What Is Tidal Renewable Energy?
The principle of tidal power generation is similar to that of ordinary hydropower. By going out of the reservoir, the seawater is stored in the reservoir at high tide and stored in the form of potential energy. Then, the seawater is released at low tide. The difference between high and low tide levels is used to drive the turbine to rotate. To drive the generator to generate electricity.
- Chinese name
- Tidal power
- Phenomenon
- Tide as a natural phenomenon,
- Features
- Similar to the principle of ordinary hydropower generation
- Make use of
- Tidal energy
- Features
- Suitable for low head and large flow
- Power generation characteristics
- Tidal energy is a clean, non-polluting environment
- Tidal power is similar to the principle of ordinary hydropower. By going out of the reservoir, seawater is stored in the reservoir at high tide and stored in the form of potential energy. Then, seawater is released at low tide, and the difference between high and low tide levels is used to drive the turbine to rotate. To drive the generator to generate electricity.
Tidal power generation principle
Tidal power
- In the bay or tidal estuary, sea water or river water can be seen to fluctuate twice a day. In the morning
- Tidal power
Use of tidal power
- The main use of tidal energy is tidal power generation. The principle of tidal power generation is similar to that of ordinary water conservancy power generation. By going out of the reservoir, seawater is stored during high tide.
- Tidal power generation schematic
- Tidal power is a type of hydropower. Dams, sluices and powerhouses are constructed in conditional bays or tidal mouths to form a reservoir, and a certain tidal difference (that is, working head) is formed between the reservoir water level and the tidal level in the open sea, which can drive the hydro-generator to generate electricity.
- Technological progress related to tidal power generation is extremely rapid. A variety of mechanical equipment has been developed to convert tidal energy into mechanical energy, such as propeller-type turbines, axial-flow turbines, open-loop turbines, etc. Japan has even started to use artificial satellites to provide Trend information. The use of tidal power has become increasingly mature and has entered the practical stage.
Tidal power generation history
- The main use of tidal energy is tidal power generation.
- In the early 20th century, some countries in Europe and the United States began to study tidal power generation. In 1913 Germany established the first tidal power station on the North Sea coast. The first tidal power station with commercial value was the French Langs Power Station, which was completed in 1967. The power station is located at the estuary of the Rance in Saint-Malo, France. The Lance Estuary has a maximum tidal range of 13.4 meters and an average tidal range of 8 meters. A 750-meter-long dam crosses the Lance River. Above the dam is a highway bridge for passing vehicles, and ship locks, sluice gates and generator rooms are set under the dam. There are 24 two-way turbine generators installed in the machine room of the Lance Tidal Power Station, which can generate electricity at high and low tides. The total installed capacity is 240,000 kilowatts, and the annual power generation is more than 500 million kWh, which is imported into the national power grid.
- In 1968, the former Soviet Union built an 800-kilowatt test tidal power station in the Kislya Bay near Murmansk in the north. In 1980, Canada built a 20,000-kilowatt intermediate test tidal power station in Fundy Bay. The test and pilot power stations are used for demonstration and preparation for the construction of larger practical power stations.
- Due to the competition of cheap electricity costs of conventional power stations, not many commercial tidal power stations have been completed and put into operation. However, due to the huge amount of tidal energy and the many advantages of tidal power generation, people still attach great importance to the research and experiment of tidal power generation. [1]
- In 1957, China built the first tidal power station in Shandong. On August 1, 1978, Baishakou Tidal Power Station in Rushan County, Shandong Province started generating electricity with an annual power generation of 2.3 million kilowatt hours. On August 4, 1980, China s first single-storage and two-way tidal power station, Jiangxia Tidal Test Power Station, officially started generating power with an installed capacity of 3,000 kilowatts and an average annual power generation of 10.7 million kilowatt-hours. The tidal power station (with an installed capacity of 240,000 kilowatts and an annual power generation of 540 million kWh) was the second largest tidal power station in the world at that time. [1]
- Simply put, tidal power generation is to build a dam in a bay or a tidal estuary to form a reservoir, and place a hydro-generator set in or near the dam to make use of the rise and fall of the seawater level when the tide rises and falls to pass the water through the turbine Push the hydro-generator unit to generate electricity from time to time. From an energy point of view, it uses the potential and kinetic energy of seawater to convert it into electricity through a hydro-generator.
- Globally, tidal energy is one of the most mature technologies and the largest scale of utilization of marine energy. Tidal power has developed rapidly abroad. European countries have vast oceans and long coastlines, so they have a large number of stable and cheap tidal resources, and they have always been at the forefront of the world in the development and utilization of tidal waves. France, Canada, Britain and other countries maintain leading advantages in the field of tidal power research and development.
- China's coastline is long and tortuous, mainly concentrated in the coastal areas of Fujian, Zhejiang, Jiangsu and other provinces. The development of tidal energy in China began in the 1950s. After years of research and trials on the construction of tidal power stations, China's tidal power generation industry has not only become more mature in technology, but has also made great progress in reducing costs and improving economic benefits. A group of tidal power stations with good performance and significant benefits have been built.
- Power shortage is an important factor restricting the development of our national economy, especially in the eastern coastal areas. Tidal energy has the advantages of reproducibility, cleanliness, and predictability. Under the background of optimizing the power structure and promoting the upgrading of the energy structure in our country, the development of tidal power in line with social trends will help alleviate the energy shortage in the eastern coastal areas. The construction of tidal power stations can create good economic, social and environmental benefits, and the investment potential is huge.
Tidal power generation details
Tidal power
- The occurrence of tides is also regular. The occurrence of tides is related to the sun and the moon, and also corresponds to the traditional Chinese lunar calendar. The sun and the moon are on the side of the earth at the moment of the first day of each month of the lunar calendar [1] , so it has the greatest tidal force, so it will cause a "tide". On the fifteenth or sixteenth of the lunar month, Nearby, the sun and the moon are on both sides of the earth. If you push and pull the tidal force of the sun and the moon, you will also cause a "tide"; when the moon phase is upper and lower, that is, the eighth and twenty-third of the lunar calendar, the sun triggers the tide. The force and the lunar tidal force cancel each other out partly, so a "little tide" occurred. Therefore, there is a saying in the farm saying "the tide rises on the fifteenth day, and the beaches are seen everywhere on the eighth and twenty-third days." In addition, there is also a high tide on the first day. As the moon moves eastward on the celestial sphere more than 13 degrees a day, the total is about 50 minutes. That is, the midday moment on the moon (1 lunar day = 24:50) is delayed by about 50 minutes. (The tide will also occur twice in the middle of the day. Generally, the tide will occur twice a day.) Therefore, the time of high tide every day is delayed by about 50 minutes. [1]
- Many working people in our country have summed up their experience over the centuries and come out of many tide calculation methods (moment of tide pushing) such as the eight-point tide calculation method. One example is this: the concise formula is:
- At orgasm = 0.8h × [= 0.8h × [Lunar date ---- 1 (or 16)] + Orgasm clearance
- The above formula can be calculated as one high tide of the day. For the regular half-day tide sea area, the value can be added or subtracted at 12:25 (or for the convenience of calculation, it can be added or subtracted at 12:24) to obtain another high tide. . If the value is added or subtracted at 6:12, you can get the moment of low tide-low tide. However, due to the complexity of the motion of the moon and the sun, the tide may sometimes be delayed by a day or a few days. The climax of the day is often behind the moon by the hour or hours, A tide occurred on a cloudy day. Therefore, the high tide and low tide times are different every day, and the intervals are also different.
Tidal power generation conditions
- The use of tidal power must have two physical conditions: first, the amplitude of the tide must be large, at least a few meters; the second coastal terrain must be able to store a large amount of seawater, and civil engineering can be performed. That is, it is very important that the area contains enough tidal energy. The tidal energy census calculation method is to first select the sites suitable for the construction of tidal power stations, and then calculate the installed power generation capacity that can be developed at these locations. The amount of resources.
- The working principle of tidal power generation is similar to that of general hydroelectric power generation, that is, a dam is built at the estuary or bay to form a natural reservoir, and the hydro-generator unit is installed in the dam. Because the water level difference of seawater tides is much lower than that of ordinary hydropower stations, tidal power stations should use low-head, high-flow hydro-generator units. Because of its small shape, light weight, short pipelines and high efficiency, the full-flow hydroelectric generating units have been widely adopted by various tidal power stations.
Tidal power generation type
- Tidal power stations can be single or double reservoirs. The single-reservoir tidal power station has only one dam and one reservoir, and the double-reservoir tidal power station has two adjacent reservoirs.
Tidal power generation
- That is, only one reservoir is used, and electricity is generated only at high tide (or low tide), so it is also called a single reservoir single program tidal power station. Shashan Tidal Power Station in Wenling City, Zhejiang Province, China is this type.
Tidal power generation single storage two-way power station
- Use a reservoir, but high and low
- Tidal power generation
Tidal power double storage two-way power station
- In order for the tidal power station to be able to continuously generate electricity throughout the day, a tidal power station with double reservoirs must be used. It uses two adjacent reservoirs so that one reservoir enters water at high tide and the other reservoir discharges at low tide.
- Practical device for tidal power generation
Features of tidal power generation
Advantages of tidal power
- 1. Tidal energy is a renewable energy source that is clean, does not pollute the environment, and does not affect ecological balance. The tide rises and falls daily, and it starts and ends again and again, inexhaustible and inexhaustible. It can develop into an important supplementary energy source for living, production and national defense in coastal areas.
- Tidal generator
- 3. The tidal power station does not need to flood a large amount of farmland to form a reservoir, so there are no complex problems such as population migration and flooded farmland. In addition, sea dams can be used to promote silt reclamation of large tidal flats, and aquaculture, water conservancy, marine chemicals, and transportation can be combined for comprehensive utilization. This is an outstanding advantage for coastal areas with many people and less land and very valuable farmland.
- 4. Tidal power stations do not need to build high dams. Even if natural disasters such as war or earthquake occur and the dams are damaged, they will not cause serious disasters to downstream cities, farmland, people's lives and property.
- 5. The combination of primary energy and secondary energy for tidal energy development does not require fuel, is not affected by the price of primary energy, and has low operating costs. It is an economic energy source. But like river hydropower stations, it has the characteristics of large one-time investment and low power generation cost.
- 6, the number of units is large, there is no need to set up a standby unit.
Disadvantages of tidal power
- 1. The tidal range and water head often change within a day. Without special adjustment measures, the output is intermittent, which brings inconvenience to users. However, the operation plan can be made in advance according to the tide forecast, and it can be operated in parallel with the large power grid to overcome its intermittent nature.
- Tidal power
- 2. There is a half-month change in the tide, and the tide difference can be doubled. Therefore, the output and installed annual utilization hours are also low.
- 3. The tidal power station is built in the estuary of the harbour. The water depth is usually long, and the construction, foundation treatment and silt prevention are difficult. Therefore, the construction and mechanical and electrical investment is large, and the cost is high.
- 4. The tidal power station is a low-head, large-flow power generation form. The flow direction of the rising and falling tides is opposite, so the turbine is large in volume, consumes a lot of steel, and the structure of the in and out water structure is complicated. And because it is immersed in seawater, seawater and marine organisms have a corrosive and contaminating effect on metal structures and marine structures, so special anticorrosion and anti-sea creature adhesion treatment is required.
- 5. The tide change period is the overcast day (24h50min), the monthly cycle is about 14 days, and the high tide is about 50 minutes behind, so it is not well matched with the daily power load chart given by the solar day. Although tidal power generation has the above shortcomings, it can be improved with the continuous improvement of modern technology. For example, the use of two-way or multi-reservoir power generation, the use of pumped storage, and adjustment of the power grid can make up for the first shortcoming; the use of modern floating caissons for construction can save civil investment; the use of stainless steel production units, the use of vinyl resin coating Then, cathodic protection can be used to overcome the corrosion of seawater and the adhesion of sea creatures.
Tidal power usage
Tidal Power Domestic Situation
- As a clean energy source, tidal power generation is vigorously developing the marine economy. Today, it has not only received the attention of government departments, but also a new business opportunity for equipment manufacturing enterprises to enter strategic emerging industries. As a renewable energy source, tidal energy has become an important part of new energy in the "Twelfth Five-Year" strategic emerging industry plan. Compared with wind and solar energy, tidal energy is more reliable. Its power generation does not produce large fluctuations, and it does not occupy farmland and does not pollute the environment. The cost is only one-eighth that of thermal power. However, China has abundant tidal resources. Tidal power offers ample opportunities. As traditional fossil energy sources such as coal, oil, and natural gas are declining, and energy shortages are increasing, people have shifted their focus on energy development to the larger sea. Tidal power has the characteristics of rich resources, large reserves, renewable, etc., and is environmentally friendly and pollution-free, which has become the focus of the development of "blue energy". In the context of vigorously developing the marine economy, tidal power generation has been listed as an important part of new energy in the "Twelfth Five-Year" strategic emerging industry plan in China, and it has provided huge business opportunities for the equipment manufacturing industry to enter strategic emerging industries. The potential is huge. Tidal power requires higher natural and equipment requirements. Tidal power is the use of tidal bays, estuaries and other favorable terrains to form a reservoir through the construction of dams. A hydro-generator set is placed in or near the dam. The tidal gap during the tidal rise and fall drives the turbine to rotate and the potential energy of the seawater And kinetic energy into electricity. In addition, because tidal power generation uses seawater as the medium, power generation equipment is soaked in seawater all year round, so there are strict requirements for equipment corrosion prevention and prevention of sea creatures from attaching.
- China is rich in tidal energy resources, with a coastline of more than 18,000 kilometers on the mainland, starting from the Yalu River estuary in the north and the Beilun River estuary in the south, plus more than 14,000 kilometers of coastlines on more than 5,000 islands. A total of more than 32,000 kilometers of coastlines contain rich tides Energy resources. According to incomplete statistics, the national tidal energy reserve is 190 million kilowatts, of which about 38.5 million kilowatts are available for development, and the annual power generation is 87 billion kilowatt hours, which is equivalent to about 40 Xinanjiang Hydropower Stations. At present, the total installed capacity of tidal power stations in China has exceeded 10,000 kilowatts. According to the results of China's marine energy resource zoning, there are 424 tidal power station dam sites that can be developed by China's coastal tidal energy, with Zhejiang and Fujian having the largest number of coastal dam sites. [3]
- Zhejiang coast
- According to the "Zhejiang Marine Function Zoning" issued by the Zhejiang Province government, the province's marine energy utilization zones include four tidal energy zones, with key areas being Nantian Island Bay Tidal Energy Zone, Sanmen Bay Tidal Energy Zone, and Jiangxia Tidal Energy Zone. , Haishan tidal energy zone; one tidal energy zone, namely the Guishan waterway tidal energy zone, where the Zhoushan Islands account for about half of China's tidal energy, and has great potential for development.
- It is understood that the coastal areas of Zhejiang are all strong tide areas. The average tidal range along the coast of Zhejiang is 4.29 meters, and the theoretical installed tidal energy capacity is 28.96 million kilowatts. The developable tidal energy installed capacity is 8.8 million kilowatts, accounting for about 40% of the country's total. The average coastal wave height is 1.3 meters and the theoretical wave energy. The density is 5.3 kilowatts / meter, the installed capacity is 2.5 million kilowatts, and the wave energy accounts for 16.5% of the national total.
- Fujian Province
- On December 16, 1980, the Fujian Provincial Hydropower Department, the Provincial Institute of Water Conservancy Research, and the Provincial Agricultural Machinery Research Institute organized technical personnel to investigate tidal energy in Pingtan. In October 1983, the Provincial Science and Technology Commission decided to build a tidal power station on the inner side of Xiaojieyu seawall in Xingfuyangken District, Pingtan County. The project is designed by the Fujian Provincial Institute of Water Resources and Electric Power Survey and Design, and the construction headquarters of Pingtan County Xingfuyang Experimental Tidal Power Station Project. The tidal power station uses flood drainage ditch and deepwater aquaculture pond (area 73 hectares) in the reclamation area as a storage reservoir with a storage capacity of 1.67 million cubic meters and an effective storage capacity of 1.33 million cubic meters. It uses one-way ebb tide power generation.
- In October 1984, the encirclement and foundation blasting started. On the shore of Xiaojieyu, construction of a main and auxiliary factory building was started, of which the main factory building area was 522.7 square meters and the auxiliary factory building was 184.4 square meters. The installation height of the unit is -3.8 meters, and four hydro turbines and generators are installed. The turbine is a domestic cross-flow type GDBWS-190, with a shaft power of 381.71 kW, a rotation speed of 155 rpm, and an efficiency of 83%. The generator is an AC synchronous water wheel TSWN99 / 37-12, with a capacity of 320 kilowatts, a rated voltage of 400 volts, a rated current of 577 amps, and a speed of 500 rpm. The elevation of the equipment operation layer is -1.55 meters, which includes speed governor, control screen, power screen, potentiostat, etc. There are central control room, main transformer room, in-plant transformer room and 10 kV switch cabinet. The power transmission line of the power station is a 10 kV secondary circuit. The primary circuit is 13 kilometers long through the standard sand plant to the county seat; the other circuit is connected to the county power grid via Zhonglou Township and has a length of 12 kilometers.
- The main project was completed in 1988, it was accepted on June 12, 1989, and it was connected to the county grid for power generation in September. The total installed capacity of the power station is 1280 kilowatts, and the power is generated twice a day for 10 hours. The total investment is 5.3 million yuan. In July 1991, maintenance was suspended due to motor corrosion. Since then, it has been stopped for a short period of time, and the power generation period is short and unstable. In 1995, 22,500 kilowatt hours were generated.
Tidal Power Abroad
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 6.7 | |
|
|
|
| 3.1 | |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 12.4 | |
|
|
|
| 6.7 | |
|
|
| |||
|
|
|
| 9 | |
|
| 20000 | 13.5 |
Tidal Power Prospects
- Tidal power is a huge potential business. According to calculations by oceanographers, the world s tidal power generation resources are more than 1 billion kilowatts, which is also an astronomical figure. After many years of practice, the working principle and overall structure are basically formed, and it can enter the stage of large-scale development and utilization. The prospect of tidal power generation is broad.
- It is estimated that by 2000, the annual power generation of tidal power stations in the world can reach 3X1010 6X1010kw · h. In addition to power generation, the tidal power station has broad prospects for comprehensive utilization. The biggest benefit is that it can surround the sea to build land and increase land. In addition, it can also conduct aquaculture and tourism. For these reasons, tidal power generation has received much attention from countries around the world.
- More than 20 places in the world suitable for the construction of tidal power stations are studying, designing and constructing tidal power stations. These include: Cook Bay, Alaska, USA, Bay of Fundy, Canada, Severn Estuary, San Jose Bay, Argentina, Van Diemen Bay, Darwin, Australia, Campbell Estuary, India, Far East Okhotsk, Russia, South Korea Incheon Bay and other places. With the advancement of technology, the cost of tidal power generation continues to decrease. In the 21st century, large modern tidal power stations will be built and used.
Famous Tidal Power Station
- The French Lance Tidal Power Station was completed in 1966, with a total installed capacity of 240MW and a single power of 10MW, a total of 24 hydro turbines, with an annual power generation of 540 million kWh, which was the world's largest marine power generation project at that time. Its technical innovation is different from conventional hydropower stations. It uses forward-reverse power generation, drainage and pumping bulb-type cross-flow turbine generator units, which not only improves the utilization efficiency of tidal energy, but also reduces the cost of power stations. The total infrastructure cost of the power station is 570 million francs (approximately $ 100 million). If calculated based on the actual power generation in 1973, the cost per kilowatt-hour is about twice that of hydropower. As tidal power generation is fluctuating and intermittent, the output power varies greatly, and the average annual output of electricity is 25% of the rated capacity.
- The tidal power station in Strandford Bay, Ireland , is one of the ten largest renewable energy projects in the world and is by far the largest tidal power station on the ocean. However, this record will be broken in 2015 by a project built in South Korea's Wando Hoenggan Waterways. The project invested $ 820 million, has an installed capacity of 300 megawatts, and a 60-foot-high (18-meter) turbine is fixed on the sea floor by its own gravity.
- China Jiangxia Tidal Experiment Power Station is located at Jiangxia Port at the northern end of Yueqing Bay in Zhejiang Province, China. The power station was built on the basis of the original "July" pond reclamation project in 1974. It integrates various functions such as power generation, reclamation and farming, marine aquaculture, and tourism development. The power station is characterized by the use of a two-way light bulb tubular turbine generator set similar to the French Lance power station. The site has a maximum tidal range of 8.39m and an average tidal range of 5.1m. The original design was six 500kW units with six pits. Five units were actually installed, and the first was 500kW. It was put into operation in May 1980; The second is 600 kW, the remaining three are 700 kW, and the last was put into operation in 1986. The total installed capacity was 3200kW, which was the third largest tidal power station in the world at that time. The area of the harbour above the dam site is about 8,000 acres. Because the reservoir area was originally planned to be reclamated for 5,600 acres, local farmers privately occupied land for reclamation or breeding, and the water area available for power generation was less than 2,000 acres. In 1986, the annual power output of the five units was about 6 million kWh, which was lower than the original designed annual power output of 10.7 million kWh. The economic benefits of power generation were not high. Over the years, the power plant has planned to increase the cofferdam, raise the water level in the reservoir area, and add a unit in the No. 6 pit to increase the amount of power generation and increase the economic benefits of power generation. [4]