as well as 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. 

I also wanted to remind everyone that I will be speaking at the SAMPE conference in Long Beach in May.  I’m going to be talking about the subject that I have a passion for – composites sustainability.  Maybe I can help the industry a bit again, maybe even rattle a few cages like what happened at the Carbon Fiber Conference in Salt Lake.  One can only hope.  Anyway, for anyone that is interested in materials and process engineering, SAMPE will be a great conference.  And they will have a really great exhibit as well. 

And, finally, I still need to plug my 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, except that I charge $8 shipping.  Anyway, here’s the link to get your signed copy:  And as usual, here’s a picture of the book, for those of you just tuning in. 



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