15-09-2009

TECHNOLOGY AND INNOVATION Substructure design, manufacturing and new concepts

Stockholm, 2009 September 15th

INNOVATIONS IN DESIGN AND INSTALLATION OF OFFSHORE WIND TURBINE FOUNDATIONS

15-09-2009

TECHNOLOGY AND INNOVATION Substructure design, manufacturing and new concepts

Stockholm, 2009 September 15th

INNOVATIONS IN DESIGN AND INSTALLATION OF OFFSHORE WIND TURBINE FOUNDATIONS

THE DRILLED CONCRETE MONOPILE

Presented by:

Maarten van der VeenEngineering Manager Ballast Nedam Offshore

15-09-2009

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Driven Steel monopiles• Expensive solution due to high and fluctuating steel price• Limited amount of suppliers• Limited production capacity• Drive and drill installation method• High noise impact

Drilled Concrete MonopileConcrete• Moderate and stable material price• Almost unlimited production capacity• Production can be done locally

Drilled working method• One method suitable for different soil conditions• No or limited noise impact

Monopile weight• Lifting capacity HLV Svanen (8.700 tons) more than sufficient

BasisOffshore Wind – Design & ConstructOffshore Wind – Innovation

Experience steel monopiles

15-09-2009

Client: Vattenfall Vindkraft AB; Sweden

Location: Kriegers Flak

Power: 640 MW

Turbine type: 3.6 MW / 5.0 MW

Research executed in cooperation with MT Piling (50% Ballast Nedam Company)

Rostock

Kriegers Flak

Sassnitz

Świnoujście

R&D: Drilled Concrete MonopileBasisOffshore Wind – Design & ConstructOffshore Wind – Innovation

15-09-2009

FOUNDATION DESIGN

Performed design activities:

• Monopile for 3.6 MW windturbine at water depth of 30 m

• Monopile for 5.0 MW windturbine at water depth of 30 m

Representative soil profiles:

• Profile 1: Sand

• Profile 2: Clay

Stability

ULS: section forces, post tensioning and reinforcement

FLS: section forces, concrete

Strength Drillmix

Clamping force drilling machine

Storage concrete ring elements, lifting complete monopile

Concept design concrete ice cone

BasisOffshore Wind – Design & ConstructOffshore Wind – Innovation

15-09-2009

FOUNDATION DESIGN

Kriegers Flak (Baltic Sea):

5 MW3.6 MW

I II

BasisOffshore Wind – Design & ConstructOffshore Wind – Innovation

15-09-2009

FOUNDATION DESIGN

North Sea (Moderate; Hmax = 11m):

BasisOffshore Wind – Design & ConstructOffshore Wind – Innovation

IVIII

15-09-2009

FOUNDATION DESIGN

North Sea (Extreme; Hmax = 18m):

BasisOffshore Wind – Design & ConstructOffshore Wind – Innovation

V VI VII

15-09-2009

MT PILING

MT Piling modified the horizontal drilling technique to make it drill vertically. Experience gained in vertical drilling on the following projects which were completed successfully:

•Steel pile walls Amsterdam Central Station: - 90 piles Ø 1920 mm, max. length 70 m - no settlements occurred

•Ibis hotel Amsterdam:- 10 piles Ø 1220 mm; length 24 m

•Combi pile wall Den Haag:- 13 piles Ø 1420 mm; length 20 m

•City Inn hotel Amsterdam:- 2 piles Ø 1920 mm; length 20 m

BasisOffshore Wind – Design & ConstructOffshore Wind – Innovation

15-09-2009

Drilling inside and under monopile:

Inside monopile • Start drilling process• Soft upper layers• Diameter 5300 mm

DRILLING EQUIPMENT

Under monopile• Deeper soil layers• Extended cutter head (6700/7100 mm)

BasisOffshore Wind – Design & ConstructOffshore Wind – Innovation

15-09-2009

FABRICATION

Fabrication method conform

Saudi Arabia Bahrain Causeway (1984):

• Prefab reinforcement cages

• Casting ring elements

• Storage and curing ring elements

• Monopile assembly

• Aligning elements

• Grouting element joints

• Installation post tensioning

• Grouting post tensioning ducts

• Finishing works:

• Installation cutting toe

• Installation injection lines for drillmix

• Installation pile plugs

BasisOffshore Wind – Design & ConstructOffshore Wind – Innovation

15-09-2009

COST

Assumptions for cost indication:

• Production yard in port of Sassnitz

• Investment in 2 drilling machines for complete project

• Water depth 30 m

• Production and installation of complete project (128 foundations) in continuous process

• Prefab yard equipped for production of 1 monopile each 2 days; (365 days incl. start-up)

• Installation with HLV Svanen (net cycle 48 hr; 256 days)

• Excavated soil may be discharged into the sea

• Excluding weather downtime

BasisOffshore Wind – Design & ConstructOffshore Wind – Innovation

15-09-2009

COST

Total cost per MW as function of amount and turbine type:

BasisOffshore Wind – Design & ConstructOffshore Wind – Innovation

15-09-2009

CONCLUSIONS

Design:

• The concrete monopile is a technical sound foundation concept

Installation:

• The installation of the concrete monopile by vertical tunnelling from HLV Svanen is a technical feasible concept

• Foundation weights stay well within limits of HLV Svanen

Cost:

• The drilled concrete monopile is economically very competitive, especially for projects consisting of 40 or more foundations

Way forward:

• Further study and detailing of concept

• Conceptual design certificate – Det Norske Veritas

• Scale test

• Project realisation

BasisOffshore Wind – Design & ConstructOffshore Wind – Innovation

15-09-2009

15-09-2009

Thank you for your interest

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