Renewable Energy Research Laboratory amazonaws com
Renewable Energy Research Laboratory
Optimization of Offshore Wind Turbines and Layouts
www.middelgrunden.dk
EBC Seminar Series on Offshore Wind Energy November 28, 2007
J. F. Manwell, Professor and Director Renewable Energy Research Laboratory Department of Mechanical and Industrial Engineering Univ. of Mass./Amherst, MA
University of Massachusetts
Renewable Energy Research Laboratory
Overview • Offshore wind overview • Design of offshore wind turbines themselves • Considerations: – – – – – – – – –
Wind Waves Seabed soil characteristics Water depth Distance from shore Spacing Installation options Environment Operation and maintenance University of Massachusetts
Renewable Energy Research Laboratory
Offshore Wind Farms • Cost per MW decreases with increasing project size • New merchant plant projects are typically100s of MWs each
University of Massachusetts
Renewable Energy Research Laboratory
Offshore Wind Cost Elements • There is much more to the cost than the turbine itself Operation and Maintenance 25%
Electrical Infrastructure Engineering 15% and Managem ent 3%
Turbine 33%
Support Structure 24%
University of Massachusetts
Renewable Energy Research Laboratory
Economics: Cost of Energy • Total installed costs – Turbines, support structures, electrical system – Distance from shore, depth, Installation
• Energy produced – Wind resource – Turbine operating characteristics – Turbine spacing
• Operation and Maintenance (O & M) – Scheduled maintenance and repairs
• Financial considerations (interest rates, etc.) University of Massachusetts
Renewable Energy Research Laboratory
Turbine Design Drivers • • • • •
Wind speed/extremes Waves/extremes Seabed properties Water depth Design standards
University of Massachusetts
Renewable Energy Research Laboratory
Wind Turbine Support Structures • Typical offshore wind turbine support structure options • Type used will depend on seabed properties
rotor-nacelle assembly
tower
tower support structure
platform
water level sub-structure
sub-structure
pile
sea floor pile seabed
foundation
University of Massachusetts
Renewable Energy Research Laboratory
The Wind • Higher average wind speeds increase energy production; greater revenue • Higher average winds are associated with higher extreme winds structures must be more robust; higher costs • Fluctuating winds result in fatigue more or better material may be required; higher costs
University of Massachusetts
Renewable Energy Research Laboratory
Waves • Waves produce forces on support structures support structures must withstand those forces; higher costs • Periodic nature of waves can excite undesirable response in structure must be considered in the design; possibly higher costs
University of Massachusetts
Renewable Energy Research Laboratory
Seabed Soil • Seabed soil characteristics affect type of support structures that can be used, and their cost • Sand, gravel allow monopiles; lower costs • Rock may require drilling; higher costs
University of Massachusetts
Renewable Energy Research Laboratory
Water Depth • Greater water depth more site options • Greater water depth more extensive support structures; higher costs • Greater water depth higher waves, more rugged support structures; higher costs • Greater water depth limited options of installation vessels; more expensive installations; higher costs University of Massachusetts
Renewable Energy Research Laboratory
Waves
• Waves, together with the wind, are the primary external conditions which affect the design and thus cost of offshore windUniversity turbinesof Massachusetts
Renewable Energy Research Laboratory
Wave Forces • Forces arise due to the velocity and acceleration of water particles
University of Massachusetts
Renewable Energy Research Laboratory
Example of Construction of Offshore Structure
Deeper water means more steel more expensive! University of Massachusetts
Renewable Energy Research Laboratory
Wind Farm Issues • In addition to the turbines themselves: – Wake effects – Distance from shore
University of Massachusetts
Renewable Energy Research Laboratory
Wake Effects • Upwind turbines can affect downwind turbines – Decreased average wind decreased energy – Increased turbulence increased fatigue
• Spacing of turbines is important consideration in larger wind farms – Greater spacing Less wake effect Higher cable cost University of Massachusetts
Renewable Energy Research Laboratory
Distance from Shore (1) • Greater distance higher wind speeds, greater energy production; greater revenue • Greater distance fewer objections; easier permitting; fewer delays; lower costs • But….
University of Massachusetts
Renewable Energy Research Laboratory
Distance from Shore (2) • Greater distance deeper waters; higher costs • Greater distance longer time to access turbines for operation/maintenance; higher costs • Greater distance longer electrical cables; higher costs • Greater distance different environmental impact issues, e.g. marine mammals; more extensive permitting (?); higher costs University of Massachusetts
Renewable Energy Research Laboratory
Installation: Shallow Water
University of Massachusetts
Renewable Energy Research Laboratory
Installation: Deeper Water
University of Massachusetts
Renewable Energy Research Laboratory
Access for O&M (Catamaran)
University of Massachusetts
Renewable Energy Research Laboratory
Access for O&M (Helicopter)
Helicopter landing pad University of Massachusetts
Renewable Energy Research Laboratory
Optimizing the Offshore Layout (UMass Model)
• Consider the effects of the various factors • Seek to (1) minimize cost of energy (COE) or (2) to maximize revenue • Use mathematical sub-models for performance or costs of various components • Combine in comprehensive overall model, with output that can be minimized or maximized University of Massachusetts
Renewable Energy Research Laboratory
Conclusion • Offshore wind energy attractive energy option for Massachusetts • Many issues to consider! – Wind, waves, distance from shore, depth, soil type, environment, spacing, installation, O&M…
• Thorough analysis is needed to find economic optimum
University of Massachusetts
Optimization of Offshore Wind Turbines and Layouts
www.middelgrunden.dk
EBC Seminar Series on Offshore Wind Energy November 28, 2007
J. F. Manwell, Professor and Director Renewable Energy Research Laboratory Department of Mechanical and Industrial Engineering Univ. of Mass./Amherst, MA
University of Massachusetts
Renewable Energy Research Laboratory
Overview • Offshore wind overview • Design of offshore wind turbines themselves • Considerations: – – – – – – – – –
Wind Waves Seabed soil characteristics Water depth Distance from shore Spacing Installation options Environment Operation and maintenance University of Massachusetts
Renewable Energy Research Laboratory
Offshore Wind Farms • Cost per MW decreases with increasing project size • New merchant plant projects are typically100s of MWs each
University of Massachusetts
Renewable Energy Research Laboratory
Offshore Wind Cost Elements • There is much more to the cost than the turbine itself Operation and Maintenance 25%
Electrical Infrastructure Engineering 15% and Managem ent 3%
Turbine 33%
Support Structure 24%
University of Massachusetts
Renewable Energy Research Laboratory
Economics: Cost of Energy • Total installed costs – Turbines, support structures, electrical system – Distance from shore, depth, Installation
• Energy produced – Wind resource – Turbine operating characteristics – Turbine spacing
• Operation and Maintenance (O & M) – Scheduled maintenance and repairs
• Financial considerations (interest rates, etc.) University of Massachusetts
Renewable Energy Research Laboratory
Turbine Design Drivers • • • • •
Wind speed/extremes Waves/extremes Seabed properties Water depth Design standards
University of Massachusetts
Renewable Energy Research Laboratory
Wind Turbine Support Structures • Typical offshore wind turbine support structure options • Type used will depend on seabed properties
rotor-nacelle assembly
tower
tower support structure
platform
water level sub-structure
sub-structure
pile
sea floor pile seabed
foundation
University of Massachusetts
Renewable Energy Research Laboratory
The Wind • Higher average wind speeds increase energy production; greater revenue • Higher average winds are associated with higher extreme winds structures must be more robust; higher costs • Fluctuating winds result in fatigue more or better material may be required; higher costs
University of Massachusetts
Renewable Energy Research Laboratory
Waves • Waves produce forces on support structures support structures must withstand those forces; higher costs • Periodic nature of waves can excite undesirable response in structure must be considered in the design; possibly higher costs
University of Massachusetts
Renewable Energy Research Laboratory
Seabed Soil • Seabed soil characteristics affect type of support structures that can be used, and their cost • Sand, gravel allow monopiles; lower costs • Rock may require drilling; higher costs
University of Massachusetts
Renewable Energy Research Laboratory
Water Depth • Greater water depth more site options • Greater water depth more extensive support structures; higher costs • Greater water depth higher waves, more rugged support structures; higher costs • Greater water depth limited options of installation vessels; more expensive installations; higher costs University of Massachusetts
Renewable Energy Research Laboratory
Waves
• Waves, together with the wind, are the primary external conditions which affect the design and thus cost of offshore windUniversity turbinesof Massachusetts
Renewable Energy Research Laboratory
Wave Forces • Forces arise due to the velocity and acceleration of water particles
University of Massachusetts
Renewable Energy Research Laboratory
Example of Construction of Offshore Structure
Deeper water means more steel more expensive! University of Massachusetts
Renewable Energy Research Laboratory
Wind Farm Issues • In addition to the turbines themselves: – Wake effects – Distance from shore
University of Massachusetts
Renewable Energy Research Laboratory
Wake Effects • Upwind turbines can affect downwind turbines – Decreased average wind decreased energy – Increased turbulence increased fatigue
• Spacing of turbines is important consideration in larger wind farms – Greater spacing Less wake effect Higher cable cost University of Massachusetts
Renewable Energy Research Laboratory
Distance from Shore (1) • Greater distance higher wind speeds, greater energy production; greater revenue • Greater distance fewer objections; easier permitting; fewer delays; lower costs • But….
University of Massachusetts
Renewable Energy Research Laboratory
Distance from Shore (2) • Greater distance deeper waters; higher costs • Greater distance longer time to access turbines for operation/maintenance; higher costs • Greater distance longer electrical cables; higher costs • Greater distance different environmental impact issues, e.g. marine mammals; more extensive permitting (?); higher costs University of Massachusetts
Renewable Energy Research Laboratory
Installation: Shallow Water
University of Massachusetts
Renewable Energy Research Laboratory
Installation: Deeper Water
University of Massachusetts
Renewable Energy Research Laboratory
Access for O&M (Catamaran)
University of Massachusetts
Renewable Energy Research Laboratory
Access for O&M (Helicopter)
Helicopter landing pad University of Massachusetts
Renewable Energy Research Laboratory
Optimizing the Offshore Layout (UMass Model)
• Consider the effects of the various factors • Seek to (1) minimize cost of energy (COE) or (2) to maximize revenue • Use mathematical sub-models for performance or costs of various components • Combine in comprehensive overall model, with output that can be minimized or maximized University of Massachusetts
Renewable Energy Research Laboratory
Conclusion • Offshore wind energy attractive energy option for Massachusetts • Many issues to consider! – Wind, waves, distance from shore, depth, soil type, environment, spacing, installation, O&M…
• Thorough analysis is needed to find economic optimum
University of Massachusetts
