When the concept of wind turbines came into my mind recently, I wondered if there is any specific reason for the number of blades that are on the machines. So, I did some research to find out why most wind turbines use three blades.
Why do most wind turbines use three blades? A quantity of three blades is found on most wind turbines so each individual machine can generate as much electricity as possible. Additionally, the turbines are constructed in a similar pattern with the same number of blades to create balance in the structures and prevent the machines from falling over due to high winds.
Wind turbines have been constructed with a default of three rotor blades all over the world for many years. At the current rate, the wind energy industry is continuing to grow, there are so many more turbines popping up almost everywhere. So, what are the real reasons behind this particular method of construction?
Related: Why Do Some Wind Turbines Stop Turning?
The Components of a Wind Turbine
Each wind turbine consists of many individual components that all work together to complete the function of generating electricity from the power of the wind. There are a total of four large portions of each wind turbine that each house multiple other pieces inside of them.
These four pieces are the tower, foundation, nacelle, and rotor blades. The tower is the long vertical structure that holds the turbine’s blades up so it can capture the wind as effectively as possible.
This piece can be constructed of solid steel and is often shaped into a smooth cylinder or can have an alternate pattern such as a lattice. Towers with a lattice pattern have several wires that intertwine together to make it look similar to a woven basket.
Even though there are plenty of different options for the aesthetic of the tower piece, all wind turbines also have a foundation that they are built on. The foundation can also vary in shape, size, and design depending on the type of turbine.
This is a necessary component of every wind turbine because it holds the machine still inside of the ground and prevents it from moving around when rapid wind speeds are present. In a way, the foundation and rotor blades both work together to provide a balance to the entire turbine.
Most turbines that are located onshore have foundations made out of concrete, while offshore turbines typically stand on a steel base that allows them to stand up from the surface of the water and reach the winds that constantly blow over the ocean.
Two of the most important components of every wind turbine that complete most of the work that must be done when converting electricity from the wind’s power are the nacelle and rotor blades, which are usually built in a quantity of three.
The rotor blades are one of the largest pieces of the wind turbine and face outward toward the wind in front of the tower of the machine. They have a similar look to a set of airplane propellors or a pinwheel that spins around on top of a stick.
All three of the rotor blades on the turbine will work together to harness the wind’s energy throughout the entire process. Even though the rotor blades are essential in the functions of a wind turbine, they would have no purpose without the controls that are located directly behind them in the nacelle.
The nacelle is a huge piece that sticks out behind the back of the rotor blades. It sits directly on top of the tower and essentially connects it to the blades.
The nacelle contains hundreds of smaller components that all work together in a system to send signals forward to the turbine blades to let them know when to start and stop spinning.
Why Rotor Blades are Necessary for Wind Turbines to Generate Electricity
The basic concept of wind energy is harnessing and converting power from the wind into electricity using a machine called a wind turbine. Wind turbine machines can come in a variety of different sizes, from smaller, residential-scale turbines to even larger utility grade machines that have the ability to provide energy to multiple communities of people all at once.
Additionally, you can find a wind turbine almost anywhere in the world. The number of wind turbines that are currently scattered across the globe is continuing to increase with the growing industry of wind energy. Regardless of the size of the turbine, most of them will have an average blade length of approximately 50 feet.
This number will increase with the individual turbine, but this should give you a general reference for how large the blades can possibly be. Due to the extremely large potential length of each wind turbine blade, it is increasingly important that these blades are able to balance themselves while carrying out their day-to-day spinning functions whenever the wind blows.
They should especially be able to balance themselves when wind speeds become too fast for the turbine to handle in order to avoid any damage to the machine.
Even though there are several variations of what these machines can look like or where they are commonly located, all wind turbines serve the same purpose. This purpose is creating electricity from the earth’s infinite source of wind. The wind turbine’s process of spinning its blades begins when the speeds of the current winds are picked up by a small component called the anemometer.
This piece usually sits on top of the nacelle and looks similar to a pair of horizontal helicopter blades. Similar to an actual helicopter, they will begin to rotate and spin around when they are hit with the pressure of the wind. The purpose of this piece is to measure the speeds of the wind and make the decision if it is ideal for the blades to begin collecting its energy. If the speeds are too slow or too fast, the inner components of the turbine will not be notified at all.
The speeds of the wind are sent downward to the controller, which will then send its own message to the high or low-speed shafts, depending on the current speed of the wind, and they will initiate movement outward toward the blades, allowing them to rotate and collect the wind’s energy.
The speed that the controller relays to one of the speed shafts will depend on the minimum and maximum speeds that are programmed into the turbine before it is installed. These speeds, also known as the cut-in and cut-out speeds, are very important in preserving the wind turbine machine as a whole.
Why Wind Turbines Have Just Three Blades
The concept of wind energy has been around for hundreds of years. The collection of electricity from the wind’s power first originated with the invention of the windmill, and from there the wind has become a vital resource all across the globe.
In fact, many countries and regions all around the world have made the decision to advance toward clean and renewable energy and have begun to make the full transition to using wind energy as their primary source of electricity.
Wind energy has become increasingly popular due to the sustainability and efficiency of wind turbine machines in comparison to the use of fossil fuels and power plants that are harmful to the environment.
Since wind turbines and wind farms have started to appear in the mountains and near the water, their three-blade designs have become even more noticeable than they were before the topic of wind energy became a household discussion.
The reason why most wind turbines have a set of three blades is not a coincidence. In fact, there are multiple logical and scientific reasons as to why the machines are built in this fashion. Wind engineers have put their heads together to figure out how the power of wind can be taken advantage of to the fullest through the use of wind turbines.
There are several factors that have gone into consideration from the time that the first wind turbine prototype came to life to the suggestions for future improvements to the design of wind turbines. So, what are the main reasons why most wind turbines you see across different countries all seem to have three blades?
Some of the main factors that have been taken into consideration over the years in which wind energy has progressed are the efficiency and balance of the machines.
More specifically, it is important for the wind turbines to be able to harness and collect as much energy as possible from the wind in order to power several surrounding communities of homes, schools, businesses, and other facilities.
Wind turbines with more or fewer blades than the magic number three will most likely have compromised efficiency rates, and will not be able to produce nearly as much electricity as turbines that are designed in this fashion.
Additionally, wind turbines should be able to stand up on their own without moving or toppling over onto one side when the wind blows too fast in their direction. It is essential for the blades to be held up toward the direction of the wind as often as possible to achieve their maximum energy output.
If the turbine is not able to hold its blades in place, it will result in less energy being captured from the wind and possible damage to the moving parts on the machine in the event of a storm or other similar weather conditions that are more severe than normal.
The Effect the Number of Blades has on a Wind Turbine
Now that we understand a brief description of why wind turbines must have three rotor blades in order to function properly, let’s dig a little deeper into how wind turbines are actually affected by the number of blades they have.
One of the most important concepts that should be taken into consideration when designing and building a wind turbine is aerodynamics. The term aerodynamics refers to how a still object interacts with the air that surrounds it.
To put it in the most simple terms, the blades of a wind turbine complete very similar functions to the wings of an airplane. More specifically, the turbine’s blades are designed to hold a specific shape that will help them glide through the air more smoothly and collect as much energy from the wind as they possibly can at any given time.
Think of the wings of an airplane, for example. When you are on a flight and you look out the window at the wing that is sticking out from the side of the plane, you will probably notice the slight curve that moves upwards as it gets closer to the tip.
This specific design is similar to that of a wind turbine’s blades and helps both components react to the friction of the wind as it brushes against them.
Since the blades are designed to fit this specific shape, the wind will move at a much faster speed when it is coming up behind them than it does when the wind is coming from the front of the blades.
When the wind hits the blades at this angle, they will move at a much faster speed and be able to rotate at almost identical speeds to the wind that is hitting them.
When the wind provides enough force and exerts it on the wind turbine, the process of generating electricity will begin as discussed in the earlier sections of this article.
Even though the blades are shaped with a specific curve in order to best capture momentum from the wind, the wind does not provide enough push or lift to begin a rotation of the blades on its own.
When the design of a wind turbine is being planned out, another factor that should go into consideration is the exact speed they will be able to accommodate as well as how they will drag through the air when rotations begin.
If the turbine’s blades have too much drag, this will directly translate to a much lower rate of efficiency. On the other hand, if there is not enough drag, the blades could begin spinning at such a rapid speed that they will not be able to grasp any of the wind’s energy.
Now, let’s get back to the subject at hand: why most wind turbines have three blades. As we all know, this is a standard practice that is followed in the design of almost every wind turbine on earth. If wind turbines had a number of blades that was more or less than three, it would directly affect the efficiency of the machine. Let’s take a look at why this would happen.
To start, if a wind turbine had only one blade, it would not have sufficient balance throughout the machine and would likely make the whole structure lose its balance. Over the years when the subject of wind turbine blades has come up, many people have argued that one blade is the most efficient way to collect energy from the wind.
The reason for this is the amount of drag that one blade possesses, as discussed earlier. Due to the fact that the presence of one rotor blade would provide a decreased level of drag, some scientists have considered this quantity to be the most ideal for all wind turbines.
However, there is just one problem with this entire theory. Even though one turbine blade has the potential to create the most efficiency out of any other wind turbine design, it would also create a huge lack of balance.
Since wind turbines must have a certain level of stability to even function properly, choosing a one blade design for a wind turbine would not be smart in terms of energy and investment return. It would essentially be a waste for both the turbine owner as well as the consumers of the energy if the turbine itself stopped working.
On the other hand, if wind turbines had two blades instead of three, there would be another set of problems. Similar to the one blade argument, two blades could potentially have a larger energy potential than the traditional design of the three blade turbine.
Despite the scientific logic that is behind these claims, there is a deeper issue with this as well. Just like the one blade turbine, a turbine with two blades would most likely be affected by a concept called gyroscopic precession. In other words, this is an imbalance within the turbine machine that will end up with a shaky and wobbly turbine machine.
This would be detrimental to the structure of the machine because if it was not stable in its foundation and able to hold itself up into the wind, it could have the potential of toppling over in the future. Additionally, the wobbling motions on the outside of the turbine would have a negative effect on the inner components of the turbine.
With constant movements that are not natural to the machine, the parts on the inside of the turbine could grind together and cause unnecessary wear and tear on the turbine as a whole.
Ultimately, even though turbines with a lower amount of rotor blades could potentially provide much more electricity than the standard three-blade machine, the current design is most practical when it comes to balance and efficiency.
A machine that can capture twice the amount of energy but will likely become unstable or suffer damages that will lessen the life span is not preferred over a sturdy wind turbine that will stand up by itself and provide electricity to hundreds of people for multiple years.
Alternatively, if a wind turbine had any number of blades that exceeded the standard design of three, the blades would create greater wind resistance. Although this might sound like a good thing, it is actually very detrimental to the production of electricity for a wind turbine.
To be more specific, the increased amount of blades would be moving through the air even slower than a turbine with three blades would, and this would prevent the machine from generating as much electricity as it possibly could.
With slower rotation speeds, the harnessing of energy from the wind would also slow down substantially. In regards to a wind turbine with more than three rotor blades, there are virtually no advantages.
When wind turbines were designed with a total of three rotor blades, it was decided that this was the perfect middle between an unstable machine that can generate tons of energy and a super-balanced machine with a much lower level of efficiency. Wind turbines with three blades are able to hold themselves up while still generating a satisfactory amount of electricity.
Even though most of the wind turbines you will come across almost everywhere in the world will have three rotor blades, the current design does not necessarily determine what any future designs will be like.
As we all know, advancements in technology have no limits, and the future of wind energy and new turbine designs have no limits as well. With brand new innovative prototypes being cooked up in the brains of scientists as wind energy develops as a worldwide source of energy, the possibilities of future turbines are endless.
In fact, there has already been a proposal for a turbine that has no blades. While the prototype is still under construction, these turbines are believed to have more cost-effective and require less maintenance throughout their lifetimes as opposed to the traditional three-blade turbine.
These brand new wind turbines with an absence of the rotor blades that we’ve all gotten so used to seeing will supposedly be able to generate much more electricity than any prior design.
While it is true that wind turbines have been around for many years with a standard of three rotating blades, there is no telling how long this design will continue to show up around the world as wind energy becomes more accepted. This has been the most efficient design up to this point, but there is always room for the improvements that are soon to come.
How Fast Can a Wind Turbine Possibly Spin its Blades?
Wind turbines have the capability to spin their blades at speeds of anywhere from 100 miles per hour to almost 200 miles per hour. These speeds are in accordance with something called the cut-in and cut-out speeds.
These are set thresholds that are built into each wind turbine before they are even installed, and work to protect the machines from outside damage and maximize rates of efficiency. The maximum speed that a wind turbine can spin its blades will also depend on the size and type of wind turbine.
For example, a smaller residential wind turbine that would be found on a farm would most likely be able to spin at about 50-60 miles per hour. However, a huge utility-scale wind turbine in a commercial wind farm would be able to extend its blades at speeds toward the limit of 200 miles per hour.
What is the Rate of Efficiency for the Average Wind Turbine?
The average rate of efficiency for any wind turbine is approximately 70-85 percent. In other words, a wind turbine will be spinning its blades and effectively collecting energy from the wind up to about 85 percent of its entire lifetime.
These limits also fall under a theory known as Betz Law, which concludes that a wind turbine can only collect up to 59.3 percent of the wind’s energy at any time. Therefore, most wind turbines will be able to achieve up to the 85 percent limit of this maximum value of energy that can be harnessed from the wind in the first place.
How Do Wind Turbines Effect the Spread of Global Warming?
For many years, it has been rumored that wind turbines cause global warming due to their size and constant movement. However, this statement couldn’t be farther from the truth. Wind turbines have been known to move the hot air in the atmosphere down toward the ground level, but this action is not permanent and does not contribute to global warming in any way.
This process usually happens at night when the cold air settles toward the ground level. When wind turbines pick up on adequate wind speeds, they will begin to rotate their blades through the air. As a result of this action, the hot air that has separated from the cool air and floated up toward the sky is directed downward to mix in with the cold air that is already resting near the surface.
This causes temporary warming of the ground directly underneath the turbine, but it does not create any permanent warming to the actual surface of the earth. If anything, wind turbines have helped to limit global warming instead of causing more harm to the earth.
If you’re serious about learning more about wind energy, I recommend the Wind Energy Handbook on Amazon. This book is great for both students and professionals, and it holds invaluable information on the subject of wind power.