Universal Foundation Suction Bucket
A solution in support for offshore wind
Henrik Lundorf Nielsen
April 2013
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
The Evolution of
– Innovative – yet years of experience:
1997
TekNord
1999
MIG Business
Development
2002
Prototype 1
2001
MBD Offshore Power –
R&D of Bucket
Foundation
2005
Prototype 2
2009
Prototype 3
2011:
Press Release – August 2011:
Fred. Olsen United AS, which is owned 50/50 by Bonheur ASA and Ganger Rolf ASA, has
acquired 60% of Danish company Universal Foundation A/S
Other shareholders: DONG, Aalborg Universitet, Novasion
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
Fred. Olsen United
• Project management
• Secures a seamless
interface and serves
as single-point of
contact
Universal Foundation
• Design of support
structure
• Specialist in
engineering and subseabed installation
Harland and Wolff
• Foundation structure
manufacture at their
shipyard in Belfast
Fred. Olsen
Windcarrier
• Marine operations of
structures to final site
Natural Power - SeaRoc
• Supply and installation of
met-mast structures and
equipment
• HSEQ services
Global Wind Service
• Installation of wind
turbines
• Service & maintenance
• Fibre repair
• Commissioning
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
Stepping up the Technology Readiness Ladder
Targeting a 2015/16 contract
2016 Execution of WF Project
2015 - Wind Farm Contract - Commercially Ready
2014 – WTG foundation - Field proven - TRL 7
2013-14 – Trial installations - Carbon Trust – TRL 5 and 6
2012-13 – Met Mast Foundations – Dogger Bank, Firth of Forth – TRL 4 and 5
2002–11 R&D – Technology Readiness Level , TRL 0 to 3
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
A Fred. Olsen related company
Is the Bucket an Opportunity for Near Offshore sites in Denmark ?
Question is:
Does the Suction Bucket work at a given site ?
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
How does it work – Installation ?
The Universal Foundation Suction Bucket is a Suction Installed CAisson – SICA
”All in one” Substructure and Foundation unit as support for offshore
installations, i.e. met masts, wind turbines, sub stations...
Suction is applied during installation – water evacuation
Suction is NOT maintained during operation
Once installed the SICA is a Gravity Foundation
1:
Evacuation of water creates downward
force limited by the water column
2:
Flow around skirt reduces effective
stresses in soil thereby reducing
resistance
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
How does it work – Installation ?
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
How does it work – In Operation ?
Once installed the SICA is a Gravity Foundation
Failure mode is overturning
V
M
H
Point of rotation
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
Where does it work ?
Installability & Capability – under which conditions ?
Design Drivers:
Geology
Met Ocean conditions
Superstructure (Wind Turbine)
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
Main Driver
Type
Soil
Geology
Rock
Family
Grade
Penetrability
Capacity
Soft
Firm
Clay
Stiff
Very Stiff
Hard
Silt
Tansition from Clay to Sand
Very Loose
Loose
Sand
Medium Dense
Dense
Very Dense
Clay - Sand - Clay
Layered Soils
Sand - Clay - Sand
Glacial Till Stiff - Hard
Organic Soil
Igneous
Magma (Granite, Basalt)
Sedimentary Lithification (Limestone, Sandstone...)
Metamorphic Recrystallization (Slate, Gneiss)
Remark:
In Clay – due to low permeability – flow around skirt is prevented. Penetration
resistance shall be overcome by vertical downward force (Water column).
Experience in Clay is limited,- i.e. Carbon Trust Trial Installation Scheme !
3 Internal Bulkheads to allow additional down force
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
Main Driver
Type
Soil
Geology
Rock
Family
Grade
Penetrability
Capacity
Soft
Firm
Clay
Stiff
Very Stiff
Hard
Silt
Tansition from Clay to Sand
Very Loose
Loose
Sand
Medium Dense
Dense
Very Dense
Clay - Sand - Clay
Layered Soils
Sand - Clay - Sand
Glacial Till Stiff - Hard
Organic Soil
Igneous
Magma (Granite, Basalt)
Sedimentary Lithification (Limestone, Sandstone...)
Metamorphic Recrystallization (Slate, Gneiss)
Remark:
In Clay – due to low permeability – flow around skirt is prevented. Penetration
resistance shall be overcome by vertical downward force (Water column).
Experience in Clay is limited,- i.e. Carbon Trust Trial Installation Scheme !
3 Internal Bulkheads to allow additional down force
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
Main Driver
Type
Family
Grade Penetrability Capacity
0 - 10 m
10-20 m
Bathymetry Water Depth 20-30 m
30-40 m
Met Ocen
>40-50m
T < f0 (system)
Waves Dynamics T = f0 (system)
T > f0 (system)
Remark:
Water column defines downward force
Dynamic effect gradually governs
Wave load takes dominance over turbine loads
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
Main Driver
Type
Family
Grade Penetrability Capacity
0 - 10 m
10-20 m
Bathymetry Water Depth 20-30 m
30-40 m
Met Ocen
>40-50m
T < f0 (system)
Waves Dynamics T = f0 (system) Load Response Amplification
T > f0 (system)
Remark:
Water column defines downward force
Dynamic effect gradually governs
Wave load takes dominance over turbine loads
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
Wind Turbine
Main Driver
Type
Family
Grade
3 MW
4 MW
5 MW
MW nameplate 25 to 45 m WD
6 MW
7 MW
8 MW
System f0 below
Allowable frequency interval System f0 within
System f0 above
Capacity
Remark:
Threshold of structure tonnage = app. 1200 tonnes (Green colour). Very dependent on
installation vessel crane capacity & method
Integrated design – WTG <> Substructure – will accommodate for for correct system f0
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
Wind Turbine
Main Driver
Type
Family
Grade
3 MW
4 MW
5 MW
MW nameplate 25 to 45 m WD
6 MW
7 MW
8 MW
System f0 below
Allowable frequency interval System f0 within
System f0 above
Capacity
Remark:
Threshold of structure tonnage = app. 1200 tonnes (Green colour). Very dependent on
installation vessel crane capacity & method
Integrated design – WTG <> Substructure – will accommodate for for correct system f0
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
Wind Turbine:
Case study .... Fine tuning system f0 to avoid resonance = load
amplification
Typical deflection shapes for first few modes and load
amplification as fuction of damping.... Typical damping
estimate = 10 – 15% (soil contribution 2% - 4%) =>
H(f) = 3 to 4
Note: This affects SLS and FLS load cases only
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
The Bucket = ”MP like” shaft but stiffer however not as stiff
as Jacket... Can be tailored by tapered shaft, lid design ...
Typical WTG ranges
System f0 depends on Nacelle/Rotor Mass, Tower, Water
Depth...
Narrow feasible frequency band – here soft - hard
f0
It calls for Integrated design – load loop iteration
Trade off to find the cost optimal solution
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
Then lets assume we got the integrated design right – what value
proposition is to be expected:
Simplified ULS perspective:
ULS moment as function of Rotordiameter
1000
ULS Overturning Moment
MNm
900
800
700
30 m Mudline
600
500
40 m Mudline
Wave & WTG
400
25 m Mudline
300
200
Lineær (Tower bottom extreme
bending moment)
WTG
100
0
60
80
100
120
140
Rotor Diameter
160
180
200
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
Simplified ULS perspective - continued:
Universal Foundation Suction Bucket
tons
Suction Bucket Tonnage as function of
Mudline Resulting Moment
1600
1400
1200
1000
800
600
400
200
0
0
100
200
300
400
500
600
Resulting moment @ mudline
ULS, MNm
700
800
900
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
The Cost perspective
To say something clever on Cost level would need a specific project estimate…
Significant contribution to shorten Project Schedule – LCoE is reduced significantly
Cost per unit
100%
100%
96%
90%
80%
72%
69%
Index
70%
60%
60%
57%
50%
40%
31%
30%
20%
0
10
20
30
Nos of Structures
40
50
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for Near Shore Denmark ?
In conclusion:
The Bucket will be a feasible support structure given the right soils and Met Ocean
conditions…
Tonnage: Site Specific Design required…
At a cost of - too early to say…
All to be confirmed …. i.e we need:
Geotechnical info
Met Ocean info
WTG-Support Structure - integrated design initiated
- Design Basis
- Load Loop Iteration
- Detailed design / Interface concept
Universal Foundation Suction Bucket
Feasibility Assessment - A solution for the ALSTOM Hal150 @ Belwind II ?
Dogger Bank Campaign February 2013
Universal Foundation Suction Bucket
Universal Foundation Suction Bucket
Dogger Bank Met Mast East - SCADA screen dump....
Penetration:
Duration:
Verticality:
7.31 m
6 hrs 46 min
0,09 degrees
Expanding this to full scale project the positive
impact on project schedule is huge !!
Thank you !