Stan T. Rosinski Program Manager, Renewables

Wind Power Summit February 25, 2013

Technology Needs for Advancing Wind Power Generation

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Three Key Aspects of EPRI

Independent Objective, scientifically based results address reliability, efficiency, affordability, health, safety and the environment

Nonprofit Chartered to serve the public benefit

Collaborative Bring together scientists, engineers, academic researchers, industry experts

Independent

Collaborative

Nonprofit

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EPRI’s R&D Portfolio

Environment and Renewable Energy • Air Quality • Energy and Environmental

Analysis • Land and Groundwater • Occupational Health and Safety • Renewable Energy • T&D Environmental Issues • Water and Ecosystems

Generation • Advanced Coal Plants, Carbon

Capture and Storage • Combustion Turbines • Environmental Controls • Major Component Reliability • Materials and Chemistry • Operations and Maintenance • Power Plant Water Management Nuclear

• Advanced Nuclear Technology • Chemistry, Low-Level Waste, and

Radiation Management • Equipment Reliability • Fuel Reliability • Long-Term Operations • Materials Degradation/Aging • Nondestructive Evaluation and

Material Characterization • Risk and Safety Management • Used Fuel and High-level Waste

Management

Power Delivery and Utilization • Transmission Lines and

Substations • Grid Operations and Planning • Distribution • Energy Utilization • Cross-Cutting Technologies

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Key Strategic Technical Issues Long-Term Operations

Smart Grid

Energy Efficiency

Near Zero Emissions

Water Resource Management

Renewable Resources and Integration

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Renewable Resources and Integration

Key Challenges • Generation technology:

cost and performance

• Grid reliability: Operating the system with variable resources

• Environmental impacts

Many questions remain regarding renewable costs, performance, impact and integration

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Drivers for Wind Research

• Reduce cost of wind (capital, LCOE), optimize performance and expand installed capacity

• Accelerate grid parity w/o subsidies • Address wind resources variability and

grid penetration issues • Innovative cost-effective wind energy

storage options • Off-shore wind deployment challenges • Minimize/mitigate environmental impact

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Wind R&D Roadmap

Issue R&D Area Wind Turbine Components Blade design enhancements

Improve drive train reliability Improved materials/designs for taller towers (100-175m)

Integrated Turbine Systems (large-scale; >6MW)

New large-scale systems needed

Energy Storage Integrating wind energy with on-site storage

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Wind R&D Roadmap

Issue R&D Area Offshore Wind Foundations

Components suited to offshore environment (blades, rotors, drive-train) Methodologies to identify/ evaluate critical risks

Wind Forecasting Improved hour-ahead and day-ahead forecasting Seconds/minutes forecasting

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Wind R&D Roadmap

Issue R&D Area Condition Monitoring Improved on-line monitoring, data collection/

mining and analysis Non-destructive evaluation techniques

Performance Optimization Adaptive control techniques for diverse terrains/models Enhanced reliability-centered maintenance (RCM) approaches Wind turbine database Life extension

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EPRI Wind Energy Program

Wind Power Technology Assessment and

Development Wind Power Asset

Management Wind Environmental

Issues

Identify, evaluate and conduct targeted R&D on wind technologies with high potential to address critical industry issues

Model Development and Validation

• Ground-based inspection

• Life extension

• Curtailment for Bat Protection

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Ground Based Inspection of Wind Turbine Blades Drivers • Blade failure – overall reliability • Blade manufacturing improving – but defects do exist

– Bond issues (lack of, inadequate) – Delaminations, wrinkles

• Blades environmentally degrade, fatigue • Blade replacement costly

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Approach

• Develop an NDE and engineering tool integrating: – Advanced NDE technology for detection of flaws

• Preservice and in-service • Ground-based

– Flaw analysis processes • Effect of flaws • Remaining blade life

Proactive Wind Turbine Blade Life and Asset Management Tool

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Laser Shearography

• Detection of flaws in complex composite materials in aeronautical and aerospace industry (field or factory)

• Uses laser field and interferometer to detect flaws in part, under loading (heat, pressure, vacuum)

Courtesy of Laser Technology Inc.

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Laser Shearography Testing at National Renewable Energy Laboratory

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Left photo - Visual examination of lightning damage to wind turbine blade

Right photo - Laser shearogram of the same area indicating a 25 inch (635 mm) delamination extending from lightning strike.

Images Courtesy of Laser Technology Inc.

Visual Examination versus Laser Shearography Lightning Damage

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Infrared Thermography

• Enhance ground based inspection technology • High-speed inspection of blades during operation

– Cost effective – Large area inspection

• Infrared Thermography – Fast ‘screening’ scan – Identify areas for follow-up

inspection – Simultaneous imaging of

blade serial number Thermal Image of 15m segment of 2 MW rotating blade – No Indications Image – Courtesy of Digital Wind Systems

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Distance from Root: 6 meters 5 meters 3.5 meters

Laser Shearography (top) vs Thermography Imaging (bottom) Defects are Waves in the Carbon Fiber Spar Cap – HP Side (top of blade in fixture)

Images are not to scale.

Blade failed at this defect

Images – Courtesy of Digital Wind Systems

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Fatigue crack imaged 100 ft. from blade

Imaged Defect due to Spar Cap Fiber Wave after 2.2 Million Fatigue Cycles, Nominal Turbine Blade Operation Stress Load

Image – Courtesy of Digital Wind Systems

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Tower weld remains slightly warmer, heated

by sunlight during daylight.

Ground-Based Inspection Summary Wide Field Thermography of 1.6 MW Blades

Actual field tests have small field of view to image flaws

Two test types for fast survey and detailed imaging

Image – Courtesy of Digital Wind System

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Wind Power and Bats Issue and Challenge

• Financially important to Agriculture – Pollination – Insect control

• Important in the ecosystem – Very slow reproductive rate

(1-2 young/year) – High attrition rate of young

• Mortality rate increasing in the US/Canada – White Nose Syndrome – Expanding area

• Most mortality at wind sites occurs June through October

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Range of Federally Endangered Bat (and bat species proposed to be listed in 2013)

Striped – Indiana bats (Endangered) Light purple = Eastern Small-Footed (proposed for listing) Dark purple = Northern Long-Eared (proposed for listing) Gray = Little Brown Bats (proposed for listing)

Courtesy of We Energies

White-nose Fungus is driving listing consideration

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Options to Miminize Fatalaties

• Operation of turbines must be changed during bat migration (June-October) – Increase cut-in speed

• Turbines begin to rotate only at higher wind speeds

• Generation lost during periods of low wind

– Shut off turbines for the entire night • Generation lost every evening

– Restrict operation only during periods of bat activity (preferred)

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ReBAT system courtesy of Normandeau Associates

Smart Curtailment Acoustic-Based Detection

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Automated Wind Turbine Curtailment Scope

• Acoustic monitoring of bat activity at nacelle • Post-construction mortality survey • Develop predictive bat mortality model • Develop Bat Detection Shutdown System

• Monitor 4 nacelles

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Automated Wind Turbine Curtailment Summary

• Reducing bat mortality through curtailments is here – Potentially widespread – Curtailing only when necessary is preferred

• Proactive approach • Minimizes generation loss

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Together…Shaping the Future of Electricity

For additional information:

Stan Rosinski Program Manager, Renewables Electric Power Research Institute srosinski@epri.com 704-595-2621

Additional Information

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Extending Wind Turbine Life

• Reliability Challenges

• Safety Challenges

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End of Design Life Options

Decommission upon reaching end of design life

Take measures to reduce fatigue accumulation

Run beyond design life but take measures to ensure low risk of failure Run blindly beyond design life

Lower risk Higher risk

Higher return

Lower return

Combination of proactive approaches

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Proactive Life Extension Methods Examples

• Operations and maintenance (O&M) strategies including modifying operations

• Mining O&M records to understand and predict component reliability • Load measurement to track fatigue accumulation or to control the

turbine better • Flight Leader Concept: selecting turbines to serve as a sample

subset of a fleet • Targeted inspections to detect incipient failures and ensure

structural integrity beyond design life • Turbine refurbishment or retrofit • Advanced controls to reduce fatigue loading

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Engineering/Economic Assessment Three Scenarios

• Scenario 1 – Targeted Inspections – Regular inspections to monitor risk of failure:

• Foundations - 5 year interval • Blades/selected tower welds/hubs – annually

– Continued operation • Scenario 2 – Modified Operation

– Reduce operation (turbine de-rate) during high loading events • Reduce fatigue accumulation • Less power produced (1-3% annual production)

– Operational modification assumed to start in year 1

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Engineering/Economic Assessment Three Scenarios

• Scenario 3 – Advanced Controls – Implement advanced controls at year 0 and at year 10 using:

• Lidar based controls (mean load reduction of 8%) • State estimation (3-7% load reduction)

– Reduced downtime and O&M costs with reduced loads – Additional O&M costs and downtime for lidar

Case Mean Load Reduction Mean Life

Lidar implemented at year 0 8% 28 years

Lidar implemented at year 10 8% 24 years

State estimation implemented at year 0 5% 25 years

State estimation implemented at year 10 5% 22 years

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Wind Turbine Life Extension Summary Results

Scenario NPV

(millions of dollars)

NPV Percent Difference from

Base Case IRR

IRR Percent Difference from

Base Case

Base Case $38 0% 8.1% 0%

Targeted Inspections: 25 years $82 113% 9.3% 14%

Targeted Inspections: 30 years $119 210% 10.0% 23%

Targeted Inspections: 35 years $152 294% 10.4% 28%

Operational Modifications, 9% load reduction $80 108% 9.2% 13%

Operational Modifications, 5% load reduction $105 173% 9.6% 18%

Advanced Controls, Lidar implemented at year 0 $93 143% 9.2% 13%

Advanced Controls, Lidar implemented at year 10 $63 65% 8.7% 7%

Advanced Controls, State Estimation implemented at year 0 $85 121% 9.4% 15%

Advanced Controls, State Estimation implemented at year 10 $63 64% 8.9% 9%

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Wind Turbine Life Extension Conclusions

• Life extension generally cost effective (your mileage may vary).

• Project-specific uncertainties will require an analysis of consumed fatigue-life prior to any life extension program.

• Best approach to life extension will be heavily site and owner specific.

• More benefit could be achieved from a combination of approaches as they are not mutually exclusive.