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Vertical Axis Wind Turbine Usage:
Because of the environmental concerns and energy issues facing by the world today, many countries have been trying to utilize renewable sources of energy. Wind, being a clean and plentiful source of energy is now setting a new trend in renewable energy sources.
Wind turbines systems are the most efficient way to generate electricity from wind energy. They vary greatly in size from homemade wind turbines to commercial scale wind farms.
Wind had already been used by people even in early times. Sail of ships utilizes wind to travel in high seas. Early American dwellers used wind mills for grinding corn, cutting woods and pumping water. Originally, mills were invented to grind corn. As men tried to find more efficient way to operate them, they led to an earlier version of today’s wind turbines. It featured large blades set in vertical wheel shape.
Several gears were connecting the wheel’s axle and the mill stone. As the wind turns the blades, it causes the mill inside to move and grinding the corn or wheat into flour. The present version replaces the mill with a generator that in turn produces the electricity. From these concepts, modern homemade wind turbines had been developed and are now being widely used to reduce households’ electric bills.
Wind turbines are generally classified into two types. These are horizontal axis wind turbine and the vertical axis wind turbine or the HAWT and the VAWT respectively. Both designs can be adapted for homemade wind turbines but HAWTs are more common. This is because horizontal axis wind turbines are found to be more efficient in generating electricity than vertical axis turbines.
The design of the horizontal axis turbines features three blades moving in horizontal circle similar to a clock’s hand. Besides the increased efficiency, HAWTs can also transfer the power generated from rotor to gearbox in much smoother way than VAWTs. Most of these turbines are mounted on top of towers being exposed to higher wind velocities. Unlike VAWTs that are designed to operate near the ground where there could be too many wind interferences.
However this set up offers the VAWTs an advantage over HAWTs. With HAWTs setting up HAWT system would require tall cranes and a yaw system. The periodic necessary maintenance has also to be done on top of those towers.
At the present, there are also two different designs of a vertical axis wind turbine – Savonius rotor and Darrieus model. The first type is similar to anemometer. But these are very inefficient offering an efficiency of about 5 to 10 percent. The Darrieus model on the other hand looks like an egg beater. This design makes use of an airfoil that operates as the airplane wing.
Though vertical axis turbines are about less than 40 percent efficient than HAWTs, they offer benefits in low wind situations. Also, because they are mounted close to the ground, they are safer and easier to build. They can also handle wind turbulence much better than HAWTs. Another important feature of vertical axis turbines is that they can operate using winds from any direction.