Part 5: Offshore Wind Power, Small-scale and hybrid systems

Question 1

Name two positive effects of offshore wind farm on the animal life.

Answer 1

• The foundation can be used as an artificial reef

- Usually it is not allowed to fish close to offshore wind farms

Question 2

Normally, offshore wind power projects are more expensive, why? Give 4 reasons.

Answer 2

• Corrosion of materials
• Maintenance becomes more expensive due to long trips by boat or helicopter
• Construction more expensive due to complex installments.
• Often at remote places which comes with high grid costs.

Question 3

Give three advantages of offshore wind power compared to onshore.

Answer 3

• Better wind resources (stronger winds)
• Low turbulence intensity
• Lower wind shear => lower towers

Question 4

Give five disadvantages of offshore wind power compared to onshore.

Answer 4

• Requires specialized technology => more costly
• Requires protection from corrosion
• Tower resonance frequency is influenced by the waves
• Problems due to floating ice
• Difficult to access => maintenance harder
• Less turbulence => more wake losses => more space needed between turbines

Question 5

Give and describe the principles of five power control schemes for small scale wind turbines.

Answer 5

Yaw control - rotation of the nacelle towards the wind
Flip control - the turbine change the orientation from horizontal to vertical
Stall (passive) - aerodynamic shape of the blade, the drag increases so that the blade stops when the wind is strong
Pitch control - rotation of the blades
No control

Question 6

Mention 6 markets for small wind turbines < 50 kW?

Answer 6

Remote homes
Rural electrification
Telecommunication
Water pump
Oil pump
Refrigeration
Desalination

Question 7

Mention 4 reasons why offshore wind power recently has phased significant cost reductions.

Answer 7

Economics of scale
Increase in energy production
Good planning and political support
Good site location characteristics

Question 8

State 3 different ways of keeping a floating wind turbine in an upright position.

Answer 8

A long ballast and sealing it to the bottom
A platform with many bois
Many cables at the bottom of the sea

Question 9

State 4 methods for non-floating offshore wind power foundations.

Answer 9

Monopile
Tripod
Gravity foundation
Metal sachet foundation