Vertical-axis wind turbines, or VAWTs as they are often referred to as, are wind turbines that have their rotor shaft arranged vertically instead of horizontally. Instead of being mounted horizontally atop a large base like horizontal-axis wind turbines (HAWTs), VAWTs are mounted vertically — the blades of the turbine stand tall straight up and down. Many home wind power systems are comprised of VAWTs, as there are now many manufacturers making small wind turbines for home use. I had trouble keeping track of which company was which!
Earlier this year I wrote about building your own vertical axis wind turbine at home. Backyard wind power, which used to be just a hobby for a select few self-sufficient folks, has become big business as residents are looking for renewable energy sources to power their homes and small businesses. There are several types of vertical wind turbines available, along with advantages and disadvantages of them, that potential buyers should be aware of before making any decision.
There are three types of vertical wind turbines currently found in use, depending on the application.
The Savonius wind turbine was invented by Sigurd J. Savonius in 1922. This turbine generally looks like two opposed halves of a barrel or ball spinning around the central rotor. These two halves create air scoops which capture the wind and in-turn spin the turbine, generating power. It is the least efficient of VAWTs.
The Darrieus wind turbine looks like an egg beater you may find in any kitchen around the world. Simple in design, the Darrieus was invented invented by Georges Darrieus in 1931. It works using aerofoils, which is similar to the principle behind how an airplane in motion stays in the air as air flows over and under the wings.
The Helical wind turbine is a slightly more complicated version of the Darrieus turbine, in that it consists of three vertical airfoil blades spinning in a helical pattern around each other. This is the newest design for VAWTs and the most efficient.
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