Small Wind Turbines (Vertical Axis)


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Description VAWTs have the main rotor shaft arranged vertically. One advantage of this arrangement is that the turbine does not need to be pointed into the wind to be effective, which is an advantage on a site where the wind direction is highly variable. It is also an advantage when the turbine is integrated into a building because it is inherently less steerable. Also, the generator and gearbox can be placed near the ground, using a direct drive from the rotor assembly to the ground-based gearbox, improving accessibility for maintenance. A vertical axis wind turbine can be designed as one of the following subtypes;
  • Darrieus wind turbine
  • Giromill wind turbine
  • Savonius wind turbine
  • Twisted Savonius wind turbine
Advantages
  • The generator and gearbox can be housed on the ground, and even some distance away from that turbine
  • VAWT is omnidirectional and requires no yaw mechanism.
  • Requires little maintenance
Disadvantages
  • VAWT is typically about 40% less efficient than the HAWT in energy production
  • VAWTs have proven less reliable than HAWTs.
Characteristic features

Conversion of kinetic energy from the wind into electrical power

Application barriers

High initial investment cost

Information sources http://www.oelmuehle-moeriken.ch/
http://www.windturbinestar.com/vertical-wind.html
http://www.quietrevolution.com
http://www.sawt.com.cn/
Image
Trade: Building services
Parameter Minimal Value Maximal Value Unit
Nominal Power

0.1

30

kW

Nominal Wind Speed

12

14

m/s

Start Wind Speed

2

4.5

m/s

Stop Wind Speed

14

32

m/s

Maximum Wind Speed Allowed

150

255

km/h

Rotor Weight

135

430

kg

Rotor Diameter

1.5

10.25

m

Rotor Surface

2.25

102.5

m2

Mast Height

1

12

m

Maximum Rotation Speed

100

400

rpm

Transmission

No gear box

Safety

Electrical brake + disc brake

Number of Blades

2

5

Material Blades

Aluminium, Carbon epoxy composite, Composite fibre glass

Voltage (AC)

24

240

V

Minimum Operating Temperature

-40

-20

°C

Maximum Operating Temperature

40

100

°C

Noise at 20 m Distance with 5 m/s

DB

Positioning

on the ground

on the roof

Operating Efficiency

40

%

Annual Degradation Rate in Efficiency

%

Annual Produced Energy

kWh

Investment Cost

2.320

7.539

€/kW

Operational Cost

€/year

Maintenance Cost

1

3

% of the turbine cost

Life Expectancy

15

20

years

Deterioration Description
Causes
Parameter
Degradation Rate
Measurement


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