The vertical wind turbines were the first type ofwind turbinescreated by man. The setting of the vertical rotation axis sees many advantages but is not free from disadvantages when compared to the set-up horizontal.
L'vertical wind powerit is often abbreviated with the acronym VAWT, from English: Vertical Axis Wind Turbines, vertical arrangement of wind turbines. By the same principle, thehorizontal wind poweris abbreviated with the acronym HAWT, Horizontal Axis Wind Turbines.
Vertical wind turbine
Today, thevertical wind powerrepresents a small part of the turbines currently in use, it goes without saying that the wind power market is mainly focused on the design and marketing ofhorizontal wind turbines.
but yet vertical wind powerhas several advantages that should not be underestimated. First of all, thevertical wind power gives the possibility of installation even in places where it is not possible to reach high heights. Compared tohorizontal wind power, the vertical one sees lower maintenance and lower starting torque.
Among othersadvantagesofvertical wind power, absolutely not to be underestimated is the fact that thevertical wind bladeit does not require any yaw system as they can operate with wind from any direction.
Vertical wind turbines
Thewind turbinesthey see a vertical rotation axis and different operating arrangements which, at a descriptive level, are grouped into three macro-groups.
Vertical wind turbine with Savonius rotor
It was devised in 1922. This layout is still used in thosewind turbineswhich see, as a priority, low production costs even at the expense of power. They are turbines that make little noise and are mostly designed for domestic use: they work with low wind speeds.
They are often classified asmicro-windas thesizethey are in the order of magnitude of about one meter. They do not require special attention or maintenance.
Darrieus vertical wind turbines
Like Savonius, Darrieus also bears the name of the engineer who designed it. Among the various settings of thevertical wind power, this is the most promising.
I'mvertical axis wind turbines"To lift". Thewind turbinesin fact, they can be “lift” or “resistance” based on the force of the wind that they use as a driving force. In the "lift" turbines the wind flows on both sides of theshovel. The two faces have different geometric profiles to create a depression area on the upper area of the blade, compared to the lower part. This pressure difference generates what is called “aerodynamic lift”, the thrust that allows the rotational motion of the wind blade.
In thevertical wind powerthis is expressed with surfaces arranged in the wind with a particular airfoil, capable of generating the “aerodynamic lift” in an efficient way.
The starting torque is zero and therefore these turbines cannot start independently. This led to the creation of another set-up: the Darrieus-Savonius hybrid turbine.
Giromill vertical wind turbines
They are less efficient than the Darrieus setting but have the advantage of greater ease of production with a consequent reduction in costs.
Vertical and horizontal wind
The mainadvantagesof avertical wind bladehave been summarized in the introduction, however thehorizontal wind powerit should not be underestimated. Compared tohorizontal wind turbines, those based on a vertical axis have certain disadvantages such as:
- They have a lower yield
- They generate pulsating torque
- It is not possible to adjust the angle of inclination of the blades
Thewind turbines with horizontal axisthey can be “upwind” or “downwind”, they can be equipped with onesingle blade(single blade turbines) with two or three blades (the most common). Then there is no shortagemulti-blade turbines.
Wind power classification based on power
Regardless of the structure of thewind turbine, there is a classification related to potency. When it comes tovertical wind turbines, in general, reference is made to small wind turbines ordomestic wind, designed to produce small amounts of energy. In this case, as previously mentioned, we are talking about micro-wind.
Plants classified asmicro-windthey produce powers lower than 20 kW and are made up of systems intended for domestic users or small agricultural realities.
We talk aboutmini-windfor systems between 20 and 200 kW. Also in this range thedomestic windbut generally, the mini-wind plants are already destined for the production of electricity destined for sale.
We speak properly ofwind farmsreferring to systems capable of generating power greater than 200 kW. It is mainly abouthorizontal wind farmswhich produce and feed electricity into the national grid.
Is it worth installing vertical wind turbines?
The answer is far from simple. Many factors must be considered and the cost of installing and purchasing theturbinein question.
The main estimate, which can tell you whether or not it is convenient to install domestic wind turbines, is made by studying the amount of wind available on the installation site.
A first indicator can be provided by the Italian Wind Atlas, developed by CESI and the University of Genoa. However, keep in mind that the wind can vary considerably over an area of a few kilometers.