Vertical Axis Wind Turbine designs have changed gradually over the centuries. Let’s take a look at the general features all VAWTs have in common and then dive into the different types of VAWT designs.

All VAWT designs have two things in common. The first is that they all generate electricity with the power of the wind. The second is that they do it with the help of a vertically-arranged primary rotor shaft. This means the turbine does not need to face into the wind in the way that a horizontal-axis wind turbine (HAWT) would need to. The downside of this is that VAWTs often have a higher torque than that of a HAWT, as well as a more expensive drivetrain.

The upside? VAWTs can be arranged closer together than HAWTs. This is particularly useful in the city where there is usually not as much wind or available space at your disposal as in an open rural area. When engineers design VAWTs they are able to create models with gearboxes that are close to or on the ground. This makes it easy to maintain.

Of the different types of VAWTs, there are a several worth mentioning. Let’s take a look at some types of Darrieus and Savonius wind turbines.

Darrieus Wind Turbine Design

The Darrieus wind turbine is a VAWT that was patented in the early 20th century by Georges Jean Marie Darrieus. This turbine uses spinning airfoils (also known as blades or sails), which use lift force to capture wind power. This type of turbine is often unable to start by itself, so for some models it is necessary to include a starter in the design. Darrieus wind turbines have been known to have issues with pulsing rotation speeds, which can result in extra wear and tear on the turbine. As a precaution, many variants of Darrieus wind turbines include a mechanical speed control or a break to decrease rate at which the turbine breaks down. Use of helical airfoils is also useful for lessening strain on the device.

Giromills and cycloturbines are two kinds of common Darrieus wind turbines. Because giromills exclusively make use of lift power (which is used for accelerating motion), they require a motor to get the motion started. Cycloturbines do not need a motor to start; instead they are designed to include a vane that sets the generator at an optimal angle to get started with drag power. Once it gets going, it uses lift power to accelerate in the same way as a giromill. These types of wind turbines are great for areas where the wind can be extra gusty and temperamental.

Savonius Wind Turbine Design

Savonius wind turbines are a creation that also officially came to fruition in the early 20th century (shortly before the Darrieus wind turbines). They were invented by a man named Sigurd Johannes Savonius. Most Savonius turbines do not require a motor starter. Their airfoils are in the shape of scoops, which catch the wind to move the turbine with drag power.

Unfortunately drag power does not collect as much of the wind’s energy as lift power does, but Savonius wind turbines are generally much less expensive than other types of wind turbines and they are quite reliable. These types of turbines are nice for use in the city.

Helical wind turbines are a type of vertical-axis wind turbine (VAWT) with conjoined scoops or twists that are arranged in the shape of a helix. Engineers have developed this design in an effort to capture the greatest amount of kinetic energy from the wind and generate clean electricity. They are more efficient than the average VAWT, and they have a unique and (subjectively speaking) attractive design.
Since helical wind turbines come equipped with a vertically-aligned rotor shaft, it is possible to space them fairly close together on your land or rooftop. This is compared to the horizontally-aligned rotor shaft in a horizontal-axis wind turbine (HAWT), which is generally able to generate a slightly larger amount of electricity but needs a great deal of space to operate efficiently.
There are people who have voiced a few concerns about helical wind turbines (and wind turbines in general) that I’d like to quickly address.

Noise

Some communities and individuals who care very much about the well-being of the Earth have resisted using wind energy because they are concerned that the wind turbines will be too noisy. This usually isn’t the case, especially when making use of smaller turbines like helical wind turbines. The noise you encounter everyday at work is probably louder than the noise created by one of these wind generators.

Ugly Appearance

Other folks have criticised the appearance of wind turbines. In most cases I don’t agree with this at all, not for VAWTs or HAWTs. Driving up and down the California coastline in the United States, you will see wind farms all over. The giant windmills that reside on many of the hillsides are hypnotic giants that glimmer beautifully in the sunlight. That’s an example of beautiful HAWTs. In the case of VAWTs, I particularly love the appearance of helical wind turbines, which resemble strands of DNA and can be painted for a particularly lovely effect.

Bird Safety

It is usually the case that when someone is conscientious about how they are treating the environment, they’ll want their energy solutions to be kind to animals as well. A challenge that has been cited by different people is that birds sometimes fly right into wind turbines and perish. This is a real issue, but it actually doesn’t happen too often, especially when you are dealing with smaller vertical-axis wind turbines. Helical wind turbines, in particular, pose little risk to birds. Part of the reason is that their design makes them appear more solid than other turbines’ do, so birds treat the helical wind turbine as a solid object and fly around it instead of through it.

Whatever reasons you might have for not jumping on the wind turbine bandwagon, specifically the helical wind turbine bandwagon, you will find that their pro’s outweigh their con’s. This is really a great type of wind turbine. Helical wind turbines are one of the more efficient kinds of turbine for home and community use. They’re fantastic for providing power in the city, and they have a lovely sculpturesque appearance. What’s not to love?

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The father of VAWT's, Sigurd Johannes Savonius

The Savonius wind turbine is a type of vertical-axis wind turbine (VAWT) that came into being in the early 20th century. These simple turbines were invented by an engineer named Sigurd Johannes Savonius. The foundation of his design was laid by other engineers who had lived centuries before him, but his design was the most elegant and useful formation of the idea at the time. Even today, this type of wind turbine continues to be a reliable mode of generating electricity through wind power, and the design has proven to work for a variety of other uses that do not have to do with generating electricity.

Savonius Wind Turbine Design

Savonius wind turbines’ airfoils (usually numbering two or three) are shaped like scoops. These scoops catch the wind to move the turbine with drag power. While the drag power of three or more scoops is excellent for starting a turbine’s motion, a Savonius wind turbine cannot accelerate past the speed of the wind going past it. Another factor that causes the Savonius wind turbine to operate at lower speeds is its height. Usually its designed to be lower to the ground than other wind turbines. It is generally the case that wind speeds are lowest near the ground and highest up in the air. This means that other taller types of vertical wind turbines that accelerate with lift power, such as Darrieus wind turbines, are usually more effective at generating a large amount of electric power. The upside for Savonius wind turbines is that they are generally less expensive and more sturdy than Darrieus wind turbines.

A Variation on the Savonius Wind Turbine

A fairly new take on the Savonius wind turbine design is the airborne wind turbine, which would basically take a Savonius wind turbine and tether it to the ground. The axis would actually be oriented horizontally. When the wind would blow hard enough, the kite would take flight and the airborne wind turbine would spin and create energy. An entire field of these airborne wind turbines would be a fantastic sight indeed!

Where are Savonius wind turbines most useful?

Savonius wind turbines are great for generating electricity in rural and urban cities and for providing additional energy to land and sea vehicles, but they are especially useful for providing smaller amounts of electrical power in areas where it will be difficult provide ongoing maintenance or where extreme conditions require the wind turbine to be particularly strong. For example, you can find Savonius wind turbines in places like the Sahara Desert and Antarctica where the weather is extreme, the availability of appropriate transportation is hard to come by, and wind turbine experts are not necessarily hanging around biting at the bit to fix turbines when problems arise.

Other Uses

While the Savonius turbine’s design is wonderful for harvesting clean wind energy, its uses do not stop there. You can also find the Savonius design in anemometers (a device used for measure wind speed), in some types of water pump, car ventilators, and even in unique designs for backyard clothing dryers.

Image of Savonius above taken from German Wikipedia. 

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