Researchers at Delft University of Technology (TU Delft) have developed two material approaches that could improve the durability and sustainability of wind turbine blades. The research, published in Advanced Science and Advanced Materials, focuses on reducing rain erosion at blade tips and strengthening flax fibre composites. The two studies form part of the NWO-funded LICHEN BLADES project, which is investigating circular wind turbine blade designs. PhD candidates Natalia Guevara Sotelo and Deniz Sayinbas are the lead authors, supervised by Julie Teuwen and Kunal Masania.
Rain erosion at the tips of wind turbine blades can reduce aerodynamic performance and durability while increasing maintenance requirements. Guevara Sotelo investigated the addition of microscopically thin ceramic particles, known as platelets, to the polyurethane coating used at the blade tip.
The research found that simply increasing the platelet content does not improve erosion resistance. Although higher platelet contents increase stiffness, they can also create stress concentrations and internal wave reflections that accelerate damage.
Instead, the researchers developed a gradient structure in which the platelet concentration varies through the thickness of the coating. The rain-facing surface remains relatively soft, while reinforcement increases towards the glass-fibre substrate.
Inspired by the layered structures found in organisms such as insects, the bio-inspired coating architecture doubled the time before visible erosion occurred.
The second study examines flax fibres as a more sustainable reinforcement material for wind turbine blades. Flax can reduce carbon emissions and make blades easier to recycle, but its mechanical performance, including compressive strength, is lower than that of conventional glass fibres.
Sayinbas investigated bacterial biomineralisation as a method of strengthening flax fibres. The process involves treating the fibres with a solution containing bacteria that grow mineral particles directly on the fibre surface.
The mineral particles, called dolomites, roughen the fibre surfaces and form bridges between neighbouring fibres and yarns. According to the research, this connectivity improves load transfer and increases toughness, resistance to micro-buckling and the compressive strength of the resulting composite material.
Both approaches modify the structure of blade materials at a small scale while targeting improvements in blade performance and service life. The research is part of LICHEN BLADES, a consortium of universities, research institutes and companies working on circular wind turbine blade designs.
