1. “Potential of floating wind turbines in Aegean Sea” Prof
“Potential of floating wind turbines in Aegean Sea” Prof. Nikitas Nikitakos, Dr. Theodoros Lilas University of the Aegean Chios- Greece

2. Outlines Introduction State of the art review Technical issues
Case Study: Floating desalination
Legal/ Political issues
Conclusions

3. Air Space Rights Development Rights Navigation Rights Access Rights
Water Column
Rights
Fishing
Rights
Seabed Use
Rights
Mineral
Rights
Disposal
Rights
Nichols, S., It's Our Ocean: How Well Will We Govern It? Presented at the Offshore Issues Consultation Workshop. Viewed at (July 28, 2003).

4. Windpower at sea
Why at sea In some distance from the land the wind velocity is increased by 20%. The wind energy is analogous to the third power of wind speed. As result the available wind energy at sea is much more than in the land.

5. More stable resulting to the increase of produced energy by 40% related with land .
Smaller height.
Much smaller disturbances related with land = greater life time for the wind power .

7. Offshore wind projects

13. SEVERAL APPROACHES

14. AND STUDIES

15. VERY IMPORTANT ANCHORING

17. ANCHORING TECHNOLOGY TRANSFER FROM OTHER APPLICATIONS

18. ANCHORING MODES

19. RETENTION – COST

21. LAB PROTOTYPES

22. ITALIAN AND DANISH COOPERATION

23. GERMANY
The German wind industry is looking for affordable foundations for offshore turbines
Six types of foundations are considered potential candidates for offshore use:
• Steel monopile foundations are driven deep into the seabed.
• Gravity foundations made of steel and concrete are placed on the seabed.
• Bucket foundations are pressed into the ground and suction themselves into place in a vacuum.
• Tripod foundations consist of three steel piles anchored in the seabed.
• Four-legged steel jackets form a stable latticed construction.
• Floating foundations are carried by buoys and float under the water surface. Chains anchored in the seabed keep them fixed in position.

24. NORWAY
Hydro
The future goal is to have large-scale offshore wind parks with up to 200 turbines capable of producing up to 4 terawatt hours (TWh) per year and delivering renewable electricity to both offshore and onshore activities. This goal is far in the future, but if we’re to succeed in years, we have to start the work today. —Alexandra Bech Gjørv, Hydro’s director of new energy forms

25. UK
The Beatrice Wind Farm is the flagship project for offshore wind energy development in Scotland, the UK and Europe. The project aims to install two demonstrator wind turbines adjacent to the Beatrice oil field, 25 km off the east coast

28. Technical issues Water depth Wave load conditions
Wind speed conditions
Current velocity
Surge depth
Soil type and strength
Turbine size
Turbine operating conditions
Structure type
Structural response to wind, waves and currents in shallow waters.

29. FLOATING ECOLOGICAL DESALINATION
LAUNCHING 2006
INITIAL SEA TRIALS 6 months
IN AEGEAN SEA from 6/2007
27 MONTHS IN THE WAVES
27 MONTHS IN THE SEA
WIND SPEEDS UP TO 120 km/hour
INOVATION - PATENTS
LLOYD’S Innovation Award, REGIO STARS 2008
Design for m3/day

32. Selection of main dimensions
Platform parameters:
Height
Diameter of floaters
Diameter of floating structure
Evaluation with respect to:
Stability
Wave response

33. Floating Structure Response Simulation

34. Structural members of the platform
The floating platform is comprised from 4 peripheral floating cylinders with total height of 8 m and diameter 2 m each.
And a central floating cylinder the diameter of which is 4 m and height 8 m

35. Description of the structural members of the platform
The connection of all cylinders takes place with a tubular mesh with pipe diameter of 273 mm and wall thickness of 8,8 mm.
There are peripheral and central mesh connections .
Inside the peripheral cylinders there are vertical structural pipe elements which are connected on the tubular mesh, thus preventing the cylinder shell to bear the axial compressive or tensile developed forces during normal operation at sea.

36. Stress Analysis Calculations
The developed stresses are calculated with the use of finite element analysis.
The scope of the analysis is to:
Derive the maximum operating axial loads exerted on the mesh piping and compare them with those theoretically calculated with Euler and
Calculate the Misses yield stress and compare it with the material yield stress.

37. Stress Analysis Calculations
Four different loading cases are examined
1. Static loading under sagging condition.
1.1 The 4 peripheral cylinders are supported
1.2 The 2 diagonal cylinders are supported

38. Stress Analysis Calculations
2. Static loading under hogging condition.
The central cylinder is simply supported and the peripherals are free.

39. Stress Analysis Calculations
3. Dynamic motion with respect to external excitation
In this case the Platform is supported from springs.
The spring coefficient is calculated from the buoyancy characteristics of the cylinders with respect to their draft.
Maximum buoyancy is achieved when the draft of the platform equals to the height of cylinders.
Spring elements

40. Operation

41. Conclusions
Operational
Autonomous
Ecological
Scalable
Transferable

42. Political Landscape Targets Energy is a reserved issue
20% renewables by 2020
Energy is a reserved issue
Environmental issues devolved
Planning Bill
Grid connection
Marine Bill
EC Directives
Birds
Habitat
Seabed lease initiative

43. Public policy questions
Whose resource is being used?
Whose actual use is being affected?
Who bears the direct and indirect burdens of the use?
Who acquires the direct and indirect benefits?
Does the use foreclose other near-term or future uses?
Who has a say?

44. Ocean Governance Puzzle
Planning/Siting (science-based)
Where should you put/allow an activity?
Zoning (law-based)
Where can you put/allow an activity?
Permitting (stakeholder process)
Where will you put /allow an activity?
Regulating (management/enforcement)
How will the site/activity be regulated?

45. Conclusions Wind power at sea a new potential for renewable energies
Technical issues
Legal and regulatory issues
The floating desalination platform shows its potential for use of in Aegean sea

46. Thank you for your attention