1. WINTER Template Ocean Energy RENEWABLE ENERGY SYSTEMS

2. WINTER Template History of wave energy What causes waves? Wave energy converters Offshore devices Advantages/disadvantages Legal/economic encouragement Contents

3. Before 1973 First ideas patented in 1799 Between 1855 and 1973 there were 340 patents Several configurations of wave energy converters were designed and tested at model scale and some have been operated at sea History of wave energy

4. After 1973 In Europe, intensive research and development study of wave energy conversion began after the dramatic increase in oil prices in 1973 Several research programs with government and private support started mainly in the UK, Portugal, Ireland, Norway, Sweden and Denmark History of wave energy

5. International conferences in wave energy were held in Edinburgh/UK-1993, Lisbon/Portugal- 1995, Patras/Greece-1998 and Aalborg/Denmark-2000 Some commercial plants have been deployed History of wave energy

6. The wave energy resource is a concentrated form of solar energy Winds generated by the differential heating of the earth pass over open bodies of water The wind pushes surface water particles along with it, setting up a rolling motion in the water and moving the water particles in a vertical, circular path What causes waves?

8. Wave energy densities The power in a wave is proportional to the square of the amplitude and to the period of the motion Large amplitude (~2 m), long period (~7-10 s) waves have energy fluxes commonly exceeding 40-50 kW/m width of oncoming wave Wave energy is unevenly distributed over the globe

9. Wave energy densities around the globe

10. Wave climate in Europe The wave climate along the western coast of Europe is characterized by particularly high energy. The UK has over half the wave energy potential in Europe, up to 75 kW/m off Ireland and Scotland Wave climate in the US The West Coast is the most promising area with wave energy densities in the 25 – 40 kW/m range

11. Wave energy converters Four different types of WECs; Oscillating water columns Overtopping devices Point absorbers Surging devices

12. Wave energy converters The oscillating water column Partly submerged structure with an opening to the sea below the water line Waves cause the water column to rise and fall, which alternately compresses and depressurizes the air column This air flows through a turbine which drives an electric generator

13. Wave energy converters Point absorbers They provide a heave motion that is converted by mechanical/ hydraulic systems in linear or rotational motion for driving electrical generators

14. Wave energy converters Surging devices Surging devices exploit the horizontal particle velocity in a wave to drive a deflector or to generate pumping effect of a flexible bag facing the wave front

15. Placement of wave energy converters Three locations Shore Near shore Offshore

16. Placement of wave energy converters Shore/Near shore vs. offshore The potential energy The power available in the waves is much greater offshore Nearer the coastline the average energy intensity of a wave decreases due to interaction with the seabed

17. Placement of wave energy converters Other factors Engineering challenges Construction costs Maintenance and/or installation costs Transmission costs and losses Environmental impacts The scale of electricity production

18. Placement of wave energy converters The Archimedes Wave Swing An underwater buoy of which the upper part (floater) moves up and down in the wave while the lower part stays in position The floater is pushed down under a wave top and moves up under a wave trough

19. Placement of wave energy converters The Archimedes Wave Swing An underwater buoy of which the upper part (floater) moves up and down in the wave while the lower part stays in position The floater is pushed down under a wave top and moves up under a wave trough

20. Placement of wave energy converters The Floating Wave Power Vessel Consists of a floating basin supported by ballast tanks in four sections A patented anchor system allows the orientation of the vessel to the most energetic wave direction A 1.5 mW vessel is planned to be deployed at 50–80 m depth 500 m offshore Shetland

21. Placement of wave energy converters The Wave dragon Is an overtopping device, which elevates ocean waves to a reservoir above sea level Water is let out through a number of turbines and in this way transformed into electricity The prototype is deployed in Nissum Bredning, an inlet in the northern part of Denmark

22. Placement of wave energy converters The McCabe Wave Pump The device consists of three rectangular steel pontoons, which are hinged together across their beam

23. Placement of wave energy converters The McCabe Wave Pump The device consists of three rectangular steel pontoons, which are hinged together across their beam

24. Placement of wave energy converters The McCabe Wave Pump The MWP was primarily designed to produce potable water although it can also be used to produce electricity A 40 m long prototype was deployed in 1996 off the coast of Kilbaha, County Clare, Ireland

25. Placement of wave energy converters PowerBuoy Developed in the US by Ocean Power Technologies It is a wave generation system that uses a buoy to capture and convert wave energy into a controlled mechanical force which drives an electrical generator

26. Placement of wave energy converters PowerBuoy The PowerBuoy is enhanced with sensors, which continuously monitor the performance of the various subsystems and surrounding ocean environment. In the event of very large oncoming waves, the system automatically disconnects

27. Placement of wave energy converters The Pelamis Is a semi-submerged structure composed of cylindrical sections linked by hinged joints

28. Placement of wave energy converters The Pelamis The wave induced motion of these joints is resisted by hydraulic rams which pump high pressure oil through hydraulic motors via smoothing accumulators The hydraulic motors drive electrical generators to produce electricity

29. Placement of wave energy converters The Pelamis Several devices can be connected together and linked to shore through a single seabed cable

30. Placement of wave energy converters The Pelamis A typical 30MW installation would occupy a square kilometre of ocean and provide sufficient electricity for 20,000 homes Ocean Power Delivery has won a bid for a 750kW project off Islay, Scotland and has recently signed a memorandum of understanding with BC Hydro to develop a 2 MW project off the coast of Vancouver Island, Canada

31. Placement of wave energy converters The Pelamis A typical 30MW installation would occupy a square kilometre of ocean and provide sufficient electricity for 20,000 homes Ocean Power Delivery has won a bid for a 750kW project off Islay, Scotland and has recently signed a memorandum of understanding with BC Hydro to develop a 2 MW project off the coast of Vancouver Island, Canada

32. Advantages The natural seasonal variability of wave energy follows the electricity demand in temperate climates Negligible demand on land use Could secure energy supplies in remote regions Large-scale implementation of wave power technologies will stimulate declining industries, e.g. shipbuilding

33. Disadvantages Disadvantages of offshore wave energy The main wave energy barriers result from the energy carrier itself: The sea The peak-to-average load ratio in the sea is very high and difficult to predict The structural loading in the event of extreme weather conditions, such as hurricanes, may be as high as 100 times the average loading

34. Disadvantages High construction costs induce high power generation costs, thus making the technology uncompetitive The incidence of wave power at deep ocean sites is three to eight times the wave power at adjacent coastal sites, but the cost of electricity transmission from deep ocean sites is often prohibitively high

35. Environmental impacts Offshore wave energy devices may be a potential navigation hazard to ships Near shore devices will have a visual impact Wave energy devices could have an effect on some forms of recreation Impacts on the marine environment