Today’s largest wind turbines can supply enough electricity to power five thousand households and have an average life span of twenty years.
But how does a wind turbine work
A wind turbine converts the winds Kinetic energy into electrical energy. It comprises of Tower at about 80 to 90 meters high, in order to harness stronger winds at a higher altitude. A nacelle, which turns to orient the machine in the optimal direction. Nacelle houses the main components of the wind turbine and the three bladed rotors which can measure a hundred meters or more in diameter such as the Haliade 150 (an offshore wind turbine) with its 150-meter diameter rotors.
When the wind blows, the blade spin the rotor which in turn rotates the Shaft, fitted to the nacelle. This driveshaft is connected to a generator. This rotational energy will enable the production of electricity. Subsequently a transformer located inside the nacelle or tower raises the current voltage. This allows it to be transported more efficiently via the electrical grid power lines. In order to function, a wind turbine needs a minimum wind speed of 10 to 15 kilometers per hour and for safety reasons a wind turbine will automatically stop when the wind speed exceeds 90 kilometers per hour.
The power provided by wind turbine increases exponentially to winds speed. Winds of 30 kilometers per hour are eight times more productive than winds of 15 kilometers per hour. Hence the location of the wind turbine is a key, to harness the wind in the best possible way. Equipment is integrated into the nacelle to continually measure the wind speed and direction. This enables the wind turbine to be optimally oriented to the wind and to modify the rotor blade angle.
There were two main categories of wind turbines: Onshore and Offshore. The installation of offshore wind turbines usually installed some 10 kilometers or more off the coast, at a seabed depth of 25 to 30 meters is more costly. The foundation and tower must be able to with stand the force of the waves and connection to the electrical grid, means laying underwater cables. On the other hand more regular winds enable the generation of typically 6 Mega Watts of electricity compared to two to three Mega Watts for onshore wind turbines.
Modern wind turbines operate with efficiency in the range of 20 to 50 percent. This is an excellent level of efficiency, since the “fuel” the wind turbine is free. This is one of the many advantages of wind energy.
Inside of a typical wind turbine
Now exact designs may vary but almost all the turbines in use today are horizontal axis machines which have a three bladed rotor spinning in a vertical plane attached to the front of the box which we call the nacelle and in this nacelle, we have the generator, a gearbox, a high voltage transformer and the whole thing sits on top of the tower which is mostly there to keep the blades a being the hole.
We tend to class Turbines by their power output and hence their physical size. Wind Farms might use many turbines each producing 400 to 600 Kilo Watts each. All a few multi Mega Watt turbines producing may be up to 3 megawatts per unit. Apart from physical scale, they are arranged a bit differently.
Small turbines are typically 25 to 45 meters tall and at the base you’ll often find two doors. The lower door takes you into a secured compartment where we have a high voltage step-up transformer. The generator at the top of the turbine is producing about some volts and the transformer converts that into several thousand volts to send more efficiently to the substation. The main entrance to the turbine is at first floor level; on there we find control cabinet and the base of the ladder. The ladder’s runs to a series of platforms and it changes sides at each platform, to give you a rest area and a bit of fall protection.
The main one of cable’s goes up the tower dodging past any intermediate junction’s .Obviously the towers can’t be delivered in single 40 meter long section. The common 20 meter long sections are bolted together with a lot of nut and bolts. As we move higher and higher through the platforms they getting slowly narrower and narrower. The ladder will get a little bit closer but eventually the main cables stop being attached to the wall and they hang freely in the center. So that the tower can twist as the nacelle will takes to face the wind. If it twists too many times nacelle will spin itself around to remove the twist but as we move up, now the cable goes through a hole in the center platform and at the top of the tower we have a steel platform with the seal trapdoor. Just above that, we have the ring with the bearings to allow the nacelle and the rotors to rotate round to face the wind. And this seal platform acts as a bit of fire protection. Also avoids people falling back down the tower.
We have the wind sensors which give us speed and direction and allow the turbine to face into the wind and also to change the angle of the blades. The nacelle holds the three blades and they change the angle depending upon the wind. To the back, we have a shaft which leads into the gearbox and then high speed shaft through break, into a generator and that generator then supplies the electrical power about some volts all the way back down to the town to the base.
At the back we have a cooling fan as we’re generating half a million Watts of energy from which some of them is wasted as heat and without an efficient cooling system there is the potential for the turbine to catch fire.
The layout of the larger turbine is broadly similar but sometime varies depending on the output power.
According to Wikipedia, the largest and the tallest wind turbine is VESTAS V164 which has capacity of 8 Mega Watts standing in Denmark with an height of 220 meters. It is the world’s largest-capacity wind turbine. And around five companies are working to built 10 Mega Watt wind turbine.