The Types of Wind Turbines
When you think of a wind turbine, chances are the image of a horizontal wind turbine pops into your head. These turbines are the most commonly built worldwide, and you have probably seen them on drives through rural areas, near sources of water, and in any open space. Horizontal Axis Wind Turbines (or HAWT for short) are named as such because the rotor is horizontal and parallel to the direction of the wind. However, did you know vertical axis wind turbines also exist? These turbines also called VAWT for short, have rotor systems that are perpendicular to the direction of the wind making them stand vertically. Let us take a deeper look into both systems.
Vertical Axis Wind Turbines (VAWT)
Just like Horizontal Axis Wind Turbines, Vertical Axis Wind Turbines (or VAWTs) use the kinetic energy from the wind to push blades and power a generator, converting wind energy into electricity. The difference between these two turbines is the orientation of the rotor and shaft. Vertical Axis Wind Turbines, as the name suggests, are vertical and usually smaller than other wind turbines.
Two main types of VAWTs are produced today. The first type of vertical axis wind turbine is the Savonius model also known as the drag type wind turbine. These types of turbines have been used for thousands of years and their design can even be traced back to those used in ancient Persia. They use big blades that rotate around the shaft that generates electricity when pushed by the wind. These turbines have been known for their simple design and easy setup. The drawback of drag turbines is they are less efficient than other wind turbines, so they are produced less than other vertical axis wind turbines.
On the left side here, we have a Savonius, or drag type, vertical axis wind turbine. the right we have a Darrieus, or life type, vertical axis wind turbine.
The other more commonly built VAWT is the Darrieus turbine also known as a lift-type turbine. These turbines are a lot more complex than drag-type turbines, but they are more efficient. This is because they use skinnier blades that connect from the top of the shaft to the bottom. This makes the turbine omnidirectional and can create energy without the need for a yaw system pushing the turbine in the right direction. Each blade gets hit by the wind at a different angle which generates lift and rotates the turbine. Lift-type systems have many pros compared to drag-type and horizontal axis wind turbines. For one they can be placed closer together, so more lift-type systems can be placed on wind farms compared to HAWTs. They also have simpler blade geometry and lower blade tip speeds which makes them quieter than Horizontal axis wind turbines. Finally, lift-type turbines are smaller and can be repaired easier making them safer for workers who do not need to climb up tall systems to access the turbine's inner systems. However, VAWTs, in general, are not as widely produced as HAWTs due to their low efficiency, lower reliability, and their inability to be produced at a larger scale.
Horizontal Axis Wind Turbines (HAWT)
Horizontal Axis Wind Turbines, also known as HAWTs, are the most commonly found wind turbines around the world. Their reliability, efficiency, and ability to be produced at a larger scale make them perfect for producing a large amount of energy for houses, cities, and businesses. Horizontal Wind turbines can be placed directly into the wind or include a yaw system that moves the turbine in the direction of the wind. The wind turbine produces energy by converting the kinetic energy into electricity, similar to the VAWTs. Horizontal Axis Wind Turbines usually have three blades that lift and rotate when the wind is blown over them. This in turn causes an internal rotor to spin. The rotor connects to the shaft which then connects to the generator. This whole system is parallel to the direction of the wind, and it is why the system is called a Horizontal Axis Wind Turbine. These turbines have been widely adopted by countries around the world due to their high-power output and can power small towns and cities when placed together.
In all wind turbines come in many different shapes and sizes, each with their own pros and cons. Our HAWT, the Anorra, is a microgeneration home wind turbine that is rated at 1.2kWh at 900rpm and generates between 1.5 to 3 mWh of electricity over a year. That is enough to power a tiny home and reduce your dependency on grid energy if you live in a larger dwelling. Whether you plan on investing in wind energy soon or are just curious about wind turbines, hopefully, you now know the difference between all the various types of wind turbines.