TECHNOLOGY AND INNOVATION Substructure design, manufacturing and new concepts Stockholm, 2009 September 15 th INNOVATIONS IN DESIGN AND INSTALLATION OF OFFSHORE WIND TURBINE FOUNDATIONS

TECHNOLOGY AND INNOVATION Substructure design, manufacturing and new concepts Stockholm, 2009 September 15 th INNOVATIONS IN DESIGN AND INSTALLATION OF OFFSHORE WIND TURBINE FOUNDATIONS THE DRILLED CONCRETE MONOPILE Presented by: Maarten van der Veen Engineering Manager Ballast Nedam Offshore

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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 Monopile Concrete 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 Basis Offshore Wind – Design & Construct Offshore Wind – Innovation Experience steel monopiles

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) R&D: Drilled Concrete Monopile Basis Offshore Wind – Design & Construct Offshore Wind – Innovation

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 Basis Offshore Wind – Design & Construct Offshore Wind – Innovation

FOUNDATION DESIGN Kriegers Flak (Baltic Sea): 5 MW3.6 MW III Basis Offshore Wind – Design & Construct Offshore Wind – Innovation

FOUNDATION DESIGN North Sea (Moderate; Hmax = 11m) : Basis Offshore Wind – Design & Construct Offshore Wind – Innovation IV III

FOUNDATION DESIGN North Sea (Extreme; Hmax = 18m) : Basis Offshore Wind – Design & Construct Offshore Wind – Innovation VVIVII

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 Basis Offshore Wind – Design & Construct Offshore Wind – Innovation

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) Basis Offshore Wind – Design & Construct Offshore Wind – Innovation

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 Basis Offshore Wind – Design & Construct Offshore Wind – Innovation

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 Basis Offshore Wind – Design & Construct Offshore Wind – Innovation

COST Total cost per MW as function of amount and turbine type: Basis Offshore Wind – Design & Construct Offshore Wind – Innovation

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 Basis Offshore Wind – Design & Construct Offshore Wind – Innovation

Thank you for your interest