In the United States today, a wind turbine is one of the common and most clean ways of generating power. This power generation takes place from a massive wind farm to small turbines powering a single home. Wind turbine around the globe produces clean electricity that is capable of serving a variety of power needs.
Today you’ll get to know the definition, applications, function, components, diagram, types, and working of a wind turbine. You’ll also get to know the advantages and disadvantages of these types of wind turbines.
What is a wind turbine?
A wind turbine is a machine that converts kinetic energy from the wind into clean electricity. It can also be seen as a device that converts wind’s kinetic energy into clean, renewable electrical energy.
The turbine has blades that turn between 13 and 20 revolutions per minute, although it depends on their technology. This could be due to a constant or variable velocity, that is, the velocity of the rotor differs in relation to the velocity of the wind. This often helps to reach greater efficiency.
Wind turbines are designed to have an average life of over 25 years. The rapid evolution of wind technology has brought an increase in the durability and usability of wind turbines.
Wind turbines have a wide range of sizes and types, either horizontal or vertical axes. They can be called wind farms where hundreds of thousands of large turbines are installed. They generate over 650 gigawatts of power, with 60 GW added each year, which makes them an increasingly important source of intermittent renewable energy. Most countries employ wind turbines to lower energy costs and reduce the use of fossil fuels.
Read more: Things you need to know about turbine
Applications of wind turbine
The applications of a wind turbine are so vast since energy is required in almost all phenomena of humans. Ever since the early use of wind energy, it has been used to generate mechanical power. As early as 5000 B.C., Egyptians make use of wind energy to propel boats along the Nile River. American colonist uses the system to pump water, grind grain and cut wood at sawmills.
Today smaller wind turbines are used for applications like power traffic warning signs, and battery charging for auxiliary power for boats or caravans. The larger turbines are designed to contribute to a domestic power supply as the unused power is sold back to the utility supplier via the electrical grid.
Furthermore, large turbines, their applications are to provide power to the grid, which ranges from 100 kilowatts to several megawatts. These utility-scale turbines are often grouped together in wind farms so that a larger amount of electricity can be produced. Enough power produced will be able to power tens of thousands of homes.
In small wind turbines, they are typically close to the applications that will power, for instance, near the water pumping stations, homes, telecommunications dishes, etc. it generates up to 100 kilowatts. This turbine is sometimes connected to diesel generators, batteries, and photovoltaic systems. It is also called a hybrid wind system.
Finally, offshore wind turbines tend to be massive and taller. They are able to capture powerful ocean winds and generate a vast amount of energy of about 4,000 gigawatts of electricity. It is often used in many countries to harness strong energy.
Note: the primary function of a wind turbine is to generate power or directly use it for mechanical energy.
Components of a wind turbine
Wind turbines convert wind energy to electrical energy for distribution. Below are the components of conventional horizontal-axis turbines.
- The rotor – it approximately took 20% of the device cost, including the blades that convert the wind energy to low-speed rotational energy.
- Generator – it took about 34% of the wind turbine cost, including the electrical generator, control electronics, and most likely gearbox (e.g., planetary gearbox), adjustable-speed drive, or continuously variable transmission. These wind turbine components are responsible for converting the low-speed incoming rotation to high-speed rotation suitable for generating electricity.
- Surrounding structure – it is approximately 15% of the wind turbine cost, including the tower and rotor yaw mechanism.
Read more: Understanding reaction turbine
Diagram of a wind turbine system:
Types of wind turbines
There are basically two types of wind turbines out there: the horizontal axis and the vertical axis.
Horizontal axis wind turbines:
Most wind turbine used today is a horizontal axis, which means, the blades propeller-style are designed to rotate around a horizontal axis. These types of wind turbines are either upwind, that is, the wind hits the blades before the tower. Downwind is the other type, where the wind hits the tower before the blades.
The upwind uses a yaw drive and motor, components that turn the nacelle to keep the rotor facing the wind when the direction of its change. This is achieved using a wind sensor mounted on the yaw system for larger turbines. Small turbines are pointed b a simple wind vane.
A Horizontal-axis wind turbine is abbreviated as HAWT. It is common today that large three-bladed horizontal-axis wind turbines with the blades upwind of the tower produce the overwhelming majority of wind power in the world today.
The downwind turbine types were built to eliminate some additional mechanisms for keeping them in line with the wind. Its blades are designed to bend in high winds, which reduces their swept area and thus their wind resistance.
Despite the benefits, the downwind offers, upwind designs are still preferred. This is because the change in loading from the wind as each blade passes behind the supporting tower can damage the turbine.
Read more: Different types of turbine
Vertical axis wind turbines:
The Vertical-axis wind turbines or VAWTs have their main rotor shaft vertically arranged. The purpose of this arrangement is that there is no need for the turbine to point the wind for effectiveness. This is an advantage for sites where wind direction is highly variable. It is also a benefit when the turbine is integrated into a building because it is inherently less steerable.
In these types of wind turbines, the generator and gearbox can be placed near the ground using a direct drive from the rotor assembly to the ground-based gearbox. This improves accessibility for maintenance. However, these designs offer much less energy averaged over time, which is a major drawback.
The vertical turbine types have much lower efficiency than the horizontal designs. A relatively low rotational speed with the consequential higher torque and higher cost of the drive train also affects the system. These types of wind turbines fall into two main designs:
Drag-based, or Savonius turbine – they generally have rotors with solid vanes that rotate about a vertical axis.
Lift-based, or Darrieus turbines – have a tall, vertical airfoil style, although some appear to have an eggbeater shape. A wind spire is a type of lift-based turbine even though it’s still undergoing independent testing.
Working on a wind turbine
The working of a wind turbine is less complex and can be easily understood. Most wind turbines consist of three blades, though those with two blades are common. These blades are mounted to a tower made from tubular steel. The turbine makes use of faster wind speeds found at higher altitudes since the tower is 100 feet or more above the ground.
The wind’s energy is caught with the propeller-like blades, looking like an airplane wing. So, when the wind blows, a pocket of low-pressure air forms on one side of the blade. This low-pressure air pocket then pulls the blade toward it, making the rotor turn. This is known as lift. The force of the left is much stronger than the wind’s force against the front side of the blade, which is called drag. The combination of the lift and drag causes the rotor to spin like a propeller.
A series of gears are used to increase the rotation of the rotor from about 18 revolutions a minute. This is roughly 1,800 revolutions per minute, which allows the turbine’s generator to produce AC electricity.
Just as earlier stated, the nacelle is part that houses some key turbine components. These include rotors, gears, and generators, mounted atop the turbine tower. These nacelles are large enough. Another important part is the turbine controller, which keeps the rotor speeds from exceeding 55 mph. This helps to keep the system safe from high winds.
An anemometer is used in a system to continuously measures wind speed and send the data to the controller. The nacelle also contains a brake that stops the rotor mechanically, electrically, or hydraulically in an emergency case.
Watch the video below to learn more about the working of wind turbines:
Advantages and disadvantages of wind turbines
Below are the benefits of wind turbines in their various applications:
- HAWT with a tall tower, base gives access to a stronger wind in sites with wind shear.
- High efficiency, because the blades move perpendicularly to the wind, receiving power through the whole rotation in HAWT.
- They produce electricity in any wind direction
- Low production cost when compared to horizontal axis wind turbines.
- A strong supporting tower is not required
- Easy to transport from one place to another
- Low maintenance cost.
- Can be installed in urban areas.
Despite the good advantages of these types of wind turbines, some limitations still occur. Below are the disadvantages of a wind turbine.
- Massive tower construction is required.
- Components like the gearbox, rotor shaft, and brake assembly are being lifted into position.
- Downwind variants suffer from fatigue and structural failure.
- Efficiency is very low compared to HAWT.
- High vibration is experienced.
- Noise pollution is created.
- Due to vibration, bearing wear increases, resulting in high maintenance costs.
- The initial push to start is required.
Read more: Things you need to know about Kaplan turbine
Wind turbines are machines that convert kinetic energy from the wind into clean electricity. It is of two types, which are abbreviated as HAWT and VAWT. The entire work differently and offers a different benefit. That is all for this article, where we explained the definition, applications, function, components, diagram, types, and working of a wind turbine. We also list the advantages and disadvantages of these wind turbines.
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