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

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compared to the individual connection to Germany only, a two- or three-leg interconnector is created which can be used, amongst other things, to relieve the stress on the German market. Apart from techno-economic considerations, an integrated solution is heavily dependent on the political and regulatory decisions. For example, it is of course not possible without a solution for the incompatibility of support systems (see further in Chapter 6). 4.4.4 Conclusion on integrated design Sections 4.3 and 4.4 have elaborated the results of the cost-benefit analysis on integrated design options. They have been evaluated by an extensive case study analysis with the previously described combination of an infrastructure model, a power market and flow model. The results were strongly case-sensitive and it was therefore impossible to draw general conclusions or develop universal guidelines. Therefore a case-independent model was developed in order to carry out various sensitivity analyses to develop the essential concrete grid design guidelines. The analysis focused on two major design problems that form the basis of offshore grid concepts: the teeing-in of wind farms into interconnectors, and the interconnection of two wind farm hubs. The results, insights and conclusions are also valid for more complex design problems with nodes connecting more than two lines. For wind farms far from shore, teeing them into an interconnector can be an interesting option. This is especially true in two cases: • The integration of small wind farms rather far from shore but close to an interconnector (e.g. offshore wind at oil & gas platforms) that put only small electricity trade constraints on the interconnector, • The connection of big wind farms or wind farm hubs to two countries. When connecting them to both countries with the same total connection cable capacity as in a conventional solution, the additional infrastructure costs are limited and a large interconnector is created at the same time. OffshoreGrid – Final Report Hub-to-hub interconnections have shown to be interesting under certain circumstances. In general the projects should be far from shore but close to each other. If the hub-to-hub interconnector is small, it will help to send the electricity from both wind farms to the highest price area. Bigger interconnectors are interesting when the price difference between the countries is high. In both tee-in solutions and hub-to-hub solutions, oversizing one leg of the system and undersizing the other may benefit the design if the price difference profile is not balanced. Depending on the local parameters and the long term price expectations, an optimal solution can be calculated. The case-independent model, based on which these overall conclusions were developed, provides concrete numbers for pre-feasibility checks on the design for specific cases. This allows quick design assessments and avoids lengthy iterative processes. The case-independent model results are directly fed into the overall grid design where these guidelines help to guide the direct grid development. The suggestions for the overall grid design were verified by concrete model calculations. For completeness, it should be mentioned that economics are not the only basis for a decision to develop an integrated solution. Other important factors are e.g. the timing of each part of the project, the fact that an integrated solution can increase the redundancy, the ownership structure of the projects, etc. The results have been complemented and validated with an extra case study, the Cobra cable. This analysis has confirmed the conclusion on the connection of big wind farms to two countries, as discussed in section 4.4.3. Due to high wind expectations, future German spot market prices are expected to be low. This enforces the effect of the two-country-connection. The detailed results of the case-independent model are shown in Annex D.II on www.offshoregrid.eu. The results can be used as general guidelines for project developers, policy makers, regulators and TSOs to assess whether the discussed design solutions (hubto-hub, tee-in, split wind farm connection) could be beneficial for the projects planned. 57
esults 4.5 Overall grid design 4.5.1 Approach The development of the offshore grid is going to be driven by the need to bring offshore wind energy online and by the benefits from trading electricity between countries. This involves on the one hand the connection of the wind energy to where it is most needed, and on the other hand the linking of high generation cost areas to low generation cost areas. There are numerous methodologies that could be applied to achieving these objectives. In this section, the OffshoreGrid consortium demonstrates the effectiveness of two different methodologies to design a beneficial costeffective overall offshore grid. Both methodologies use as a starting point the OffshoreGrid Hub Base Case scenario 2030. This includes the direct or hub connections to each of offshore wind farm in the North and Baltic Seas (as defined in section 4.2), and the offshore reinforcements identified in the ENTSO-E Ten Year Network Development Plan (TYNDP) [56]. Based on this, the following design development strategies are applied: • The direct design Methodology mimics the current evolution as it is envisaged today: First, direct interconnectors are built to promote unconstrained trade as average price difference levels are high. Once additional direct interconnectors become non-beneficial, tee-in, hub-to-hub and meshed grid concepts are added to arrive at an overall grid design. • The Split design Methodology considers an approach that starts with a conclusion from the case-independent model (see section 4.4.4). The idea is that interconnections are built by splitting the connection of some of the larger offshore wind farms between countries. Thereby a path for constrained trade is established. These offshore wind farm nodes are then further interconnected to establish an overall ‘meshed’ design where beneficial. A large number of iterations and sensitivity analyses were carried out for each of the two methodologies 26 in order to prove that each added infrastructure module was beneficial. Each of the methodologies is explained in detail in the following two chapters. The results are compared in section 4.5.4 to see which kind of development is most efficient in terms of reducing European total system generation costs. TAblE 4.6: ENERGY PRIcE dIFFERENcES (IN €/MWh) AS dETERMINEd bY POWER MARkET MOdEl FOR ThE hUb bASE cASE ScENARIO 2030 BE De DK ee Fi Fr GB Ie lT lV Nl NO Pl se BE 4.6 9.7 6.4 23.7 10.1 9.4 8.2 6.9 6.4 7 17.5 6 25.9 De 4.6 7.5 5.4 22.1 9.5 8.8 8.8 5.4 5.4 5.3 15.7 4.4 24.0 DK 9.7 7.5 6.2 16.2 7.6 8.9 11.4 5.8 6.2 6.3 10.1 6.9 17.0 ee 6.4 5.4 6.2 18.8 8.5 10.0 10.4 1.2 0.0 8.1 13.4 3.7 21.1 Fi 23.7 22.1 16.2 18.8 16.5 20.3 23.4 19.0 18.8 20.7 9.9 20.9 7.3 Fr 10.1 9.5 7.6 8.5 16.5 8.9 11.3 8.5 8.5 8.3 10.6 9.6 17.2 GB 9.4 8.8 8.9 10.0 20.3 8.9 6.1 9.9 10.0 6.5 15.0 10.0 21.2 Ie 8.2 8.8 11.4 10.4 23.4 11.3 6.1 10.6 10.4 8.6 10.1 10.2 24.8 lT 6.9 5.4 5.8 1.2 19.0 8.5 9.9 10.6 1.2 7.8 13.4 2.8 20.5 lV 6.4 5.4 6.2 0.0 18.8 8.5 10.0 10.4 1.2 8.1 13.4 3.7 21.1 Nl 7.0 5.3 6.3 8.1 20.7 8.3 6.5 8.6 7.8 8.1 14.7 7.2 21.2 NO 17.5 15.7 10.1 13.4 9.9 10.6 15.0 18.1 13.4 13.4 14.7 14.8 8.8 Pl 6.0 4.4 6.9 3.7 20.9 9.6 10.0 10.2 2.8 3.7 7.2 14.8 22.1 se 25.9 24.0 17.0 21.1 7.3 17.2 21.2 24.8 20.5 21.1 21.2 8.9 22.1 26 Please note that the two methodologies only differ in the first step. The Direct methodology focuses first on direct interconnectors, while the Split methodology focuses first on split wind farm connections. 58 OffshoreGrid – Final Report
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OffshoreGrid: Offshore Electricity
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PRINcIPAl AUThORS: Jan De Decker, P
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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
Page 31 and 32: Methodology - Simulation inputs and
Page 33 and 34: esults This chapter explains and su
Page 35 and 36: esults (figure to the right) in Nor
Page 37 and 38: esults 4.2.1 Hubs and individual co
Page 39 and 40: esults The Baltic Sea is still a ra
Page 41 and 42: esults connections to shore where t
Page 43 and 44: esults 4.2.4 Conclusion and discuss
Page 45 and 46: esults and NordSee Ost Group into t
Page 47 and 48: esults 1986 (the Cross Channel link
Page 49 and 50: esults UK-Germany connection are re
Page 51 and 52: esults tee-in solution becomes pref
Page 53 and 54: esults • Large wind farms (capaci
Page 55 and 56: esults • Very large wind farm hub
Page 57: esults • A three-leg interconnect
Page 61 and 62: esults connectors that were benefic
Page 63 and 64: esults connections were tested in m
Page 65 and 66: esults existing HVDC converters at
Page 67 and 68: esults direct and integrated) ident
Page 69 and 70: esults configuration were rated dif
Page 71 and 72: esults FIGURE 4.31: cOMPARISON OF c
Page 73 and 74: esults farm connections, the reduct
Page 75 and 76: esults Overall design comparison Fi
Page 77 and 78: esults • Costs and benefits of th
Page 79 and 80: esults • There are other connecti
Page 81 and 82: esults These merits also hold for t
Page 83 and 84: Towards an Offshore Grid - Further
Page 91 and 92: conclusions and recommendations The
Page 93 and 94: conclusions and recommendations •
Page 95 and 96: conclusions and recommendations •
Page 97 and 98: conclusions and recommendations 6.5
Page 99 and 100: conclusions and recommendations 98
Page 101 and 102: Acknowledgements and Funding The Of
Page 103 and 104: eferences [1] Weather Research and
Page 105 and 106: eferences [47] Observatoire Médite
Page 107 and 108: 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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