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 Resource of Wave Power in Portuguese coast Povoa do Varzim

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

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%