The bigger the blades on a wind turbine, the more energy it generates. However, current blades of wind turbines are made of heavy material, which puts a lot of strain on the turbine, causing a costly maintenance. A collaboration between several organisations combined in a project called WALiD (Wind Blade Using Cost-Effective Advanced Lightweight Design) is trying to change that by developing durable thermoplastic foams and composites that could make turbine blades lighter and easier to assemble.

Current wind turbine blades are made by hand using thermosetting resins. However, these materials cannot be recycled. At best, granulated thermoset plastic is reused as filler material. The aim of the WALiD project is to develop cost-efficient and recyclable materials that can withstand the harsh conditions that wind turbines face offshore.

To do so, they use thermoplastic sandwich materials, which has never been done before. The sandwich structure consists of thermoplastic foams and fibre-reinforced plastics. The foams are made with molten plastic granules, mixed with a blowing agent, which turns into a polymer melt and is then foamed. The team is developing the foams bonded with covering layers made of fibre-reinforced thermoplastics. This combination improved the mechanical strength, efficiency, durability and longevity of the rotor blade. For the parts of the blade that bear the greatest loads, carbon-fibre-reinforced thermoplastics are used.

The foams are meltable, but while they have limited stability at high temperatures, they can withstand higher temperatures than other kinds of foam, which makes them suitable for other applications as well. They can also be quickly and easily processed.

Not only does the project use new materials for the blades, it also aims to design an improved blade root, including a new connection concept, which should also attribute to cost savings and weight reduction.

The participants in the project are the Fraunhofer Institute for Chemical Technology ICT, Smithers Rapra, Windrad Engineering, Loiretech, PPG Industries Fiber Glass, Norner Research, Coriolis Composites, NEN, TNO and COMFIL. The project, which is funded by the EU, should be completed in early 2017.