Offshore Electricity Infrastructure in Europe - European Wind Energy ...

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FIGURE 4.7: hUb cASES FOR ASSESSING cOSTS OF WINd FARM cONSTRUcTION dElAY ANd STRANdEd INvESTMENTS The results are a strong argument for hub connection and confirm the results of sections 4.2.1 and 4.2.2 where hub solutions were found to be beneficial for a large number of offshore wind farms in the 2030 offshore grid scenario. The case study further proves that the impact of stranded investments or temporary over-sizing is limited. FIGURE 4.8: cASE STUdIES ON TIME dElAYS ANd STRANdEd INvESTMENTS FOR hUb cONNEcTIONS OffshoreGrid – Final Report Case A: 60 km - Wind farm capacity: 350 MW each - Individual connection: 270 m€ each - Spur costs: ca. 65 m€ each - Hub connection costs: 415 m€ Case B: 150 km: - Wind farm capacity: 350 MW each - Individual connection: 360 m€ each - Spur costs: 65 m€ each - Hub connection costs: 525 m€ Costs (€m) 2,500 2,000 1,500 1,000 500 0 Costs (€m) 2,500 2,000 1,500 1,000 500 0 Subcase 1 Hub Subcase 1 Hub Subcase 1: All wind farms built in t=0 The economic result is of course case dependent, with wind farm size and wind farm to hub connection distance playing a role in the outcome. However the cases here were chosen to cover a wide span of possible configurations. The results properly illustrate the fundamentals of the subject and allow the drawing of general conclusions. Costs of stranded investment Costs of delay of wind farms Subcase 2 Individual connection Subcase 2 Individual connection Subcase 2: Only two wind farms built Subcase 3: Only one wind farm built Subcase 3 Subcase 3 Subcase 4 Subcase 4 Subcase 4: Wind farm nr. 1 built in t=0 Wind farm nr. 2 and 3 built 10 years later 41
esults 4.2.4 Conclusion and discussion on hubs versus individual connections Clustering of wind power projects is advantageous in many cases, depending on the distance from shore and the concentration of installed capacity in the same area. A shared hub connection is most advantageous when the sum of installed wind power capacity in a small area is relatively large and equal to standard available HVDC voltage source converter (VSC) systems. For distances from the onshore connection point of up to about 50 km, usually 50 Hertz HVAC technology is used and hubs do not generally provide much added value due to limited savings in cable length. For larger distances, the best solution depends primarily on the total available wind farm capacity in the area that could be grouped into the hub. For long distances to shore a hub connection is mostly beneficial; the benefit increases with distance. Integrating a wind farm into a nearby hub is economically advantageous for wind farm to hub connection distances of less than 20 km. For greater wind farm to hub connection distances the benefit will be rapidly reduced. However, if the hub’s size is large and if it is located far from shore, this again improves the economics. For wind farm to hub connection distances beyond 40 km, no beneficial hub cases were identified. In view of the large potential benefits of connecting wind farm clusters via hubs, political and regulatory strategies to foster their development are of primary importance. Additional considerations The above assessment is solely based on economic considerations. In cases where the hub is less beneficial, decision makers may still opt for hub solutions in order to mitigate the environmental and social impact of cable laying through environmentally sensitive or highly frequented coastal areas. A hub solution may also allow more efficient logistics during construction. Time delay costs and stranded investments It has to be highlighted that a hub project is in general more complex. Construction schedules of wind farms in a certain area seldom coincide. The economic assessment is based on their connection schedules. If projects that are supposed to be connected are abandoned, the overall hub costs increase significantly due to stranded investments or longer transition times with oversized cables that are only partly loaded. However, the case study analysis for a hub connection of three wind farms with a capacity of 350 MW each has shown that the costs of such delays or stranded investments should not be overestimated. In the case study the hub solution remains economically viable up to a 10 year time delay for two of the wind farms to be connected. Even if the one of the wind farms is not built at all, the hub connection is the preferred solution. Where hub connections are clearly shown to be beneficial, a dedicated regulatory and policy framework to mitigate this risk will be required. The risk of stranded investment can be mitigated, e.g., by strategic siting and concessions with the specific aim of having groups of projects with a capacity of 1,000 to 2,000 MW per group concentrated in an area and developed approximately at the same time. 4.3 Integrated design – case studies This section elaborates on the integration of wind farm hubs and interconnectors, the main idea behind the offshore grid in the North Sea. The OffshoreGrid project focuses on two major design concepts. Any offshore grid design can be broken down into these two fundamental building blocks: • Teeing-in of wind farms into interconnectors (jointly developed with the wind farms or already existing) as shown in Figure 4.9. • Interconnection of countries via wind farm hubs on either side as shown in Figure 4.10. 42 OffshoreGrid – Final Report
Page 1 and 2: OffshoreGrid: Offshore Electricity
Page 3 and 4: PRINcIPAl AUThORS: Jan De Decker, P
Page 5 and 6: Table of contents FOREWORd 6 EXEcUT
Page 7 and 8: FOREWORD The OffshoreGrid project i
Page 9 and 10: Executive Summary I. The OffshoreGr
Page 11 and 12: Executive Summary and TYNDP interco
Page 13 and 14: Executive Summary One of the keys t
Page 15 and 16: Executive Summary Splitting wind fa
Page 17 and 18: Executive Summary 16 OffshoreGrid -
Page 19 and 20: introduction 1.1 Context and backgr
Page 21 and 22: introduction TAblE 1.1: STAkEhOldER
Page 23 and 24: Key Assumptions and Scenarios In th
Page 25 and 26: Key Assumptions and Scenarios FIGUR
Page 27 and 28: Key Assumptions and Scenarios Curre
Page 29 and 30: Methodology - Simulation inputs and
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Page 33 and 34: esults This chapter explains and su
Page 35 and 36: esults (figure to the right) in Nor
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Page 53 and 54: esults • Large wind farms (capaci
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Page 57 and 58: esults • A three-leg interconnect
Page 59 and 60: esults 4.5 Overall grid design 4.5.
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Page 73 and 74: esults farm connections, the reduct
Page 75 and 76: esults Overall design comparison Fi
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Page 83 and 84: Towards an Offshore Grid - Further
Page 91 and 92: conclusions and recommendations The
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conclusions and recommendations •
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conclusions and recommendations •
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conclusions and recommendations 6.5
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conclusions and recommendations 98
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Acknowledgements and Funding The Of
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eferences [1] Weather Research and
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eferences [47] Observatoire Médite
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Annex A - Scenario details A.I Offs
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Annex A - Scenario details A.II Pri
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Annex A - Scenario details 2008 sce
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Annex A - Scenario details Due to t
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Annex B -technology Assumptions B.I
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Annex B -technology Assumptions tab
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Annex c - details on Methodology an
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Annex c - details on the Methodolog
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Annex d - details of results D.I Wi
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Annex d - details of results FiGuRe
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Annex d - details of results infras
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Annex d - details of results table
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Annex d - details of results table
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Annexes coal and gas, there is a de
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Annex e - regulatory Frameworks and
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Annex F - transfer to the Mediterra
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