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Tidal and Wind Power


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AN introduction to Tidal and Wind Energy Systems

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Tidal and Wind Power

  1. 1. Desai Harshad Suresh B050254EE
  2. 2. Tidal power is a form of hydropower. Exploits the rise and fall in sea levels due to the tides, or the movement of water caused by tidal currents. Although not widely used, tidal power has potential for energy generation and is more predictable than wind power.
  3. 3. Tidal energy is not a new concept. Energy in this form was used to grind grains since 11th century in France and England.
  4. 4. Tidal Stream Systems: These make use of the kinetic energy of moving water to power turbines. Barrage tidal power: This type uses the potential energy from the difference in height between high and low tides.
  5. 5. A relatively new technology. Tidal stream generators draw energy from currents in the same way as wind turbines. Water, being 832 times denser than air, provides significant power from one generator. As in wind power, location of the plant is important.
  6. 6. Location: Tidal Stream Systems need to be located in areas with fast currents where natural flows are concentrated between obstructions. Examples of such sites include entrance to bays and rivers, around rocky points, headlands, or between islands. Potential sites suggested include Channel Islands in UK, Strait of Gibraltar, East River in NYC, Cook Strait in NZ, Vancouver island in Canada.
  7. 7. The picture shows rotors in Harland and Wolff, Belfast, before installation in Strangford Lough
  8. 8. An artist s impression of the 40 MW Pentland Firth design at adepth of 60m and a 20m rotor for power generation
  9. 9. Alongside is a hybrid image of Marine Current Turbines existing SeaFlow 300kW proto type turbine which was the world s first offshore tidal turbine and was installed off Lynmouth, Devon in May 2003.
  10. 10. Turbines: An emerging tidal stream technology is the shrouded tidal turbine enclosed in a Venturi shaped shroud or duct producing a sub atmosphere of low pressure behind the turbine, allowing the turbine to operate at higher efficiency and typically 3 4 times higher power output than a turbine of the same size in free stream.
  11. 11. Economics: Tidal stream systems are low cost compared to barrage and fence types. The set-up cost for such systems is not as high as that for barrage types. Also the efficiency of the turbines can be increased using shrouded turbines.
  12. 12. This method involves building a barrage over a river. The barrage turbines generate as water flows in and out of the estuary. These systems are similar to a hydro dam that produces Static Head or pressure head. When the water level outside of the basin or lagoon changes relative to the water level inside, the turbines are able to produce power.
  13. 13. La Rance- a Barrage type Tidal Power Plant in France
  14. 14. The power can be generated using either of Ebb Generation (Outflow generation), Flood Generation, Pumping, Two- basin Schemes.
  15. 15. Environmental Impacts: The placement of a barrage into an estuary has a considerable effect on the water inside the basin and on the ecosystem. Many governments have been reluctant in recent times to grant approval for tidal barrages. The impacts can be listed as Changes in Turbidity, Salinity, accumulation of sediments at the estuary and increase in fish mortality.
  16. 16. Economics: These type of tidal plants have high capital cost and a very low running cost. As a result a tidal power scheme may not produce returns for many years.
  17. 17. CON LUSION S: A tidal power scheme is a long-term source of electricity. It is important to realize its full potential so that Many countries have initiated tidal power schemes in bay areas and in seas. In India tidal power projects are being developed in Gulf of Kutch and the Gulf of Khambat.
  18. 18. It is the conversion of wind energy into useful form of energy, like electricity using wind turbines. Wind power is used in large scale wind farms for national electrical grids as well as in small individual turbines for providing electricity to rural residences or grid-isolated locations.
  19. 19. It is estimated that there is 50-100 times more wind energy than plant biomass energy available on Earth. The power in the wind can be extracted by allowing it to blow past moving wings that exert torque on a rotor. The amount of power transferred is directly proportional to the density of the air, the area swept out by the rotor, and the cube of the wind speed.
  20. 20. As a general rule, wind generators are practical where the average wind speed is 10 mph (16 km/h or 4.5 m/s) or greater. Usually sites are pre-selected on basis of a wind atlas, and validated with wind measurements. Thus, Metrology plays an important role in turbine placement.
  21. 21. Onshore Installations: Onshore turbine installations in hilly or mountainous regions tend to be on ridgelines generally three kilometers or more inland from the nearest shoreline. This is done to exploit the so-called topographic acceleration. An on shore installation in Tamil Nadu, India.
  22. 22. Offshore Installations: Offshore wind development zones are generally considered to be ten kilometers or more from land. Offshore wind turbines are less obtrusive than turbines on land, as their apparent size and noise can be mitigated by distance An Offshore installation near Copenhagen
  23. 23. Near Shore Installations: Near-Shore turbine installations are generally considered to be inside a zone that is on land within three kilometers of a shoreline or on water within ten kilometers of land. These areas tend to be windy and are good sites for turbine installation, because a primary source of wind is convection caused by the differential heating and cooling of land and sea over the cycle of day and night.
  24. 24. A near shore installation in Denmark
  25. 25. Airborne Installations: Wind turbines might also be flown in high speed winds at altitude, although no such systems currently exist in the marketplace.
  26. 26. Asia s largest wind park in Satara district of Maharashtra with 201 MW on installation, commissioned by Suzlon Energy in 2001
  27. 27. Wind power can be generated for a grid as well for single customers. Small Wind is defined as wind generation systems with capacities of 100 kW or less and are usually used to power homes, farms, and small businesses. These systems help to reduce or eliminate electricity bills, to avoid the unpredictability of natural gas prices, or simply to generate clean power.
  28. 28. Growth and Cost trends: Due to the exponential rise in usage of wind energy worldwide the wind energy costs are reduced. However installation costs have risen significantly.
  29. 29. Scalability: A key issue debated about wind power is its ability to scale to meet a substantial portion of the world's energy demand. There are significant economic, technical, and ecological issues about the large- scale use of wind power that may limit its ability to replace other forms of energy production.
  30. 30. Economics and feasibility: Without the tax incentives (also know as subsidies) almost no wind power installation is economically feasible at present. Intermittency and Variability: Electricity generated from wind power can be highly variable at several different timescales: from hour to hour, daily, and seasonally
  31. 31. This variability can present substantial challenges to incorporating large amounts of wind power into a grid system, since to maintain grid stability, energy supply and demand must remain in balance. There is an inverse relationship with wind speed and peak demand of electricity. The intermittency of wind seldom creates problems when using wind power at low to moderate penetration levels (though such intermittency has caused problems for grid stability in Denmark and Germany, where penetration is greatest
  32. 32. Grid Management: Variability of wind output creates a challenge to integrating high levels of wind into energy grids based on existing operating procedures. Predictability: It is related to variability but essentially different. It is the short term (hourly or daily) predictability. Because of its variable nature, wind energy forecasting presents a challenge.
  33. 33. Wind energy is the best option available in alternate energy sources. India ranks 4th in world in terms of wind energy generation. According to 2006 data India has an installed wind power capacity of 6270 MW. (Global Wind Energy Council Statistics)
  34. 34. Wind Energy, as estimated is more than surplus for present day human needs. However the problems in areas of intermittency, grid management, predictability, energy storage, safety of wildlife and others must be addressed to realize its full potential.
  35. 35. This document was created with Win2PDF available at The unregistered version of Win2PDF is for evaluation or non-commercial use only.