Wave Power
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Ocean waves are a clean and renewable energy source with the potential to meet 40% of the world's power needs, equivalent to 800 nuclear power plants. Wave energy is generated from wind energy transformed into waves, which can be harnessed through various devices to produce electricity. Despite challenges such as maintenance costs and environmental impacts, wave energy technology holds significant promise as a non-polluting energy solution.
Wave Power
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- 2. Introduction • Ocean waves are both clean and renewable sources of energy with a tremendous worldwide potential of generating electricity. • If fully exploited, about 40% of the world’s power demand could be supplied by this resource – equivalent to as much as 800 nuclear power plants.
- 3. How Waves Form ? • Differential warming of the earth causes pressure differences in the atmosphere, which generate winds. • As winds move across the surface of open bodies of water, they transfer some of their energy to the water and create waves. • A few factors determine how strong an individual wave will be. These include: Speed of wind: The faster the wind is traveling, the bigger a wave will be. Time of wind: The wave will get larger the longer the length of time the wind is hitting it. Distance of wind: The farther the wind travels against the wave (known as fetch), the bigger it will be.
- 4. Wave Power Wave power is the transport of energy by ocean surface waves, and the capture of that energy to do useful work – for example, electricity generation, water desalination, or the pumping of water (into reservoirs).
- 5. What is Wave Energy? • Some of the kinetic (motional) energy in the wind is transformed into waves once the wind hits the ocean surface. • Wind energy ultimately forms due to solar energy and its influence on high and low pressure. • The density of the energy that is transported under the waves under the ocean surface is about five times higher compared to the wind energy 20 meter (about 65 feet) above. • In other words, the amount of energy in a single wave is very high.
- 6. History • The first known patent to use energy from ocean waves dates back to 1799 and was filed in Paris by Girard and his son. • An early application of wave power was a device constructed around 1910 . • From 1855 to 1973 there were already 340 patents filed in the UK alone. • Modern scientific pursuit of wave energy was pioneered by Yoshio Masuda's experiments in the 1940s. • A renewed interest in wave energy was motivated by the oil crisis in 1973. • In the 1980s, a few first-generation prototypes were tested at sea. • In 2008, the first experimental wave farm was opened in Portugal.
- 7. Wave Energy Environments The strongest winds blow between 30˚ and 60˚ in latitude. Western coastlines at these latitudes experience the most powerful waves.
- 8. Harnessing Techniques • In order to extract this energy, wave energy conversion devices must create a system of reacting forces, in which two or more bodies move relative to each other, while at least one body interacts with the waves. • There are many ways that such a system could be configured. Visit www.seminarlinks.blogspot.com to download
- 9. Harnessing Techniques • Waves retain energy differently depending on water depth Lose energy slowly in deep water Lose energy quickly as water becomes shallower because of friction between the moving water particles and the sea bed • Wave energy conversion devices are designed for optimal operation at a particular depth range.
- 10. Three Basic Kinds of Systems • Offshore (deals with swell energy not breaking waves) • Near Shore (maximum wave amplitude) • Embedded devices (built into shoreline to receive breaking wave – but energy loss is occurring while the wave is breaking)
- 11. Wave Energy Devices • Wave Profile Devices: They turn the oscillating height of the oceans surface into mechanical energy. • Oscillating Water Columns: They convert the energy of the waves into air pressure. • Wave Capture Devices: They convert the energy of the waves into potential energy.
- 12. Wave Profile Devices • If the physical size of the wave profile device is very small compared to the periodic length of the wave, this type of wave energy device is called a "point absorber". • If the size of the device is larger or longer than the typical periodic wavelength, it is called a "linear absorber“. • More commonly they are collectively known as "wave attenuators". Wave Attenuators Point Absorber
- 13. Working The waves energy is absorbed using • Vertical motion (heave) • Horizontal motion in the direction of wave travel (surge) • Angular motion about a central axis parallel to the wave crests (pitch) • or, angular motion about a vertical axis (yaw) • or a combination of all four • The energy being generated by reacting these different movements against some kind of fixed resistance called a reaction point.
- 14. Working • To make efficient use of the force generated by the wave, we need some kind of force reaction. • In other words, we want the waves force on the float to react against another rigid or semi-rigid body. • Reaction points can be inertial masses such as heavy suspended ballast plates, sea-floor anchors or a fixed deadweight or pile as shown.
- 15. The Power Buoy As the buoy bobs up-and- down in the waves, a oscillatory mutual force reaction is generated between the freely moving absorber and the heavy plate causing a hydraulic pump in between to rotate a generator producing electricity.
- 16. Wave Attenuators • As the waves pass along the length of the device, they cause the long cylindrical body to sag downwards into the troughs of the waves and arch upwards when the waves crest is passing. • Connecting joints along the body of the device flex in the waves exerting a great deal of force which is used to power a hydraulic ram at each joint. • The hydraulic ram drives oil through a hydraulic motor which drives a generator, producing the electricity.
- 17. Examples PB150 PowerBuoy with peak-rated power output of 150 kW. USA 750 kW Pelamis Wave Energy Converter, Scotland
- 18. Oscillating Water Column (OWC) • The Oscillating Water Column, (OWC) is a popular shoreline wave energy device normally positioned onto or near to rocks or cliffs which are next to a deep sea bottom. • They consist of a partly submerged hollow chamber fixed directly at the shoreline which converts wave energy into air pressure.
- 19. OWC- Working • As the incident waves outside enter and exit the chamber, changes in wave movement on the opening cause the water level within the enclosure to oscillate up and down acting like a giant piston on the air above the surface of the water, pushing it back and forth. • This air is compressed and decompressed by this movement every cycle. • The air is channeled through a wind turbine generator to produce electricity
- 20. LIMPET (Land Installed Marine Powered Energy Transformer), Scotland, Capacity-500 kW Oceanlinx’s world's first 1MW wave energy converter unit 'greenWAVE, Australia 500 kW offshore OWC, Port Kembla,AustraliaLIMPET
- 21. Wave Capture Device • A Wave Capture Device also known as a Overtopping Wave Power Device, is a shoreline to nearshore wave energy device that captures the movements of the tides and waves and converts it into potential energy. • Wave energy is converted into potential energy by lifting the water up onto a higher level. • The wave capture device, or more commonly an overtopping device, elevates ocean waves to a holding reservoir above sea level. • It require sufficient wave power to fill the impoundment reservoir.
- 22. Working • As the waves hit the structure they flow up a ramp and over the top (hence the name "overtopping"), into a raised water impoundment reservoir on the device in order to fill it. • Once captured, the potential energy of the trapped water in the reservoir is extracted using gravity as the water returns to the sea via a low-head Kaplan turbine generator located at the bottom of the wave capture device.
- 23. Tapered Channel (TAPCHAN) • The TAPCHAN is designed by a company called Norwave, and a 350kW prototype commenced operation in 1985 on a small Norwegian island. • The principle behind the design is to capture waves in a raised reservoir (about 3 metres above the mean sea level) and then extracting useful work as the water is allowed to flow back to the sea.
- 24. Wave Dragon Overtopping Device, Denmark 1.5 to 12 MW of capacity Toftestallen Wave Power Plant, TAPCHAN, Norway 500 kW
- 25. New Idea Use Bottom Waves • Wave Roller device anchored to the sea floor (obviously near the cost) • Easiest to build electricity export infrastructure. • But energy density is lower; still prototypes are being developed
- 26. Oyster wave power technology , Scotland , peak output of 435kW Visit www.seminarlinks.blogspot.com to download
- 27. The Future: Wave farms
- 28. Challenges • Some devices already been destroyed by the forces of tides and strong storms. • Accessibility, maintenance and repair can also be costly. • The typical efficiency of a wave energy device at the moment being only about 30%. • There is a potential impact on the marine environment. • Noise pollution, for example, could have negative impact if not monitored, although the noise and visible impact of each design varies greatly. • The major competitor of wave power is offshore wind power. • Wave farms can result in the displacement of commercial and recreational fishermen from productive fishing grounds. • Waves generate about 2,700 gigawatts of power. • Of those 2,700 gigawatts, only about 500 gigawatts can be captured with the current technology.
- 29. Conclusion • There is much potential in worldwide wave energy; 1000 TerraWatts available. • Capturing wave energy and converting that into electricity is difficult but this allows for innovate devices to be designed • Technology produces no greenhouse gas emissions making it a non- polluting and renewable source of energy. • The technical challenges are solvable. • The problems lie in facilitating the testing and development of the technology to make it more affordable Need government funding Need a regulatory process conducive for rapid deployment of prototypes and research equipment.
- 30. References • http://en.wikipedia.org/wiki/Wave_power • http://www.alternative-energy-tutorials.com/wave-energy/wave-energy- devices.html • http://www.renewablepowernews.com/archives/1043 • http://www.darvill.clara.net/altenerg/wave.htm • http://www.smartplanet.com/blog/pure-genius/wave-power-how-it-works/3769 • http://energyinformative.org/wave-energy/ • http://science.howstuffworks.com/environmental/earth/oceanography/wave- energy.htm • http://www.emec.org.uk/marine-energy/wave-devices/ • http://people.bath.ac.uk/mh391/WavePower/tapchan.html
- 31. Visit www.seminarlinks.blogspot.com to download