UE 06: Wind power

Question 1

Energy yield of a wind turbine - weibull distribution

True or false?

A smaller k-value means very variable wind speeds.

A larger k-value means very constant wind speeds.

Answer 1

True!

Question 2

Energy yield of a wind turbine - weibull distribution

Provide the k-value for different climatic regions.

Answer 2

Arctic regions –> k = 1

Central Europe –> k = 2

Trade wind regions –> k = 3 - 4

Question 3

Energy yield of a wind turbine

• Assumption: Central Europe (k = 2)

Advantages of using Rayleigh distribution:

• Requires only the mean wind speed
• Mean wind speed is known for many locations
• The yield calculation of wind turbines of many manufacturers is based on the assumption of a Rayleigh distributed wind

Answer 3

True!

Question 4

How is the theoretical upper limit of the power of a wind turbine described?

Answer 4

Theoretical upper limit of the power of a wind turbine

• Due to aerodynamic, electrical, and mechanical losses there is a theoretical limit on the fraction of wind energy that can be extracted by an ideal (lossless) wind turbine
• Maximum power coefficient: c_Betz = 0,593
• P_Betz,i = P_wind,i * c_Betz
• P_wind_turbine = P_wind,i * c_p,i
• P_Betz,i >= P_wind_turbine