Types Of Wind Turbines: Everything You Need To Know
Uneven heating of the earth by the sun is what causes wind, creating a renewable source of energy. Wind turbines harness the kinetic energy in wind to create electricity and power grids. Turbines are systems made up of turning blades and a generator that makes electricity. They are a great source of renewable source of energy in urban and rural settings.
Turbines in varying sizes, and the blade length is the biggest factor that determines the amount of electricity a wind turbine can generate. Smaller turbines are capable of generating up to 10 kilowatts of electricity, which is enough to power 1-3 households. Some of the largest turbines can generate 10,000 kilowatts, and are often grouped together to create wind farms.
Wind turbines rely on a central axis that feeds into a generator to produce electricity. Depending on its placement, turbines can be classified into horizontal axis and vertical axis.
Horizontal Axis Wind Turbines
Horizontal axis turbines can be traced to the 1820s when they were used in American wind farms. They have a rotor with up to 20 flat sheet metal blades. A tail vane is responsible for ensuring that the rotor faces into the wind. Turning the wheel off the wind direction helps prevent over speeding and operational governance is automatic.
Traditionally, horizontal axis turbines were used to pump water. Modern models have 1-4 metal blades that rotate at higher speeds than ordinary windmills. The blades are twisted like airplane propellers and their rotation is automatically governed. This ensures that a constant generator speed is maintained.
One of the most popular horizontal axis turbines is the Jacobs three-bladed windmill. It was used between 1930 and 1960, and had the ability to produce 1 kilowatt of power at a speed of 6.25 meters per second.
Large horizontal axis turbines with two blades have been developed in recent years. One of the first such devices was installed in 1976 in Ohio. It has a diameter of 11.6 meters and its power was rated at 100 kilowatts. Another one installed in Oahu has an axis that is 76 meters above the ground and a rotor diameter of 122 meters. Its output at an average wind of 32 meters per second is 6200 kilowatts.
Advantages of Horizontal Axis Turbines
Disadvantages of Horizontal Axis Turbines
Vertical Axis Wind Turbines
The main rotor shaft of a vertical axis turbine is set transverse to the wind while the main components are located at the base of the turbine. Because the gearbox and generator are close to the ground, maintaining them is easy. Vertical axis turbines don’t have to be pointed to the wind during installation, and this eliminates the need for wind sensing and orientation mechanisms.
The axis of these turbines is vertical to the ground and perpendicular to the wind streamlines. Vertical axis turbines were used in Middle ages and later in 1922, when S.J. Savonius invented a new rotor. The rotor had semicircular blades made from sections of an oil drum and cut in half along the vertical axis. They were welded together to form an open S.
An advanced version of the Savonius rotor was installed in the 1970s in Manhattan. It produced 5 kilowatts of electricity at a speed of 12 meters per second. The most recent vertical axis turbine is based on the device patented by G.J.M. Darrieus in 1931. It has two blades with twisted metal strips that are tied to the shaft at the top and bottom. The blades bow down in the middle, much like those of a food mixer. The Darrieus turbine installed in New Mexico generated 60 kilowatts at an average of speed of 12.5 meters per second.
Advantages of Vertical Axis Turbines
Disadvantages of Vertical Axis Turbines
Ducted Wind Turbines
These are less popular turbines designed to produce electricity from the airflow on the side of a building. They are positioned on the edge of the building such that when the air flows upwards, it hugs the building and enters the ducts. They are small and their blades have an average diameter of 600mm.
Advantages of Ducted Turbines
Disadvantages of Ducted Turbines
A lot of work needs to be done to improve the efficiency of wind energy. There has been considerable progress over the past few decades, with vertical axis turbine technology making headway. That said, we hope you know more about different types of turbines and understand how they work.