Stronger, lighter blades hold promise for more efficient wind turbines

The world's first carbon nanotube reinforced polyurethane wind blades have been developed by a researcher in the US.

The prototype blades measure just 29in, but in preliminary test proved to be eight times more durable, tougher and substantially lighter than conventional epoxy blades. Case Western Reserve post doctoral researcher Marcio Loos, believes the technology could be scaled up and eventually enable lighter, stiffer blades as long as 250m. "The idea behind all this was the need to develop stronger and lighter materials to enable the manufacturing of blades for larger rotors," said Loos. "Results of mechanical testing for the carbon nanotube reinforced polyurethane show that this material outperforms the currently used resins for wind blades applications." In a comparison of reinforcing materials, Loos found that carbon nanotubes were lighter per unit of volume than carbon fiber and aluminium, and had more than 5 times the tensile strength of carbon fiber and more than sixty times that of aluminum. In addition, fatigue testing showed that the reinforced polyurethane composite lasted about eight times longer than epoxy reinforced with fiberglass. The new material was also about eight times tougher in delamination fracture tests. Loos and his team are now testing for the optimal condition for the stable dispersion of the nanotubes. They have successfully installed the blades on a 400W 12V wind turbine generator in Ashtabula, Ohio.