Current Status ofPhase VI Floating Design

Operated for the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy by the Alliance for Sustainable Energy, LLC

IEA Wind Task 30Kick-Off Meeting

June 8, 2010

Jason Jonkman, Ph.D.Senior Engineer, NREL

IEA Wind Task 30 Kick-Off Meeting 2 National Renewable Energy Laboratory

• TLP & semi-submersible were both suggested candidates for Phase VI

• More interest in semi-submersible b/c:– Greater system motions & couplings– Importance of hydrodynamic radiation &

diffraction– Catenary moorings

• Principle Power Inc. (PPI) has kindly agreed to design a semi-submersible, based on the WindFloat, & make it available to Task 30 participants Spar Concept by SWAY

Phase VI Floater Concept

IEA Wind Task 30 Kick-Off Meeting 3 National Renewable Energy Laboratory

• WindFloat by PPI, USA

• Designed to support existing WTs:– Modifications only to tower & controller

• Pitch & roll restoring through waterplane area & fixed water ballast

• Tower mounted on one column

• Active ballast system maintains zero-mean pitch angle

• Heave plates improve natural response periods & damping

Spar Concept by SWAY

WindFloat Key Design Features

WindFloat (Image: D. Roddier, PPI)

IEA Wind Task 30 Kick-Off Meeting 4 National Renewable Energy Laboratory

• Tower would be moved to center:– Simplify system’s asymmetry– Avoid issues associated with shift in origin

• Heave plates would be eliminated by compensating with larger columns:– Heave plates require empirically derived

drag– Heave plate IP protected by PPI

• However, design iteration revealed:– Tower in center requires a lot of extra

support structure– Columns would have to be unreasonably

large to achieve desired response periods Spar Concept by SWAY

Original Design Plan by PPI

Semi-Submersible Concept(Image: D. Roddier, PPI)

IEA Wind Task 30 Kick-Off Meeting 5 National Renewable Energy Laboratory

• Keep tower on one column

• Keep heave plates:– PPI will supply suitable drag properties

• Platform will support NREL 5-MW WT

• Aiming for response periods similar to that of OC3-Hywind spar buoy

• Scaled system will be tested in a wave tank within DeepCWind project:– Data will become available for model validation

• Design status:– Design iteration in progress– Developing specifications report– Expected completion in Summer, 2010

Spar Concept by SWAY

Current Design Plan by PPI

Semi-Submersible Concept(Image: D. Roddier, PPI)

IEA Wind Task 30 Kick-Off Meeting 6 National Renewable Energy Laboratory

Spar Concept by SWAY

Preliminary Design Details

Parameter Value Unit

Column diameter 9.7 m

Length of heave plate 13.7 m

Column center to center 46.0 m

Operating draft 16.8 m

Airgap 10.0 m

Pontoon diameter 2.1 m

Bracing diameter 1.5 m

Displacement 4552 tonnes

Thank You for Your Attention

Operated for the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy by the Alliance for Sustainable Energy, LLC

Jason Jonkman, Ph.D.+1 (303) 384 – 7026jason.jonkman@nrel.gov