3. Origin of Sea Waves storm swell wind wave direction fetch Sea waves formation due to a storm trough Waves - The combination of forces due to the gravity, sea surface tension and wind intensity are the main factors of origin of sea waves. Fetch - distance over which the wind excites the waves To distances far from the fetch, sea waves have a regular shape and the phenomenon is called swell . Water particle Sea Wave

5. Power Associated to a Sea Wave The power associated with a wave of wavelength  and height H and a front b is given by  H b  Power per metre (b = 1 m) of front wave is approximately When wave height is doubled then generates four times as much power.

6. The world resource of wave power is estimated in about 2 TW. Resource of Wave Power Europe represents about 16% of the global wave power resource (320 GW) Only about 10 to 15% of the global estimated resource can be converted in electrical energy. Global wave power distribution in kW/m Increased wave activity is found between the latitudes of 30° and 60° on both hemispheres Height (m) Period (s) A good wave have ~50 kW/m Equator

7. 5000 MW

13. Pelamis Converter Profile view Top view Sea snake Pelamis

14. Some aspects of Pelamis construction Rolling the steel plate Steel tubes of 3.5 m in diameter Transportation Articulation

15. Pelamis layout Power module of 250 kVA D/ 3 Power transformer de 950 kVA 6.6/15 kV Three phase cable 15 kV Three phase cable 15 kV T D = 3.5 m Articulation Power Module 120 m ~  30 m 5 m Nose P-750 Articulation

16. Hydraulic arm High pressure container Motor/ generator set Distributor Reservoir Vertical articulated axis Horizontal articulated axis Power module Inside view of the power module Efficiency = 35 %

17. Hydraulic circuit Electric generator Gas under pressure HP Valve 1 Hydraulic motor Hydraulic arm 1 Hydraulic arm 2 Fluid under pressure Reservoir LP force force Valve 2 High pressure Low pressure Hydraulic arms

18. Pelamis wave energy converter of 750 kW Pelamis Wave farm of Aguçadora of 2.25 MW Association of Pelamis units in a total of 30 MW (waiting for legislation) 2100 m 600 mof Wave direction Pelamis Seabed Anchorage Pelamis anchorage to the seabed Flexible cable

19. Pelamis installation Total power = 2.25 MW. (3 units of 750 kW) 15 kV 2001 2002 2003 3 year average Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun 150 125 100 75 50 25 0 Wave Seasonal Variability Average incident power (kW/m)

20. Costs distribution for a wave power plant Wave Energy Market mechanical and electrical equipment 49% structures 27% assemblage 13% grid connection project management 2% 5% anchorage 4%