Repurposing EoL WTB Components into a Large-Scale PV-Floating Demonstrator
Abstract
1. Introduction
2. Materials and Methods
2.1. PV-Floating Demonstrator Design for Circularity
2.1.1. Material Sourcing from an EoL Enercon E66 WTB
2.1.2. Geometrical Characterization of EoL WTB Segments
2.1.3. Design Steps and Support Integration
2.2. Demonstrator Assembly
2.2.1. Repair Methods to Ensure WTB Segments Floatability
2.2.2. PV-Floating Demonstrator Assembly
2.3. Experimental Setup and Testing Methodology
2.4. Numerical Simulation for Further Optimization of the Design
2.5. Life Cycle Assessment Methodology and Scope
2.5.1. Goal and Scope Definition
2.5.2. Life Cycle Inventory (LCI)
3. Results
3.1. Experimental Results of Buoyancy and Wave Tests
3.2. Numerical Simulation Results of the Environmental Conditions of the Demonstrator
- (i)
- To mitigate high IRF values near the connection bolts of the WTB segments, a higher number of bolts should be introduced to distribute the load more evenly. Additionally, the use of Class 12.9 Hex Bolts is recommended, as internal stresses in the bolts can be high (see Figure S3)).
- (ii)
- Plastic end caps connecting the side and bottom spar cap beams could be added for additional reinforcement purposes.
- (iii)
- If less lateral flexibility in the solar panel structure is desired, lowering the height could save material, increase more rigidity, and offer less contact area for additional wind loads in aquatic conditions.
- (iv)
- A lower height combined with wider spar cap beams could also reduce bending stresses in the corner beams.
3.3. LCA of Repurposed Floating Demonstrator
4. Discussion
5. Conclusions
Supplementary Materials
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
Abbreviations
ACP | ANSYS Composite PrepPost |
AP | Acidification Potential |
CC | Climate Change Potential |
CE | Circular Economy |
CFRP | Carbon fibre-reinforced polymer |
CM | Centre of Mass |
CT | Human Toxicity Potential |
DoF | Degrees of Freedom |
EoL | End-of-life |
ET | Freshwater Ecotoxicity Potencial |
FE | Freshwater Eutrophication Potential |
FR | Fossils Resource Use Potential |
FRP | Fibre-reinforced polymer |
GFRP | Glass fibre-reinforced polymer |
GLO | Global |
HMDS | Hexamethyldisilazane |
IR | Ionizing Radiation Potential |
IRF | Inverse Reserve Factor |
LCA | Life Cycle Assessment |
LCI | Life Cycle Inventory |
LD | Longitudinal direction |
LU | Land Use Potential |
ME | Marine Eutrophication Potential |
MR | Metals Resource Use Potential |
NT | Non-Cancer Human Toxicity Potential |
OD | Ozone Depletion Potential |
OF | Photochemical Ozone Formation Potential |
PM | Particulate Matter Potential |
PSD | Power Spectral Density |
Pt | Points |
PT | Portugal |
PV | Photovoltaic |
RER | Europe |
RoW | Rest of World |
TD | Transverse direction |
TE | Terrestrial Eutrophication Potential |
TRL | Technology Readiness Level |
UD | Unidirectional |
WP | Wave Probe |
WTB | Wind turbine blade |
WU | Water Use Potential |
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Input/Output | Dataset | Amount | Unit | Comment |
---|---|---|---|---|
EoL wind turbine components | n.a. | 2 × 300 | kg | - |
Spar cap beams | n.a. | 97 | kg | - |
Epoxy putty for surface defects | Created composition | 1.5 | kg | based on [42] |
Epoxy resin and glass fibres for laminating | Created composition (resin); Glass fibre, market, GLO | 1 L (resin); 400 g (fibre) | L; grams | based on proxy |
Waterproof maritime-grade paint | Created composition | 14.7 | kg | from [43] |
Steel (i.e., brackets, plates, bolts, nuts, washers) | Chromium steel 18/8, hot-rolled, market, GLO | 16.7 | kg | - |
Silicone | Silicone product, market, RER | 320 | g | - |
Cement sawing, for TD cuts (stage C1) | Soft stone cutting using diamond wire technology, created process | 1.06 | m2 | from [44] |
Surface abrasion with pneumatic orbital sander (stage A5) | Electricity, Compressed air, Waste | 2 × 6 | h | process compiled from various sources |
Cutting shear web components (stage A5) | Power sawing, with catalytic converter, RER | 1 | h | - |
Table saw for cutting spar beams (stage A5) | Electricity, high voltage, market, PT | 20 kWh/10 h | KWh, h | from Joteo calculator [45] |
Drilling holes on steel connections (stage A5) | Steel removed by drilling, computer numerical controlled, RER | 229 | grams steel removed | - |
Drilling holes on composite (stage A5) | Electricity, high voltage, market, PT | 38 MJ/6 h | MJ, h | from [46] |
Cutting steel brackets and plates (stage A5) | Power sawing, with catalytic converter, RER | 3 | h | - |
Inbound transport EoL components (stage A4) | Transport, freight, lorry 16–32 metric ton, EURO4, market, RER | 2310 or 100 | km | actual distance and assumed distance |
Inbound and Waste transport (other materials) (stage A4 and C2) | Transport, freight, lorry 16–32 metric ton, EURO4, market, RER | 100 | km | Assumed distance |
Product: Repurposed floating system | n.a. | 6.72 | m2 | Surface area of PV panels |
EoL treatment: composite structures | Created process | 2 × 300 | kg | Based on stated composition [47] |
EoL treatment: shredding composite structures | Electricity, high voltage, market, PT | 102 per structure; 0.71 per kg | MJ | from [48] |
EoL treatment: spar cap beams | Waste polyethylene, treatment, municipal incineration, GLO | 61% × 97 | kg | Based on composition, from [49,50] |
Waste glass, treatment, municipal incineration, GLO | 39% × 97 | kg | ||
EoL treatment: coatings | Waste plastic, mixture, treatment, municipal incineration, GLO | 18 | kg | - |
EoL treatment: steel | Waste reinforcement steel, treatment, recycling, RoW | 16.7 | kg | - |
Indicator | Conventional Structure A | Conventional Structure B | Repurposed |
---|---|---|---|
Weight percentage steel (%) | 3% | 30% | 2% |
Contribution to CC of steel (%) | 1% | 24% | 8% |
Weight percentage plastic/WTB parts (%) | 92% | 70% | 95% |
Contribution to CC of plastic/WTB parts (%) | 55% | 44% | 0% |
Weight percentage coating (%) | n.a. | n.a. | 3% |
Contribution to CC of coating (%) | n.a. | n.a. | 8% |
Total structure weight (per m2) | 12.4 kg | 20.3 kg | 109 kg |
Contribution to CC of EoL plastic/WTB parts (%) | 38% | 31% | 47% |
Contribution to CC of WTB/plastic parts inbound transport (%) | <1% | <1% | 26% |
Contribution to CC of tools (%) | n.a. | n.a. | 5% |
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Moutinho, M.; Rocha, R.; Atteln, D.; Johst, P.; Böhm, R.; Chatzipanagiotou, K.-R.; Stamkopoulou, E.; Koumoulos, E.P.; Araujo, A. Repurposing EoL WTB Components into a Large-Scale PV-Floating Demonstrator. Sustainability 2025, 17, 8717. https://doi.org/10.3390/su17198717
Moutinho M, Rocha R, Atteln D, Johst P, Böhm R, Chatzipanagiotou K-R, Stamkopoulou E, Koumoulos EP, Araujo A. Repurposing EoL WTB Components into a Large-Scale PV-Floating Demonstrator. Sustainability. 2025; 17(19):8717. https://doi.org/10.3390/su17198717
Chicago/Turabian StyleMoutinho, Mário, Ricardo Rocha, David Atteln, Philipp Johst, Robert Böhm, Konstantina-Roxani Chatzipanagiotou, Evangelia Stamkopoulou, Elias P. Koumoulos, and Andreia Araujo. 2025. "Repurposing EoL WTB Components into a Large-Scale PV-Floating Demonstrator" Sustainability 17, no. 19: 8717. https://doi.org/10.3390/su17198717
APA StyleMoutinho, M., Rocha, R., Atteln, D., Johst, P., Böhm, R., Chatzipanagiotou, K.-R., Stamkopoulou, E., Koumoulos, E. P., & Araujo, A. (2025). Repurposing EoL WTB Components into a Large-Scale PV-Floating Demonstrator. Sustainability, 17(19), 8717. https://doi.org/10.3390/su17198717