Tidal power generationSimilar to the principle of ordinary hydropower generation, seawater is stored in the reservoir at high tide and stored in the form of potential energy by leaving the reservoir, and then released at low tide to promoteWater turbineRotationalternatorelectricity generation.
Chinese name
Tidal power generation
Phenomenon
Tide, as a natural phenomenon,
Features
Similar to the principle of ordinary hydropower generation
In the bay or tidal estuary, it can be seen that the sea water or river water fluctuates twice a day. The tide in the morning is called tide, and the tide at night is called tide.Tide, as a natural phenomenon, provides convenience for human navigation, fishing and salt drying.This phenomenon is mainly caused by the moon and the sunTidal forceas well asearth rotationEffect.When the tide rises, a large amount of sea water surges in with great kinetic energy;At the same time, the water level gradually rises,kinetic energyConvert topotential energy。When the tide falls, the sea water rushes back, the water level drops gradually, and the potential energy is converted into kinetic energy.The kinetic energy and potential energy of seawater in motion are collectively referred to asTidal energy。[1]Tide is a kind of clean and pollution-free environment with huge reserves, inexhaustible resources, no need for mining and transportationrenewable energy。The construction of tidal power stations does not require resettlement, inundation of land, and environmental pollution. It can also be combined with tidal power generation to develop reclamationAquacultureAnd marine chemical industry.[2]
utilize
Schematic diagram of tidal power generation
The main utilization mode of tidal energy is tidal power generation.Tidal power generationSimilar to the principle of ordinary water conservancy and power generation, the seawater is stored in the reservoir in the form of potential energy when it is out of the reservoir at high tide, and then the seawater is released at low tide, and the fall between high and low tide levels is used to drive the turbine to rotate and drivealternatorelectricity generation.The difference is that the sea water is different from the river water. The accumulated sea water has a small fall, but the flow is largeintermittentTherefore, the turbine structure of tidal power generation should be suitable for the characteristics of low head and large flow.
Tidal power generation is a kind of hydropower generation.Embankments, gates and power houses shall be built in conditional bays or tidal inlets to form a reservoir. A certain tidal range (i.e. working head) shall be formed between the water level of the reservoir and the tide level of the open sea, so as to drive the water turbine generator set to generate electricity.
The technology related to tidal power generation has made rapid progress, and various technologies have been developed to transform tidal energy intomechanical energyMechanical equipment, such as propeller turbineAxial flow turbine, open loop turbines, etc. Japan even began to use artificial satellites to provide tidal current information.The use of tidal power generation has become increasingly mature and has entered the practical stage.
Usage History
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The main utilization mode of tidal energy is tidal power generation.
At the beginning of the 20th century, some countries in Europe and the United States began to study tidal power generation.In 1913, Germany built the firstTidal power station。The first tidal power station with commercial value was built in 1967France Lens Power Station。The power station is located at the mouth of the Lance River in Saint Malo Bay, France.The maximum tidal range at the Lance Estuary is 13.4m, and the average tidal range is 8m.A 750 meter long dam crosses the Lance River.On the damIt is a highway bridge for passing vehicles, and ship lock, sluice gate and generator room are set under the dam.There are 24 two-way turbine generators installed in the machine room of the Lens Tidal Power Station, which can generate electricity at rising tide and falling tide.The total installed capacity is 240000 kilowatts, and the annual power generation is more than 500 million kilowatt hours, which is input into the national grid.
In 1968, the former Soviet Union built an 800 kilowatt experimental tidal power station in Kislaya Bay near Murmansk in its north.In 1980, Canada built an intermediate test tidal power station of 20000 dry watts in Fertile Bay.Test power stations and pilot power stations are used for demonstration and preparation of building larger practical power stations.
Due to the competition of cheap electricity charges for conventional power stations, few commercial tidal power stations have been built and put into operation.However, due to the huge potential of tidal energy and many advantages of tidal power generation, people still attach great importance to the research and test of tidal power generation.[1]
In 1957, China built the first tidal power station in Shandong.August 1, 1978 ShandongRushan CountyBaishaThe Kou tidal power station started to generate electricity, with an annual output of 2.3 million kilowatt hours.On August 4, 1980, China's first "single reservoir two-way" tidal power station Jiangxia Tidal Test Power Station officially generated electricity, with an installed capacity of 3000 kilowatts and an annual average power generation of 10.7 million kilowatt hours, which is second only to France in scaleLance Tidal Power Station(The installed capacity is 240000 kilowatts, and the annual power generation is 540 million kilowatt hours), which was the second largest tidal power station in the world at that time.[1]
In brief, tidal power generation is to build a water retaining dam in the bay or tidal estuary to form a reservoir and place it in or near the damTurbine generator unit, use the rise and fall of the sea water level when the tide rises and falls to make the sea water pass throughWater turbineThe water turbine generator set is driven to generate electricity.From the energy point of view, it is to use the potential energy and kinetic energy of seawater to convert intoelectric energy。
Tidal energy is one of the most mature technologies and the largest scale of ocean energy in the world. Tidal power generation is developing rapidly abroad.European countries have vast oceans and long coastline, so they have a large number of stable and inexpensive tidal resources. They have always been leading the world in the development and utilization of tides.France, Canada, the United Kingdom and other countries maintain a leading edge in the research and development of tidal power generation.
China's coastline is long and tortuous, mainly inFujian, ZhejiangJiangsuAnd other provinces.The development of tidal energy in China began in the 1950s. After years of research and pilot work on the construction of tidal power stations, the tidal power generation industry in China has not only become increasingly mature in technology, but also made great progress in reducing costs and improving economic benefits. A number of tidal power stations with good performance and significant benefits have been built.
Inadequate power supply is an important factor restricting the development of China's national economy, especially in the eastern coastal areas.Tidal energy has the advantages of renewability, cleanness, predictability, etc. In the context of optimizing the power structure and promoting the upgrading of the energy structure in China, the development of tidal power generation conforms to the social trend, which is conducive to alleviating the energy shortage in the eastern coastal areas.The construction of tidal power stations can create good economic, social and environmental benefits, with huge investment potential.
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Tidal law
Tides also occur regularly.tideOccurrence andsunlightThe moon is related to the Chinese traditional lunar calendar.The sun and moon are on the side of the earth on the first day of the lunar month, the new moon[1]Therefore, there is the maximum tidal force, which will cause "spring tide". Near the 15th or 16th day of the lunar month, the sun and moon are on both sides of the earth, and the tidal force of the sun and moon will also cause "spring tide" if you push and pull;When the moon phase is the first and last quarter, that is, at the eighth and twenty third day of the lunar calendar, the tidal forces of the sun and the moon offset each other to some extent, so "neap tide" occurs. Therefore, there is a saying in the Chinese proverb that "spring tide rises on the first 15 days of the lunar calendar, and beaches are everywhere on the eighth and twenty third days of the lunar calendar".In addition, the rising tide also occurred on the day. Since the moon moves more than 13 degrees eastward on the celestial sphere every day, the total time is about 50 minutes, that is, the time when the moon goes up to the middle of the sky (1 lunar day=24:50) is about 50 minutes late every day, (the tide also occurs in the lower middle of the sky, and there are usually two tides every day), the time of rising tide every day is also about 50 minutes late.[1]
The working people of our country have summed up many tide calculation methods (tidal moment) for thousands of years, such as the octet tide calculation method: the simple formula is:
High tide time=0.8h × [=0.8h × [lunar date --- 1 (or 16)]+high tide interval
The above formula can calculate one high tide in a day. For the regular semi diurnal tidal sea area, add or subtract 12:25 (or add or subtract 12:24 for the convenience of calculation) to get another high tide.If the value is increased or decreased by 6:12, the time when low tide occurs - low tide.However, due to the complexity of the movement of the moon and the sun, spring tide may sometimes be delayed by one day or several days, and the climax of a lunar day is often an hour or several hours behind the time when the moon is at or below the mid day. In some places, a tide occurs on a lunar day.Therefore, the time of rising tide and ebb tide is different every day, and the interval is also different.
Power generation conditions
The use of tidal power generation must meet two physical conditions: first, the amplitude of the tide must be large, at least a few meters;The topography of the second coast must be able to store a large amount of seawater and carry out civil works.That is, it is very important to have enough tidal energy in the region. The method of tidal energy census and calculation is to first select the station sites suitable for building tidal power stations, and then calculate the installed capacity of power generation that can be developed at these sites. The superposition is the estimated resources.
Working principle and general of tidal power generationHydropowerThe principle is similar, that is, a dam is built at the estuary or bay to form a natural reservoir, and the water turbine generator set is installed in the sea retaining dam.Since the water level difference of sea water tide is far lower than that of ordinary hydropower stations, the tidal power station should adopt low head and large flow turbine generator units.Due to its small shape, light weight, short pipeline and high efficiency, the full tubular turbine generator unit has been widely used in various tidal power stations.
Power generation type
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The tidal power station can be a single reservoir or a double reservoir.The single reservoir tidal power station only builds one dam and one reservoir, while the dual reservoir tidal power station has two adjacent reservoirs.
Single reservoir one-way power station
That is, only one reservoir is used to generate power only when the tide is rising (or falling), so it is also called single reservoir single program tidal power station.Zhejiang Province, ChinaWenling CityShashan tidal power station is of this type.
Single reservoir two-way power station
Type of tidal power generation
One reservoir is used, but power can be generated at rising tide and falling tide, but power cannot be generated at flat tide when the water level inside and outside the reservoir is the same. This kind of power station is called single reservoir two-way tidal power station, which greatly improves the utilization rate of tidal energy.[1]Zhenkou Tidal Power Station in Dongguan City, Guangdong Province and Wenling City, Zhejiang ProvinceJiangxia Tidal Power StationThis is the type.
Double reservoir two-way power station
Tidal power generation utility
In order to enable the tidal power station to generate electricity continuously all day, it is necessary to adopt the tidal power station with double reservoirs.It uses two adjacent reservoirs to make one reservoir inflow at high tide and the other reservoir discharge at low tide, so that the water level of the former reservoir is always higher than that of the latter reservoir, so the former is called the upper reservoir (high level reservoir), and the latter is called the lower reservoir (low level reservoir).The water turbine generator set is placed in the partition dam between the two reservoirs. The water level difference between the two reservoirs is always maintained, so it can generate electricity all day long.[2]
Power generation characteristics
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advantage
Tidal generator
1. Tidal energy is clean, does not pollute the environment, and does not affectecological equilibriumRenewable energy.The tide rises and falls every day,Inexhaustible。It can be developed into an important supplementary energy for life, production and national defense in coastal areas.2. It is a relatively stable and reliable energy source, rarely affected by climate, hydrology and other natural factors. The total power generation throughout the year is stable, and there is no impact of wet and dry years and wet and dry periods.
3. The tidal power station does not need to submerge a large number of farmland to form a reservoir, so there is no complicated problem such as population migration and farmland inundation.In addition, sea blocking dams can be used to promote siltation and reclamation of large areas of coastal land, combine aquaculture, water conservancy, marine chemicals, and transportation, and promote comprehensive utilization.This is an outstanding advantage for the coastal areas with more 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 properties.
5. Tidal energy development, primary energy andSecondary energyIn combination, it does not use fuel, is not affected by the price of primary energy, and has low operating costs. It is an economic energy.But alsoHechuan Hydropower StationSimilarly, it has the characteristics of large one-time investment and low power generation cost.
6. There are many units, so there is no need to set standby units.
shortcoming
Tidal power generation
1. Tidal range and water head often change in a day, and the output is intermittent without special adjustment measures, which brings inconvenience to users.However, the operation plan can be formulated in advance according to the tide forecast, and it can be connected to the large power grid for operation to overcome the intermittency.
2. The tide changes half a month, and the tidal range can vary twice, so the output and installed capacity can be guaranteedAnnual utilization hoursAlso low.
3. The tidal power station is built at the estuary of the harbor, usually with deep water and long dam. It is difficult to construct, treat the foundation and prevent siltation.Therefore, the land construction and electromechanical investment are large and the cost is high.
4. Tidal power station is a form of power generation with low water head and large flow.The flow direction of rising and falling tide is opposite, so the turbine has large volume, high steel consumption and complex structure of inlet and outlet structures.In addition, since seawater and marine organisms can corrode and contaminate metal structures and marine structures when immersed in seawater, special anti-corrosion and anti adhesion treatment should be carried out.
5. The tidal change cycle is lunar day (24h, 50min), the monthly cycle is about 14 days, and the daily high tide lags behind about 50min, so it is poorly matched with the daily power demand load chart given according to the solar day.Although tidal power generation has the above shortcomings, it can be improved with the continuous improvement of modern technology.For example, two-way or multi reservoir power generation, pumped storage and grid regulation can make up for the first shortcoming;Modern floating caisson construction can save civil engineering investment;The corrosion of sea water and adhesion of marine organisms can be overcome by using stainless steel production unit, vinyl resin series coating and cathodic protection.
Usage
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Domestic situation
Tidal power generation, as a kind of clean energy, has not only received the attention of government departments, but also become a new business opportunity for equipment manufacturing enterprises to enter strategic emerging industries in today's vigorously developing marine economy.As a kind of renewable energy, tidal energy has become an important part of new energy in the "12th Five Year Plan" strategic emerging industry planning.Compared with wind energy and solar energy, tidal energy is more reliable, its power generation will not produce large fluctuations, and does not occupy farmland and pollute the environment. Its cost is only one eighth of that of thermal power. China's abundant tidal resources provide ample opportunities for the development of tidal power generation.Along with coal, oilnatural gasWith the decline of traditional fossil energy and the worsening of energy shortage, people have shifted the focus of energy development to the broader sea.Tidal power generation has the characteristics of rich resources, large reserves, renewable, environmental protection, pollution-free, and has become the focus of developing "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 "12th Five Year Plan" strategic emerging industry planning in China, which provides huge business opportunities for the equipment manufacturing industry to enter strategic emerging industries, with huge development potential.Tidal power generation requires high natural conditions and equipment conditions.Tidal power generation is to use favorable terrain such as tidal bays and estuaries to form reservoirs by building water retaining dams, place water turbine generator units in or near the dams, use the drop of tide level when the tide rises and falls to drive the turbine to rotate, and convert the potential energy and kinetic energy of seawater into electric energy.In addition, since tidal power generation uses seawater as the medium, and power generation equipment is immersed in seawater all the year round, there are strict requirements on equipment corrosion prevention, anti adhesion of marine organisms, etc.
China is rich in tidal energy resources, with more than 18000 kilometers of mainlandcoastline, starting from the northYalu River Estuary, South tobeilun estuary With more than 14000km coastline of more than 5000 islands, a total of 32000km coastline contains rich tidal energy resources.According to incomplete statistics, the tidal energy reserve in China 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, equivalent to more than 40Xin'anjiang Hydropower Station。At present, ChinatideXi Power StationThe total installed capacity has exceeded 10000 kilowatts.According to the results of China's marine energy resource zoning, there are 424 tidal power station dam sites that can be developed for tidal energy in China's coastal areas, with the largest number in Zhejiang and Fujian coastal areas.[3]
Zhejiang Coastal
According to the Marine Functional Zoning of Zhejiang Province issued by the Zhejiang Provincial GovernmentOcean energyThe utilization area includes 4 tidal energy areas, and the key areas are Nantian Island Bay tidal energy areaSanmen BayTidal energy area, Jiangxia tidal energy area, Haishan tidal energy area;One tidal current energy zone, namelyGuishanWaterway tidal energy area, whereZhoushan IslandsIt accounts for about half of the tidal current energy in China and has great development potential.
It is understood that Zhejiang nearshore is a strong tide area.The average tidal range along the coast of Zhejiang is 4.29 meters, the theoretical installed capacity of tidal energy is 28.96 million kilowatts, and the developable installed capacity of tidal energy is 8.8 million kilowatts, accounting for about 40% of the national total;The average wave height along the coast is 1.3 m, the theoretical wave energy density is 5.3 kW/m, the installed capacity is 2.5 million kW, and the wave energy accounts for 16.5% of the national total.
Fujian Province
On December 16, 1980, Fujian Provincial Department of Hydropower, Fujian Provincial Water Resources Research Institute, Fujian Provincial Agricultural Machinery Research Institute and other units organized technicians toPingtanInvestigate tidal energy sources.In October 1983, the Provincial Science and Technology Commission decided toPingtan CountyA tidal power station will be built inside the Xiaojieyu seawall in Xingfuyang Reclamation Area.The project was designed by Fujian Water Resources and Electric Power Survey and Design Institute, and constructed by the headquarters of Xingfuyang Experimental Tidal Power Station Project in Pingtan County.The tidal power station uses the flood drainage ditch and deep-water aquaculture pond (covering an area of 73 hectares) in the reclamation area as the water storage reservoir, with a reservoir capacity of 1.67 million cubic meters and an effective reservoir capacity of 1.33 million cubic meters. It uses one-way ebb tide for power generation.
In October 1984, the construction of cofferdam and foundation was started.On the shore of Xiaojieyu Island, the construction of main and auxiliary power houses was started, of which the construction area of the main power house was 522.7 square meters and that of the auxiliary power house was 184.4 square meters.The installation elevation of the unit is -3.8m, and there are 4 water turbines and 4 generators.The turbine is a domestic tubular GDBWS-190 type, with shaft power of 381.71 kW, rotating speed of 155 rpm and efficiency of 83%.The generator is an AC synchronous water turbine TSWN99/37-12, with a capacity of 320 kW, a rated voltage of 400 V, a rated current of 577 A, and a speed of 500 rpm.The elevation of the equipment operation floor is -1.55m, in which the governor, control panel, power panel, potentiostat, etc. are set.Central control room, main transformer room, in plant transformer room and 10kV switch cabinet are set inside.Power stationTransmission lineIt is a 10kV secondary circuit, and the primary circuit is 13km long from the standard sand factory to the county seat;The other circuit passes throughZhonglou TownshipIt is connected to the county power grid, with a length of 12 kilometers.
The main project was completed in 1988, accepted on June 12, 1989, and connected to the county grid for power generation in September.The total installed capacity of the power station is 1280kW, generating electricity twice a day for 10 hours, and the designed annual generating capacity is 3151700kWh, generating electricity 22800kWh that year.The total investment is 5.3 million yuan.In July 1991, the motor was stopped for maintenance due to corrosion.Since then, it has stopped and started from time to time, with short power generation time limit and instability.In 1995, the power generation was 22500 kilowatt hours.
Foreign situation
Country or region
place
Installed capacity (MW)
Annual power generation (10000 MW · h)
Unit
Tidal range (m)
France
Lance
two hundred and forty
four point eight
twenty-four
eight
britain
Seyin estuary
seven thousand and two hundred
one thousand and three hundred
two hundred and thirty
nine point three
Moxi estuary
six hundred and twenty
one hundred and twenty
twenty-one
six point seven
Stratford Bay
fifty-three
fifty-three
thirty-one
three point one
Ireland
Shannon estuary
three hundred and eighteen
seventy-one point five
thirty
three point eight
India
Cage Bay
six hundred
one hundred and sixty
forty-three
five point two
the republic of korea
Jialulin Bay
four hundred and eighty
one hundred and twenty
thirty-two
four point six
Brazil
Baganga
thirty
five point five
two
four point one
U.S.A
Saronic
two thousand two hundred and twenty
five hundred and fifty
eighty
seven point eight
Canada
Cumberland Bay
one thousand one hundred and forty-seven
three hundred and forty-two
thirty-seven
ten point five
Quebec Bay
four thousand and twenty-eight
one thousand two hundred and sixty
one hundred and six
twelve point four
Annapolis Rolle
twenty
five
one
six point seven
Russia
Lunbowski
four hundred
Myanjanskaya
fifteen thousand
five thousand
eight hundred
nine
Pinren
eighty-seven thousand
twenty thousand
thirteen point five
prospect
Tidal power generation is a business with great potential. According toOceanographerCalculation of tidal power generation in the worldResourcesAt more than 1 billion kilowatts, it is also an astronomical figure.After years of practice, it is basically shaped in working principle and overall structure, and can enter the stage of large-scale development and utilization.The prospect of tidal power generation is broad.
It is estimated that the annual power generation of tidal power stations in the world could reach 3X1010 ～ 6X1010kw · h in 2000.In addition to generating electricity, tidal power stations have broad prospects for comprehensive utilization, of which the greatest benefits areReclaiming land from the sea, increase land, in addition to marine breeding and tourism development.Because of the above reasons, tidal power generation has been attached great importance by all countries in 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.Including: AlaskaCook BayFendi Bay in Canada, Severn Estuary in Britain, St. Joseph Bay in Argentina, Darwin Vandimen Bay in Australia, Cambay Estuary in India, Far East in RussiaOkhotsk SeaPinren Bay, Incheon Bay, South Korea, etc.With the technological progress and the continuous reduction of the cost of tidal power generation, large-scale modern tidal power stations will continue to be built and used in the 21st century.
Famous power station
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France Lens Tidal Power StationIt was completed in 1966, with a total installed capacity of 240MW, a single unit power of 10MW, a total of 24 water turbines, generating 540 million kilowatt hours of electricity annually. It was the world's largest marine power generation project at that time.Its technical innovation is to use bulb type tubular turbine generator units with forward and reverse power generation, water discharge and pumping, which are different from conventional hydropower stations. This not only improves the utilization efficiency of tidal energy, but also reduces the cost of the power station.The total capital construction cost of the power station is 570 million francs (about 100 million dollars). If calculated according to 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 annual average output power is 25% of the rated installed capacity.
Tidal power station in Ireland's Stratford BayThe Stratford Bay Tidal Power Station is one of the top ten renewable energy projects in the world, and is by far the largest tidal power station in the ocean.However, this record will be broken by the project built in South Korea's Wando Hoenggan Waterways in 2015. The project has an investment of $820 million, an installed capacity of 300 megawatts, and a 60 foot high (18 meter) turbine is fixed to the seabed by its own gravity.
China Jiangxia Tidal Experimental Power StationJiangxia Port is located at the north end of Yueqing Bay, Zhejiang Province, China.The power station was built in 1974 on the basis of the original "July 1st" pond reclamation project, integrating power generation, reclamation, mariculture, tourism and other functions.The power station is characterized by the use of two-way bulb tubular turbine generator units similar to the French Lens power station.The maximum tidal range of the station site is 8.39m, and the average tidal range is 5.1m. The original design is six 500kW units with six machine pits. Five units are actually installed, the first one is 500kW, which was put into operation in May 1980;The second one is 600kW, the other three are 700kW, and the last one 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 harbor area above the dam site is about 8000 mu. As the reservoir area was originally planned to reclaim 5600 mu of land, local farmers privately occupied land for reclamation or breeding, and the water area available for power generation is less than 2000 mu.In 1986, the annual power generation of the five units was about 6 million kilowatt hours, lower than the original design annual power generation of 10.7 million kilowatt hours, and the economic benefits of power generation were not high.For many years, the power plant plans to raise the cofferdam, raise the water level in the reservoir area, and add a unit in the No. 6 turbine pit to increase the power generation and improve the economic benefits of power generation.[4]
