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Market Research Report

End of Warranty Wind Farm O&M Options Report 2012: Increase Reliability and Productivity By Implementing New Retrofitting and Repowering Strategies

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Published Content info 252 Pages; 150 Figures & Graphs
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End of Warranty Wind Farm O&M Options Report 2012: Increase Reliability and Productivity By Implementing New Retrofitting and Repowering Strategies
Published: February 20, 2012 Content info: 252 Pages; 150 Figures & Graphs

This publication has been discontinued on August 2, 2017.


Improve your levelised cost of energy by increasing reliability and productivity, with new retrofitting and repowering strategies.


At the time of publication the future of new wind installations in North America is unclear. Long term Production Tax Credit (PTC) uncertainly and government lobbying in the run-up to elections mean that renewable energy as a whole, not only wind energy, is viewed as a political tool as much as part of a long term sustainable power generation solution.

In addition to this, grid access is now at a premium for wind energy developers; Still the intermittent nature of wind energy entering the system causes transmission and distribution headaches.

This means that if existing wind farm owners wish to maximise generation potential they must look to refine their existing operation to ensure maximum power is generated and sold. Operations and maintenance (O&M) strategies need to reflect this shift and O&M managers need the latest information on why, how and when to repower once their fleet comes out of warranty.

Purchase this exclusive report and you'll benefit from the following analysis:

  • LCOE: Insight into the practical techniques being used to improve LCOE
  • Analysis of the key reliability issues affecting the onshore wind industry
  • Costs and Benefits: Gain in-depth information on the costs and benefits of retrofitting and repowering wind farms
  • Accurate Market Assessment: Find out where the market is and the real possibilities for purchasing and repowering existing wind sites to take advantage of government incentives and improved modern technology
  • How to mitigate the risk: Learn what the try risks are for retrofitting and repowering, understand how to avoid them and make the most out of any constraints
  • Analysis of the excellent payback that decommissioning can now provide to a repowered wind site
  • Exclusive Industry Case Studies: Get first hand insight of sites that have implemented both retrofit and repowering solutions for increased reliability and productivity
  • Growth and Investment: Identify key growth and investment opportunities in Europe, USA and Asia

Drill down into the financial benefits possible from timely retrofit and repowering of wind sites

  • Identify the key times to consider upgrades to your wind farm
  • Uncover the paybacks experienced by recent retrofit and repowering projects
  • Learn from the experiences of developers undertaking these projects
  • Understand how to mitigate the risk of your investment
  • Gain information on Government incentives and permitting process in each market

In-depth reliability analysis

  • Find out which components are contributing the greatest number of downtimes
  • Benchmark your productivity against that of other onshore wind farms
  • Get an insight into the reality that age of turbine contributes to down time and lack of productivity
  • Learn how companies are improving productivity from their existing assets
  • Find out how continued reliance of unscheduled maintenance keeps O&M costs prohibitively expensive

The retrofit and repowering market

  • Discover what the opportunities are now available for wind farms with decreasing productivity
  • Understand what technology you can utilise to revolutionise your wind production
  • Uncover how repowering a wind site can utilise existing infrastructure and add to huge ROI

Chapter Overviews and Research Highlights

Market Assessment

A thorough assessment of trends and growth prospects for wind repowering and retrofitting worldwide. It outlines where and when projects have already been completed, which developer or manufacturer was chosen to carry out the work, and which projects are currently being undertaken and which are on the planning stage.

Research Highlights

  • $40billion worth of turbines will come out of their warranty period in 2012
  • Developers are replacing multiple numbers of turbines with fewer but larger and more powerful units, and increasing capacity by on average between three and five times
  • China will be the largest repowering and retrofitting market in 2020, with 44.7 GW, followed by the USA with 37 GW


An in-depth analysis all of the components of a wind turbine, what failures could occur post-warranty, how much they could cost to repair and how lengthy the downtime and subsequent loss of productivity would be. The section also offers in-sight into the impact of turbine size and age on reliability and productivity.

Research Highlight

Continuous Reliability Enhancement for Wind (CREW) Database, 2011


An assessment of the rewards and risks of retrofitting weighing increased availability and productivity against costs. This section also outlines the types of retrofits available, lead times and how the finances of retrofitting compare to routine O&M component replacement.

Research Highlight


Analysis of repowering options with a focus on costs, rate of return and growth potential. The report considers all repowering options, ranging from replacing a single turbine with a modern version to a complete overhaul of all turbines in a wind farm.

The report provides real wind farm repowering case studies from Germany and Spain and considers the technological benefits of new turbines.


Crucial information on the cost of decommissioning wind farms and how to recover a sizeable proportion of this expenditure through recycling components and the second-hand sale turbines. Includes an in-depth case study from the decommissioning of the Stony Creek wind farm in the USA.

Research Highlight


  • We surveyed 168 Operators/developers - collating a detailed look at the reliability of components, the cost of repowering/retrofitting and the benefits that have been achieved from this.
  • Second survey we surveyed 150 component manufacturers and service providers - again ascertaining the true reliability of components, as well as establishing what bonuses to productivity for a wind site could be gained for retrofitting and repowering.
  • We undertook in-depth interviews with operators, independent service providers, OEMs and reliability centers to bring together multiple opinions on improving wind LCOE.
Table of Contents

Table of Contents

Chapter One - Introduction

Chapter Two - Market assessment: growth prospects for wind farm repowering and retrofitting worldwide

  • 2.1. The UK 9
    • 2.1.1. Main repowering projects in the UK
    • 2.1.2. Retrofitting projects in the UK
  • 2.2. Germany
    • 2.2.1. Main repowering projects in Germany
  • 2.3. Denmark
    • 2.3.1. Main repowering projects in Denmark
    • 2.3.2. Retrofitting projects in Denmark
  • 2.4. Netherlands
    • 2.4.1. Repowering projects
  • 2.5. Other European projects
    • 2.5.1. Sweden
    • 2.5.2. Portugal
    • 2.5.3. France
  • 2.6. United States
    • 2.6.1. Repowering projects in the United State
    • 2.6.2. Retrofitting projects in the United States
  • 2.7. Canada
    • 2.7.1. Retrofitting projects in Canada
  • 2.8. China
    • 2.8.1. Retrofitting projects in china
  • 2.9. India
    • 2.9.1. Repowering projects in India
    • 2.9.2. Retrofitting
  • 2.10. Lost productivity
  • 2.11. Declining landscape

Chapter Three - Reliability of wind turbines

  • 3.1. Introduction to reliability
    • 3.1.1. Availability of reliability data
    • 3.1.2. Wind turbine components overview
    • 3.1.3. Common post warranty issues
  • 3.2. Main issues with onshore wind turbines components
    • 3.2.1. Drive train and bearings
    • 3.2.2. Electronic controls
    • 3.2.3. Gearbox
    • 3.2.4. Generator
    • 3.2.5. Hydraulic system
    • 3.2.6. Mechanical brake system
    • 3.2.7. Rotor blades
    • 3.2.8. Rotor hub
    • 3.2.9. Sensors
    • 3.2.10. Yaw system
    • 3.2.11. Blade pitching system
    • 3.2.12. Support and housing
    • 3.2.13. Tower
    • 3.2.14. Foundations
  • 3.3. Reliability of wind turbine components
    • 3.3.1. Annual failure rate
    • 3.3.2. Downtime per failure
    • 3.3.3. Mean annual downtime
    • 3.3.4. Major failures
    • 3.3.5. Downtime per major failure
    • 3.3.6. Mean annual downtime for major failures
    • 3.3.7. US continuous reliability enhancement for wind (crew) database
    • 3.3.8. Effects of wind speed on loss of productivity
  • 3.4. Cost of maintenance
    • 3.4.1. Operation and maintenance of a wind turbine
    • 3.4.2. O&M costs and wind turbine size
    • 3.4.3. Cost of repair
    • 3.4.4. Financial impact of the unscheduled maintenance
    • 3.4.5. O&M costs and wind turbine age
    • 3.4.6. Lack of productivity from old technology

Chapter Four - Retrofitting wind turbines

  • 4.1. Introduction to retrofitting
    • 4.1.1. Benefits of retrofitting
    • 4.1.2. What to look out for
  • 4.2. What is suitable
    • 4.2.1. Insurance and certification
    • 4.2.2. Retrofitting vs repowering
    • 4.2.3. Importance of optimising maintenance strategies
  • 4.3. Control monitoring system
    • 4.3.1. Maintenance strategies
    • 4.3.2. Benefits of CMS
    • 4.3.3. How monitoring systems work
    • 4.3.4. Vibration analysis
    • 4.3.5. Fluid analysis
    • 4.3.6. Thermography
    • 4.3.7. Acoustic monitoring
    • 4.3.8. Stain measurements
    • 4.3.9. Process parameters
    • 4.3.10. Fibre optics measurement
  • 4.4. Cost data and examples for CMS
    • 4.4.1. Vibration based CMS for gearbox
    • 4.4.2. Comparison between replacement and refurbishment
    • 4.4.3. Comparison between visual inspection and vibration analysis
    • 4.4.4. Monitoring systems for predictive maintenance strategy
    • 4.4.5. Bearing fault - wind farm in Canada
    • 4.4.6. Vibration analysis to detect gear damage
    • 4.4.7. Simulation of financial benefits of condition monitoring
  • 4.5. Scada systems
    • 4.5.1. Features and benefits of Scada systems
    • 4.5.2. How scada systems work
    • 4.5.3. Gearbox health monitoring with scada system
  • 4.6. Blades retrofitting
    • 4.6.1. Blades retrofitting for changed wind regime
    • 4.6.2. Tubercle technology for blades retrofitting
    • 4.6.3. Suzlon retrofits its blades
    • 4.6.4. Clipper retrofit project
    • 4.6.5. Potential savings from avoiding blade damages
  • 4.7. Electrical components retrofitting
    • 4.7.1. Converter upgrade for grid connections
    • 4.7.2. Sealing solutions for electrical cables
    • 4.7.3. Retrofit for grid compatibility in Spain
    • 4.7.4. Potential savings from avoiding generator damages
  • 4.8. Couplings and bearings retrofitting
    • 4.8.1. Wind turbine couplings for retrofitting
    • 4.8.2. Wind turbine bearings for retrofitting
    • 4.8.3. Potential savings from avoiding bearing damages
  • 4.9. Gearbox retrofitting
    • 4.9.1. Gearbox design technologies
    • 4.9.2. Direct drive wind turbine technology
    • 4.9.3. Potential savings from avoiding gearbox failure
    • 4.9.4. Savings through retrofitting automated lubrication maintenance
    • 4.9.5. Cost savings from scheduled maintenance of main shaft bearings
    • 4.9.6. Return on investment of an automatic lubrication system
  • 4.10. Foundations
  • 4.11. Yaw and pitch systems
  • 4.12. Other technologies available
    • 4.12.1. Bolts load measurement
    • 4.12.2. Benefits of bolts load measurement
    • 4.12.3. Cost saving from a bolt load system
    • 4.12.4. Laser wind sensor system

Chapter Five - Repowering wind turbines

  • 5.1. Introduction to repowering
    • 5.1.1. Options for repowering
  • 5.2. Technology improvement of modern wind turbines
    • 5.2.1. Increased energy yield from new wind turbines
    • 5.2.2. Increase of height in new wind turbines
    • 5.2.3. Increase of rotor diameter in new wind turbines
    • 5.2.4. Reduction of rotor speed in new wind turbines
    • 5.2.5. Increased productivity at low wind speed
    • 5.2.6. Reduction of noise emissions
    • 5.2.7. Improvements in grid compatibility
    • 5.2.8. Reduction of O&M costs in newer wind turbines
  • 5.3. Turbine size trend for repowering market
  • 5.4. When to think about repowering
    • 5.4.1. Benefits from repowering
    • 5.4.2. Technical benefits
    • 5.4.3. Economic benefits
    • 5.4.4. Social and environmental benefits
    • 5.4.5. Further technical considerations
    • 5.4.6. Further environmental considerations
    • 5.4.7. Further commercial considerations
  • 5.5. Economic policy for repowering
    • 5.5.1. Germany
    • 5.5.2. Denmark
    • 5.5.3. Spain
    • 5.5.4. other countries
  • 5.6. planning aspects of repowering
  • 5.7. investments developed in repowering
    • 5.7.1. repowering experience in Germany
    • 5.7.2. DEWI database on german repowering projects
    • 5.7.3. comparison of turbine size
    • 5.7.4. comparison of number of turbines
    • 5.7.5. comparison of ratio of mw installed
    • 5.7.6. comparison of hub height
    • 5.7.7. comparison of year of completion
    • 5.7.8. overall repowering experience 2010
    • 5.7.9. repowering experience in other countries
  • 5.8. case studies
    • 5.8.1. wind farm in lower Saxony - Germany
    • 5.8.2. cash flow comparison for a german project
    • 5.8.3. potential cash flow simulated in Germany
    • 5.8.4. cost comparison for a repowering project in Spain
    • 5.8.5. repowering feasibility assessment in Spain
    • 5.8.6. Sensitivity analysis of the Spanish project
  • 5.9. Growth potential of repowering
    • 5.9.1. Growth potential in Germany
    • 5.9.2. Growth potential in California
    • 5.9.3. Growth potential in India
    • 5.9.4. Trend of wind turbine sizes in India
    • 5.9.5. Investment in wind power sector
    • 5.9.6. Potential benefits from repowering
    • 5.9.7. Challenges and barriers of repowering in India
    • 5.9.8. Growth potential in India

Chapter Six - Decommissioning wind turbines

  • 6.1. Introduction to wind turbines decommissioning
    • 6.1.1. Decommissioning and planning permission
    • 6.1.2. Decommissioning and investment analysis
  • 6.2. The cost of dismantling
    • 6.2.1. Record hill wind project
    • 6.2.2. Stony creek wind farm
  • 6.3. What to do with old turbines
    • 6.3.1. Recycling of wind turbine components
    • 6.3.2. Second hand market for wind turbines
    • 6.3.3. The advantages of employing used wind turbines
    • 6.3.4. The challenges associated with employing used wind turbines
    • 6.3.5. Residual value of a wind turbine
    • 6.3.6. Profitability of new and old wind turbines
    • 6.3.7. Considerations on the maintenance of old wind turbines
    • 6.3.8. Final considerations on second hand wind turbines

Chapter Seven - Conclusions

Chapter Eight - References


  • Table 1: Post-warranty wind farm capacity suitable for repowering or retrofitting by 2020
  • Table 2: Overview of Solutions and Practices to Reduce O&M Costs
  • Table 3: Factors determining the Suitability of Components for Certain Types of Wind Turbine
  • Table 4: Effect of the Retrofitting on the Insurance
  • Table 5: Effect of the Retrofitting on the Certification
  • Table 6: Reasons for Not Considering Repowering as a further Option other than Retrofitting
  • Table 7: Brief Overview of O&M and Retrofitting Services
  • Table 8: Summary of Advantages and Disadvantages from Different Maintenance Strategies
  • Table 9: Overview of Control Monitoring Technologies
  • Table 10: Potential Break Even Point for a CMS
  • Table 11: Potential Savings when Refurbishing rather than Replacing Components
  • Table 12: Potential Escalation of Cost for Gearbox Failure due to Lack of Preventive Maintenance Strategy
  • Table 13: Comparison of Effectiveness between Various Grades of Monitoring Techniques for Gearbox
  • Table 14: Potential Savings provided by a CMS System
  • Table 15: Potential Savings provided by a CMS System
  • Table 16: Potential Savings provided by a CMS System
  • Table 17: Assumptions for Simulation of Financial Assessment of a CMS System
  • Table 18: Economic Feasibility for Retrofitting a SCADA System
  • Table 19: Economic Feasibility for Retrofitting a SCADA System
  • Table 20: Potential Savings from Avoiding Blade Failure
  • Table 21: Potential Savings from Avoiding a Generator Failure
  • Table 22: Main Benefits provided by Retrofitted Bearings
  • Table 23: Representative Costs for Replacing Drive Train Components
  • Table 24: Main Benefits provided by Direct Drive Technology
  • Table 25: Potential Savings from Avoiding Gearbox Failure
  • Table 26: Main Tasks and Cost for Main Shaft Replacement
  • Table 27: Economic Feasibility for Retrofitting an Automated Lubrication System
  • Table 28: Potential Savings from Avoiding Foundations Failure, (Own Production based on direct source
  • Table 29: Potential Loss of Profitability due to Energy Loss during Downtime caused by Yaw Systems Failures
  • Table 30: Estimated Cost Savings generated by Bold Load Measurement System
  • Table 31: Estimated Economic Feasibility of Laser Wind Sensor
  • Table 32: An Example of Optimised Generation through the Repowering of an old Wind Farm
  • Table 33: Estimation on O&M costs for Existing and Repowered Sites
  • Table 34: Distribution of Wind Turbines
  • Table 35: Comparison between an Old Wind Farm and the Repowered Site
  • Table 36: Commercial Example of Repowering Project
  • Table 37: Main Parameters and Results of Financial Analysis
  • Table 38: Simulated Financial Data of the Repowering Project
  • Table 39: Simulated Financial Data of the Repowering Project
  • Table 40: Total specific cost comparison between a new and a remanufactured 15 MW wind farm project
  • Table 41: Scenario investigated
  • Table 42: Wind Turbine Models Employed in the Feasibility Study
  • Table 43: Options Investigated by the University Research Team
  • Table 44: Technical Performance of the three Wind Turbine Models Investigated
  • Table 45: Economic Assessment of Various Options Investigated
  • Table 46: Record Hill Wind Project - Estimated Decommissioning Costs
  • Table 47: Record Hill Project - Estimated break down of Decommissioning Costs
  • Table 48: Stony Creek Energy Wind Farm Estimated Decommissioning Costs after 1 year
  • Table 49: Example of Material Recycling Opportunities from a Dismantled Wind Turbine


  • Graph 1 : xample of Capital Cost Breakdown for a Commercial Onshore Wind Turbine
  • Graph 2: Causes of Wind Turbine Failure - Survey on 15,500 German Machines
  • Graph 3: Annual Failure Rate
  • Graph 4: Downtime Days per Failure
  • Graph 5: Mean Annual Downtime
  • Graph 6: Ratio between annual Major Failures and Total number of Failures
  • Graph 7: Downtime Days associated to Major Failures
  • Graph 8: Mean Annual Downtime for Major Failures
  • Graph 9: Availability of a sample of US wind turbines
  • Graph 10: Correlation between Failure Rate and Wind Energy Index
  • Graph 11: Correlation between Wind Speed and Failure Rate
  • Graph 12: Example of Distribution of O&M Costs for Onshore Wind Turbines
  • Graph 13: O&M Costs for 3 Different Countries
  • Graph 14: Relationship between O&M Costs and Turbine Size
  • Graph 15: Relationship between Prices of O&M Service Contracts and Turbine Nameplate Capacity
  • Graph 16: Cost Breakdown of Large Component Replacement
  • Graph 17: Commercial Operation Data on Average Annual O&M Costs
  • Graph 18: Average Annual O&M Costs Increase for Five Wind Turbines
  • Graph 19: O&M Cost Trends for Two Wind Turbines
  • Graph 20: Loss of Energy Production due to Component Failure
  • Graph 21: Cost of Retrofitted Components compared to the Cost of Original Parts
  • Graph 22: Lead Time of Replaced Components
  • Graph 23: Effect of Retrofitting on Insurance or Certification of a Wind Turbine
  • Graph 24: Retrofitting considered as a Better Alternative than Repowering
  • Graph 25: Simulated Simple Pay-Back of a CMS
  • Graph 26: Technological Development of Wind Energy Generators
  • Graph 27: Wind Energy Technology Development - Relationship between Rated Power and Average Energy Yield
  • Graph 28: An example of Optimised Generation through Repowering
  • Graph 29: Wind Energy Technology Development - The Relationship between Rated Power and Max Height to the Tip
  • Graph 30: The increased Productivity of Higher Wind Turbines
  • Graph 31: Wind Energy Technology Development - The Relationship between Rated Power and Rotor Diameter
  • Graph 32: Wind Energy Technology Development - The Relationship between Rated Power and Max Rotor Speed
  • Graph 33: Wind Speed and Generation Time Account
  • Graph 34: The Noise Emission Comparison between an Old Wind Turbine and a Modern Multi-Megawatt Turbine at Ground Level
  • Graph 35: O&M Costs Comparison between Old Wind Turbines and Newer Wind Turbines
  • Graph 36: O&M Costs Trend of selected Wind Projects
  • Graph 37: Turbine Size Trends
  • Graph 38: Comparison between the Average Size [kW] of Wind Turbines (WTs) installed in Germany before 2000 and WTs Repowered
  • Graph 39: Repowering Projects developed in Germany (early 2009)
  • Graph 42: Comparison of Turbine Size for Repowering Projects developed in Germany
  • Graph 43: Comparison of the Number of Turbines for Repowering Projects developed in Germany (early 2009)
  • Graph 44: Ratio of Capacity installed over original Capacity for Repowering Projects developed in Germany
  • Graph 45: Comparison of Hub Height for Repowering Projects developed in Germany
  • Graph 46: Comparison of Year of Completion for Repowering Projects developed in Germany
  • Graph 47: Repowering Projects completed in Germany in 2010
  • Graph 48: Comparison between the Old Wind Farm and Repowered Wind Farm; Wind Farm in the Lower Saxony Region - Germany
  • Graph 49: Potential Cash Flow of German Project (Bremer Landesbank) - Comparison between Repowered Farm and Existing Site
  • Graph 50: Comparison between the Old Wind Farm and Repowered Wind Farm
  • Graph 51: Cash Flow of the Repowering Project
  • Graph 52: Cost Distribution for New 15 MW Project
  • Graph 53: Cost Distribution for Remanufactured 15 MW Project
  • Graph 54: Cost Comparison between two Assessed Options
  • Graph 55: Variables affecting the NPV of a Repowering Project
  • Graph 56: Variables affecting the IRR of a Repowering Project
  • Graph 57: Variables affecting the Payback Time of a Repowering Project
  • Graph 58: Percentage of Small Wind Generators in India in 4 Reference Years
  • Graph 59: Trend of the Average Wind Turbine Size installed in India
  • Graph 60: Estimated Decommissioning Costs, Record Hill Project
  • Graph 61: Loss in Value of a Wind Turbine
  • Graph 62: Estimated Decommissioning Costs, Stony Creek Project
  • Graph 63: Percentage of Estimated Decommissioning Costs
  • Graph 64: Percentage of Estimated Income from Material Sale following Decommissioning
  • Graph 65: Percentage of Estimated Net Decommissioning Costs, Stony Creek Project
  • Graph 66: Relationship between Age and Price of a Wind Turbine
  • Graph 67: Comparison of Costs between Wind Projects with New Wind Turbines and with Old (Used) Wind Turbines


  • Figure 1: Main Components of a large Wind Turbine
  • Figure 2: Typical Shape of Bath-tub Curve for a Mechanical System
  • Figure 3: Diagram of a typical Drive Train with main connected components
  • Figure 4: Example of Gearbox
  • Figure 5: Example of Rotor Blade damaged by lighting
  • Figure 6: Example of Damaged Blade
  • Figure 7: Example of Rotor Hub
  • Figure 8: Example of Yaw System
  • Figure 9: Example of Possible Consequences on Reliability from two different Approaches in Maintenance Strategy
  • Figure 10: Damaged input bevel Gear Teeth
  • Figure 11: Gear tooth damaged
  • Figure 12: Blades Retrofitting
  • Figure 13: Blades Retrofitting
  • Figure 14: Whalepower Tubercle Technology
  • Figure 15: Example of Converter produced by ABB
  • Figure 16: Example of couplings
  • Figure 17: Example of Bearings produced by SKF
  • Figure 18: Example of Turbine with Direct Drive Generator
  • Figure 19: Example of Layout Variation in a German Wind Farm
  • Figure 20: Example of the Site before Repowering
  • Figure 21: Example of the Site after Repowering
  • Figure 22: Disposal Routes for Wind Turbine Components
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