Prospects for the Valorization of Wind Turbine Blade Waste: Fiber Recovery and Recycling
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript having title” Prospects for the Valorization of Wind Turbine Blade Waste:
Fiber Recovery and Recycling “ present a review of the state-of-the-art on the recycling of fiber reinforcements used in the wind turbine blades.
The subject of the submission is worthy to explore and to discuss in the form of a review in Sustainability MDPI. Following are my comments:
The structure of the review must of changed starting from the heading as introduction followed by other heading.
- Please follow the structure of any review paper.
- All the figures and tables must be reffered from where these have been used.
- The review must be further enhanced with additional literature.
- Authors are encouraged to cite and follow below articles in which one is a review paper and the other is using glass fiber epoxy.
https://doi.org/10.1016/j.jcomc.2024.100496
https://doi.org/10.1016/j.coco.2025.102368
Author Response
The structure of the review must of changed starting from the heading as introduction followed by other heading.
1. Please follow the structure of any review paper.
We revised and rearranged our manuscript according to your recommendation and inserted an additional Introduction part. Line 27-89
2. All the figures and tables must be referred to where they have been used.
Most of the Figures and data in the Tables are our unpublished results. Therefore, we indicated them in the captions as you suggested.
3. The review must be further enhanced with additional literature.
Thank you for your recommendation. We added new references, most of which are reviews (line 27-89). Since there are numerous reviews on the WTBW utilization and application, we considered including them in the introduction so that readers can follow them. Totally 22 new references were additionally included in the review.
4. Authors are encouraged to cite and follow the articles below, one of which is a review paper and the other uses glass fiber epoxy. https://doi.org/10.1016/j.jcomc.2024.100496 and https://doi.org/10.1016/j.coco.2025.102368
Thank you for the suggestion. Following the guidance in the first link, we incorporated the introduction part and rearranged the manuscript. However, we considered not citing the article in the second link because instead of WTBW, which is the main topic of the review, the plain weave E-glass fabric purchased from Gurit®, UK, was used as the reinforcement in the glass fiber reinforced polymers (GFRPs) composites.
Reviewer 2 Report
Comments and Suggestions for AuthorsThis review paper was well written. The title of this paper : Prospects for the valorization of wind turbine blade waste: fiber recovery and recycling. It is a valuable review paper. What do you think are the possibilities for recycling and reusing wind turbine blade waste? This paper is interesting for readers. You reported that the review indicates that only the mechanical processing of WTBW creates prerequisites for its possible use as fillers in construction materials. What are the main reasons for the above? Are there any other methods for recovering fibers from thermosets of WTBW through pyrolysis or converting WTBW into fibers besides plasma processing? Is it applicable if arc melting or laser heating is used? What is the biggest difficulty and the advantages and disadvantages if people used the plasma processing method? None of this review paper contained data of mechanical properties. I think that mechanical properties are also an important consideration for recycling. Therefore, I suggest that authors must add some literature review and content about mechanical properties in this article. In general, the references in this article are appropriate.
Author Response
This review paper was well written. The title of this paper : Prospects for the valorization of wind turbine blade waste: fiber recovery and recycling. It is a valuable review paper. What do you think are the possibilities for recycling and reusing wind turbine blade waste?
To our knowledge, there is a lack of comprehensive LCA including cost analysis on the recycling and reusing of WTBW. It is unlikely that wind turbine blades will be widely recycled in the near future. Nevertheless, several technically feasible methods already exist, though their large-scale implementation is still limited by economic or technical challenges. However, as recycling technologies become more efficient, large-scale recycling could accelerate over the next decade.
This paper is interesting for readers. You reported that the review indicates that only the mechanical processing of WTBW creates prerequisites for its possible use as fillers in construction materials. What are the main reasons for the above?
Answering your question, we can refer to the recent study by E.B. Paulsen and P. Enevoldsen (2021) https://doi.org/10.3390/en14144247 . Mechanical processing method has attained a Technology Readiness Level (TRL) of 9 and involves crushing blades, making them most applicable as filler in construction materials.
Are there any other methods for recovering fibers from thermosets of WTBW through pyrolysis or converting WTBW into fibers besides plasma processing?
Thank you for your comment. We included an introduction part that briefly describes other recycling methods and refers to several comprehensive reviews on that topic.
Is it applicable if arc melting or laser heating is used?
Laser heating is not within our area of expertise, as our work focuses on thermal plasma technologies. Arc melting could be applicable for the melt production though not the fiber. We do not included this technique since it falls outside the scope of this article, dealing with recovering or recycling of glass fiber and its further application.
What is the biggest difficulty and the advantages and disadvantages if people used the plasma processing method?
Plasma-assisted recycling technologies offer numerous advantages, including high efficiency, flexibility in processing various materials, and minimal environmental impact. A key benefit of plasma processing for wind turbine blades (WTBs) is its ability to prevent the release of harmful organic compounds and contaminants, resulting in a clean, solid-phase product. During plasma gasification, the organic components of composite polymers are broken down into their fundamental molecular constituents. However, the high costs associated with the substantial initial investment required for equipment represent a significant barrier to the broader adoption of plasma technology. Thermal plasma systems also face common challenges such as high energy consumption. Nonetheless, as green energy technologies continue to advance rapidly, the impact of energy costs gradually diminishing. The mechanical shredding of wind turbine blades is an unavoidable step in any recycling method. During this process, individuals may be exposed to health risks due to fine particulate dust, which can irritate the skin or contaminate the respiratory system. To mitigate these risks, appropriate protective measures must be implemented, including effective filtration and ventilation systems, as well as the use of personal protective equipment.
None of this review paper contained data of mechanical properties. I think that mechanical properties are also an important consideration for recycling. Therefore, I suggest that authors must add some literature review and content about mechanical properties in this article.
We appreciate your feedback. The data on the changes in mechanical properties have been summarized in Table 2 based on various references.
In general, the references in this article are appropriate.
Thank you.
Reviewer 3 Report
Comments and Suggestions for AuthorsThis manuscript reviews prospects for the valorization of wind turbine blade waste: fiber recovery and recycling. It covers 4 subjects with 78 references: 1. mechanically treated glass fiber-reinforced plastic (GFRP), 2. pyrolysis process in fiber recovery from GFRP, 3. plasma method in WTBW recycling, 4. geopolymers with WTBW, 5. durability of fiber recovered by pyrolysis, 6. durability of recycled fiber derived from plasma processing. ESG is an important issue all over the world. How the used products or material be recycled is a challenge task. This review covered many methods to recover the fiber in wind blades, however, I have several comments as follows;
1. Line 149, 5% and 10% GFRP ‐> are they by weight or volume?
2. Please leave a space between value and unit, like 37.1%, 13.98%, 10%, and 480°C
3. Typo: Line 177, materials. [34], ‐> materials [34].
4. Xu, Mingxin and Liangyu Li, and Supriya, R. Chaudhury, U. Sharma,
P.C. Thapliyal in reference, please unify the order of last name and first name.
5. Line 208: CO2 and O2, SiO2, 2 is a subscript.
6. Line 214: 15% -> by volume?
7. Line 220: R.S.Ginder -> R. S. Ginder
9. A.Rahimizadeh -> A. Rahimizadeh
10. Line 238: et. al -> et al.
11. XRF -> What is XRF? Maybe XRD?
12. Line 328: B.Figiela -> B. Figiela; 25 to 75% -> are they by weight or volume?
13. Line 340: 5-30% -> Is it by weight or volume?
14. Line 343: 2 % wt -> 2 wt%
15. Line 456; [73,74,76] -> [73-74, 76]
16. What is No. 1 WTB and No. 2 fibers in Fig.8 ?
17. If the figures were cited, like Figures 3, 4, and 5, from other authors, must get permission from them.
Author Response
This manuscript reviews prospects for the valorization of wind turbine blade waste: fiber recovery and recycling. It covers 4 subjects with 78 references: 1. mechanically treated glass fiber-reinforced plastic (GFRP), 2. pyrolysis process in fiber recovery from GFRP, 3. plasma method in WTBW recycling, 4. geopolymers with WTBW, 5. durability of fiber recovered by pyrolysis, 6. durability of recycled fiber derived from plasma processing. ESG is an important issue all over the world. How the used products or material be recycled is a challenge task. This review covered many methods to recover the fiber in wind blades, however, I have several comments as follows;
1. Line 149, 5% and 10% GFRP ‐> are they by weight or volume? - weight
2. Please leave a space between value and unit, like 37.1%, 13.98%, 10%, and 480°C
3. Typo: Line 177, materials. [34], ‐> materials [34].
4. Xu, Mingxin and Liangyu Li, and Supriya, R. Chaudhury, U. Sharma, P.C. Thapliyal in reference, please unify the order of last name and first name.
5. Line 208: CO2 and O2, SiO2, 2 is a subscript.
6. Line 214: 15% -> by volume? 15% of CO2 gas – gas is typically controlled by volume. Line 215.
7. Line 220: R.S.Ginder -> R. S. Ginder
9. A.Rahimizadeh -> A. Rahimizadeh
10. Line 238: et. al -> et al.
We made corrections according to the ten comments provided by the Reviewer. Since we rearranged the manuscript and included the introduction part, the corrections do not follow the lines mentioned by the Reviewer.
11. XRF -> What is XRF? Maybe XRD?
Thank you for your comment. We made a correction, inserting the full name of the equipment instead of the abbreviation X-ray fluorescence (XRF) in line 309. XRF differs from XRD since it is a nondestructive analytical technique used to determine the elemental composition of materials. XRF analyzers determine the chemistry of a sample by measuring the fluorescent (or secondary) X-ray emitted from a sample when it is excited by a primary X-ray source. We also corrected the text on line 313, explaining abbreviation FTIR.
12. Line 328: B.Figiela -> B. Figiela; 25 to 75% -> are they by weight or volume?
13. Line 340: 5-30% -> Is it by weight or volume?
14. Line 343: 2 % wt -> 2 wt%
Corrections have been made. In most of the studies, researchers used weight %.
15. Line 456; [73,74,76] -> [73-74, 76]
16. What is No. 1 WTB and No. 2 fibers in Fig.8 ?
Thank you for the comment. In the Figure8 (now it is Figure 10), WTB is waste turbine blade waste, and should be indicated as WTBW (W letter is missing). Notations are inserted in the text in Line 560-562
If the figures were cited, like Figures 3, 4, and 5, from other authors, must get permission from them.
Most of the Figures and data in the Tables are our unpublished results. Therefore, we indicated them in the captions as you suggested.
Reviewer 4 Report
Comments and Suggestions for AuthorsThis manuscript reviews literature on waste management of wind turbine blade waste, which would be of interest to the readership in fiber recovery/recycling and construction material design/development field. However, there are several points to be addressed before the manuscript can be reconsidered.
- More references or a more thorough literature review is needed for all sections.
- It would be better to summarize and categorize the information mentioned in section 3.1 in Tables. For example, list all significant mechanical treatment methods in a table column with references attached. For cutting the waste into needles or other shapes, use tables to illustrate the impact of different geometry on mechanical properties (e.g., fracture resistance, tensile properties) of the prepared construction materials with references attached. Also for physical or chemical mechanism analysis.
- Suggestions for section 3.2 and 3.3 are similar to the aforementioned revision logic for section 3.1.
- For discussion under same treatment methodology, please reorganize the sections and make the discussion clearer. For example, section 3.3 and 3.6 can be combined and reorganized. Now the logic seems a little bit messed up.
- For all sections, please include appropriate Figures from literature review with as much information/details as possible. The Figures should guide the readers on the methodology and the resultant materials’ appearance/physical performance/chemical performance, instead of just showing one small point of the discussion.
Author Response
This manuscript reviews literature on waste management of wind turbine blade waste, which would be of interest to the readership in fiber recovery/recycling and construction material design/development field. However, there are several points to be addressed before the manuscript can be reconsidered.
- More references or a more thorough literature review is needed for all sections.
Thank you for your recommendation. We added new references, most of which are reviews. Since there are numerous reviews on the WTBW utilization and application, we considered including them in the introduction so that readers can follow them (line 27-89). Our review is focused on the application of recovered or recycled glass fibers obtained from WTB. Most of the reviews, dealing with WTB management or recycling, do not distinguish the application of recovered or recycled glass fibers, and moreover, their application in geopolymer (Table 1 line 239). On the other hand, there is a lack of studies on this topic; therefore, the number of references is low, though still larger than in other reviews. Additional literature was included in the plasma section (line 246-252; 265-268). Totally 22 new references were included in the review.
It would be better to summarize and categorize the information mentioned in section 3.1 in Tables. For example, list all significant mechanical treatment methods in a table column with references attached. For cutting the waste into needles or other shapes, use tables to illustrate the impact of different geometry on mechanical properties (e.g., fracture resistance, tensile properties) of the prepared construction materials with references attached. Also for physical or chemical mechanism analysis.
We summarized and categorized the data presented in the references in Tables 1,2 and 3.
- Suggestions for section 3.2 and 3.3 are similar to the aforementioned revision logic for section 3.1.
We summarized and categorized the data presented in the references we cited. Additional Table 1,2, and 3 were included.
- For discussion under same treatment methodology, please reorganize the sections and make the discussion clearer. For example, section 3.3 and 3.6 can be combined and reorganized. Now the logic seems a little bit messed up.
Thank you for your suggestion. We rearranged the manuscript according to your recommendation by indicating the durability experiments on glass fiber derived from different thermal treatment methods. The text was also corrected.
- For all sections, please include appropriate Figures from literature review with as much information/details as possible. The Figures should guide the readers on the methodology and the resultant materials’ appearance/physical performance/chemical performance, instead of just showing one small point of the discussion.
We agree with your comment and, therefore, consider inserting a few pictures (Fig.1,2) for the reader's guidance. Nevertheless, repeating the Figures from the numerous reviews on WTB management or recycling is excessive and may reduce the paper's attractiveness. On the other hand, we included our unpublished new results related to the durability of glass fibre recovered and recycled from WTB. Contrary to our results, most studies present data from the accelerated durability tests. In our case, natural durability tests lasted for 180 days and 550 days.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsI do not have further remarks.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors' responses were well for the first round review. Therefore, I recommend this paper for publication in Sustainability.
Reviewer 4 Report
Comments and Suggestions for AuthorsN/A
