In this edition of our Beyond Bax interview series, we return to the topic of wind energy. Speaking to Philippe Spring, structural design engineer at TPI Composites — the largest US-based independent manufacturer of composite wind blades — we cover the main challenges regarding the wind industry’s waste, and ways to address them using available technologies and practices.
Q: Deployment of wind turbines is growing every year, and so is their size. That means quite a lot of composite waste when these turbines reach their end of life. What are the main challenges that need to be addressed in order to tackle this issue?
PS. The wind industry, through its design of structures and material choices, bears most of the responsibility for accounting for end-of-life strategies. To strengthen its steadily growing importance, these solutions must correspond to the fundamental concept of sustainability that underpins renewable energies. The overarching challenge is to recover as much value as possible from structures or materials using processes that are more cost-effective than sourcing virgin raw materials or manufacturing new structures.
From a technical standpoint, there are two levels of challenge. The first, and most urgent, is dealing with existing thermoset glass-fibre blades, which were designed without consideration for recycling requirements. For blades that require immediate treatment, dismantling and recycling networks need to be enabled to act responsibly and reproducibly.
The second challenge lies in developing blades with significantly reduced impacts both before and after their life cycle. It’s not just about increasing recycling rates, but also analysing the environmental impact of material sourcing and blade manufacturing — for example, identifying and avoiding sources of CO₂ emissions.
Q: Which technologies or practices do you think will help us address the above challenges, and which are you focusing on at TPI Composites?
PS. Recycling rates of composite parts can increase significantly if the industry adopts recyclable resins, such as recyclable/reprocessable/repairable thermoset (3R-TS) or thermoplastic (TP) resin systems, instead of traditional crosslinked thermoset resins. A TP-resin formulation specific to wind energy is already on the market, and TPI Composites had the opportunity to study its capabilities in a research programme.
For future blade designs, new materials should be evaluated using Life-Cycle Analysis (LCA) to demonstrate their advantages in emissions and socio-ecological terms. Reusing fibres, resin, or entire blade sections in the wind or other industries can be interpreted as energy credit, improving LCA outcomes.
In the present and near future, the cement kiln route is available: using glass fibre reinforced plastic (GFRP) flakes as refuse-derived fuel reduces coal use, while the residual silicon dioxide in the glass fibres helps avoid the need for mining siliceous sands. To enable better segmentation, transport, and processing of blades, companies must have access to details of material composition, mass, and dimensions — potentially documented through an Environmental Product Declaration (EPD). TPI Composites provides EPD creation services for customers and their blades.
Instead of investing high effort in separating resin and fibres, I prefer second-life applications of full wind blade parts —such as shell and web sandwich panels or massive spar caps.
– Philippe Spring, TPI Composites
Q: Although technologies for recycling and retrieval of full fibres from composites exist, it’s difficult to make the business case for glass fibre, as the added costs for recycling it are much higher than those of virgin glass fibre. How do you think we could address this issue?
PS. The chemistry of existing thermoset matrices isn’t designed for the economically feasible recovery of full-length fibres. Instead of investing high effort in separating resin and fibres, I prefer second-life applications of full wind blade parts —such as shell and web sandwich panels or massive spar caps — which retain their integrity and can be repurposed in construction or transportation sectors. Cross-industry recycling networks can manage supply and demand. All of this should be analysed using LCA methods to show that reuse is preferable to producing new components from virgin materials.
In parallel, to enable full-length fibre recovery, we can work on reformulating thermoset hardeners to create 3R-TS resins with dynamic crosslinks. Further development and adoption of TP resins as an alternative is also a promising path.
Q: Achieving sustainability in the energy sector requires the involvement of all stakeholders within the value chain. How can we raise attention/awareness among designers and manufacturers regarding product responsibility?
PS. Suitable standards, methods, and documentation already exist, particularly in the construction sector. Environmental Product Declarations and sustainability product labels can demonstrate energy and emissions ratios via LCA, material characterisation, and assessment of manufacturing processes. Wind turbines already have a strong LCA profile. Design guidelines for recyclability can help improve this further and promote better end-of-life solutions.
All these practices and technology developments require time and investment. I see companies stepping up, publishing sustainability plans, and policymakers offering incentives — such as those from the Horizon 2020 programme, to help steer the transition.
When I began my career as a structural engineer focused on lightweight materials, my concerns about issues like land-use change from balsa farming in Ecuador, questionable use of PVC-core materials, or consumables waste generated by vacuum infusion were not commonly shared.
– Philippe Spring, TPI Composites
Q: You have been working in the wind industry for a few years already. How do you see the progress made towards sustainability, and what’s next?
PS. When I began my career as a structural engineer focused on lightweight materials, my concerns about issues like land-use change from balsa farming in Ecuador, questionable use of PVC-core materials, or consumables waste generated by vacuum infusion were not commonly shared. That has changed significantly. Today, professionals in renewable energy are more engaged with sustainability. Many of my contacts are eager to contribute within the constraints of time and budget.
The next step could be a rewards system for sustainable design and manufacturing. Alternatively, pricing ecological costs to raise the levelised cost of energy (LCOE) would achieve a similar effect. Solutions like thermoplastic resins and EPDs are already available. By offering blade design for sustainability, TPI Composites is ready to support customers in preparing for these changes.
Do you want to make wind turbine blades circular?
We help composite value chain partners from wind energy—and other sectors—gain the knowledge, resources, and contacts to kick off and implement circular practices. We guide industry leaders in circular transformations by uniting the right partners, providing insights on risks and opportunities, and defining and monitoring the circular innovation processes that create impact. We also have experience building European-wide community networks that facilitate stakeholder collaboration, knowledge exchange, and capacity building.
