This project explores the potential market opportunities and applications for a novel bamboo fiber-reinforced composite material with bio-HDPE matrix. The research, conducted in collaboration with Eve Reverse, focuses on developing a thermoplastic composite with aligned short bamboo fibers to enhance mechanical properties in specific directions, allowing for programmable strength. The goal is to research the desirability of the new carbon-negative bio-based short fiber composites and designing its appropriate application.
The project adopts the Material Driven Design (MDD) method, combining experiential characterization studies, mechanical testing, together with prototyping to assess the composite’s desirability, feasibility, and viability.
The testing of the bamboo fiber composite's mechanical properties, including its stiffness and strength, which showed comparable performance to traditional materials like plywood. Experiential characterization studies involved a series of observation-based experiments, questionnaires, and interviews to gather insights on potential consumers' perceptions and emotional responses to the material.
The results indicated that the bamboo fiber composite material offers a natural, warm aesthetic that elicited positive emotional feedback from users, including feelings of comfort and curiosity. These findings are crucial for establishing the desirability of this material in the marketplace, as they demonstrate consumer interest in products made from sustainable materials. Despite some concerns about the material's sustainability, it offers a compelling alternative for eco-conscious consumers.
The design vision can be concluded from mapping the findings of material characterization and market research. Following the vision, with the help of ideation groups, the idea of ceiling fan blade perfectly fit the vision and the requirement. Prototyping and functional testing further confirmed the feasibility of using bamboo composite materials The study validated vacuum bag thermoforming as an effective manufacturing method for producing smooth, uniformly thick bamboo composite blades capable of complex curves. The project also explored the feasibility of remanufacturing a multi-layer plate by pile up bamboo composite which demonstrated the potential for producing larger composite structures. Finally, from a viability perspective, the project aligns with the increasing demand for carbon-neutral products in the European Union, with legislation likely to support the development of sustainable materials. The result of quick LCA proved the sustainability impact is relatively low from cradle-to-gate calculation. The easy accessibility of raw materials, and relatively simple manufacturing process ensure it can be produced affordably while maintaining profitability. In the future, bamboo fiber composite has great potential to realize a low-cost automatic production line, with the combination of environmental sustainability and economic efficiency, providing bio-based thermoplastic materials in the market as a sustainable alternative.

The Dutch Government has raised the offshore wind energy target from 11GW to 21GW by 2030, approximately 50GW by 2040, and approximately 70GW by 2050 (Agency, 2021). The trade-off between achieving sustainable energy sources and extracting raw materials for constructing these infrastructures gives rise to the efforts to transition towards a circular economy. This transition offers solutions to several societal challenges, one of which is resource security (PBL, 2023). Further, academic research emphasizes the necessity of a circular mindset from the beginning of life to achieve a high level of circularity and economic benefits at the end of life (Hall, Topham, & João, 2022; P. D. Jensen, Purnell, & Velenturf, 2020). However, reusing the components and materials of decommissioned wind turbines can act as a driving force for the future requirement of raw materials (Demuytere et al., 2024). In this regard, implementing circular strategies for the existing offshore wind turbines plays a significant role in the energy transition as well as the aim of having a fully circular economy by 2050.

However, circular strategies have limited applicability higher up the R-Ladder in the offshore wind industry due to various technical, economic, regulatory, and environmental challenges. The focus within science and industry has been either on developing circular strategies for the beginning of life or recycling materials to limit future ecological impacts (Hall et al., 2022; P. D. Jensen et al., 2020). The need to address end-of-life resource management for the existing offshore wind turbines is emerging but still needs a systematic approach for sustainable end-of-life decision-making (Delaney et al., 2021; Jadali, Ioannou, & Kolios, 2021; Vielen-Kallio, van Diest, Room, & Knol, 2021; Windemer & Cowell, 2021). Hence, to address the identified gap, the research developed a comprehensive circular decision-making framework that leverages a standardized data management system, specifically a Digital Product Passport. To achieve this research objective, the main research question is framed as follows:

“In what ways can a decision-making framework for a standardized data management system,
specifically tailored for the end-of-life phase of OWTs, contribute to enhancing circular practices by efficient resource management within the industry?”

Current wind turbine blades are made from a material that is difficult to recycle, while a lot of them are being decommissioned. A large influx of high-performance and high embodied energy wind turbine waste material (WTBM) is forming. Next to structural applications, very few novel applications that make proper use of the excellent material properties of decommissioned WTBM are known.

To identify novel applications for WTBM sourced from decommissioned wind turbines a focus on the acoustic properties of WTBM was taken. Various strategies including a variation on material driven design, i.e. circular application through selection strategies (CATSS), were used to identify applications. For that, relevant acoustic WTBM properties were determined to properly identify a knowledge gap. To evaluate the applications identified through CATSS, experiments were set up in the anechoic chamber of the Applied Sciences faculty of the Delft Technical University. The data generated from these experiments, together with the knowledge gained during earlier parts of the project were used for concept ideation of an acoustic application. Sitka Spruce, a natural tone wood used for making tone boards in acoustic instruments, has been found to be the most acoustically similar to WTBM. Based on that, various applications including a distributed mode loudspeaker (DML) line array, acoustic instruments and a resonating acoustic amplifier (RAA) have been identified and evaluated. An application based on replacing tone wood in a resonating acoustic amplifier (RAA) was chosen to embody through a functional prototype. The performance of this RAA prototype showed that WTBM has potential to replace tone woods in acoustic applications; however, more research is needed to identify all the advantages and limitations of such a replacement.

This thesis showcases applications for structural reusing wind turbine blades. Wind turbine blades are extremely difficult to recycle and thus reuse avenues are being researched to extent the useful lifetime of these blades. The goal of this thesis is to generate applications that utilise segments cut from wind turbine blades. This goal is approached in four steps: end of life, wind turbine blade design, cutting strategies and applications.
The first part focuses on the end of life of wind turbine blades. Analysing current and future waste management solutions that have been explained trough the lens of a waste hierarchy. Showing why reuse is a better option than current solutions and how this thesis fits into the entire reuse landscape.
The second part analyses wind turbine blades to better understand the design philosophies behind them and how this influences the reuse of wind turbine blades. It was found that the design, materials and the state of blade all influence reuse strategies.
The information found these first two parts is then used to generate the possible cutting strategy, cutting pattern and applications in the final two parts off this thesis.
The third part ideated on a possible cutting strategy showcasing what steps should be taken to reuse wind turbine blades. Looking into the logistical and processing difficulties.
The last part uses all the information found and combines the knowledge to create a cutting pattern and a proposal for an applications. A cutting pattern using rectangular or triangular segments and simple beams was created that is used to create a concept of an adventure park.

Wind turbine blades have a service life of around 20 to 25 years and are then decommissioned while generally still having excellent structural performance and high-value material properties. Currently, the recycling options for the fibre-reinforced polymer (FRP) composite components that make up the blade are limited, so most blades are either landfilled or incinerated at the End-of-Life, essentially wasting these qualities. By repurposing the blades instead, the qualities can be preserved while also lowering the environmental impact of the new structure. This research focusses on repurposing decommissioned wind turbine blades as main structural elements in traffic bridges, where the focus is on the structural design and feasibility.

The possibilities for repurposing largely depend on the type, size and condition of the specific batch of blades. Based on literature research regarding the common features of blades that are soon to be decommissioned, a custom 38-meter-long blade model is developed. Next, a variety of design options including multi-membered bridge structures have been created and arranged in an overview. By combining these options with the findings from the literature study, several designs for ‘blade bridges’ are proposed, most of which have the potential to already be realised in the upcoming years. Some of these designs are only intended for pedestrians and cyclists, while others are intended for regular road traffic. The maximum allowable spans for these bridge designs are all between 15 and 20 meters, thus confirming the large potential for repurposing blades in bridges.

Based on the structural analysis of the blade bridge designs, it can be concluded that for blade bridges as pedestrian and bicycle bridges, the natural frequency is governing. A prerequisite is that the blade-to-support connections at the aerofoil parts are designed to prevent stress concentrations, but this should be easily achievable. For road traffic bridges, it is found that the deflections are of greater importance than the natural frequencies. Also, the blades in a road traffic bridge will be highly stressed, especially locally near the supports of the aerofoil parts. These local stresses are likely to be governing, making the connection design at these supports crucial. A thorough investigation of these local stresses is therefore recommended in a real-life blade bridge project.

The goal of this thesis project was to explore how material originating from thermoplastic composite wind turbine blades (TPC WTB) can be reshaped. The insights gained during exploratory activities were used to design a re-use application. The demonstrator model should inspire people to develop other applications and build upon the foundations laid here.
While wind turbines are a big contribution to the green energy supply, their blades form a problematic waste stream of hard to recycle material. One upcoming blade design innovation aimed at enhancing recycling, that of thermoplastic composites, has opened up a new opportunity in circular end of life strategies: structural re-use through reshaping.
A reference TPC blade was drafted based on insights gained from literature and experts, which defines characteristics like material composition, structure and curvature. These were needed for subsequent material tinkering activities aimed at understanding the material, exploring forming limits and process parameters (Figure 1).
 
These findings, together with material properties and opportunities and threats were combined in a SWOT matrix and design requirements. Blade segmentation was used to make a panel classification table which contains information on panel characteristics which were later used in designing an application. To be able to shape smaller radii, it was decided to split the top layers from the sandwich panel which resulted in much thinner laminates but also more unused material (15 wt%).
After a solid understanding of the material was built, an application could be designed. Standard ideation tools like brainstorming were used but also less standard methods aimed at finding applications yielded diverse application ideas. Following the design vision, one idea was selected: a lamppost. Embodiment of the lamppost based on earlier findings and a norm resulted in a conceptual application design. To prove the feasibility of this application, the strength and stiffness of the post were calculated to comply with the NEN EN 40 norm.
This design was translated to a demonstrator which can be seen in Figure 2. The goal of this demonstrator was to evaluate the performance of the material in reshaping and to simultaneously inspire people to develop new applications, which was validated using interviews. An evaluation of the amount of material used in this application showed that about a third of the yearly supply of WTB material saturates the yearly demand of lamppost.
It can be concluded that the material performs well in reshaping single curved geometries, however reshaping could be problematic for double curved surfaces. The smallest single curved radius tested was 30mm while the largest double curved radius which was tested was 1000mm. A meaningful application which makes use of the material’s value can be made within the reshaping limits while also utilizing a significant amount of blade waste.

With the emerging demand for energy-efficient products, the composite material has become a point of attraction for many product manufacturers. Furthermore, with its high strength to weight ratio, long life span, low maintenance and design flexibility, composite materials offer tailored properties by choosing an appropriate combination of reinforcement and matrix material. Being one of the leading users of composite material, the Netherlands is a global player in the field of design, automation, material development and sustainability in the field of high-grade-reinforced plastic.

Recycling of the decommissioned composite material remains underdeveloped research. The current shredding and inefficient recycling result in the loss of material property, struggling to find its scalable application in the market. However, the composite material has a longer life than its entire product, resulting in premature decommissioning of the material due to constant development in the product design. One way around this problem is repurposing. Therefore, there is a need to look for an alternative approach.

Repurposing aims to keep the material alive by utilising its shape and remaining potential in serving an additional product life with a different application. However, the concept of repurposing is undiscovered in the field of composite material.

This graduation thesis aims to create a set of guidelines for industrial designers and companies, guiding them to efficiently utilise the composite material’s value with the practice of scalable repurposing.

Further to industrialise and streamline the repurposing practice, there is a need for product lifecycle management, assisting repurposing industrial designers and companies with the set of prerequisite information.

By case study of repurposing an aircraft galley made from the glass fibre reinforced plastic into a bicycle cart for kids, various operations, including disassembly, dismantling and re-manufacturing, were executed to gain a closer look into the repurposing. In addition, different stakeholders’ roles in repurposing were identified by conducting interviews with various actors involved in the composite industry. With the help of the theoretical and practical insights gathered during the exploratory phase, the PLM framework and guidelines were formulated focusing on scalable repurposing of the composite material.

A revised set of guidelines was proposed by evaluating the draft guidelines through an interview with the repurposing company and a co-creation session involving various stakeholders, education experts and industrial designers. Based on the evaluation, it can be concluded that the guidelines can serve as a base for implementing the repurposing practice, where the industrial designer can connect the detached stakeholder and guide the implementation of composite repurposing.

However, to make these guidelines well qualified for all the composite products from different sectors, a wide range of case studies should be conducted. Although these guidelines are formulated to support industrial designers to impact repurposing positively, further work is needed to conduct a business model, real case scenario, and policy management to look into the guidelines’ pertinency.

Within this project a design approach of 3 phases is created to guide designers in the redesign of an existing product for Repurpose: 1.Starting point: To find certain opportunities in the future by highlighting essential valuable aspects of the current product that could be maintained in future products. 2.Product Opportunity: The Designer is guided from evolved ‘valuable aspects’ towards 1 chosen product opportunity, by which the current product can be Repurposed. ‘Search Areas’:This phase aims to inspire how value of a current product can be extended towards the future. 3.Design for Change: Redesign product and parts for efficient and effective transition into the subsequent use-cycle.