75 Arlington Street, Suite 704

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75 Arlington Street, Suite 704 Boston, MA
02116 [phone] [phone] fax Web
www.cape wind.org
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RENEWABLE TECHNOLOGIES

• Photovoltaic
• Tidal
• Wave
• Biomass
• Wind- Onshore
• Wind- Offshore

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Technology Criteria

• Commercially feasible technology
• Commercial size technology availability

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Alternative Wind Park Screening Analysis Criteria

• Renewable resource availability
• ISO New England grid connection availability
• Suitable land or offshore area
• Legal/regulatory constraints
• Engineering limitations

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OFFSHORE WIND

• Availability of larger continuous areas
• Higher wind speeds
• Less turbulence
• Low wind shear
• Utilization of larger turbine designs

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Typical Offshore Wind Turbines
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The Offshore Environment

• Ambient turbulence
• Salinity, humidity temperature
• Icing and snow
• Ship impact, breaking ice
• Waves and their variation in time space
• Current, tides and scour effects
• Foundation behavior
• Marine growth

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Important Concepts

• ESW-extreme storm wave (50 or 100 year return)
• Breaking wave
• Hydrodynamic loading
• Fatigue life
• Aerodynamic fatigue
• Hydrodynamic fatigue
• Dynamic behavior

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TECHNICAL ECONOMIC SITING CRITERIA

• Wind Resource
• Water Depth
• Energy Loss
• Available Space
• Environmental Conditions
• Grid Connection

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Economic Sitting Issues

• Grid connection cost AC-high dielectric loss
  .
  DC-expensive
  conversion
• 
  commercial availability
• Foundation cost
• Accessibility construction and OM

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Power in Wind

• Kinetic energy gt mass of air moving through a
  unit of area
• Power is proportional to the cube of wind speed
• Wind speed varies with height
• Surface roughness influences wind speed

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Met-ocean Design Parameters

• Wind
• Waves
• Wind and Wave correlation
• Currents
• Bathymetry Sea Level Variations
• Marine Growth
• Icing and Sea Ice

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Design Criteria-Extreme Conditions

• Wind
• Wave
• Current
• Coincident Conditions (wind, wave and current)
• Coincident Flood Level (storm surge)

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Breaking Waves

• As waves approach shallower waters they become
  steeper and the probability of breaking increases
  significantly
• Breaking can be surging, spilling or plunging
• Plunging breakers occur in shallower water
• The normal breaking limit is ( height.78depth)
• Plunging breakers cause very high impact loads
• Designing may be impractical due to large stiff
  structures and economic impact

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Analysis of Aerodynamic and Hydrodynamic Fatigue

• Wind Contribution
• Wave Contribution
• Simultaneous Response

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Typical Foundation Types
a) Gravity Base
b) Monopole
c) tri-pod Hybrid
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Proposed Wind Turbine Generator Profile Detail
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Design Extreme Wave Comparison

• Nantucket Sound
• Storm tide 12 feet
• Design wave 16 feet
• Total 28 feet

• Georges Bank Nantucket Shoals
• 5 feet 6 feet
• 85 feet 42 feet
• 90 feet 48 feet

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North America Offshore Challenges as Compared to
Europe

• Wave heights in the Atlantic are on the average
  higher than those in the North Sea Baltic
• The North Atlantic has 30 higher wave height
  than the North Sea
• Fetch length and wind speed is reason

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Wind Park Siting Analysis Nantucket Sound
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