1. An Integrated System Design to
Lower Cost of OSW Energy
Deployment in the Mid-Atlantic
Willett Kempton
University of Delaware
willett@udel.edu 302-831-0049

2. Goal of Project
Develop an integrated system design for an
offshore wind farm in order primarily to reduce
the cost of energy and secondarily to shorten
deployment timeline of offshore wind energy.
Project Sponsor: US Department of Energy, award DE-EE0005484
Principal Investigator: Willett Kempton
Project Managers: Andrew Levitt (Former), Richard Bowers (rpbowers@udel.edu)

3. Pick-up Transport
Installation
Suction Bucket
Deployment
Integrated Design

4. Characteristics of Study Area

5. Turbine, 38%
Foundation, 25%
Installation,
22%
Electrical,
13%
Development, 2%
• Turbine
• Foundation
• Port Assembly and Vessel
• Transmission
Design Cost Elements

6. Design Decisions: Turbine
• Choice of 10 MW turbine with 150m rotor
• Fewer machines per MW (fewer turbines, foundations,
installations, maintenance trips)
• Turbines not designed for transport
with blades on. Install blades offshore

7. Design Decisions: Foundation
• Foundation driven not by static loads but by dynamic loads
(waves and rotor movement). Designs focus on stiffness.
• Fabrication labor roughly 4x-8x the cost of the steel commodity.
• Lattice can withstand larger wave loading.
• Use lattice for lower section of vertical
support: lattice is stable; allows
for multiple seabed fastening points.

8. • Design Alternative 1: Piled
– Jacket structure with piles
– Multi-step offshore assembly
– Jack-up vessel
• Design Alternative 2: Suction Bucket
– Turbines assembled in quay on jacket structure
with suction buckets
– Deployment in a single offshore step via stiffleg crane barge
– EACH HAS MAJOR VESSEL, PORT, AND INSTALLATION
IMPLICATIONS
– Following is for tripod suction bucket
Design Decisions: Foundation

9. Photo courtesy of DONG Energy: https://www.youtube.com/watch?v=w9Qz1PiG1Y8#t=12
Suction buckets placed in water beside quay;
Jacket lifted onto structure;
Workers attach jacket to suction buckets
Entire turbine structure put on foundation
Foundation Construction with Crane

10. Transport vessel arrives clamping the
turbine tower and at two points of the
lattice structure.
Pick-Up

11. Lower supports prevents the turbine from moving inward
towards the vessel during transport, reducing the risk of
unnecessary forces on the turbine and foundation structure.
Sea Mounting

12. Transport uses rig on tower and
rigid sea mount above buckets to
stabilize during transport to site.
Transport

13. Vessel arrives at installation site and
uses crane to lower the turbine to
the bottom.
Suction buckets are placed on the seabed,
and smaller support vessel begins
running suction pumps; then transport
vessel returns to pick up another turbine
Installation

14. • “Integrated Design” was achieved by a series of meetings with all design teams, challenging
each how they can modify costly components
• Result of design work: Simultaneously changed seabed mounting, along with assembly (more
Quayside), different vessel and deployment changes
• Bigger rotor/generator yields large cost savings
• Eliminate: Jack-up vessel; large component assembly at sea; pile driving; Reduce: large
vessel time at sea
• Further cost reductions enabled, but not given as main path forward
• Not ready to do this in one step; requires demonstration to de-risk
Conclusions