Cost of Fatigue Damage to Wind Turbines


In the paper entitled "Development of an Operations and Maintenance Cost Model to Identify Cost of Energy Savings for Low Wind Speed Turbines", R. Poore and C. Walford estimate Operation and Maintenance costs (in 2004 US$) for various wind turbines over their 20-year lifespan. View paper »  The following is a quote from the paper:


The O&M cost estimates for the five turbine sizes demonstrate that the major contributor to overall O&M costs over the project life is parts replacement, followed by labor. Figure 9 shows that in the first 5 years, parts costs are estimated to be 30% of the total cost, and by the end of the project life, they exceed 65% of the total cost. Additionally, if the 20-year average of $37,000 per turbine were used to gauge warranty costs for contract negotiations, rather than the average for years 1−5 of $19,000, valuable reserve funds could easily be forfeited to the warranty service provider.


These maintenance costs would significantly increase for offshore applications. Another paper describing Wind Power Costs was published by the International Renewable Energy Agency (IRENA) entitled "Renewable Energy Technologies: Cost Analysis Series". View paper »  The following quote from the paper shows the operations and maintenance costs relative to the levelized cost of electricity.


Operations and maintenance costs (O&M) can account for between 11% and 30% of an onshore wind projects levelised cost of electricity (LCOE). O&M costs for onshore wind farms in major wind markets averages between USD 0.01/kWh and USD 0.025/kWh. The O&M costs of offˆshore wind farms are higher due to the difficulties posed by the oˆoffshore environment and can be between USD 0.027 and USD 0.048/kWh. Cost reduction opportunities towards best practice levels exist for onshore wind farms, while experience oˆffshore should help to reduce costs over time, but they will always be higher than onshore.


In this same paper, a breakdown in the costs of various components as a percentage of the total costs is provided and summarized in the following table.  The table shows that the cost of the rotor hub (1.37%) is relatively minor, however costs of the other components (rotor blades, rotor bearings, main shaft, gearbox, yaw system) that can benefit by use of a teetering hub are very substantial.  The ratio of the cost of the impacted components to the cost of the rotor hub is 39.49/1.37, or 28.8/1.  It would be expected that a teetering hub would cost more than a rigid hub so this ratio would be lower, however it would still be very substantial.


Component

Percentage of Total

Tower

26.3

Rotor blades

22.2

Rotor hub

1.37

Rotor bearings

1.22

Main Shaft

1.91

Main frame

2.80

Gearbox

12.91

Generator

3.44

Yaw system

1.25

Pitch system

2.66

Power converter

5.01

Transformer

3.59

Brake system

1.32

Nacelle housing

1.35

Cables

0.96

Screws

1.04