One of the most fundamental components of wind turbines is their blade. Wind turbine blades rotate with the wind and this energy is transferred to the generator. The generator converts the mechanical energy into electricity.
However, by using lighter materials and improving the design of the blades, researchers have developed the conditions to function by wind turbines in generating more efficient wind energy.
In recent decades, wind turbines have become bigger, more powerful, and more cost-effective. One of the vital improvements to wind turbines is modern blades, the design of which has become more sophisticated in terms of aerodynamic properties and materials used.
This improvement helps to enhance other turbines, including turbines with larger size and height, where the turbine can have higher speeds and less noise.
Here we look at the evolution of the blades, which has led to some significant changes.
Forty years ago typical wind-turbine blades were around 26 feet long. Today, with lighter materials, the blades have reached 351 feet, longer than the Statue of Liberty is tall, and are packed with new technology.
Early wind-turbine blades were made from fiberglass and resin. The materials limited their size and thus their power output.
Modern blades, made from carbon fiber and other advanced materials, are 90% lighter than 1980s blades would be if scaled to current turbine sizes. Because of their size and design, turbines with the new blades can produce up to 15,000 kW of energy.
- Spar cap
This section of the blade takes an enormous amount of stress. It is now reinforced with a carbon-fiber strip the entire length of the span for strength. Sometimes the strip is made with carbon-fiber planks instead of cloth.
- Innovations for the modern wind-turbine blades include higher strength that can withstand more stress, bend-twist coupling to reduce loads, and aerodynamic improvements to the blade tip for noise mitigation.
- Since the blade tip moves faster than the blade nearest the hub, more noise is generated on the tip.
- Rounded tips and serrated edges make blades quieter.
- Greater swept area captures more wind, but requires longer blades that are more slender and flexible in bending. Manufacturing in a bend in the blade (known as a pre-bend) allows more room to deflect while avoiding contact with the tower.
- Passive bend-twist coupling reduces the sensitivity to natural turbulence in the wind and allows even longer blades without increasing the weight.
- Blades were attached to the hub first with bolted flanges, then using heavy T-bolts. Inserts are a lighter alternative that is even stronger.