Here’s a guide to the main component parts that make up our members’ turbines and how they help get them cheaper, greener energy.
Despite looking like just a tower and blades, turbines are complex bits of kit with typically over 8,000 parts. A wind turbine consists of five major and many auxiliary parts. The major parts are the tower, rotor, nacelle, generator, and foundation.
The foundation is under the ground. Only a very short ‘turret’ section can be seen. The rest is covered by soil. It’s a large and heavy structured block of concrete and steel mesh that connects the tower to the ground and holds the turbine and the forces that affect it in place.
The tower is made up of round tubular steel with a diameter of 3-4m. The tower is normally composed of 3 – 5 parts (for ease of transport and lifting), which are assembled together on site during construction. The tower is wider at the base than it is at the top to increase stability and thicker steel is used at the bottom to increase strength. On larger turbines like the Graig Fatha and Kirk Hill machines, with taller towers of around 70m, the walls might be 30mm thick at the base, and 12-15mm thick at the top. On a typical turbine, the walls of the tower may be double the width at the bottom than the top section of the tower. On larger turbines, the tower sections could each weigh 15-50 tonnes – about 170 tonnes in total.
Because wind speed increases with height, a tower’s height is crucial for wind turbines. Graig Fatha, our members’ first turbine, is 75m tall to hub height, and the Kirk Hill towers will be 69m tall – that’s roughly three and half times the height of The Angel of the North, or about half the height of the London Eye.
The hub holds all 3 blades together and makes it possible for them to rotate with respect to the rest of the turbine body. During the Graig Fatha build, the 3 blades were attached to the hub on the ground before being lifted up by 2 cranes and attached to the turbine’s generator.
The blades are normally about 50m long. For lightness and flexibility, blades are generally made of fibreglass. Technology to reuse and recycle old blades has come a long way. . Recently, a factory in the UK has started producing fully recyclable blades for offshore turbines, and we’re likely to see more of this technology in the near future. A few specialist firms are starting to process turbine blades. There are also lots of initiatives to reuse them in innovative ways, including for bike shelters, playgrounds, and pedestrian bridges, to give them a second life. The blades can be adjusted in pitch to maintain optimal speed and reaction and capture as much wind as possible.
The rotor is the rotating part of a turbine; it consists of (normally) three blades and the central part that the blades are attached to, the hub.
The nacelle is the housing on top of the tower that accommodates all the components that need to be on the top of a turbine. A major part among these components is the generator. This is responsible for creating all the cheaper, greener energy, by converting the rotational kinetic energy of the rotor into electrical energy.
Wind Vane and Anemometer
This is effectively a small weather system at the top of the turbine. The wind vane measures wind direction and ensures the turbine rotor always faces into the wind. The anemometer measures wind speed and transmits wind speed data to the controller.
Wind turbines turn to face the direction of the wind. The yaw motors power the yaw drive, which rotates the nacelle on the turbine to keep it facing the wind when the wind direction changes.
The pitch system adjusts the angle of the wind turbine’s blades with respect to the wind, controlling the rotor speed. By adjusting the angle of a turbine’s blades, the pitch system controls how much energy the blades can extract.
The generator is responsible for creating all the cheaper, greener energy, by converting the rotational kinetic energy of the rotor into electrical energy. The turbines used at Graig Fatha and Kirk Hill use direct drive designs (this means they don’t have a gearbox in their generator). Instead, they generate power using a giant ring of permanent magnets that spin with the rotor to produce electric current as they pass over stationary copper coils. This approach helps to reduce noise and maintenance.
The controller allows the machine to start at wind speeds of about 5–11 miles per hour (mph) and shuts off the machine when wind speeds exceed 55–65 mph. The controller turns off the turbine at higher wind speeds to avoid damage to different parts of the turbine. Think of the controller as the nervous system of the turbine. It can be monitored remotely by the turbine manufacturers and also transmits the data we use for your customer dashboards.
Some turbines used friction brakes like cars to slow down the rotor if the turbine needs to stop, but others slow the rotor aerodynamically by changing the angles of the blades. Once the rotor has been stopped by the controller, a manual brake can be applied to lock the rotor in place during maintenance.
The turbine generates electricity in variable alternating current. This isn’t suitable for the grid so a converter converts the electricity into direct current, then to grid-standard alternating current. A transformer near the turbine base ‘steps up’ the voltage for transmission to the grid, ready to power our homes and businesses.
Want to see a turbine build in action?
Check out this time lapse of our members’ first turbine, Graig Fatha, which was switched on in March this year. Over 900 people have begun receiving their low cost, greener energy from their share of the turbine’s generation. Watch the video here