Alternative Energy


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Alternative Energy

  1. 1. Tidal Energy
  2. 2. What is Tidal Energy?  Tidal Energy is a form of hydropower that creates forms of energy by converting the energy of the incoming and outgoing tides.  Tidal energy is a reliable source of power because of its predictability, tide cycles are always known as opposed to the inconsistent power of the wind and sun.  The stronger the tide, either in water level height or current strength, the greater the potential for power generation.
  3. 3. Methods of Harnessing Energy from The Tides  There are multiple methods of obtaining energy from the changing tides and each has their own set of advantages and disadvantages.  Depending on the location, one particular method could be more appropriate than another
  4. 4.  A barrage would be used in an estuary with a large fluctuation between high and low tide  Wave methods would be used farther out in the sea if there is a particular area with large waves.  Underwater turbines are useful if there are strong underwater currents
  5. 5. Tidal energy Wave energy What is ocean wave energy Energy harnessed from waves is an alternative energy source that has been in use for centuries. The kinetic energy (movement) exists in the moving waves of the ocean. There is tremendous energy in the ocean waves. Ocean wave energy is captured directly from surface waves or from pressure fluctuations below the surface.
  6. 6. Tidal energy Wave energy •depends on the waves – variable energy supply •needs a suitable site, where waves are consistently strong •some designs are noisy •the energy is free – no fuel is •mist be able to withstand very rough weather costly to develop needed and no waste is produced •visual impact if above water or on shore •not expensive to operate and can disturb or disrupt marine life – including changes in the distribution and types of marine life near the shore maintain •poses a possible threat to navigation from collisions due to •can produce a significant amount the low profile of the wave energy devices above the water, making them undetectable either by direct sighting or by of energy. radar •may interfere with mooring and anchorage lines with commercial and sport-fishing •may degrade scenic ocean front views from wave energy devices located near or on the shore, and from onshore overhead electric transmission lines.
  7. 7. Tidal energy Wave energy Wave-Energy Conversion Devices Wave power devices extract energy While all wave energy technologies directly from the surface motion are intended to be installed at or near of ocean waves or from pressure the water's surface, they differ in their fluctuations below the surface. orientation to the waves with which they are interacting and in the A variety of technologies have manner in which they convert the been proposed to capture the energy of the waves into other energy energy from waves. forms, usually electricity. The Wave technologies have been following wave technologies have designed to be installed in near been the target of recent shore, offshore, and far offshore development. locations. Terminator Point Oyster Attenuators Overtopping devices absorber devices
  8. 8. Tidal energy Wave energy Wave-Energy Conversion Devices Aquamarine Power is the owner and developer of Oyster, the world’s largest working hydro-electric wave energy converter. Oyster has been designed to harness the abundant natural energy found in near shore waves and convert it into sustainable zero- emission electricity. Oyster is a simple mechanical hinged flap connected to the seabed at around 10m depth. Each passing wave moves the flap, driving hydraulic pistons to deliver high pressure water via a pipeline to an onshore electrical turbine. Multiple Oyster devices are designed to be deployed in utility-scale wave farms typically of 100MW or more. Oyster will combine high efficiency and survivability with low cost operations, maintenance and manufacture to
  9. 9. Tidal energy Wave energy Wave-Energy Conversion Devices Terminator devices extend perpendicular to the direction of wave travel and capture or reflect the power of the wave. These devices are typically onshore or near shore; however, floating versions have been designed for offshore applications. The oscillating water column is a form of terminator in which water enters through a subsurface opening into a chamber with air trapped above it. The wave action causes the captured water column to move up and down like a piston to force the air though an opening connected to a turbine. Potential wave energy extraction technology.
  10. 10. Tidal energy Wave energy Wave-Energy Conversion Devices A point absorber is a floating structure with components that move relative to each other due to wave action (e.g., a floating buoy inside a fixed cylinder). The relative motion is used to drive electromechanical or hydraulic energy converters.
  11. 11. Tidal energy Attenuators are long Wave energy multisegment floating structures oriented parallel to the direction of Wave-Energy Conversion Devices the waves. The differing heights of waves along the length of the device causes flexing where the segments Pelamis : connect, and this flexing is connected to hydraulic pumps or other World’s First converters. Commercial Wave Energy Project The wave energy converter shown is a semi-submerged, The device is a long, tubular articulated structure composed Structure which floats on the of cylindrical sections linked by surface of the ocean and converts hinged joints. These structures incoming waves from all directions can also be aligned in a row, one
  12. 12. Tidal energy Wave energy Wave-Energy Conversion Devices Overtopping devices have reservoirs that are filled by incoming waves to levels above the average surrounding ocean. The water is then released, and gravity causes it to fall back toward the ocean surface. The energy of the falling water is used to turn hydro turbines. Specially built seagoing vessels can also capture the energy of offshore waves. These floating platforms create electricity by funneling waves through internal turbines and then back into the sea.
  13. 13. Tidal Barrage •A special kind of dam called a "barrage" is used to capture the power of the tides. •As high tide comes in, gates in the barrage are opened. The rush of water rotates the turbines at the sides of these gates. •When the tide is fully in, the gates are closed, and the water is trapped until low tide. •At low tide, the water within the barrage is higher than the water beyond. •The gates are reopened, and water rushes back toward the ocean. The torrent of water again turns the wheels of the turbines. •Therefore, the turbines generate electricity during the surge of both high and low tides and make this system on harnessing energy a very productive one.
  14. 14. Tidal Barrage Pros Vs. Cons • Clean, renewable energy. • Costs of building is • Good for the environment. tremendous. • Once installed, little • Only provides power when the maintenance. tide is going in and out (around 10 hours per day) • Power is free once barrage is built. • Affects transportation in the waterway. • Tides are very reliable and • Affects wild life in the area easy to predict. • Maximum energy is limited to • Cost of technology is likely to 2.5 terawatts. Total amount of fall tidal dissipation or the friction • Sustainable measured by slowing of the lunar orbit.
  15. 15. Barrage Diagram
  16. 16. Bay of Fundy Tidal Project • A possible project site close to here is the Bay of Fundy. • A Barrage is planned to be built in the minas basin just off the coast of Nova Scotia. • The Bay of Fundy has the highest tides in the world making this a desirable location for this project.
  17. 17. •Tidal Turbines are an alternative way to conserve energy using tidal currents •They are very close in concept to using a windmill under the sea, river, or ocean • Water currents turn the turbines, which activates a generator that produces electricity •The blades are designed for bi-directional flow , so they turn regardless of which way the tide is moving •They usually spin between 10 and 20 times per minute
  18. 18. •Northern Ireland's Strangford Narrows – this is a green electricity generator that relies on the changing tide to produce power for about 1000 homes •It is the worlds largest ever tidal turbine •New York City’s East River has six 35 kilowatt turbines will produce enough energy to provide for a supermarket and a parking garage •They can be as close as six feet from the surface and they are 16 foot, rotors that spin with the tidal change Northern Ireland’s Strangford Narrows East River Turbines
  19. 19. •Tidal dams restrict fish migration and cause silt build •They produce no up which affects tidal basin atmospheric waste ecosystems in negative ways •It does not need fuel to run •People are working on more •Although it is expensive to fish friendly turbines, yet it is hard to prevent all fish from build, it is not expensive to avoiding these turbines. This maintain means that there are some fish •All the tides of the rivers, killings from the use of seas, and oceans are turbines predictable so one can know •There are only about 40 high when the most energy will be flow areas on Earth where produced these turbines would work to • It is completely renewable their highest potential
  20. 20. Bibliography • Kidd, J. S., and Renee A. Kidd. "clean energy and reducing air pollution." Air Pollution, Science and Society. New York: Facts On File, Inc., 2005. Science Online. Facts On File, Inc. = AIR0013&SingleRecord=True (accessed March 1, 2010). • Nichols, C. Reid, and Robert G. Williams. "tidal power plant." Encyclopedia of Marine Science. New York: Facts On File, Inc., 2008. Science Online. Facts On File, Inc. = EMS0497&SingleRecord=True (accessed February 28, 2010). • William K. Fox, "Energy sources", in AccessScience@McGraw-Hill,, DOI 10.1036/1097-8542.233000 • George G. Adkins, "Tidal power", in AccessScience@McGraw-Hill,, DOI 10.1036/1097-8542.696700