Anyone who has been to the seaside knows that the sea has high tides and low tides. At high tide, the sea rises, the waves roll and the scenery is spectacular; At low tide, the sea receded quietly, revealing a beach. An ancient book in China said: "The water in the sea is a tide at sunrise and a sunseeker at sunset." So, how do tides come into being?
In ancient times, many Tessa discussed this problem and put forward some hypotheses. Plato, an ancient Greek philosopher, believed that the earth, like human beings, also needs to breathe, and tides are the breath of the earth. He guessed that it was caused by the vibration of underground caves, just like the beating of human heart.
With the constant observation of tidal phenomena, people gradually realize the real reason of tidal phenomena. Yu Daoan, an ancient China, said in his book "Preface to Tides": "The ebb and flow of tides will only follow unless the sea is in high tide or low tide and the moon is covered." Wang Chong, a thinker in the Han Dynasty, wrote in Lun Heng: "Tao rises and falls with the moon." They all pointed out that tides have something to do with the moon. /kloc-In the 1980s of 0/7, after discovering the law of universal gravitation, British scientist Newton put forward the hypothesis that tides are caused by the attraction of the moon and the sun to seawater, thus scientifically explaining the causes of tides.
It turns out that seawater is also rotating with the rotation of the earth, and the rotating objects are subjected to centrifugal force, which makes them tend to leave the center of rotation. It's like spinning an open umbrella, and the water drops on the umbrella will be thrown out. At the same time, seawater is also attracted by celestial bodies such as the moon and the sun. Because the moon is closest to the earth, it is more attractive. In this way, seawater forms the tidal force under the combined action of these two forces. Because the earth and the moon are in constant motion, and the relative positions of the earth, the moon and the sun are changing periodically, the tidal force is also changing periodically, which makes the tidal phenomenon happen periodically. 2. Tidal power generation: Due to the tidal force, the sea water is constantly fluctuating. At high tide, a large amount of seawater flows in, with great kinetic energy; At the same time, the water level gradually rises, and kinetic energy is converted into potential energy. At low tide, the seawater is washed away, and the water level drops one after another, and the potential energy is converted into kinetic energy. The kinetic energy and potential energy of seawater in motion are collectively called tidal energy.
An important application of tidal energy is power generation. Tidal power generation is to build a dam in a bay or tidal estuary to form a reservoir, and place a hydro-generator set in or near the dam. By using the fluctuation of seawater level during tidal fluctuation, the seawater will push the hydro-generator set to generate electricity when it passes through the turbine. From the point of view of energy, it is to use the potential energy and kinetic energy of seawater to convert it into electrical energy through hydro-generators. The advantage of tidal power generation is its low cost, which is only one-eighth of that of thermal power plants.
19 13 Germany established the world's first tidal power station on the North Sea coast. China has a long coastline and abundant tidal energy resources. The first tidal power station was built in Shandong in 1957. According to incomplete statistics, China's tidal energy reserves are 1. 1 100 million kilowatts, and the annual power generation can reach 2750 kwh, of which about 38.5 million kilowatts can be developed and the annual power generation is 87 billion kwh, equivalent to more than 40 Xin 'anjiang hydropower stations.