Published on : Jun 09, 2016
Worldwide, the increased focus on the development of renewable energy has resulted in the launch of a large variety of vertical axis wind turbines in the market. The majority of wind turbines currently used on a commercial scale are the horizontal axis type; however, with technological advances, vertical axis wind turbines are expected to be promising for the future.
Vertical axis wind turbines are of three main types: Darrieus model, Savonious model, and giromill model. Of the three, the Darrieus wind turbine, also referred to as ‘eggbeater’ turbine, displays distinct features due to its design configuration. The turbine has a low torque and high speed, because of which it has proven to be highly efficient for power generation. However, this type of vertical axis wind turbine machine usually requires a thrust from an external power source to initiate operations. Darrieus wind turbines have two blades that are vertically oriented that revolve around a shaft.
On the other hand, a Savonious wind turbine is a high torque and low speed rotating machine. The design of a Savonious wind turbine is quite similar to that of an anemometer. It uses lift produced by airfoil-shaped blades for functioning of the rotor. As such, Savonious vertical wind turbines operate at a slower speed that that of approaching wind.
Vertical axis wind turbine are advantageous in several ways over horizontal wind turbines. They do not need orientation mechanism for the purpose of electricity generation, thereby resulting in substantial reduction in cost incurred in manufacturing the turbine. Moreover, the repair and maintenance of vertical axis wind turbines is relatively easier and convenient as major power generating parts such as gearbox and generator are placed toward the base of the turbine.
Other than this, vertical axis wind turbines assert to require lesser wind for producing an equivalent amount of energy, hence are suitable for lower altitudes where the wind velocity is generally lower. These factors collectively are primarily driving the vertical axis wind turbines market. Due to the commercial advantages of vertical axis wind turbines, the deployment of these units in small-scale applications is being considered.