Cross Section of the nacelle
Labeled cross section of the working parts of a wind turbine. (http://www.galileoscientific.com/wind_energy.jpg 2009).
How Do Wind Turbines Work?
Wind turbines work by capturing wind energy and using it to turn a rotor blade to run a generator. Wind represents potential energy that can be converted into electrical energy through a turbine. The rotors and turbines are governed by a rule known as Betz’s Law. According to this rule a turbine may only capture 59.3% of the potential energy from the wind (Gipe 2003). Betz’s limit refers to the fact that if more than this amount of wind energy is captured a “build-up” in front of the rotor creates a limiting factor for future wind capture. In addition, if enough wind is not allowed to pass through the wind turbine and continue travel on the other side then it would no longer be considered a renewable form of energy production (AWEA 2009).
Wind turbines at their core are comprised of a few basic mechanisms. These mechanisms are a foundation, tower, nacelle, rotor, and transformer (Gibe 2003). The foundation is the base of the turbine that keeps the structure secured to the ground. The tower is the largest and most visual aspect of the structure. The tower size will vary based on the size of the turbine, required height to achieve optimal wind input, and size of the rotor. The nacelle is an important structure that connects the tower to the generator and eventually the rotor. The rotor is comprised of blades that ultimately capture the wind and run the turbine. Lastly, the transformer actually holds the electricity that is produced. The next essential part is the controller inside the base of the tower. The controller is basically a computer that ensures that all aspects of the turbine are running properly. Any problems will be reported electronically to the owner of the turbine (Wind Power Works 2008).
Most of the inner-workings of the turbine are located inside of the nacelle. As stated above the rotor is attached to the nacelle by way of the main shaft. As the wind turns the rotor it turns the large main shaft, which is attached to a gearbox. The gearbox is used to turn the fairly low rotations per minute (RPMs) of the rotor into a much higher number of rotations to generate more electricity. This ratio will vary depending on the size of the turbine, but for example the gearbox in an industrial sized turbine could turn 22 RPMs into around 1500 revolutions (Wind Power Works 2008). The next essential part connected to the gear box is the yaw bearing. This is a bearing mounted right at the top of the tower. A large yaw wheel fits into the bearing and turns the nacelle and rotor in the direction of the wind when the yaw motor is engaged by the controller. A large generator is then attached to the gearbox. This is the mechanism that actually creates the electricity. The current from the generator is sent down through the tower and into the transformer through large electrical cables. The generator is connected to the gearbox by a small shaft that runs very quickly compared to the rotor and large main shaft. In addition to the large controller at the base of the tower, there is a smaller controller in the nacelle that will allow the rotor to start when the anemometer reads that there is enough wind. The anemometer is a small wind meter that will read the wind speed and the wind vane attached to the top of the anemometer will read out the dominant direction and tell the yaw motor and wheel to turn accordingly. Lastly in the nacelle there is a mechanical brake that will allow the rotor to be stopped if mechanical repairs are necessary.
Take a virtual tour with through the mechanics of a wind turbine:
This link will take you to a website site where Miller will walk you through a virtual tour of the different parts of a wind turbine to help you gain a basic understanding for how a turbine functions.