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The Shadow Flicker Effect: What Is It? (Wind Turbine Shadows)

The Shadow Flicker Effect: What Is It? (Wind Turbine Shadows)

When I was reading about wind turbines recently, I came across an article that highlighted something called the “shadow flicker effect”. So, I did some more digging to find out what exactly this term means. 

What is the shadow flicker effect? The shadow flicker effect is caused by the shadows that are given off by wind turbines when they are in full rotating motion. This phenomenon is due to the light that is escaping through the gaps between the blades of the turbine from the light that is shining behind them. The shadow flicker of wind turbines has been rumored to cause several negative effects. 

Out of all the negative effects that have been rumored to come with the spread of wind energy and construction of more wind turbines all around the world, one of the most reported issues with the new technology is something called shadow flicker.

Also known as the “Shadow Flicker Effect”, this epidemic has become a consistent complaint within the communities of homes that are left in the shadows of newly built wind turbines.

So, what are the negative effects of the shadow flicker that comes from wind turbines and what else are the machines capable of?

Related: What Is Wind Turbine Syndrome?

The Negative Effects Caused By The Shadow Flicker Effect 

The Shadow Flicker Effect, or “Shadow Flicker” is something that is caused by wind turbine machines when they produce shadows that enter through windows and nearby barns.

This can become a nuisance to people who live in homes that are directly next to the wind turbine because they will frequently experience the flicker of shadows through their windows at various times of the day.

This can become very annoying because the shadow flicker can cause strains in vision or even headaches to the people who are affected. 

Just imagine sitting in your living room one day and trying to watch a movie on your television screen. You have the blinds on the window closed all throughout the room, but the light is still coming through the gaps.

If a nearby wind turbine began rotating due to high wind speeds with the sun located directly behind it, there would be a constantly flickering light in the corner of your eye that would expand to the walls around the room and reflect off of them as well.

Soon enough, there would be something similar to the effect of a strobe light shimmering on and off all around you and distracting your eyes from the task you are trying to complete. 

The Shadow Flicker Effect of wind turbines has been rumored to have caused several negative effects on the nearby people an animals that regularly experience the flashes.

The most common complaint that has to do with the shadow flicker given off by a lot of wind turbines is the stress that it causes to the people who have to deal with it within their homes.

Since wind turbines move with the speeds of the wind, there is no way to control them or turn them off when they become annoying. Additionally, the weather forecast is often unpredictable with no way of knowing exactly when the wind will be blowing.

So, there is also no way to prepare for the effects that might come with the wind for those who live in the shadows of the enormous machines.

Shadow flicker becomes increasingly severe in certain times of the day and of the year. When it gets closer to the early morning or late afternoon, the sun is usually placed at a very low position in the sky and gives off minimum light as a result.

Usually, these times have a much higher volume of wind and will cause the wind turbines to spin even more than usual, letting off a shadow flicker into the windows of nearby homes. Additionally, wind speeds can pick up or become more frequent during the winter months when it is colder outside. 

The shadow flicker effect has also been reported to have various negative effects on nearby farm animals like cattle and horses that might be in the path of the bright lights between the blades of the towering turbines.

More specifically, many owners of horses have claimed that the flickering lights can scare their horses and prevent them from grazing in the fields below the wind machines. 

The negative health effects that can be caused by shadow flicker is not limited to the short list of possibilities that have been mentioned so far. In addition to the annoyance and headaches that can come from the constant flickering lights being cast out by wind turbines, they can also cause depression in some people.

In fact, it has been scientifically proven to increase the average risk of becoming depressed.

The World Health Organization conducted research on this specific topic and concluded that the average risk for depression will be increased by a rate of forty percent in those who are affected by the shadow flicker of wind turbines. This is due to the visual disturbance that is frequently caused by the unusual lighting within nearby homes and facilities. 

Additionally, those who suffer from the shadow flicker effect do not have a good view outside of the window. Although the wind turbines do not physically block the view of the windows, the annoyance of the constant shadow flicker will cause most people to keep their curtains closed at some point when the effects of the lighting become too much to bear.

As proven in previous scientific studies, a deficiency of sunlight is directly linked to depression or the risk thereof. Therefore, if those who experience the flickers caused by wind turbines are constantly keeping their windows closed tightly to avoid the nuisance that comes with the unstable lighting, they become more at risk for depression than they would be in most other living situations. 

Unfortunately, the list of negative effects still does not stop here. Aside from the nuisance that comes with the shadows as well as the stress of not being able to stop it, there is an even more severe risk that comes with the shadow flicker effect.

This effect is the heightened risk for epilepsy seizures. If the flashes that come through the window exceed three per second, the turbine could be contributing to the risk of seizure.

However, if these limits are programmed into the turbine by the wind energy developer, this effect can potentially be avoided. 

With the growing amount of complaints that have surrounded the shadow flicker effect that comes with wind turbines, there have been some proposed solutions to solve or at least relieve the problem slightly.

There have been systems created in order to more easily shut down the wind turbines in the event of an annoying shadow flicker that is bothering the nearby people and animals within the proximity.

On the other hand, there have been proposals of planting trees or large bushes directly in front of the wind turbines in order to obstruct the path between the potential shadow flicker and nearby facilities.

A general guideline has been set in place for wind energy developers not to build their projects within too close of a proximity to humans, and if there are more than 30 hours of shadow flicker within one year a solution to the problem should be initiated immediately.

How Wind Turbines Spin Their Blades

Wind turbines are constantly rotating their blades in order to collect energy from the wind and generate electricity. This function, which is directly linked to the shadow flicker effect that can sometimes be given off by the blades, is determined by a variety of factors.

So, let’s take a look at the process a wind turbine goes through in order to begin blade rotations. 

When the wind begins to blow, the anemometer will spin according to the force that the wind is exerting on it and send a message through to the inside of the turbine. The signal will be received by the controller inside of the nacelle and the turning action will commence.

Depending on the direction of the wind, the pitch system will rotate the blades to keep them safe from any damage and in order to get the most energy possible. 

The blades will then receive the signal that the current wind speed is ideal, and will begin to turn freely according to the speed of the wind. The force that is exerted on the blades is known as lift, where the wind speeds past the blades and they react by turning around the axis of the tower. The faster the wind blows, the faster the turbine’s blades will spin. 

When the wind is blowing, it is producing something called kinetic energy, which is created by movement. This kinetic energy will enter the inside of the turbine through the rotor hub in the middle of the blades as they are spinning according to the pace that the wind is blowing.

When the energy is received by the generator, it will be spun around multiple loops of copper wire to be multiplied and transformed into mechanical energy. Mechanical energy is created when the wind’s kinetic energy is added to the potential energy from within the turbine.

During the process of creating mechanical energy, electrons will be given off in order to turn it into electricity. The electrons travel through another component called the step-up transformer that increases the capacity of the electricity it was given by almost five times more. 

Once the electricity has been fully converted after passing through each one of the turbine’s inner parts, it will travel down the tower’s shaft and be transported to an electrical substation to be distributed from there.

In addition to the process, turbines go through in order to spin their blades, there are certain times where they will take a break from the rotation. 

How Often Wind Turbines Are Really Spinning Their Blades 

The shadow flicker effect is obviously caused by wind turbines spinning their blades and reflecting a shadow onto the nearby homes and buildings in its path. When considering the frequency of flickering shadows, it is important to be aware of when wind turbines will likely spin their blades.

So, how often are wind turbines really completing rotations and creating an opening for the lights to flicker and affect the people below them?

There are certain factors that influence when a wind turbine will spin its blades and when it will stand still instead. All of these factors, however, are dependent on the speed of the wind at the given time.

Turbines have advanced technology that is programmed within them to detect when the blades will be able to consume enough energy from the wind. These speeds are determined by thresholds that are built into the machine at the installation called cut-in and cut-out speeds, or in other words, the minimum and maximum turning speeds. 

The cut-in speed is the absolute minimum amount of wind power that is required for the turbine’s blades to be able to spin. Without this minimum speed, it will be impossible for the blades to notice the presence of some kind of friction against them and begin to turn the opposite way.

The average cut-in speed for a regular wind turbine lands around 3 to 4 meters per second or up to 8 miles per hour. In the absence of sufficient energy being created by the wind, the anemometer function will not detect enough pressure to pass the message along the machine through the nacelle in order to start up the blades’ turning function.

The minimum speed of 8 miles per hour is essential for the turbine to gain any kind of energy off of the wind’s momentum.

The cut-out speed, on the other hand, is the absolute highest speed that the turbine can handle before there is any damage done to its moving parts. This function will be used when the wind speeds are extremely high in the event of a severe storm or natural disaster that could attack the blades.

The typical cut-out speed for a wind turbine on the smaller end could be programmed to anywhere from 60 to 100 miles per hour, whereas a larger utility-grade turbine might be able to withstand speeds up to 180 miles per hour before shutting down completely.

Both the cut-in and cut-out speed are beneficial features to the wind turbine because they help protect the hardware as well as achieve as much energy efficiency as possible. 

If there was no minimum speed requirement, the wind turbine might be spinning its blades constantly without any kind of control. This would be a significant waste of energy because the cut-in speed corresponds with the minimum wind speed to where sufficient electricity can even be generated. 

On the other hand, without a maximum speed threshold in place, the turbine’s blades would constantly be spinning out of control and would eventually get damaged or break altogether. In the event of extreme weather conditions, the cut-out speed helps to keep the machine in-tact as much as possible until it is permitted to resume functions. 

Both of these important functions prevent premature damage and wear and tear to the wind turbines, helping them to reach as close to their full life expectancy as possible. 

Wind turbines will not be spinning their blades and producing energy non-stop throughout their entire life for a few different reasons. First of all, the earth’s wind patterns are very scattered and unpredictable.

There is no way to know exactly how much wind there will be every day for the rest of the wind turbine’s lifetime. Even if so, it would be impossible to expect the wind to blow at sufficient speeds all year long in the area of each wind turbine. 

With that being said, statistics show that the average wind turbine will be able to effectively create energy up to 85 percent of the time. As you can see, there are a few common circumstances that will cause a wind turbine to stop turning its blades, all of which are directly related to the wind speeds that it depends on.

However, the frequency of these circumstances will depend on the size and location of each individual turbine. 

A Similar Theory: The Wind Turbine Syndrome

In addition, the shadow flickers that have been reported in relation to the appearance of wind turbines near existing homes and farms, there have been several reports about the machines giving off loud noises into the atmosphere.

These loud noises are also believed to contain harmful infrasound rays that can directly affect the farm animals that share the fields with the turbines and cause them to exhibit changes in their normal behavior. 

In the business of wind energy, it is common for turbine owners to lease out a section of land for a set period of time in order to operate their machines. Additionally, most landowners and farmers that offer some of their lands up for rent to wind turbine owners already have an existing farm with animals.

Although there is no direct research that has focused on this topic and come up with anything solid to support these claims, there have been stories over the years that cattle and livestock have suffered negative side effects when wind turbines were newly built on the same farm they lived on.

It has been reported that, along with the loud sound effects that occur when the turbines’ blades begin to spin at rapid speeds, the turbines can produce infrasound rays that transfer to the animals on the farm and cause them to display changes in behavior.

This list of changes in behavior includes eating, sleeping, and reproductive patterns that they normally followed before the appearance of the wind turbines. Countless farmers all over the world have told stories about their animals suffering injuries or even deaths in large quantities shortly after wind turbines were built in the area.

Overall, the animals were just reported to have behaved very strangely after the wind turbines were installed and began generating electricity from the wind. It has even been reported that some house pets suffered negative effects due to nearby wind turbines that were never experienced before they were added to the equation. 

The increased claims of the wind turbine syndrome affecting farms worldwide flooding the media also came with consistent backing. With several stories surfacing in the news and on the internet, the wind turbine syndrome quickly spread and became a household discussion.

There was even a book that was written by an esteemed doctor to tell these individual stories in more detail and asses them from a scientific standpoint. The book is titled Wind Turbine Syndrome and was written by Nina Pierpont. 

The “wind turbine syndrome” has been a huge epidemic in various locations all around the world for several years, with no specific rhyme or reason for the frequent and scattered claims. There have been signs of adverse effects of wind turbines on nearby farm animals from Taiwan all the way to France, with all different species of animals in between.

With no common denominator in hundreds of separate cases, many people have jumped to the conclusion that the wind turbines must have caused these sudden injuries and deaths. 

In conclusion, despite the long list of positive effects that come with the installation of wind turbines and the spread of the wind energy industry as a whole, there are plenty of negatives that come with them. The shadow flicker effect has been an issue for several years and has plagued various communities throughout the world.

With the potential risks that come with frequent flickering lights in homes and buildings, it is definitely an issue that must be addressed when it occurs too frequently. Considering the steady uphill growth that the wind energy industry is currently experiencing, we can expect to see a lot more wind turbines being built in the future. 

Related Questions

What Kind Of Effects Have Wind Turbines Had On The Environment?

Since wind turbines have started appearing all over the world, they have had various effects on the environment, both good and bad. For starters, wind turbines have significantly limited levels of greenhouse gases and other toxic emissions in the atmosphere.

Wind turbines themselves give off virtually no waste or harmful chemicals into the environment around them and have actually been working for several years to prevent the spread of global warming.

On the other hand, wind turbines come with their fair share of negative effects along with all of the benefits that they give to the environment. First of all, they have been proven to cause multiple deaths to flying animals like birds and bats. 

Unfortunately, these mortality rates can also apply to the endangered species that exist in some places where wind turbines are located throughout the world.

In response to the harm that is done to animals by wind turbines, scientists have proposed several solutions to the problems including turning the machines off during certain seasons and painting the exteriors a different color that is less alluring in the sunlight. 

The last negative effect that can be caused by wind turbines is the contribution to massive toxic lakes in China. This happens when wind turbines are constructed with rare earth materials that are mined and imported from across the world.

Although most wind turbines do not use these toxic minerals, the ones that do contribute to the severe pollution that affects multiple Chinese cities. 

How Fast Do Wind Turbines Spin Their Blades?

Each individual wind turbine is programmed with a specific threshold that includes a minimum and maximum speed of rotation. These speeds, also known as the cut-in and cut-out speeds, are put in place to ensure the safety of the machine and help it reach its maximum efficiency at all times.

These speeds will vary between each individual turbine, depending on the size and energy capacity it holds. An average range of maximum speeds of a wind turbine from the smaller to the lower end of the spectrum can be anywhere from 50 to 180 miles per hour. Some utility-scale wind turbines have the potential to reach speeds up to 200 miles per hour. 

How Much of the Wind’s Energy Can Actually Be Collected?

As mentioned earlier, there is a limit to how much of the wind’s energy can actually be captured by a wind turbine at any given time, no matter how fast the blades are spinning or what the energy capacity of the turbine itself is.

This limit is known as Betz Law, which theorizes that wind turbines only have the capability of capturing 59.3 percent of the wind’s energy. In other words, wind turbines will never be able to intake more energy than the 59.3 percent regardless of the factors that are present at the time, including the speeds of the current winds. 

Learn More

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.