Advantages of tidal power generation:
Due to the force of tides, sea water continually rises and falls. When the tide rises, a large amount of sea water surges forward, with large kinetic energy, at the same time, the water level gradually rises, and the kinetic energy is converted into potential energy; At low tide, sea water recedes, the water level gradually drops, and potential energy is converted into kinetic energy. The kinetic energy and potential energy possessed by moving seawater are collectively called tidal energy.
The Chinese mainland has a long coastline with many islands. It extends from the mouth of the Yalu River in the north to the mouth of the Beilun River in the south, which is more than 18,000 kilometers long. In addition, there are more than 5,000 islands with a coastline of more than 14,000 kilometers, and the total coastline is more than 32,000 kilometers long. Tidal energy resources are therefore very abundant. According to incomplete statistics, the national tidal power reserves are 110 million kilowatts, and the annual power output can reach 2,750 kilowatt hours, of which about 38.5 million kilowatts are available for development, and the annual output of The electricity is 87 billion kilowatt hours, which is equivalent to more than 40 hydroelectric power stations in Xin'anjiang. At present, the total installed capacity of tidal power plants in China exceeds 10,000 kilowatts.
One of the important applications of tidal energy is electricity generation. In 1913, Germany built the first tidal power station on the North Sea coast. In 1957, China built its first tidal power station in Shandong. On August 1, 1978, Houshakou Tidal Power Station, Rushan County, Province of Shandong, started generating electricity, with an annual electricity generation capacity of 2.3 million kilowatt hours. On August 4, 1980, China's first "single-tank, two-way" tidal power station, the Jiangxia Experimental Tidal Power Station, officially began generating electricity. It has an installed capacity of 3,000 kilowatts and an average annual electricity production of 10.7 million. kilowatt hours. Its scale is second only to Lens, France. The tidal power station (with an installed capacity of 240,000 kilowatts and an annual electricity production of 540 million kilowatt hours) was at the time the second largest tidal power station in the world. .
Simply put, tidal power generation involves building a dam in a tidal bay or estuary to form a reservoir, and placing a hydroelectric generator in or adjacent to the dam to use thehe sea water level when the tide The water rises and falls, which causes the sea water to pass through the turbine to drive the turbine-generator unit to produce electricity. From an energy point of view, it uses the potential energy and kinetic energy of seawater to convert it into electrical energy using a hydroelectric generator.
There are three types of tidal power generation.
The first type is a single-bank, unidirectional power plant. That is, a single reservoir is used to generate electricity only during high tide (or ebb tide). Figure 10-2 is a tidal power plant that uses the ebb tide to generate electricity. The Shashan tidal power station in Wenling County, Zhejiang Province, China, is of this type.
The second type is a single-bank two-way power plant. Thanks to a reservoir, it can produceelectricity at high and low tide, but cannot produce electricity at flat tide. Zhenkou Tidal Power Station in Dongguan County, Guangdong Province, and Jiangxia Tidal Power Station in Wenling County, Zhejiang Province are of this type. .
The third type is a two-bank two-way power plant. It uses two adjacent reservoirs, so one reservoir receives water at high tide and the other reservoir releases water at low tide. This way the water level of the first tank is always higher than that of the second tank, so the first is. called the upper tank, and the latter is called the upper tank. It is called lower tank. The hydroelectric generator is placed in the dam between the two reservoirs. The difference in water level between the two reservoirs is always maintained, which allows electricity to be produced throughout.ong of the day.
The advantage of tidal power generation is its low cost. The cost of a kilowatt hour of electricity is only one eighth of that of a thermal power plant.
Disadvantages of tidal power generation:
Energy stability and electricity production without thermal energy, nuclear power generation is stable and large and must be built on board sea (I haven't heard of it (it's built in other places) Yes, maybe it's because the tidal power in other places is too weak to use with current technology)
1. Tidal range and water height change frequently during the course of a day. , and the output is intermittent without special adjustment measures, causing inconvenience to users. However, an operating plan can be formulated in advance based on tide forecasts and operated in conjunctionn with the large electrical network to overcome its intermittency.
2. The tide changes in half a month, and the tidal amplitude can vary by two times, so the annual usage hours to guarantee production and installed capacity are also low.
3. Tidal power plants are built at the mouth of ports, usually with deep water and long dams, making construction, foundation treatment and anti-siltation difficult . Therefore, the investment in civil engineering and mechanical and electrical engineering is large and the cost is high.
4. The tidal power plant is a form of electricity production with a low water level and a large flow rate. The flow direction of the ebb and flow tide is opposite, so the turbine is large in size and consumes a lot of steel, and the water inlet and outlet building structure is complex. Moreovers, due to immersion in seawater, seawater and marine organisms will corrode and contaminate metal structures and offshore buildings. A special anti-corrosion and anti-adhesion treatment of marine organisms is therefore necessary.
5. The tide change cycle is one lunar day (24h50min), the monthly cycle is about 14 days, and the daily high tide is about 50min late, so it does not match well to the daily power demand load diagram given as a function of solar day. Although tidal power generation has the above disadvantages, it can be improved with the continuous improvement of modern technology. For example, adopting measures such as bi-directional or multi-reservoir power generation, the use of pumped storage and the integration of electricity grid regulation can compensate for the first gap; the use of cModern floating supports for construction can save investment in civil construction; and use vinyl series coatings, then use cathodic protection to overcome seawater corrosion and marine organism adhesion.
River water can produce electricity, and sea water can also produce electricity.
Use the tides to produce electricity. Tidal power plants and hydroelectric power plants on rivers are based on the same principle. People build a dam in an estuary or bay near the sea and install a hydroelectric generator in the middle of the dam. At high tide, the tide flows from the ocean through the dam into the estuary or bay, driving the turbogenerator to produce electricity; At low tide, when seawater returns to the ocean, it drives the turbine in the opposite direction again. produce electricityricity. This type of tidal power plant generates more stable energy than hydroelectric plants built on rivers because it is not affected by floods and droughts.
There are three-foot waves on the windless sea. Waves are also a kind of energy, but converting wave energy into electrical energy is much more difficult than generating hydroelectricity. In the 1970s, Japan developed the first wave power generation device. There is also a generator of this type installed on a barge in the United Kingdom.
Using the temperature difference between the surface and deep layers of seawater, electricity can also be generated. Such energy productionThe device is similar to a thermal power plant: water vapor drives a steam turbine, which drives a generator to produce electricity. The high temperature of sea watersurface water serves as a heat source for the steam engine, while deep, low-temperature seawater serves as a cold source to cool the waste steam. The United States has built an experimental seawater temperature difference power plant near Hawaii. Using a temperature difference of 20°C, 50 kilowatts of electricity are generated.