Tidal energy refers to the potential energy of water obtained from the day and night fluctuations of sea water. It is related to the gravitation of celestial bodies. The attraction between the earth-moon-sun system and heat energy are the sources of tidal energy. The energy of tidal energy is proportional to the tidal volume and tidal range, but the energy density is very low.
The principle of tidal power generation is similar to that of ordinary hydropower. By building a reservoir on the seashore, the seawater is stored in the reservoir when the tide is high, and it is preserved in the form of potential energy. Then, when the tide is low, sea water is released, and the difference between the high and low tide levels is used to drive the turbine to rotate and drive the generator to generate electricity. The difference is that seawater is different from river water. The accumulated seawater has a small drop, but the flow is large and intermittent, so the turbine structure for tidal power generation should be suitable for the characteristics of low head and large flow.
The flow of tide water is different from the flow of river water. It changes direction continuously. There are three forms of tidal power generation: single-pool one-way power generation, single-pool two-way power generation, and double-pool two-way power generation.
Utilizing tidal energy to generate electricity has the following advantages:
1. Clean and environmentally friendly
Tidal energy relies on tidal water to rise and fall every day, repeating cycles, inexhaustible and inexhaustible. It is a clean, renewable energy that does not pollute the environment and does not affect the ecological balance.
2. Stable and reliable
Tidal power generation is seldom affected by natural factors such as climate and hydrology. The total power generation throughout the year is stable, and there is no impact of high and low water years and high and low water periods. It is a relatively stable and reliable energy source.
3. Save land resources
Unlike hydropower stations, tidal power stations do not need to inundate a large amount of farmland to form a reservoir, and there are no complex issues such as population migration and inundation of farmland. It is an outstanding advantage for coastal areas where there are a lot of people and land and farmland is very precious.
4. Better security
Tidal power stations do not need to build high dams. Even if the dam is destroyed by natural disasters such as war or earthquake, it will not cause serious harm to downstream cities, farmland, people’s lives and property.
5. High cost performance
Tidal energy development is not affected by the price of primary energy, and its operating cost is low, making it an economic energy source.
Of course, tidal power generation also has some disadvantages:
1. Intermittent
Tidal range and water head often change within a day. When there are no special adjustment measures, the output of tidal power stations is intermittent, which brings inconvenience to users.
2. High initial investment
Tidal power stations are built in the estuary of the harbor, usually with long water depths and long dams. Problems such as construction, foundation treatment, and silt prevention are more difficult. Therefore, the investment in civil construction and electromechanical engineering is large and the cost is high.
3. The unit is prone to corrosion
The generator set of tidal power station is immersed in sea water for a long time, and sea water and marine organisms have corrosion and contamination effects on metal structures and offshore structures.
