5.1 Optimal integrated combination of foundation concept and installation method

Transcription

1 5.1 Optimal integrated combination of foundation concept and installation method Results of research in perspective December 1 2, Den Helder, The Netherlands

2 Goal and Partners The project s goal is to find an integrated optimal foundation solution. For this moment and for future developments by taking in account turbine sizes up to 8,5 MW. Being a Dutch R & D project the project looked primarily at the Dutch conditions, though some conclusions could be valuable for other sites and countries as well. Ballast Nedam Fabricom (Cofely) Gusto MSC Lloyds Register Edwin van de Brug Reinout Prins Wim de Boom Peter Kuijpers December 2009, 2 / 28

3 Approach Basic data Foundation concepts Installation concepts Overall foundation costs Conclusions Optimal, Integrated, Foundation and Installation December 2009, 3 / 28

4 Basic Data Site conditions Site conditions Case A Case B Water depth 21,0 m 32,0 m Wave (Hm0/ period) 7,0 m / 10,0 s 9,5 m / 10,5 s Soil Profile Profile A. Average Profile B. Worst Profile A. Average Soil Profile Depth below seabed Soil type γ(kn/m3) ϕ(deg) C u (kpa) 0,0 10,0 10,0 20,0 20,0 and deeper Sand, silty Sand, dense Sand, very dense Profile B. Worst Soil Profile Depth below seabed Soil type γ(kn/m3) ϕ(deg) C u (kpa) 0,0 6,0 6,0 16,0 16,0 and deeper Sand Clay Sand, dense December 2009, 4 / 28

5 Basic Data Turbines 5,0 MW Turbine Rotor diameter : 126 m; Hub Height : 90 m; Total Weight at hub height (nacelle + blades) : 350 tons; Weight of tower : 500 tons; 8,5 MW Turbine Rotor diameter : 160 m; Hub Height : 110 m; Total Weight at hub height (nacelle + blades) : 800 tons; Weight of tower : 1000 tons; Wind loads are based on and derived from existing turbines. Clipper 10 MW turbine - rotor diameter 150 meter - hubheight 100 meter December 2009, 5 / 28

6 Basic Data Sites Harbours NOORD 1 NOORD 2 MIDDEN ZUID December 2009, 6 / 28

7 Foundation concepts Case A-WEC1: 5,0 MW wind turbine with average site conditions Case A-WEC2: 8,5 MW wind turbine with average site conditions Case B-WEC1: 5 MW wind turbine with worst-case site conditions Case B-WEC2: 8,5 MW wind turbine with worst-case site conditions December 2009, 7 / 28

8 Foundation concepts A. Case A-WEC1: 5 MW wind turbine with avg site conditions Steel monopile (ø 7000 x 63 /90, 680 tons) transition piece (ø 7300 x 65, 360 tons) C. Case B-WEC1: 5 MW wind turbine with worst-case site cond. Concrete tripod on piles (12000 x x 12000, 7875 tons) December 2009, 8 / 28

9 Foundation concepts B. Case A-WEC2: 8,5 MW wind turbine with avg site conditions Concrete gravity based foundations (33000 x 33000, 7750 tons) D. Case B-WEC2: 8,5 MW wind turbine worst-case site cond. Steel jacket structure (36000 x 36000, 650 tons) December 2009, 9 / 28

10 Foundation concepts December 2009, 10 / 28

11 Foundation concepts Photo Jos Beurskens Photo Jos Beurskens Photo Jos Beurskens Photo Jos Beurskens Photo Jos Beurskens Photo Jos Beurskens December 2009, 11 / 28

12 Foundation concepts Fabrication costs Concept Weight (tons) Mw Fabrication price Fabr. Price / mw A1. Monopile - 5 mw ,9 m 0,58 m A2. Concrete monopile -5 mw ,8 m 0,36 m B. Concrete gbs - 8,5 mw ,5 3,4 m 0,40 m C1. Concrete tripod - 5 mw ,1 m 0,62 m C2. Concrete monopile - 5mw ,3 m 0,66 m C3. Concrete gbs -5 mw ,2 m 0,45 m C4. Steel jacket -5,0 mw ,9 m 0,57 m D. Steel jacket - 8,5 mw 650 8,5 3,2 m 0,38 m December 2009, 12 / 28

13 December 2009, 13 / 28 Artist Impression by Reinout Prins

14 December 2009, 14 / 28 Artist Impression by Reinout Prins

15 December 2009, 15 / 28 Artist Impression by Reinout Prins

16 December 2009, 16 / 28 Artist Impression by Reinout Prins

17 Installation concepts December 2009, 17 / 28

18 Installation concepts December 2009, 18 / 28

19 Installation concepts December 2009, 19 / 28

20 Installation concepts December 2009, 20 / 28

21 Overall foundation costs December 2009, 21 / 28

22 Conclusions Foundation concept Monopile + transition piece - Steel Proven foundation type for smaller turbines up to 5 MW at shallow conditions. Installation best by small jack-up platforms with large crane (1000 tons) combined with transport by barges. Critical but manageable point is the offshore loading of the jacket. High number of installation per year possible (up to 200/ year). The all-in-one vessels (self propelled jack-ups / vessels) are 50% - 60% more expensive on the net cycle time costs. Including the higher workability of the self propelled jack-ups the performance of the latter improves but the costs are still 20% to 40% higher. High pay-load is advisable to reduce the transport time, especially at higher distances from a harbour. December 2009, 22 / 28

23 Conclusions Foundation concept Jacket - Steel Installation characteristics equal to the monopile installation spread. As a result of the higher cycle time are the installation costs 30% to 60% higher and the number of installation approx. 35% lower (up to 130 / year). Especially at higher depths and with larger turbines the jacket proves to be a cost efficient solution as they still can cope with the loads from the site and the turbine and combine this with acceptable amount of steel. Foundation concept Tripod on piles concrete Combines the disadvantages of the steel jacket and the concrete gravity based foundation and is therefore not an advisable solution. December 2009, 23 / 28

24 Conclusions Foundation concept Gravity Based Foundation concrete Main disadvantage is that the transport and installation must bedone by one vessel as there is no method available yet for offshore loading or successful floating and submerging of the foundation. Due to this the installations per year will be 50% to 70% lower compared to the monopile. Only limited number of installation vessels is available. Main advantage is that the fabrication costs are low compared to the steel structures, especially if the investment costs are spread out ona large number of foundations. December 2009, 24 / 28

25 Conclusions Foundation concept Drilled concrete monopile The drilled concrete monopile can be installed using a heavy lift vessel and a vertical drill. Within this calculation the majority of the investment costs are included for a small number of projects resulting in installation costs being 3 to 4 times higher compared to the monopile installation costs. Nevertheless the total picture is positive, particularly for the mid-size range projects. At projects with high design waves new innovations are needed to reduce the wave impact and thus the diameter and weight of the concrete monopile. December 2009, 25 / 28

26 Optimal, Integrated, Foundation and Installation The project s goal is to find an integrated optimal foundation solution. For this moment and for future developments by taking in account turbine sizes up to 8,5 MW. December 2009, 26 / 28

27 Optimal, Integrated, Foundation and Installation December 2009, 27 / 28

28 Thank you for your attention December 2009, 28 / 28 Belwind 2009