Vertical Axis Wind Turbine: All You Wanted to Know

When it comes to the topic of the wind turbine, you probably think of turbines that look like aircraft propellers which are known as horizontal axis wind turbines. But there is another type of wind turbine which is still under development and seems to have a great potentiality to reduce the limitations of horizontal axis turbines. 

Vertical axis turbines are easily distinguishable because of their vertical shape. Unlike the horizontal axis turbines, vertical ones come with a variety of shapes and designs.

This article will tell you about vertical axis turbine, its types, and why it can be an alternative to horizontal ones.

Vertical Axis Wind Turbine (VAWT)

A wind turbine cannot be a wind turbine unless it has few blades. Likewise, the horizontal axis turbines, vertical axis ones also have a set of blades. But instead of spinning horizontally, they spin vertically. So, the rotational axis of a VAWT is in the vertical direction, and that’s why it got such a name.

The engineers designed VAWT to make the turbine more economical and practical than the traditional ones. But unfortunately, the designs are not as effective as horizontal axis turbines. That's why this type of turbine is rarely used to produce a large amount of electricity. 

Key Characteristics of Vertical Axis Wind Turbines

  • There are two of three main rotor shaft that operate vertically. The more blade a turbine has, the more efficiently it will receive wind energy and produce electricity.
  • These turbines stay low close to the ground and this is the reason why people mostly use them at a residential location. Also, the turbine is easy to maintain.
  • It makes quiet less noise than a HAWT.
  • The main drawback of VAWTs is, they produce less energy compared to horizontal units.
  • Energy production can be maximized if the turbine is set onto the roof.

Types of Vertical Axis Wind Turbine

There are primarily two types of VAWT; Darrieus and Savonius wind turbine.

Darrieus Wind Turbines 

Darrieus wind turbines look like an eggbeater, and that’s why they are also known as eggbeater turbines. This type was invented in 1931 by Georges Darrieus. It works with at least two blades that are vertically oriented and revolve around a vertical shaft. These turbines are high speed and low torque machine that generate AC electricity.

The generator of the turbine is located at the bottom of its blades. Blades are mounted with the help of a monopole. There are few guy wires connected to the pole that keeps the pole in place when the wind flow rotates the blades.

One of the main drawbacks of this kind of turbine is, it cannot start by its own. So, an external power source is required to make it rotate as the initial torque is quite low.

Some of the main features of the Darrieus wind turbines are –

  • These turbines are great in terms of efficiency compared to the Savonius turbines.
  • It requires an outside source of power to start.
  • Turbines with more blade are more efficient.
  • High efficiency, low reliability.

Savonius Wind Turbines

Savonius wind turbines on the other hand, are low speed and high torque machine. Instead of using blades, this one uses scoops to capture wind energy. Each turbine has two or more scoops to produce electricity. The scoops turn around when the wind energy applies positive force on the front side of the scoops and a negative force on the back of the scoops.

Instead of using lift generated airfoil shaped blades, savonius wind turbines use drag, and that’s the reason why they don’t rotate the scoops faster than the wind speed.

Now let's have a look at some of the key features of savonius wind turbines.

  • Suitable for areas with the strong wind flow.
  • Unlike the darrieus one, a savonius wind turbine doesn't require an additional machine to start it up. The turbine starts whenever wind flow strikes.
  • Quite larger than darrieus wind turbines.
  • Less efficient but high torque capability.

Advantages of Having Vertical Axis Wind Turbines

VAWT has some characteristics that make people choose it over a HAWT for residential and business uses. Let's have a look at what are the benefits that a VAWT can bring to your home or office.

  • You don’t require to set the turbine too high from the ground. Even if you don’t have an appropriate rooftop for placement, you can build the turbine close to the ground easily. Just make sure, wind flows through the area without any obstacle.
  • The maintenance cost of such turbines is way less than horizontal ones. Due to the fact that the turbine stays close to the ground, it's also easy to perform necessary maintenance and it's safe as well.
  • If you are an animal lover, you will love the fact that vertical axis wind turbines are bird friendly and do no harm to the wildlife.
  • These turbines don't make a loud noise like HAWTs. Operating noise is quite less than the traditional turbines.
  • You don't require to point the turbine towards the wind. They work pretty well even if they are exposed to a variable wind direction.
  • Doesn't require an additional mechanism to operate.
  • You can set up multiple VAWTs close to each other. There is no need for having a large field and farm.
  • Suitable for areas that don’t allow tall structures.
  • You can transport the turbine from one place to another without much hassle.
  • Vertical axis wind turbines are very economical and suitable for small residential energy production. Perfect for urban areas.
  • Compared to horizontal turbines, they cost much less.
  • Many of these turbines can resist various weather elements. You can easily choose a unit that suits your local environment the best.

Disadvantages of Having Vertical Axis Wind Turbines

Although VAWTs have many benefits over traditional HAWTs, they have some limitations as well. You might be thinking about getting one for your home after knowing the advantages that it brings, but before making the final decision, it would be worth to know where this new innovation lacks the most.

  • Vertical axis wind turbines are no match in the performance and efficiency level comparing to the horizontal ones. This is due to the fact that VAWTs operate according to the less effective drag method.
  • Even if there is high wind speed, you cannot take advantage of producing more power.
  • Wind flows at a higher speed above the ground. So, such turbines cannot harness high wind flow as they stay comparatively in low position.
  • You cannot build these turbines in towers.
  • For commercial and places where you need a large amount of electricity, having a vertical axis wind turbine will not suffice your need.

So, Does it Worth to Invest in a VAWT?

Although vertical axis wind turbines don’t produce much energy like horizontal axis wind turbines, still they are great for small scale electricity production. If your energy requirement is moderate and you don’t have space for a HAWT, go with a vertical one without any hesitation. They suit best in limited space area and are easier to maintain.

Final Words

Considering small scale energy production for urban areas, one cannot deny the effectiveness of using a vertical axis wind turbine. Despite having some limitations in a larger scale of production, engineers are trying to improve and develop vertical axis wind turbines which indicates its great potentiality.

Hopefully, this article was able to give you a clear understanding of vertical axis wind turbines and help you to decide whether you should get one for your household or not.

  • Updated August 3, 2019
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