Nicholas Ward
Wind Turbine Definition: The Way of the Future
For generations, humans have relied on fossil fuels and hydrocarbons such as oil, natural gas and
coal for most of our power generation in the world. However, what if we can find an alternative
source of energy that is less polluting, provides a substantial amount of electrical power, and
consumes less water? One of the most prominent innovations that match these credentials is a
wind turbine. It is an energy generating device that converts the kinetic energy from wind into
electrical energy provided by moving mechanical parts. The picture below demonstrates a typical
example of what an offshore wind turbine looks like:
Figure 1: Overall Picture of a Wind Turbine
Image from < http://cleantechnica.com/2013/05/30/first-offshore-turbine-in-north-america/>
Each of the main components of a wind turbine can be categorized into three different sections:
the nacelle (denoted as turbine in the picture above), the tower, and the hull (or foundation).
The Nacelle
The nacelle is a wind turbine component that contains a group of mechanical parts working
together to provide electrical energy
converted from the kinetic energy of
the wind at a range of wind speeds.
The picture on the left shows a
diagram of the nacelle commonly
used in both onshore and offshore
wind turbines.
The nacelle is the most important
component of a wind turbine with
respect to energy conversion because
it contains the initial mechanisms and
devices necessary for power
generation. It also protects the
interior equipment from inclement
weather. There are many complicated
parts located within the nacelle,
Figure 2: Diagram of the components of a nacelle
Image from
<http://www.srl.gatech.edu/education/ME6105/Projects/Fa11/Wind%20Turbine/>
so only the most important devices will be subsequently discussed.
Anemometer. The wind speed is the driving force in the energy conversion of a wind turbine.
The anemometer is a device that measures and collects the data of wind speeds at certain heights
above the base, as well as at certain time intervals. This information will tell an engineer or
project manager how much energy can be “extracted” from the wind resource, and whether or
not the weather conditions are appropriate for turbine operation.
Blades. The very first moment that the wind interacts with most wind turbines occurs at the wind
turbine blades. The blades are elongated airfoils that the wind drives in order to initiate the
mechanical energy which powers the rest of the devices located inside the nacelle. Most wind
turbines located on land, due to transportation limitations, have blades that can measure up to 30
meters (over 98 feet) in length; offshore wind turbines can have wind turbines up to 40 meters
(over 131 feet) in length.
Rotor or Hub. The rotor is a group of components that collaboratively drive the inner devices of
the nacelle. The rotor includes the wind turbine blades and the hub, or the connection of the wind
turbine blades and the low-speed shaft. The wind causes the rotor to rotate at the same angular
velocity as the low-speed shaft, which eventually assists in powering the generator.
Low-speed Shaft. The low-speed shaft is a metal pipe that turns the first (and the larger) gear of
the gearbox. Like the wind turbine blades, the low-speed shaft rotates at the same angular
velocity. It gets its name from spinning at the same angular velocity as the rotor, which spins at a
relatively slow rate (approximately 30-60 revolutions per minute, or one revolution every one to
two seconds).
Gearbox. Subsequently following the low-speed shaft is the gearbox, or a pair of “toothed
wheels” that powers the generator of the wind turbine. Each of the gears is different sizes
because the generator requires a certain amount of energy in order to operate. The larger gear is
attached to the low-speed shaft, whereas the smaller gear is attached to the high-speed shaft; by
means of elementary mechanics, the larger gear will cause the angular velocity of the smaller
gear to increase, and therefore drive the high-speed shaft. A gearbox isn’t always required
because some designs have been adapted to not include one.
High-speed Shaft. Analogous to the low-speed shaft, the high-speed shaft is a metal pipe that
rotates at the same angular velocity as the second (the smaller) gear of the gearbox. It therefore
gets its name from spinning at a faster rate than the rotor blades and the low-speed shaft. This is
very important because the high-speed shaft is the device that immediately powers the generator.
Generator. The generator is an electrical device powered by the high-speed shaft that creates
electrical energy in the form of alternating current (commonly known as AC). It is important that
the generator produces electricity in AC rather than DC because AC is able to travel for very
long distances at high voltage and low current, and cheaper in material costs for wires (like
power lines, for example).
The Tower
Aside from the foundation, the tower is one of two structural features in a wind turbine that not
only provides support to the nacelle and the rotor above, but also runs electrical wires to and
from the nacelle. The diagram below indicates a good example the parts of a tower before fully
constructed:
Figure 3: Parts of a wind turbine tower prior to assembly
Image from <http://www.windgreenergy.com/product_in.asp?bigclassid=7>
The visible outer layer of the tower is constructed out of the same material used in the nacelle
and the wind turbine blades. When the tower arrives on a construction site, its modular design
allows for it to be easily assembled on site. Each piece of the tower is stacked on top of each
other, and then secured with thick bolts and precast concrete. The strength of the structural
material allows for the wind turbine to survive numerous environmental conditions, like strong
wind gusts and heavy precipitation. Because they are also fabricated in a factory, the required
materials also prevent rust from forming, which allows for a long lasting and sustainable wind
turbine design.
Foundation
The final, and perhaps the most crucial, component of a wind turbine is the foundation (this is
also called a base in wind turbines on land, and a hull in offshore wind turbines). The foundation
is a structural feature that allows for the wind turbine to maintain its structural integrity and
purpose. Actual representations of foundations are variable, depending on where the wind
turbine is located and what the land or water conditions are. For example, foundations of wind
turbines on land typically are constructed from a meshed cage made of rebar, which is eventually
filled in with precast concrete. However, offshore wind turbines can have foundations that are
either drilled into the sea floor with cables or metal pipes, or designed to behave like a buoy
floating in deep water. A couple of examples of offshore foundations are shown below:
Figure 4: Examples of offshore wind turbine foundations
Image from < http://www.windfarmbop.com/category/foundations/>
The categories of offshore wind turbine foundations are explained below:
 A gravity foundation is a type of foundation used in shallow water that supports the
turbine using a rebar cage and concrete. This is the most common type of foundation used
in contemporary designs.
 A monopole foundation is a type of foundation which has a thick, elongated pipe drilled
deep into the sea bed to ensure maximum stability.
 A tripod foundation is a type of foundation that “props up” the wind turbine on stilts
which hold the turbine in place.
 A jacket foundation is a type of foundation which uses a metal cage of pipes that acts like
a stool for the turbine to sit on top of.
How Does It Work?
After completing a preliminary resource assessment and construction of the turbine itself, the
“life cycle” of a wind turbine is subsequently stated. The anemometer collects and interprets the
wind speed data at a given height with certain intervals of time. This data is then presented to an
engineer, who then decides whether or not the wind turbine should operate. If the engineer thinks
the weather conditions are appropriate, then the wind turbine therefore provides power. The wind
blows towards the wind turbine blades, which then causes the rotor to spin at an appropriate rate.
As the rotor spins, the low-speed shaft then begins to drive the first gear in the gearbox. The first
gear then drives the second gear, which enables the high-speed shaft to provide enough power to
the generator. The generator converts the mechanical energy from the high-speed shaft to
electrical energy under alternating current. The electricity then travels from the generator,
through the electrical cables located inside the tower. The cables are then fed underneath the
foundation and out to a power station, providing electricity to nearby communities.*
*
1,446 words