Deepwater Offshore Wind Technology Research RequirementsDeepwater Offshore Wind Technology Research RequirementsWalt MusialWalt Musial

Windy onshore sites are not close to coastal load centers 

The electric utility grid cannot be easily set up for interstate electric transmission 

Load centers are close to the offshore wind sites 

Credit: Bruce Bailey, AWS Truewind 

Offshore Wind — U.S. Rationale Why Go Offshore? 

Offshore Wind — U.S. Rationale Why Go Offshore?

Courtesy of GE Energy % area class 3 or above 

U.S. Population Concentration U.S. Wind Resource 

DOE Deepwater Wind EnergyWorkshops

Washington D.C. Oct. 15-16, 2003 –Washington D.C. Oct. 26-27, 2004 

DOE Deepwater Wind EnergyWorkshops

Washington D.C. Oct. 15-16, 2003 –Washington D.C. Oct. 26-27, 2004

Deepwater Wind Energy 

Marine and Offshore Oil 

and Gas Experience 

Offshore Wind Shallow Water 

Experience 

Workshop Objectives • Leverage experience and expertise from offshore industries such as oil and gas, marine engineers, offshore 

wind, ocean climatologists, ecologists, and oceanographers. • Identify technology gaps to achieve a mature offshore wind industry in the United States. 

Key Technology Findings • Monopiles are limited to 25-m depths due to limits in 

structural stiffness and installation equipment capacity. • Fixed bottom tripod or space frame substructures can 

transition into greater depths – e.g. Talisman Energy 42-meters. 

• Floating platforms will be more economical in deep water but the cross-over depth must be determined by careful study. 

• Added difficulties working at sea will become the major cost driver and must be minimized by new technology. 

• MET-Ocean measurement techniques must be enhanced to accurately predict loads and energy production. 

• Demonstration projects in the ocean will be essential to establish a basis for design. 

U.S. Offshore Wind EnergyResource

U.S. Offshore Wind EnergyResource

Region 0 - 30 30 - 60 60 - 900 > 900 New England 10.3 43.5 130.6 0.0 Mid-Atlantic 64.3 126.2 45.3 30.0 Great Lakes 15.5 11.6 193.6 0.0 California 0.0 0.3 47.8 168.0 Pacific Northwest 0.0 1.6 100.4 68.2 Total 90.1 183.2 517.7 266.2 

GW by Depth (m) 

Resource Not Yet Assessed 

Offshore Turbine Design BasisOffshore Turbine Design BasisDefine external conditions Measurements – Extreme wind, extreme wave, wind/wave combinations, seastate, wind shear, ice, currents, tide, soil mechanics, ship collisions, turbulence, wind farm turbulence. 

Design studies – Narrow the options • What is the design load envelope • What foundations achieve the lowest cost? • What are the design drivers? Code development • Coupled platform/turbine responses • Ocean Test Bed Validation Design standardsIEC, ABS, DNV, GL, API 

Current Technology 

Offshore labor and equipment costs are key drivers. Current turbine designs use onshore practices. 

Installation Strategies • Standardize and mass-produce platforms and 

substructures • Float-out whole systems • Reduce large vessel dependency • Develop low cost mooring systems 

Operation and Maintenance Strategies As machines get larger and more remote smarter systems will become economical. • Offshore turbines must close the loop between 

O&M and turbine design. • High reliability designs • Designs for in-situ repair • Remote condition monitoring • Turbine self diagnostics • Safer and faster personnel transport 

Minimize Work at SeaMinimize Work at SeaHigh offshore availability will require turbine designs that are tolerant of 

inaccessible periods 

40 

60 

80 

100 

406080100 

Accessibility 

Ava

ilabi

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Deepwater Design Offshore Design Onshore Design 

onshore offshore remote 

Research and Development needed 

tot  implement deepwat

 implementer ste raterat gies 

Photo Courtesy of GE Energy 

Research and Development needed 

gieso

deepwat r st e

Testing and ValidationTesting and Validation•Scale model testing – Configuration tradeoff studies in wind/wave tank. •Hybrid testing – Wave simulations can be conducted in a subscale test-bed on land under real wind conditions to measure turbine response to rare load combinations. 

•Full-scale blade and drivetrain test facilities – Large wind turbine components must be tested and verified before field deployment. 

•Field testing – Full-scale test loads in real ocean environments are essential. – Certification – Code validation – Safety verification 

5 Offshore R&D Subcontracts – $ 11M (multi-year) 

Offshore Wind Collaborative - $100K 

Environmental and Regulatory Issues -

$200K 

Offshore Wind Resource Assessment 

Wind Mapping & Validation - $400K 

Offshore Wind Research and Analysis Activities - $225K • Deepwater Workshops – Research Gap Analysis • IEA Offshore Annex 23 – Modeling Needs for Deepwater • Deepwater Technology R&D – Codes/Reference Turbine • Technology Characterization – COE, Technology Impact • Offshore Standards Development – IEC 61400-03 

FY 2005 DOE Offshore Wind Energy Activities and Funding FY 2005 DOE Offshore Wind 

Energy Activities and Funding

What is the Wind Speed = ?? 

Understanding Offshore WindUnderstanding Offshore Wind 

Neutral boundary layer 

Convective boundary layer 

Stable boundary later with low level jet 

Courtesy of Bruce Bailey, AWS Truewind 

• Develop new measurement techniques and sensors for accurate wind speeds at heights where wind turbines operate – Without MET towers! 

• Understand and utilize available offshore data sets – Offshore MET measurements maycome from many sources. 

• Validate wind speed/potential – From meso-scale to micro-scale. • Validate profile variations (wind shear) – Profiles may change with wind speed, season,and time of day. 

Offshore System OptimizationOffshore System Optimization• Higher speed rotors (lower aerodynamic noise constraints) 

will lower system weight and increase energy capture. • Larger turbine sizes can lower offshore balance of station 

and operation and maintenance costs. • Lower shipping and erection constraints may favor direct 

drive, yawing platforms, etc. • Greater weight penalties on floating systems will drive use 

of lighter materials (e.g. extended use of composites in towers, hubs, bedplates, shafts) and multi-rotor systems. 

• Wind/wave/hydrogen/storage energy technology convergences may spawn new energy supply models 

SummarySummary• U.S. offshore wind energy potential is over 1000-GW. • U.S. offshore wind resource is complementary to the 

on-shore wind resource due to geographic separation. • U.S. deepwater wind technology is necessary for full 

offshore wind energy deployment. • Offshore experience in shallow water is essential for 

deepwater technology to move forward. • Expanded R&D (technological and environmental) is 

necessary for cost-effective deepwater wind energy. • Commercial deepwater technology will take10–15 years 

to develop. The information contained in this poster is subject to a government license. Prepared for the American Wind Energy Association (AWEA) WindPower 2005 Conference, 15-18 May 2005, Denver, Colorado NREL/PO-500-38135