Types and design of wind turbines
There are two main types of wind turbines:
- wind turbines with vertical axis of rotation
- wind turbines with horizontal axis of rotation
A simplified design scheme for the most common wind turbine with a horizontal axis of rotation is shown below.
Wind turbines with horizontal axis of rotation
The most popular modern class turbine blades. There are continental or coastal wind turbines and seas located at a certain distance from the shore (they have an advantage in terms of noise, since they are far from human dwellings, and use the energy of sea winds that are more constant and stronger than continental winds). Sea wind turbines are much more complex in installation and operation and, therefore, much more expensive.
The operating height of the wind turbine generally varies between 25 and 180 m at a power of 100 kW to 5 MW.
Prevailingly operated double-or triple-winding wind turbine generators, however, there are single-hull and multi-pile.
Australia has developed a wind turbine with 30 blades. It also works with low-speed winds, does not produce a lot of noise or vibrations, and at the same time produces 30% more power than the windmills-competitors.
Wind turbines for an individual (home) use have up to 12 m in height and a power between 100 W and 20 kW.
Wind turbines with vertical axis of rotation
Wind turbines with a vertical axis of rotation are more expensive than the same ones with a horizontal axis, have a more complicated structure, but are more adapted to the area with frequent change of wind direction. Wind turbines with a vertical axis of rotation are more compact.
There are two types of wind turbines with a vertical axis of rotation: the rotor of Savonius and the rotor of Darrieus.
Wind turbines with Darrieus rotor do not require much space, do not require guidance systems (not dependent on wind direction), easy to install. Among the disadvantages are the fact that they have a low wind power factor (approximately 0.05 for the classical Darrieus rotor, with a practical coefficient of 0.45-0.47 for classical horizontal axial wind turbines with a theoretical maximum of 0.593), bad self-starter (requires preliminary rotor acceleration), low mechanical strength, greater noise during operation.
The Savonius wind turbine also has a low wind power factor compared to conventional wind turbines, requires more materials, but has the advantage of working with winds of any direction.
Wind turbine as a submerged turbine
Wind turbine designs can be used as submersible turbines.
The development of water turbines is very new in alternative energy and is already very promising, because water turbines can have much greater power at much smaller sizes than wind turbines. This is due to the fact that the energy of the sea currents is 800 times greater than the wind energy. Changes in the direction of ocean currents are also much smaller than changes in the direction of the wind.
The main disadvantage of water turbines is their impact on the marine environment (turbines create large areas of turbulence that impede the development of wildlife and marine flora at great distances from them). Turbines are under water, where the erosion of the metal is very strong, and because of this, the life of the water turbines is limited.