Pros and cons of hydroelectric power. Advantages and disadvantages of hydroelectric power plants
A power plant is a complex of buildings, structures and equipment designed to generate electrical energy. That is, power plants convert various types of energy into electricity. The most common types of power plants are:
— hydroelectric power stations;
— thermal;
- atomic.
A hydroelectric power plant (HPP) is a power plant that converts the energy of moving water into electrical energy. Hydroelectric power stations are being installed on rivers. With the help of a dam, a difference in water heights is created (before and after the dam). The resulting water pressure sets the turbine blades in motion. The turbine drives generators that produce electricity.
Depending on the power, hydroelectric power plants are divided into: small (up to 5 MW), medium (5-25 MW) and powerful (over 25 MW). According to the maximum used pressure, they are divided into: low-pressure (maximum pressure - from 3 to 25 m), medium-pressure (25-60 m) and high-pressure (over 60 m). Hydroelectric power stations are also classified according to the principle of use of natural resources: dam, near-dam, diversion and pumped storage.
Advantages of hydroelectric power plants are: generation of cheap electricity, use of renewable energy, ease of control, quick access to operating mode. In addition, hydroelectric power plants do not pollute the atmosphere. Disadvantages: attachment to water bodies, possible flooding of arable land, detrimental effect on river ecosystems. Hydroelectric power stations can only be built on lowland rivers (due to the seismic danger of mountains).
Thermal power plant (TPP) generates electricity by converting thermal energy obtained as a result of fuel combustion. The fuel for thermal power plants is: natural gas, coal, fuel oil, peat or hot shale.
As a result of fuel combustion in the furnaces of steam boilers, feed water is converted into superheated steam. This steam at a certain temperature and pressure is supplied through a steam line to a turbogenerator, where electrical energy is generated.
Thermal power plants are divided into:
— gas turbine;
— boiler-turbine;
- combined cycle;
— based on combined cycle gas plants;
- based on piston engines.
Boiler-turbine thermal power plants, in turn, are divided into condensing (CPS or GRES) and combined heat and power plants (CHP).
Advantages of thermal power plants
— low financial costs;
— high speed of construction;
— possibility of stable work regardless of the season.
Disadvantages of thermal power plants
— work on non-renewable resources;
— slow return to operating mode;
- receiving waste.
Nuclear power plant (NPP)- a station in which electricity (or thermal energy) is generated through the operation of a nuclear reactor. For 2015, almost 11% of electricity.
During operation, a nuclear reactor transfers energy to the primary coolant. This coolant enters the steam generator, where it heats the secondary circuit water. In the steam generator, water is converted into steam, which enters the turbine and drives electric generators. The steam after the turbine enters the condenser, where it is cooled with water from the reservoir. Mainly water is used as the primary coolant. However, lead, sodium and other liquid metal coolants can also be used for this purpose. The number of circuits may vary.
Nuclear power plants are classified according to the type of reactor used. Nuclear power plants use two types of reactors: thermal and fast neutrons. Reactors of the first type are divided into: boiling water, water-water, heavy water, gas-cooled, graphite-water.
Depending on the type of energy received, nuclear power plants are of two types:
Stations designed to generate electricity.
Stations designed to generate electrical and thermal energy (CHP).
Advantages of nuclear power plants:
— independence from fuel sources;
— environmental cleanliness;
The main disadvantage of stations of this type- severe consequences in case of emergency situations.
In addition to the listed power plants, there are also: diesel, solar, tidal, wind, geothermal.
ADVANTAGES OF HPP:
Flexibility
Hydropower is a flexible source of electricity because hydroelectric power plants can very quickly adapt to changing energy demands, increasing or decreasing electricity production. A hydraulic turbine has a startup time of the order of several minutes. It takes 60 to 90 seconds to bring the device from cold start to full load; this is much less than for gas turbines or steam plants. Electricity production can also be quickly reduced when there is excess power.
Ffestiniog power station can produce 360 MW in 60 seconds
Low energy costs
The main advantage of hydroelectric power is the absence of fuel costs. The cost of operating a hydroelectric power plant is almost immune to increases in the cost of fossil fuels such as oil, natural gas or coal, and no imports are required. The average cost of electricity from a hydroelectric power plant larger than 10 megawatts is 3 to 5 US cents per kilowatt-hour.
Hydroelectric power plants have a long service life, some hydroelectric power plants still provide electricity after 50-100 years of operation.
Operational maintenance costs are low, few people are required to control the operation of the hydroelectric power station.
The dam can be used for several purposes at once: accumulate water for hydroelectric power stations, protect territories from floods, create a reservoir.
Suitability for industrial use
While many hydroelectric dams supply energy to public utility networks, some are created to serve specific industrial plants. For example, in New Zealand, a power station was built to supply electricity to the Tiwai Point aluminum smelter.
Reduced CO 2 emissions
Hydroelectric power plants do not burn fossil fuels and do not directly produce carbon dioxide. Although some carbon dioxide is generated during the production and construction process of the project. According to a study by Paul Scherrer from the University of Stuttgart, hydropower produces the least carbon dioxide among other energy sources. Wind was in second place, nuclear energy was third, solar energy was in 4th place.
Other uses of the reservoir
Hydroelectric reservoirs often provide opportunities for water sports and become tourist attractions themselves. In some countries, aquaculture in reservoirs is common. Water from reservoirs can be used to irrigate crops, and fish can be raised in it. Dams also help prevent flooding.
DISADVANTAGES OF HYDRO POWER PLANT:
Ecosystem damage and land loss
The large reservoirs required to operate hydroelectric dams flood vast areas of land upstream from the dam, destroying forest valleys and swamps. Land loss is often compounded by habitat destruction in the surrounding areas occupied by the reservoir.
Hydroelectric power plants can lead to the destruction of ecosystems, as water passing through turbinescleared of natural sediments. Hydroelectric power plants on large rivers are especially dangerous, as they lead to serious changes in the environment.
The photo shows a reservoir resulting from the construction of a dam.
Siltation
When water flows, heavier particles float downstream.
This has a negative impact on dams and subsequently their power plants, especially on rivers or in catchments with high levels of siltation. Silt can fill the reservoir and reduce its ability to control floods, causing additional horizontal pressure on the dam. Reducing the river bed can lead to a decrease in electricity production. In addition, even a hot summer or low rainfall can lead to a decrease in the river.
Methane emissions (from reservoirs)
Hydroelectric power plants in tropical regions have the greatest impact; reservoirs of power plants in tropical regions produce significant amounts of methane. This is due to the presence of plant material in flooded areas that decays in an anaerobic environment and produces methane and a greenhouse gas. According to the report of the World Commission on Dams, in cases where the reservoir is large compared to the generating capacity (less than 100 watts per square meter of surface area) and the forests in the area of the reservoir have not been cleared. Then greenhouse gas emissions in the reservoir may be higher than those of a conventional thermal power plant.
Everyone has heard about the main disadvantage of nuclear power plants - the severe consequences of accidents at nuclear power plants. Tens of thousands of dead and many fatally ill people, powerful radiation exposure affecting the health of a person and his descendants, cities that have become uninhabitable... the list, unfortunately, can be continued endlessly. Thank heavens that accidents are rare; the vast majority of nuclear power plants in the world have been operating successfully for decades without ever encountering system failures.
Today, nuclear energy is one of the fastest growing areas in world science. Let's try to move away from the persistent myth that nuclear power plants are a danger of nuclear disasters and learn about the advantages and disadvantages of nuclear power plants as sources of electricity. In what ways are nuclear power plants superior to thermal and hydroelectric power plants? What are the advantages and disadvantages of nuclear power plants? Is it worth developing this area of electricity production? About all this and more...
Did you know that you can get electricity using an ordinary potato, lemon or indoor flower? All you need is a nail and copper wire. But potatoes and lemons, of course, will not be able to supply electricity to the whole world. Therefore, since the 19th century, scientists began to master methods of generating electricity using generation.
Generation is the process of converting various types of energy into electrical energy. The generation process takes place in power plants. Today there are many types of generation.
You can get electricity today in the following ways:
- Thermal power engineering – electricity is produced through the thermal combustion of organic fuel. To put it simply, oil and gas burn, release heat, and the heat heats the steam. Pressurized steam causes the electric generator to rotate, and the electric generator produces electricity. Thermal power plants in which this process occurs are called thermal power plants.
- Nuclear energy - the operating principle of nuclear power plants(nuclear power plants that receive electricity using nuclear installations) is very similar to the operation of thermal power plants. The only difference is that heat is obtained not from the combustion of organic fuel, but from the fission of atomic nuclei in a nuclear reactor.
- Hydropower – in the case of hydroelectric power plants(hydroelectric power plants), electrical energy is obtained from the kinetic energy of water flow. Have you ever seen waterfalls? This method of generating energy is based on the power of waterfalls that rotate the rotors of electric generators that produce electricity. Of course, waterfalls are not natural. They are created artificially using natural river flows. By the way, not so long ago scientists found out that the sea current is much more powerful than the river current, and there are plans to build offshore hydroelectric power stations.
- Wind energy – in this case, the kinetic energy of the wind powers an electric generator. Remember the mills? They fully reflect this operating principle.
- Solar energy - in solar energy, the heat from the sun's rays serves as the conversion platform.
- Hydrogen energy – electricity is produced by burning hydrogen. Hydrogen is burned, it releases heat, and then everything happens according to the scheme already known to us.
- Tidal energy - what is used to produce electricity in this case? The energy of the sea tides!
- Geothermal energy is the production of first heat and then electricity from the natural heat of the Earth. For example, in volcanic areas.
Disadvantages of alternative energy sources
Nuclear, hydro and thermal power plants are the main sources of electricity in the modern world. What are the advantages of nuclear power plants, hydroelectric power plants and thermal power plants? Why aren't we warmed by wind energy or tidal energy? Why did scientists not like hydrogen or the natural heat of the Earth? There are reasons for this.
Wind, solar and tidal energies are usually called alternative due to their rare use and very recent appearance. And also due to the fact that the wind, sun, sea and heat of the Earth are renewable, and the fact that a person uses the solar heat or the sea tide will not cause any harm to either the sun or the tide. But don’t rush to run and catch the waves, not everything is so easy and rosy.
Solar energy has significant disadvantages - the sun shines only during the day, so at night you won’t get any energy from it. This is inconvenient, because... The main peak in electricity consumption occurs in the evening hours. At different times of the year and in different places on Earth, the sun shines differently. Adapting to it is costly and difficult.
Wind and waves are also capricious phenomena; they blow and tide when they want, but not when they want. But if they work, they do it slowly and weakly. Therefore, wind and tidal energy have not yet become widespread.
Geothermal energy is a complex process because... It is possible to build power plants only in zones of tectonic activity, where maximum heat can be “squeezed” out of the ground. How many places with volcanoes do you know? Here are some scientists. Therefore, geothermal energy will most likely remain narrowly focused and not particularly efficient.
Hydrogen energy is the most promising. Hydrogen has a very high combustion efficiency and its combustion is absolutely environmentally friendly, because combustion product is distilled water. But, there is one thing. The process of producing pure hydrogen costs an incredible amount of money. Do you want to pay millions for electricity and hot water? Nobody wants. We wait, hope and believe that scientists will soon find a way to make hydrogen energy more accessible.
Nuclear energy today
According to various sources, nuclear energy today provides from 10 to 15% of electricity worldwide. 31 countries use nuclear energy. The largest amount of research in the field of electric power is carried out on the use of nuclear energy. It is logical to assume that the advantages of nuclear power plants are clearly great if, of all types of electricity production, this is the one that is developed.
At the same time, there are countries that refuse to use nuclear energy and close all existing nuclear power plants, for example, Italy. On the territory of Australia and Oceania, nuclear power plants did not exist and do not exist in principle. Austria, Cuba, Libya, North Korea and Poland have stopped the development of nuclear power plants and temporarily abandoned plans to create nuclear power plants. These countries do not pay attention to the advantages of nuclear power plants and refuse to install them primarily for safety reasons and the high costs of constructing and operating nuclear power plants.
The leaders in nuclear energy today are the USA, France, Japan and Russia. It was they who appreciated the advantages of nuclear power plants and began to introduce nuclear energy into their countries. The largest number of nuclear power plant projects under construction today belong to the People's Republic of China. About 50 more countries are actively working on the introduction of nuclear energy.
Like all methods of generating electricity, nuclear power plants have advantages and disadvantages. Speaking about the advantages of nuclear power plants, it is necessary to note the environmental friendliness of production, the refusal to use fossil fuels and the convenience of transporting the necessary fuel. Let's look at everything in more detail.
Advantages of nuclear power plants over thermal power plants
The advantages and disadvantages of nuclear power plants depend on what type of electricity generation we compare nuclear energy with. Since the main competitors of nuclear power plants are thermal power plants and hydroelectric power stations, let us compare the advantages and disadvantages of nuclear power plants in relation to these types of energy production.
TPPs, that is, thermal power plants, are of two types:
- Condensing or briefly CESs serve only to produce electricity. By the way, their other name comes from the Soviet past, IESs are also called GRESs - short for “state district power plant”.
2. Combined heat and power plants or combined heat and power plants only allow producing not only electrical, but also thermal energy. Taking, for example, a residential building, it is clear that CES will only provide electricity to the apartments, and CHP will also provide heating in addition.
As a rule, thermal power plants operate on cheap organic fuel - coal or coal dust and fuel oil. The most popular energy resources today are coal, oil and gas. According to experts, the world's coal reserves will last for another 270 years, oil – for 50 years, gas – for 70. Even a schoolchild understands that 50-year reserves are very small and must be protected, and not burned in furnaces every day.
IT IS IMPORTANT TO KNOW:
Nuclear power plants solve the problem of shortage of organic fuel. The advantage of nuclear power plants is the elimination of fossil fuels, thereby preserving endangered gas, coal and oil. Instead, nuclear power plants use uranium. World uranium reserves are estimated at 6,306,300 tons. No one is counting how many years it will last, because... There are a lot of reserves, uranium consumption is quite small, and there is no need to think about its disappearance yet. In extreme cases, if uranium reserves are suddenly carried away by aliens or they evaporate on their own, plutonium and thorium can be used as nuclear fuel. Converting them into nuclear fuel is still expensive and difficult, but it is possible.
The advantages of nuclear power plants over thermal power plants include a reduction in the amount of harmful emissions into the atmosphere.
What is released into the atmosphere during the operation of thermal power plants and thermal power plants and how dangerous it is:
- Sulfur dioxide or sulfur dioxide– a dangerous gas that is harmful to plants. If ingested in large quantities, it causes coughing and suffocation. When combined with water, sulfur dioxide turns into sulfurous acid. It is thanks to sulfur dioxide emissions that there is a risk of acid rain, which is dangerous for nature and humans.
2. Nitrogen oxides– dangerous to the respiratory system of humans and animals, irritating the respiratory tract.
3. Benapyrene– is dangerous because it tends to accumulate in the human body. Long-term exposure may cause malignant tumors.
The total annual emissions of thermal power plants per 1000 MW of installed capacity are 13 thousand tons per year at gas and 165 thousand tons at pulverized coal thermal stations. A thermal power plant with a capacity of 1000 MW per year consumes 8 million tons of oxygen to oxidize fuel; the advantages of nuclear power plants are that in nuclear energy oxygen is not consumed in principle.
The above emissions are also not typical for nuclear power plants. The advantage of nuclear power plants is that emissions of harmful substances into the atmosphere at nuclear power plants are negligible and, compared to emissions from thermal power plants, are harmless.
The advantages of nuclear power plants over thermal power plants are low fuel transportation costs. Coal and gas are extremely expensive to transport to factories, while the uranium needed for nuclear reactions can be placed in one small truck.
Disadvantages of nuclear power plants over thermal power plants
- The disadvantages of nuclear power plants over thermal power plants are, first of all, the presence of radioactive waste. They try to recycle radioactive waste at nuclear plants as much as possible, but they cannot dispose of it at all. The final waste at modern nuclear power plants is processed into glass and stored in special storage facilities. Whether they will ever be used is still unknown.
2. The disadvantages of nuclear power plants are their low efficiency compared to thermal power plants. Since processes in thermal power plants occur at higher temperatures, they are more productive. This is still difficult to achieve in nuclear power plants, because zirconium alloys, which indirectly participate in nuclear reactions, cannot withstand extremely high temperatures.
3. The general problem of heat and nuclear power plants stands apart. The disadvantage of nuclear power plants and thermal power plants is thermal pollution of the atmosphere. What does it mean? When generating nuclear energy, a large amount of thermal energy is released, which is released into the environment. Thermal pollution of the atmosphere is a problem of today, it entails many problems such as the creation of heat islands, changes in microclimate and, ultimately, global warming.
Modern nuclear power plants already solve the problem of thermal pollution and use their own artificial pools or cooling towers (special cooling towers for cooling large volumes of hot water) to cool water.
Advantages and disadvantages of nuclear power plants over hydroelectric power plants
The advantages and disadvantages of nuclear power plants over hydroelectric power plants are mainly related to the dependence of hydroelectric power stations on natural resources. More about this...
- The advantage of nuclear power plants over hydroelectric power plants is the theoretical possibility of building new nuclear power plants, while most rivers and reservoirs capable of working for the benefit of hydroelectric power plants are already occupied. That is, the opening of new hydroelectric power stations is difficult due to the lack of necessary places.
2. The next advantage of nuclear power plants over hydroelectric power plants is their indirect dependence on natural resources. Hydroelectric power plants directly depend on the natural reservoir, nuclear power plants only indirectly on uranium mining, everything else is provided by the people themselves and their inventions.
The disadvantages of nuclear power plants compared to water stations are insignificant - the resources that a nuclear power plant uses for a nuclear reaction, and specifically uranium fuel, are not renewable. While the amount of water, the main renewable resource of a hydroelectric power station, will not change in any way from the operation of a hydroelectric power station, and uranium itself cannot be restored in nature.
Nuclear power plants: advantages and disadvantages
We examined in detail the advantages and disadvantages of nuclear power plants over other methods of generating electricity.
“But what about radioactive emissions from nuclear power plants? It is impossible to live near nuclear power plants! Is it dangerous!" - you say. “Nothing like that,” statistics and the world scientific community will answer you.
According to statistical comparative estimates carried out in different countries, it is noted that the mortality rate from diseases that appeared from exposure to emissions from thermal power plants is higher than the mortality rate from diseases that developed in the human body from the leakage of radioactive substances.
Actually, all radioactive substances are firmly locked in storage facilities and are waiting for the hour when they will learn to reprocess and use them. Such substances are not released into the atmosphere; the level of radiation in populated areas near nuclear power plants is no more than the traditional level of radiation in large cities.
Speaking about the advantages and disadvantages of nuclear power plants, one cannot help but recall the cost of building and launching a nuclear power plant. The estimated cost of a small modern nuclear power plant is 28 billion euros, experts say that the cost of thermal power plants is approximately the same, no one wins here. However, the advantages of nuclear power plants will be lower costs for the purchase and disposal of fuel - uranium, although more expensive, can “work” for more than a year, while coal and gas reserves must be constantly replenished.
Accidents at nuclear power plants
Previously, we did not mention only the main disadvantages of nuclear power plants, which are known to everyone - these are the consequences of possible accidents. Accidents at nuclear power plants are classified according to the INES scale, which has 7 levels. Level 4 and higher accidents pose a risk of exposure to the population.
Only two accidents in history were assessed at the maximum level 7 - the Chernobyl disaster and the accident at the Fukushima 1 nuclear power plant. One accident was considered level 6, this is the Kyshtym accident, which occurred in 1957 at the Mayak chemical plant in the Chelyabinsk region.
Of course, the advantages and disadvantages of nuclear power plants pale in comparison with the possibility of nuclear disasters that claim the lives of many people. But the advantages of nuclear power plants today are an improved safety system, which almost completely eliminates the possibility of accidents, because The operating algorithm of nuclear reactors is computerized and with the help of computers, reactors are switched off in case of minimal violations.
The advantages and disadvantages of nuclear power plants are taken into account when developing new models of nuclear power plants that will operate on processed nuclear fuel and uranium, the deposits of which have not previously been put into operation.
This means that the main advantages of nuclear power plants today are the prospects for their modernization, improvement and new inventions in this area. It seems that the most important advantages of nuclear power plants will be revealed a little later, we hope that science will not stand still, and very soon we will learn about them.
Recently, as an alternative to classic medium-high-pressure dam hydroelectric power stations, low-pressure hydroelectric power stations operating on natural flow, which are quite widespread in Western Europe, have been actively proposed. Let's try to figure out what these hydroelectric power plants are and what their pros and cons are.
An example of a low-pressure run-of-the-river hydroelectric power plant is the Iffezheim hydroelectric power station on the Rhine, commissioned in 1978. Photo from here
The concept of a low-pressure run-of-river hydroelectric complex involves the creation of a hydroelectric power station on a flat river with a head of several meters, whose reservoir is usually located in the natural flood zone of the floodplain during heavy floods. Such waterworks have the following advantages:
* A small flood area, which usually does not include (or almost does not include) built-up lands. Consequently, no one needs to be resettled, and the impact on ecosystems is much less significant.
* It is much easier to integrate fish passages into low-pressure dams, and fish pass down through the turbines with less injury.
The Saratov hydroelectric power station is the lowest pressure one in the Volga-Kama cascade.
Now let's move on to the disadvantages:
* Such hydroelectric power stations form small reservoirs, suitable at best for daily flow regulation, or even operating on a watercourse. As a result, the production of such hydroelectric power plants is highly dependent on the season and weather conditions - during low-water periods it drops sharply.
* The efficiency of using runoff by such hydroelectric power plants is much less than that of classical ones - not being able to accumulate runoff during high waters and floods, they are forced to empty a lot of water.
* Without a capacious reservoir, such hydroelectric systems cannot combat floods.
* From the point of view of navigation, the construction of several low-pressure hydroelectric complexes instead of one large one leads to an increase in locking time - instead of one lock, you need to go through several.
* Low-pressure hydroelectric power plants have a significantly higher unit cost (calculated per kW of power and kWh of generated electricity). The lower the pressure, the larger the dimensions and, accordingly, the metal consumption of the equipment; the inability to accumulate runoff in the reservoir leads to the need to create more powerful culvert structures; several sluices are more expensive than one, etc. For comparison, we can cite the low-pressure Polotsk hydroelectric power station in Belarus and the high-pressure Boguchanskaya hydroelectric power station. The first costs approximately $4,500 per kW, the second — about $1,000 per kW. The difference, as we see, is 4.5 times.
Hydroelectric power station Tucurui in Brazil. In the Amazonian jungle, as in the Siberian taiga, large hydroelectric power plants are more efficient.
Let's summarize. The advantages of low-pressure hydroelectric power plants are most significant in densely populated areas, where the high cost of land and the large amount of work involved in relocating people, removing structures and infrastructure make large hydroelectric power stations with large reservoirs unacceptable. That is why low-pressure hydroelectric power plants are most widespread in Europe, where the population density is high and there are few own energy resources, which forces the use of all available hydro potential, albeit in expensive ways.
At the same time, in relatively sparsely populated regions, the advantages of large hydroelectric power stations are obvious - in fact, they are mostly being built there now all over the world (although the criteria for sparse population in different countries vary significantly, for China, with its billion-strong population, the resettlement of several tens of thousands of people is quite acceptable) .
Low-pressure run-of-river hydroelectric power plants do not compete with medium- and high-pressure hydroelectric power stations - each type of hydroelectric power station has its own “ecological niche” in which they are most effective. And references to run-of-the-river hydroelectric power stations in Western Europe when discussing hydropower projects in Eastern Siberia are a comparison of the incomparable.
In the wake of interest in renewable energy sources around the world, hydroelectric dams are being built here and there. some of them amaze the imagination with their grandeur. But, while paying tribute to bold engineering solutions, it should be remembered that the huge masses of water held by dams are fraught with terrible destructive power
Editorial PM
Considered one of the environmentally friendly methods of energy production, hydropower has a serious impact on nature. And this impact has both positive and negative sides. In the photo - the dam of the Chirkey hydroelectric station in Dagestan
Enguri Hydroelectric Power Station The dam on the Georgian Enguri River can be considered the pride of Soviet hydropower: it is the world's tallest concrete arch-type dam. Its height is 272 m. Construction of the dam began in 1961, and was fully completed only in 1987. Currently, the Enguri hydroelectric power station is divided between Georgia and Abkhazia, which was recently recognized by Russia, which owns 40% of the energy produced
Zeya Hydroelectric Power Station The dam, erected on the Zeya River in the Amur Region (1965−1980), belongs to a massive buttress type unique for Russia. It divided the river into two pools that are not connected to each other - the design does not provide for either locks or fish lifts. The reservoir is of great flood control value.
Bureya Hydroelectric Power Station is being built on the Bureya River in the Amur Region. The construction of this hydroelectric power station began in 1978, but work on it continues to this day. From the late 1980s to the late 1990s, construction was essentially mothballed. The project provides for six hydraulic units at the station, two of which have already been put into operation, and the third should start operating this year. The dam is of the gravity type and has a length of 736 m with a height of 140 m. The reservoir flooded large areas of forest, mainly in the Khabarovsk Territory
America: Hoover Dam Named after President Herbert Hoover, the tallest gravity-arch dam in the United States blocked the Colorado River in 1936. Construction goals: hydropower, field irrigation, improvement of navigation conditions, flood control
America: Panama Canal One of the most famous hydraulic structures in the world is the Panama Canal (completed in 1914). Vessels are guided through the canal's locks by locomotive tugs that move along rack rails along the lock.
America: “Glory Hole” The arched dam Monticello Dam, blocking the Californian Piuta Creek, is not particularly famous for anything other than its “glory hole”. This strange name goes to an unregulated spillway made in the form of a concrete funnel. When the level in the Berryessa Reservoir exceeds its design level, water overflows over the edges of the funnel, creating a beautiful, but slightly eerie spectacle
Parade of giants: Itaipu hydroelectric dam One of the world's largest dams blocked the Paraná River near the Brazil-Paraguay border. To build the dam, made of earth, stone and concrete, a 150-meter canal was cut into the rocks, through which the river water was diverted away from the riverbed. After the riverbed dried out at the selected site, construction of the dam began in 1979. Its total length is 7235 m.
Strictly speaking, the construction of dams and dams is not necessarily related to hydropower. Moscow dams simply raise the level of a once almost shallow river, and, for example, the Krasnodar reservoir on the Kuban River was created for irrigation needs. But still, the overwhelming majority of large hydraulic structures in Russia are associated with the energy industry. Since the approval of the GOELRO plan in 1921 by the IX All-Russian Congress of Soviets, our country has been actively using the energy of small and great rivers.
Treacherous bottom
Without going into details of the classification, power plant dams are mainly divided into gravity and arch dams. A gravity dam—usually having a triangular cross-section—is constructed from soil, rock, or concrete blocks. From the very term “gravity” it is clear that such a dam holds a mass of water due to its gravity - the flow of the river is not able to move this giant from its place, and the water begins to rise. Arch dams are used in mountainous areas. Due to its shape (essentially it is a fragment of a dome curved towards the advancing water), such a dam transfers the load to the sides of the canyon. An arch dam is more difficult to construct, but more economical in terms of material consumption. With a height of 100 m, a gravity dam should have a base 70-80 m wide, and an arch dam of the same height will have a base width of only about 5 m. There are also dams of a mixed gravity-arch type (for example, the dam of the largest Sayano-Shushenskaya hydroelectric power station in Russia) and buttress type.
In order for the dam to fulfill its purpose and not present unpleasant surprises, a thorough geological study of the river sections in the place where the construction of the hydroelectric power station is proposed is required. History knows of cases when a dam was placed on the bottom, in which there were karst cavities. After filling the reservoir, water seeped into these cavities and then found an outlet in the downstream. The reservoir began to drain, and in order to prevent this, concrete had to be pumped into the karst voids, the volume of which was approximately equal to the volume of the dam itself.
A rocky bottom is ideal for building a dam; slippery clay soil is less preferable. In the latter case, if the dam’s weight is insufficient, it can simply “go” downstream.
Water will find a hole
A hydroelectric dam is a structurally complex structure. It consists of blind dams - over the crest of which water does not overflow (or, in any case, should not overflow); station dams through which water from the reservoir enters chambers with turbines that rotate the shafts of electric generators; and spillway dams through which water is released to regulate the water level in the upstream (reservoir).
The spillway system is one of the key elements of the waterworks. Water levels in a dammed river can fluctuate significantly depending on the time of year and climatic factors such as melting snow and ice in the upper reaches or heavy rainfall. Uncontrolled discharge of water from the upstream can lead to the destruction of the entire structure.
Perhaps most of the dramatic events associated with the destruction of dams are caused by the overflow of the upper pool due to the ingress of large amounts of melt or storm water. The last such incident occurred in March of this year in Indonesia, when a dam built by the Dutch colonial authorities in 1933 failed to withstand the onslaught of tropical rainfall. The water that broke free caused the death of about a hundred people. One of the largest accidents at hydraulic structures occurred in the USA in 1976. First, a small leak appeared in the earthen dam that blocked the Teton River (Idaho). At first, they didn’t pay much attention to it, then, when the leak became more noticeable, they tried to eliminate it with the help of construction equipment. In the end, the bulldozers had to be abandoned to save lives. Having finally broken through the earthen dam, the water washed it away in a matter of minutes.
Predatory seas
Reservoirs are perhaps the main Achilles heel of hydropower. And it is around them that ongoing discussions are taking place between energy specialists and environmentalists. It is obvious that the artificial “seas” that appeared as a result of the construction of hydroelectric complexes cannot be considered only a necessary evil. Reservoirs are of great importance for the organization of navigation and fishing, serve as reservoirs of drinking water and perform a recreational function (such as, for example, the cascade of reservoirs of the watershed pool of the Moscow Canal). They often help solve flood problems in areas downstream of the dammed river. However, the price for this is the transformation of land into the bottom, serious changes in the environmental situation and even climate change. Forests are often flooded and anaerobic decay in the shallows of large masses of plant organic matter leads to the release of methane, one of the “greenhouse gases,” into the atmosphere. This fact somewhat spoils the image of hydropower as an alternative to burning fossil fuels.
The child of the first five-year plans, the gigantic Rybinsk Reservoir, as we know, swallowed up a huge, anciently populated territory in the very center of European Russia. The “sea” filled the Molgo-Sheksninskaya lowland, formed as a result of the melting of the glacier. Hundreds of villages and the entire city of Mologa, churches, monasteries, cemeteries and even three hundred residents who did not want to leave their “small homeland” were under water. “They cut down the forest and the chips fly” - this was one of the fundamental principles of Stalin’s policy. In more humane times, during the construction of other reservoirs of the Volga Cascade, man-made seas were no longer allowed to overflow uncontrollably, leaving their coastline at the mercy of the relief. However, the only way to stop the water spill is embankment, that is, the construction of earthen dams along the established boundaries of the reservoir. In practice, this means that houses, roads or industrial facilities located near the dam are below the level of the reservoir and ensuring their safety becomes a separate problem. We are talking not only about maintaining dams in good technical condition, but also about protecting these hydraulic structures from, so to speak, the human factor. Currently, police patrols are being conducted along the dams of some reservoirs of the Volga Cascade and fences are being erected.
Dam and eternity
We must not forget about another problem associated with the emergence of reservoirs. Under the pressure of a huge mass, moisture seeps into the surrounding soil, raising the groundwater level. Sometimes this can be taken advantage of: for example, in areas where wells regularly dry up, damming a local river will help refill them. However, when it comes to macroscales, rising groundwater leads to waterlogging of vast areas and other unpleasant consequences. In particular, one of the arguments of environmentalists opposing the construction of the Evenki hydroelectric power station on the Nizhnyaya Tunguska River is the likely infiltration of water into the cavities left from underground nuclear explosions carried out in the area. In this case, there may be a danger of radioactive materials entering the Lower Tunguska and Yenisei. The creation of reservoirs can also lead to flooding of underground communications, basements of buildings and mines in the surrounding area. Of course, when designing waterworks, they try to calculate such side effects, but the effect of the water element cannot be 100% predictable.
Large hydraulic structures have one unique feature. Unlike a mine or quarry, they cannot be abandoned, left to the mercy of the forces of nature. Either the dam must be maintained in working order forever (which is practically hardly feasible), or after a certain period the hydraulic unit must be dismantled and the reservoir drained or turned into a closed reservoir. This is the only way to avoid the catastrophic consequences of natural destruction. By the way, this shows the common features of nuclear energy and hydropower. The cost of decommissioning a nuclear power plant is comparable to the cost of its construction. The same applies to hydroelectric power plants. Hydroelectric dams built in the USSR are designed to operate for a hundred years. On the one hand, a century is a long time, but on the other, some hydroelectric power plants, for example the Zhigulevskaya hydroelectric power station on the Volga, have already reached about half their lifespan, or even more. Thus, the question of what to do with spent hydraulic structures and how much their dismantling or major reconstruction will cost will arise before the living generations.
It is obvious that working with huge masses of water requires competent engineering solutions, technological discipline and responsibility. Fortunately, in Russia, a country where hydroelectric power stations make a huge contribution to the energy economy, we have both technology and highly qualified specialists capable of developing hydropower on the principles of efficiency, environmental friendliness and safety.
Articles on the topic
