Large-scale off-shore wind power

1. Large-scaleoff-shorewindpower Ilinca Julian, Heikki Ojanen, Juha - Matti Lukkari

2. Windpower at sea • Higher and steadierwindspeeds. • Usuallyinstallationsunvisiblefromland. • Theirnoisecannotbeheardfromland. • Moredemandingenvironmentthan for onshore. • Moreexpensivemaintenancecosts.

3. Turbines • Rotordiameter 90 m nowcommonplace. • Designed to withstandverticalwindgradient and alsoathmosphericturbulance.

4. Foundations • Monopile, for < 20 m depth • Jacket, used already in oil industry • Tripod, for < 20 m depth • Tripile, up to 50 m depth • Gravity, been used up to 10 m depth • Floating, for deep waters • At least monopile and tripod cannot be used on a stony sea bed.

6. Placing • Trend is to locate wind farms close to eachother. • Knowledge of wind profiles is key importance • Knowledge of composition of seabed sediment layers is essential.

7. Off-Shorewindfarms in europe

9. Layout of Turbines • Haseffecton projectperformance, size and cost • Legal, regulatory and geophysical reasons • Spacing between turbines aligned in a row is on the order of 5 to 10 rotor diameters, and spacing between rows is between 7 and 12 rotor diameters.

10. Environmentaleffects • Affects on organisms and habitats. • Data gatheringfarfromsimple. • Manyplannedwindfarmsclose to fisherysites in North Sea.

11. Electricalsystemoverview • Collectionsystem • Medium voltagegridwithin the windfarm • Connects the windturbines to the offshoresubstation • Offshoresubstation • Transmission system • Between the offshore and onshoresubstations • Highvoltage AC or DC

12. Collectionsystem • Usually a stringclusterconfiguration • Severalturbines in everystring • Each WT with a step-uptransformer • Generationvoltage 690V • Grid voltagetypicallyaround 30kV • The gridmustcarryall the generatedpower in the string • Limited by the size of the step-uptransformers

14. Offshoresubstation • Lines of the collectionsystemmeethere • Substationbased on a platform • Power transformer • Ratedpowerup to severalhundred MVA • Limited by the weight of the transformer • Stepsup the voltage to a transmission voltage • Power electronics (In case of a HVDC link) • Rectifier and filterunits

15. Lillgrundwindfarm (Sweden) Nystedwindfarm (Denmark)

16. Transmission system: HVAC vs HVDC • Distance to the on-shoresubstation • Reactivelosses (AC) vsresistivelosses (DC) • d < 50km  AC • 50km < d < 80km  AC or DC • d > 80km  DC • HVDC technologymoreexpensive • Newertechnology • Requiresmorecomponents & space

17. Off-shorewindfarm with HVAC

18. Off-shorewindfarm with HVDC

19. Comparison to on-shorewind • The cost of cable connection from the farm to the onshore grid. • Foundations costs. • Operation and maintenance costs. • Protection from corrosion due to saltwater.

20. Developers • Competition • 2012 work was carried out on 13 wind farms. • Developmentgrowing and encouraged • Governmentsupport Off-Shore wind developers’ share of grid connected capacity from 1st January to June 30th. Source: EWEA

21. Current Construction Source: EWEA

22. Grid connectionCosts Initiative to buildlargerturbines. Currently demand outstrips supply for the significant global requirements. Full capacity for a larger fraction of the year. Price of power.

23. Finance • Solid and continues to grow • Trust -Suitablefundingstructures -non-resourcefinancing

24. PrivateCosts • Capital costs, maintenance costs and operation costs • Annual Cost • leveled costs are expected to decrease Source. C: Howland, Caitlin M., "The Economics of Offshore Wind Energy" (2012). Honors College. Paper 60.

25. Capital Costs • High and predicted to increase • Macroeconomic reasons • Supply and Demand! • Forecasting improvement • Competition

26. Turbines and Structures • Turbines contribute most to the cost • Materials • Costs of different base structures have the second largest impact on the finance • Cost efficiency may be grater in deep water farms • stable energy production

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