潮汐能 tides and waves

1、Group members:Wu Aizhen 3112011089Diao Lizhu Wang Yue 3112011178CONTENTS二级目录 过渡页What causes tides?What is tides?characteristicsTides Tides What is tide?Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotatio

2、n of the Earth.Tides What causes tides?1The moon, being nearest, has the greatest effect even though the sun is the larger of the two.High tides are generated on sides of the earth nearest to and farthest from the moon.Tides What causes tides?2During new and full moon phases the moon, sun, and earth

3、 are aligned causing a greater gravitational pull on the earth.Tides What causes tides?3Gravitational pull on the earth.Tides What causes tides?3This results in higher high tides and lower low tides.Tides Characteristics:Sea level rises over several hours, covering the intertidal zone; flood tide.Th

4、e water rises to its highest level, reaching high tide.Sea level falls over several hours, revealing the intertidal zone; ebb tide.The water stops falling, reaching low tide.characteristicsTides Tidal power3Tidal power, also called tidal energy, is a form of hydropower that converts the energy of ti

5、des into useful forms of power - mainly electricity.Tides Tidal power3Generating methods:Tidal stream generatorTidal barrageDynamic tidal power二级目录 过渡页What is waves?What causes waves?Waves characteristicsWaves What are wave?A wave is a rhythmic movement that carries energy through matter or space.Wa

6、ves Main partsAll waves have the same main parts:Still-water line:静水线 the level of the ocean if it was flat without any waves.Crest:波峰 the highest part of the wave above the still-water line.Trough:波谷 the lowest part of the wave below the still-water line.Waves Main partsAll waves have the same main

7、 parts:Waves Main partsAll waves have the same main parts:Waves Main partsAll waves have the same main parts:Waves What causes waves?1Most ocean waves are caused by wind that blows across the surface of the water.Friction between the wind and water transfer energy from the wind to the water.Waves Wh

8、at causes waves?2Wave movementThe wave travels forward, but the water particles do not.The water particles move in a circular pattern as they are temporarily displaced by the energy of the wave. Transfer of energyA wave is really a transfer of energy from one water molecule the to next. If all the w

9、ater itself moved forward all the oceans would empty onto the shore.Waves Wave energy1Wave energy 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). Mac

10、hinery able to exploit wave power is generally known as a wave energy converter (WEC).Waves Wave energy1Modern technology 二级目录 过渡页Advantages Disadvantages Waves and tides 二级目录Advantages Waves and tides 1) they are inexhaustible sources of energy.2) they are environment friendly energy and dont produ

11、ce greenhouse gases.3) As 71% of Earths surface is covered by water, there is scope to generate this energy on large scale.4) As for tides, we can predict the rise and fall as they follow cyclic fashion.5) Efficiency of them is far greater as compared to coal, solar or wind energy. their efficiency

12、is around 80%.二级目录Advantages Waves and tides 6) Although cost of construction is high but maintenance costs are relatively low.7) Tidal and wave Energy dont require any kind of fuel to run.8) The life of energy power plant is very long.9) The energy density of energy is relatively higher than other

13、renewable energy sources.二级目录Disadvantages Waves and tides 1) Cost of construction of power plants is high.2) There are very few ideal locations for construction of plant and they too are localized to coastal regions only.3) Intensity of sea waves is unpredictable and there can be damage to power ge

14、neration units.4) Influences aquatic life adversely and can disrupt migration of fish.5) The actual generation is for a short period of time. The tides only happen twice a day so electricity can be produced only for that time.二级目录Disadvantages Waves and tides 6) Frozen sea, low or weak tides, straight shorelines, low tidal rise or fall are some of the obstructions.7) This technology is still not cost effective and more tec