Wind turbine parts are a mystery to most of us. We are all familiar with wind turbines, what they look like, both large and small. However, when it comes to knowing what components make up a wind turbine and how they work together to make electricity – well, that's another story.
So let's take a look at the basic anatomy of a wind turbine – what parts are involved and how they relate to each other.
The Anatomy Of A Wind Turbine
The following diagram illustrates the various wind turbine parts that are necessary to ensure the effective functioning of the turbine.
Source: National Renewable Energy laboratory (NREL)
Now let's take a closer look at some of the more important wind turbine parts.
Wind turbine parts - the blades
The blades play a crucial role in turbine operations. It is the blades over which the wind passes and their design is such that they create a pressure differential so that the blades begin to turn.
Blade manufacturers are constantly being challenged to come up with more efficient designs. This has led to increased experimentation with different materials. It is easy to forget, as we see the blades on these big turbines slowly revolving, the enormous strains under which the blade is placed. This is particularly true at times of high winds. The development of offshore turbines increases the need for stronger blades without increased weight.
Just to give you a feel for the size of the problem – in a large commercial turbine where the blade length is 120m (394 ft) the blade weight is probably between 25-30 tons. You can't take that home on your trailer!The sheer size of blades in commercial turbines has led some manufacturers to develop jointed blades which helps address the issues involved in transporting the blades to field locations.
Wind turbine parts – the tower
The tower has played a critical role in the performance of the wind turbines, since their inception. We know that higher is better as far as power in the wind is concerned. However, that has to be balanced against costs and other factors such as aesthetics.
In the early days of commercial turbines the tower heights, usually defined as the height from the ground to the hub, were around 40-50 m. However, as the wind industry grew, the capacity of the turbines grew and so did the tower height.
A tower height of 80-90m is now the norm for large commercial turbines with a capacity of 2.0-3.0 MW. Planning in some companies for larger turbines with 5MW capacity is seeing tower designs approaching 100m.
The tubular steel design is now an industry standard and is a far cry from the early days of truss or lattice towers. These tubular structures are stronger and much safer when it comes to maintenance.
One feels that the technicians who have to service these machines would love a lift to be installed, but costs may always work against that.
Wind turbine parts - the nacelle
The nacelle is the term used to describe the cabin or housing at the top of the tower that house all the major components, including the hub to which the blades are attached. The nacelle has two important attachments – an anemometer for measuring wind speed and a wind vane for determining wind direction so that a motor can turn the whole assembly into the wind.
Given that the nacelle houses so many parts it is no surprise to find that on large commercial turbines the nacelle is the size of a large bus and weighs in excess of 50 tons. There are some that sport a helicopter landing pad – a great boon for technicians.
The gear box and generator
The rotor on the turbine drives a shaft that turns at quite low speed. Therefore in traditional turbine design we have a gearbox to increase the revolutions beyond the initial speed. Without this the revolutions would not be sufficient to generate electricity.
Once the gear box has increased the drive shaft speed, the generator takes over and converts the rotational energy into electrical energy.
The gearbox in large commercial turbines is a very large and expensive piece of equipment. It is also the “achilles heel” of the turbine. History shows that a very high percentage of all equipment failure in these turbines is due to gearbox failure - often related to problems with bearings.
These gear box issue has led to research into producing a better system, but only very recently. This is a direct drive system which eliminates the gearbox and uses permanent magnets. This direct drive system has great advantages, notably, fewer parts, reduced weight, greater reliability and reduced maintenance.
The material primarily used for the magnets is NdFeB, an alloy of Neodymium, Iron & Boron and with projected growth of the wind industry; some analysts predict that NdFeB will be in short supply within 10 years. China is by far the largest source of rare earth metals, including Neodymium and is reducing export quotas to facilitate its own increased demand.
As a result research is now focusing on generators that use other types of magnets such as ferrite magnets or even the development of generators that avoid permanent magnets altogether.
We've covered the more critical parts so now have a look at the following video to see how it all hangs together. The video is an excellent presentation of wind turbine parts and how they work together - poetry in motion!