Introduction to Modern Wind Turbines - Wind Turbine Technology: Fundamental Concepts of Wind Turbine Engineering - page 89

Table 2-5.
Estimated Costs for an Offshore 3.0-MW Wind Turbine in a 51-MW Wind Power
Station, Compared to Costs for an Equivalent Onshore System
[Data from Fingersh et al. 2006]

Item Offshore

Turbine Cost
(2005 $1,000)

Onshore
Turbine Cost (a)
(2005 $1,000)

Ratio of Offshore
Costs to Onshore
Costs

TURBINE CAPITAL COST 2,377 2,136 1.1

Nacelle and Drive Train 1,425 1,276

Rotor 477 498

Tower 415 324

Control, Safety, and Condition Monitoring 60 38

BALANCE OF STATION COSTS 2,855 872 3.3

Foundations 1,114 66 17.0

Electrical Interface & Connections 926 241 3.8

Assembly & Installation 371 71 5.2

Transportation 281 272

Engineering, Permits, & Site Assessment 119 75

Roads, Civil Work, Port, & Staging 74 147

OFFSHORE ADDITIONAL COSTS 1,169 0 NA

Off-Shore Warranty Premium 405 0

Turbine Marinization 321 0

Scour Protection 204 0

Surety Bond for Decommissioning 176 0

Special Personnel Access Equipment 64 0

INITIAL CAPITAL COST (2005 $1,000) 6,431 3,008 2.1

(a) Scaled for inlation from 2002$ (reference data) to 2005$, by factor of 1.074

Table 2-6.
Gross Annual Energy Outputs for Mod-5B 2.5-MW HAWTs at Representative
Offshore and Onshore Sites with the Same Wind Resource at 100 m Elevation (a)

Parameter Offshore Site:

Cleveland Water
Intake Crib

Onshore Site: DOE/
NASA Reference

Surface roughness length, z 0 0.000115 m 0.0445 m

Annual average wind speed at 10m, U A,R 6.71 m/s 4.66 m/s

Annual average wind speed at 100m, U A (100) 7.63 m/s 7.63 m/s

0.0561 0.2141

Wind shear power-law exponent, a

Gross Annual Energy Output, AEO G 7,840 MWh/y 6,420 MWh/y

Ratio: Offshore output to onshore output 1.22

(a) Rotor diameter = 97.5 m; rotor mid-elevation = 60.9 m