Universal Foundation. MBD introduction The Universal Foundation Framework The prototypes The supply chain Conclusion

Transcription

1 Universal Foundation A novel wide ranging substructure installation concept 1 Søren A. Nielsen, MBD, CPO. Lars Bo Ibsen, Aalborg University, Research Professor. MBD introduction The Universal Foundation Framework The prototypes The supply chain Conclusion

2 2 MBD Offshore Power A/S R&D company founded in 2001 Shareholders: DONG Energy, >50% Aalborg University Novasion Primary cooperation: Aalborg University Dong Energy NearshoreLAB Fred. Olsen Group

3 3 Universal Foundation Concept: A framework for industrialization A concurrent process, adding new processes and experiences to a database, used by a configuration methodology to produce the required documentation in each step of the wind farm projects focusing on: The optimal foundation for each turbine position Design is parameter driven Structure based on scaleable modules and elements Production based on series or mass production Installation in widest possible weather window Installation based on common available vessels Owner Configurator Consultant Construc -tion Installati on Feedback Feedback Feedback Feedback Sales Engineering Feedback Development Production Installation Site data Database Principles, methodes, procedures, expirences Product configuration Risk / cost assesment Feed back Standard output Feasibility studies Conseptual design Tender design Detail design Construction documentation Operation documentation

4 Main focus area: The bucket foundation technology as large diameter monopile Concept advantages: Reduced use of steel compared to any other substructure solution. Use of simple geometric welded steel structures. The structure is omnidirectional symmetrical with respect to the vertical axis. Few offshore operations, with utilizing smaller equipment/vessels during installation. No seabed preparation and no or reduced need for scour protection. Adjusting the upper part of the shaft to fit the standard wind turbine tower. Simple decommissioning. 4 Installation advantages: Minimum noise impact. No pile driving hammers or drill drives are used. No grouted connections. Minimum disturbance to the existing seabed. The use of excess material for scour protection is reduced or not necessary. All steel materials can be recovered from the seabed and reused / recycled when the foundation is decommissioned

5 5 Offshore wind turbine foundations The flexibility of the bucket foundation gives wider range of application. Sites with complex geotechnical properties can be cover by a single foundation concept Platform Bucket Mono pile Tripod

6 Basic geotechnical design principles 6 Bracings Skirt

7 Basic steel structure design 7 Steel structure: Coned platform Standardized upper structure Internal J tupe Guides for pump unit Steel quality: 355 Plates mm

8 Basic steel structure design Structure analyzes: Ultimate load Fatigue load Eigenfrequen 8

9 The prototype for Pos. 1, Frederikshavn The Ø12x6 m prototype bucket foundation was designed for a Vestas V90 3MW turbine placed on 4 m of water. The design is certified by DNV. The bucket was installed in late 2002 and is in normal operation. The structure/soil interaction has been investigated with sophisticated modal analyse equipment. 9

10 The Mobile Met Mast "The Mobile Met Mast" is a prototype of a bucket foundation designed as support structure for a metmast. Purpose: To gain confidence that a monopod bucket foundation can be successfully installed offshore. Specification Total height: 34 m Weight: 165 tones Skirt length: 6 m Skirt diameter: 12 m Fabricated in Aalborg in August Installed at Horns Rev 2 Offshore wind farm in March To obtain a movable metmast, which can be used in several offshore wind farms. 10

11 Installation A penetration velocity of 2 m/hour was obtained. After 2.5 m penetration, the foundation started tilting. At 4 m penetration, the process was reversed until 3 m penetration. Then the penetration process was repeated without tilting problems. The tilt problem was properly caused by a stone along the skirt circumference. The flow induced in the soil was blocked, indicating that a clay layer was present. Installation continued. The foundation was successfully installed with a 0.1 degree inclination out of vertical. 11

12 12 Universal foundation solutions Variation in seabed properties Hard clay, soft clay, sand, silt EWEC 2011, 16th March 2011 Variation in water depth 0-60 m

13 Logistics Transport: Production in Northern Europe, facilities placed by a harbour. Transport to interim harbour nearby site on barge 13 Installation: Foundation is launched in horizontal position, and is trimmed with ballast water Buoyant towing to site by tug boat Clip on pump unit conneted The structure is upended by manipulating ballast water Crane is hooked on to stabilize touch down After initial penetration, suction is applied

14 Supply Chain 14 The implementation of the concept is conducted by a facilitator organization (solution provider) with access to the IP rights of the bucket concept. Close cooperation with the project developer/owner of the wind farm project. The functions of the facilitator are to the ensure that the technology, methodologies and procedures is optimized throughout the entire supply chain as well as ensure that the contract relations in between the different stakeholder is managed to utilize the full potential of the concept.

15 Conclusion 15 Universal Foundation is found to be: Applicable in a wide range of offshore conditions water depth / soil conditions A focused concept development and design procedures A cost effective fabrication / installation concept > reduced cost of energy Environmental feasible no noise impact and seabed disturbance Plan for commercialization and further development: One package complying of: Geotechnical calculation / design manual Production basis Transport concepts Installation manual Decommission concepts Concurrent concept development Next step: Prototype reference full scale implementation 2 Ph.D.s working on steel/concrete composites and soil/structure interaction in clay Development of click on pump unit and soil investigating equipment