Kriegers Flak Wind Farm

European Offshore Wind 2009

Conceptual Foundation Study or for Kriegers Flak Göran Loman, Vattenfall Thomas Stalin, Vattenfall Helge Gravesen, Grontmij | CarlBro

2009 09 15 | Kriegers Flak Wind Farm | Göran Loman | PYP

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A Marathon race in 15 minutes

Participants in the project • • • • • • • • • • • •

Ballast Nedam Cowi GrontMij|Carlbro ISC AS MT Højgaard MT Piling Per Arsleff AS Pihl & Søns AS Rambøll SGS Skanska Vattenfall 2009 09 15 | Kriegers Flak Wind Farm | Göran Loman | PYP

Financed by Vattenfalls project Kriegers Flak Wind Farm and by the Swedish Energy Agency

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Vattenfall Windpower Vattenfall • Owned by the Swedish government Activities • Today – DK, FI, DE, NL, PL, SE, UK, – 2 TWh/a – One of the leading generators in the Nordic countries – Significant share of the world offshore market

• Development – Seven ongoing large projects under construction – Several under development • Goal – Climate neutral 2050 (Vattenfall group) 2009 09 15 | Kriegers Flak Wind Farm | Göran Loman | PYP

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Kriegers Flak Wind Farm • • • • •

30 km south of Trelleborg 17-40 m water depth 128 plants Each 5 MW 2.6 TWh/y


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The scope of work Aims • Evaluate existing kinds of foundations • Develop more cost efficient concepts

Project development • Open seminar in February 2008 presentation of concept • Some ten consultants and contractors where engaged • The experts work with design • Evaluation of fabrication, installation, costs • Adjustments and final design • Final presentation at EOW • Final report

Regular meetings where the concepts where discussed and evaluated


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Actual site assessment was used • Geotechnical surveys • Fino2 • Hydrographic measurements


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The concepts • Foundations – Steele monopile – Steele quadroped – Concrete gravity – Concrete gravity tripod – Concrete monopile • Sea bed preparation robot


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Steel monopile Rambøll and MT Højgaard • Conventional design • Suitable conditions for monopile – Drilling needed where boulders occur • 3.1 M€ (35 m, 5 MW) – More compatible at shallow depth • Limited storage area needed


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Steele quadroped Rambøll and MT Højgaard • Design – Concrete transition piece – 2 levels of X-braces • Less wave load • 3.0 M€ (35 m, 5 MW) – More competitive at deeper water • Possibilities for further optimisations


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Steele quadroped Installation


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Concrete gravity Cowi and Aarsleff • Three designs – Conventional cone – Floating (KIS) – Semi floating • Conventional – Cost effective, 2.4 M€ (35 m, 5 MW) – Durable and robust – Maintenance friendly – Heavy lifting floating cranes • Floating – The floating concept need more concrete and deeper harbour – KIS 4 M€, semi floating 3 M€ – No heavy lifting floating crane – Could be improved 2009 09 15 | Kriegers Flak Wind Farm | Göran Loman | PYP

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Concrete gravity triopod ISC and Skanska • Design – Three legs, triangular shape – Standardised parts – Prefab elements, in situ casting – Total installation concept • Heavy (>3,000 tons) • Expensive 3.8 M€ (35 m, 5 MW) • Need to be improved


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Concrete monopile Ballast Nedam and MT Piling • Design – Prefab concrete monopile – Vertical drilling • Concrete – Less expensive than steel – High fabrication capacity • No uw noise or vibration during installation • Unproven technique (or?) • 3,1 M€ (5 MW, 40 pc) – 2 M€ for 130 pc


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Stone bed preparation robot, Pihl • No divers needed • One stop for – Soil investigation (vibro cores, CPT) – Final levelling of the sea bed – Surface measurements – Creating the stone bed (fall pipe)


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Summary • Several interesting concepts were evaluated and improved • There is a potential for further optimization • Need to iterate with turbine suppliers


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The foundations, you don’t see them, but you need them!

Kriegers Flak Wind Farm

More information: www.vattenfall.com/kriegersflak


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