Some time ago I was interested in this project. A grandiose structure. And then an informational occasion came up recently:
On July 5, 2012, the commissioning of the last power unit of the world's largest hydropower unit "Sanxia" / "Three Gorges" / was announced in China. Thus, the hydroelectric power station located in the middle reaches of the Yangtze River has reached full capacity.
For the first time, all 32 turbines of the station started operating simultaneously, their total capacity reaching 22.4 million kW. This event coincided with the beginning of the flood season, according to the local press.
The construction of the hydroelectric complex, in which almost $ 30 billion was invested, began in 1993. The implementation of a large-scale project required the resettlement of about 1.3 million rural residents from the region.
In 2006, the world's largest dam was completed, and two years later, 26 hydroelectric power units were commissioned on both banks of the giant reservoir. Then their number was increased by six more due to the installation of hydraulic units with a capacity of 700 thousand kW in the underground turbine hall.
Let's take a closer look and read about this creation of human hands.
The Three Gorges (Sanxia) hydroelectric power plant on the Yangtze River in China occupies a special place in the hydropower industry. There are a lot of "very-very" in it - the most powerful and expensive power plant in the world, the largest number of resettled population, the hottest debates around its construction.
Promotional video:
Standing in the way of the Yangtze River - the main water artery of the country, even the unfinished one, it confidently held the lead among the world's dams in terms of physical size, the amount of used building materials and money spent, and the hydroelectric power plant with it - in terms of the amount of electricity generated.
The Yangtze River is the largest waterway in China and one of the most powerful rivers in the world. A significant part of the river flows through mountainous regions, and given the fact that the source of the river is located in Tibet at an altitude of 5600 m, the huge hydropower potential of the river is obvious. One of the most attractive sections of the river for development is the "Three Gorges" region, where the river breaks through the Wushan mountains and out onto the plain. The combination of a narrow valley, large falls and significant river flows created the conditions for the construction of a huge hydroelectric power plant.
The idea of building a large hydroelectric power station in this place was put forward back in 1919 by the first president of China, Sun Yat Sen. In 1932, the Chiang Kai-shek government took up the preliminary work on the project, then the Japanese-Chinese war began and Japanese engineers became interested in the project. After the Japanese were expelled, the Americans worked on the alignment, after which the case was stalled due to the civil war. After the communist victory, Mao Zedong also supported the project, especially after the devastating 1954 flood that killed more than 30,000 people. Soviet engineers came to the aid of the Chinese, conducting surveys in the section and drawing up a scheme for using the river.
However, later in China, the well-known "cultural revolution" began, and the country's leadership was not up to the hydroelectric power station. In addition, relations with the USSR deteriorated, while Chairman Mao's relations with Western countries were always bad; the Chinese could not then build such a large-scale facility on their own. It was decided to start the development of the Yangtze with a smaller project, namely the Gezhouba HPP, a 3.15 GW run-of-river hydroelectric power plant downstream, which now acts as a counter-regulator for the Three Gorges. Its construction, which began in 1970, was completed by 1988, and the question arose of what to build next.
By this time, China could already afford the most ambitious projects, but the decision to build the largest and most expensive power plant in the world was not so easy. Various options were considered, in particular, the creation of three smaller ones instead of one grandiose dam, but the need to create a capacious reservoir capable of protecting the underlying lands from floods became a serious argument for the construction of one large dam. The decision on the construction was made by the supreme governing body of the country - the National People's Congress in 1992, out of 2633 delegates, 1767 people supported the project.
The construction of the hydroelectric power station began on December 14, 1994. The river was closed in 1997, the first hydroelectric unit was launched in 2003, and the construction of the dam was completed in 2006. What happened in the end?
For all its grandeur, the Three Gorges HPP is quite simple in constructive terms. This is a typical gravity concrete dam with a surface spillway; for example, the Krasnoyarsk HPP has a very similar structure. The height of the dam is 185 m, the length is 2.3 km, 27.2 million cubic meters of concrete have been laid in the dam and the building of the hydroelectric power station. The spillway is located in the center of the dam and is designed to pass 116,000 m3 / s of water (just think - more than 100,000 tons of water falls from a height of more than 100 meters per second!).
For such a large-scale construction, one building of the hydroelectric power station was not enough, and there are as many as three of them at the Three Gorges - the left-bank (14 hydraulic units), the right-bank (12 hydraulic units) and underground (6 hydraulic units). In total, the station has 32 (!) Hydraulic units with a capacity of 700 MW, not counting two “small” (50 MW each) hydraulic units for their own needs. Thus, the total capacity of the station after completion of construction will be 22.5 GW, and the average annual output will be about 100 billion kWh. At the moment (November 2011), work on the installation and adjustment of three hydroelectric units in the underground building of the hydroelectric power station has not yet been completed, respectively, the capacity of the station is 20.4 GW. For comparison, the second largest Brazilian hydroelectric power station Itaipu has a capacity of 14 GW.
Electricity from the hydroelectric power station is provided through the 500 kV power transmission network, both alternating and direct current. The hydroelectric power station should play the role of the center of the emerging unified energy system of China. When the construction of the station was just beginning, it was planned that the Three Gorges will provide 10% of China's electricity needs; however, energy consumption has grown at a rate that is now down to 2%.
During the construction of the hydroelectric power station, particular importance is given to ensuring navigation. River transport on the Yangtze is very well developed (the river does not freeze) and is of great importance. Usually, at such pressures, vessels are passed through ship lifts (for example, this is installed at the Krasnoyarsk HPP with a dam height of 121 m). There is also a ship lift on the Three Gorges (more precisely, it is being built), but it is designed to pass mainly passenger ships weighing up to 3,000 tons. Cargo ships are passed through unique two-line five-stage locks designed for vessels with a displacement of up to 10,000 tons. improved conditions for shipping, freight traffic increased 5-6 times.
The dam of the station created a large reservoir with a total capacity of 39 km3, of which the usable capacity is 22 km3. This capacity makes it possible to effectively use the reservoir of the hydroelectric power station for flood protection; According to calculations, the probability of severe floods after the commissioning of the dam has been reduced from 10% to 1% per year. In 2010, the dam passed the test of the strongest flood - with an inflow of 70,000 m3 / s (the maximum in 130 years!), Almost half as much was dumped down - 40,000 m3 / s, the rest was accumulated in the reservoir, the level of which increased by 3 m per day This saved many lives and prevented billions of dollars in damage.
In dry seasons, the water accumulated in the reservoir is discharged, which allows it to be used for irrigation.
However, for a large and capacious reservoir I had to pay (literally and figuratively) a large price. 1.24 million (!) People had to be relocated to new places of residence, including the population of two fairly large cities. There were 1,300 archaeological objects in the flooded zone (however, they were thoroughly investigated and partially brought out to non-flood marks). The preparation of the flood zone took about half of the total project costs, estimated at $ 22.5 billion. However, only due to the generation of electricity, these colossal costs will pay off 10 years after the completion of construction.
The Three Gorges is the largest, but by no means the last hydropower plant on the Yangtze. Upstream, a whole cascade of very solid stations is being built, which upon completion will become the largest in terms of capacity in the world. But this is already a topic for a separate conversation.
The Three Gorges are designed not only to generate "clean" electricity on a huge scale, but also to prevent large-scale floods in the Yangtze Basin.
At the same time, an increasing number of experts now admit that the construction of such a mega-complex, along with huge positive achievements, resulted in a number of negative side effects. It is believed that this object has disturbed the ecological balance in the region, provoking geological disasters, more frequent droughts and abnormal natural phenomena.
The Three Gorges Dam is a grandiose structure 2309 m long, 600 m wide and 185 m high. For comparison: the largest dam in the world until 2006 - the Grand Coulee in the United States is only 1592 m long, 503 m wide and 168 m high. And if the construction of the largest American dam required 9.16 million cubic meters of concrete, then the “Three Gorges” already took 28 million cubic meters.
The construction of the hydropower plant began in 1992 and is scheduled to be completed in 2010.
The composition of the HPP structures:
- gravity concrete dam 2309 m long and 185 m high;
- the left-bank dam building of the hydroelectric power station with 14 hydraulic units;
- the right-bank dam building of the hydroelectric power station with 12 hydraulic units;
- the right-bank underground building of the hydroelectric power station with 6 hydraulic units;
- a two-line five-stage navigable lock (mainly intended for cargo ships, the time of passage of locks is about 4 hours);
- ship lift (mainly designed for passenger ships, carrying capacity 3,000 tons, lifting time 30 min.)
The design capacity of the HPP is 22.4 GW, the average annual output for 2008 was 80.8 billion kWh. In the three buildings of the hydroelectric power station, 32 radial-axial hydraulic units with a capacity of 700 MW are to be placed, operating at a maximum head of 113 m. After the addition of an underground turbine hall, the amount of electricity generated per year will largely depend on the size of the flood on the Yangtze, which is intended for processing.
additional power generators.
Pressurized structures of the hydroelectric power station form a large reservoir, during the creation of which 27 820 hectares of cultivated land were flooded, approx. 1.2 million people. The cities of Wanxian and Wushan went under the water.
Downstream of the dam.
One of the reasons for the construction of a dam on the Yangtze - the largest river in China, was the constant floods, which resulted in truly catastrophic floods. Over the millennium, there have been 215 of them. The last one was quite recently - in 1998, in the midst of the implementation of the Three Gorges project. At that time, a temporary dam had already been built, diverting the Yangtze bed from the main construction site. However, she could not in any way interfere with the usual riot of nature. As a result, the 1998 Yangtze flood claimed the lives of 4,000 farmers who cultivated the land downstream of the river, and deprived 14 million of their homes. The country's total economic losses were then estimated at $ 24 million.
However, both supporters and opponents of the Three Gorges project use the sad consequences of the 1998 flood as an argument in favor of their position. Proponents say the flood victims are now a thing of the past, thanks to the dam's flood control. On the contrary, the opponents are convinced that the main tragedy is still ahead. The fact is that as a result of the construction of a dam in the area of the Quitang, Wuxia and Xiling gorges in the central province of Hubei, a reservoir of 1000 square kilometers and a depth of 175 meters was formed. Thus, 22 billion cubic meters of water are pressed against the dam. If - God forbid - a dam collapses, for example, as a result of an earthquake, then the consequences of this collapse cannot even be imagined,after all, 360 million people live on the banks of the Yangtze, and most of the agricultural land is located in its delta.
In addition to an earthquake, an overflood can also cause a dam to collapse, as a result of which water can overflow the edge of the dam and undermine the bottom at its base. History knows examples of such tragedies. So, in the middle of the 20th century in the state of Pennsylvania, USA, heavy rain caused a flood, as a result of which water simply overflowed over the edge of a concrete dam. Falling from a height of several tens of meters, the water hit the river bottom at the base of the dam with such force that its foundation floated, and it collapsed, clearing the way for the captive river Austina. The small town of Georgetown, which was located downstream, was washed off the face of the earth by a wall of water 18 meters high. More than 2,000 people are missing. In other words, the scale of the disaster was such that not even the bodies of the dead were found.
An erroneous assessment of the properties of the clay that was at the base of the structure caused the destruction of the Bezen Dam in the Vosges in France. Four settlements and 150 human lives are the result of the disaster. And the biggest disaster in post-war Europe also happened due to the collapse of the dam. The Molpasse dam in French Provence near the city of Frejuson in 1959 completely repeated the scenario of the Pennsylvania disaster, claiming more than a thousand human lives. And this despite the fact that the height of the Molpasse dam was only 65.5 meters, i.e. exactly three times below the Three Gorges Dam.
True, it was this tragedy that made engineers around the world reconsider the principles of installing the foundations of all future dams. Since then, the foundations of dams have been placed on concrete soles of various shapes, the purpose of which is to strengthen the bottom and spray the masses of falling water so that it, losing most of its destructive power, does not erode the soil.
The system of spraying the water mass is also on the Three Gorges dam, but this does not bring the long-awaited calm to the opponents of the megaproject. And all because the tragedies associated with the functioning of dams in history are the same sequence as the family portraits in the living room of Baskerville Hall. And each of them is theoretically ready to repeat itself in three gorges.
Another problem with dams of this magnitude is concrete and its properties. In theory, even a small crack in the body of a dam can lead to its complete destruction, and it is almost impossible to avoid these microcracks when you deal with so much concrete. The reason lies in the properties of this common building material.
HPP units.
Concrete is composed of cement, water and sand, which are heated to form a concrete mixture. At the same time, in natural conditions, concrete hardens from the outside to the inside, and when too much concrete cools down, it remains hot inside for a long time. As a result, it cools down and, accordingly, shrinks later than the outer shell, and thus the probability of deformation of the fill shape and the occurrence of cracks is very high. For example, it would take 125 years to naturally cool the amount of concrete required for the famous Hoover Dam on the Colorado River in the United States. To shorten this process to 22 months, American engineers walled up more than 950 km of steel concrete pipes into the body of the dam, through which they let water cooled in a specially built plant. Nevertheless,finally, the Hoover Dam continues to solidify to this day. And this is "only" 3.33 million cubic meters of concrete. Yes, yes, “only”, because the construction of the Three Gorges dam required 28 million cubic meters of this popular building material.
Despite almost eight times the amount of concrete, the Three Gorges Dam has abandoned its artificial cooling. Instead, the decision was made to fill the mixture in very small batches. But all the same, it was necessary to cover the flooded areas with ice and from time to time let artificial fog over the dam so that the sun did not slow down the solidification process. And, of course, it took more time: if the Hoover Dam was erected in five years, then the construction of the dam on the Yangtze River took all nine. In a word, the builders did everything so that the structure could, as the boxers say, “take a blow” of any force.
However, the strength of the dam's body is not an absolute guarantee of preventing water accidents. The story is so interesting because, with a strong desire, skeptics can find in it a lot of horror stories for an inexperienced layman. So, in 1967 in southwestern India there was an earthquake with an amplitude of 6.3 points on the Richter scale. As seismologists later concluded, it was caused by a reservoir formed in 1962 by the Coyne Dam to supply water to Bombay. According to scientists, the tremendous pressure of water on the ground brought the rocks underneath into tension, which led to their displacement five years later, causing an earthquake. The sad result of the tragedy is 2300 wounded and 177 dead.
The area of the three gorges has never been considered seismically active. However, in 2001, a magnitude 4 earthquake was recorded here. Despite the fact that there was no need to talk about any pressure of water on the soil and rocks at that moment - during the construction the river was bypassed, this gave the opponents of the project another reason to predict the irreversible. Whether the tremors were the result of the natural movement of the earth's crust (after all, the dam was built at the junction of three mountain gorges, where, in fact, its name comes from) or they were provoked by earthworks, remained unclear. But huge landslides along the banks of the reservoir formed later are an obvious and, therefore, indisputable fact, and in itself can lead to a disaster, as, for example, in the Italian Alps. On October 9, 1963, 240 million cubic meters of soil slid from the slope of Mount Tok in the reservoir of the Vayont Dam. A wave 100 meters high swept over the crest of a standing dam and washed away the village of Longarone and with it 2,500 people.
Garbage collection along the bed of the reservoir.
It is quite obvious that the banks of the rivers on which the dams are built are not designed to contain such volumes of water in their channel. This also applies to the Three Gorges: since the beginning of the construction of the dam, banks have collapsed in almost a hundred places with a total length of about forty kilometers. Even according to the head of the headquarters for the prevention of geological disasters, created during the Three Gorges campaign, these landslides cause waves several tens of meters high, which leads to further erosion of the banks.
However, the fight against this inevitable phenomenon during the construction of dams is being carried out seriously: by 2006, the government of China spent more than $ 1.5 billion on works to prevent landslides in the Three Gorges region. And in general, if we analyze the construction budget, which, depending on of the one who covers it ranges from $ 25 billion to $ 75 billion, it becomes clear that 2/3 of the maximum amount is planned for related construction costs. These include the fight against landslides, resettlement of people and the removal of historical objects from the flooded area, as well as various kinds of previously unforeseen phenomena. For example, for the construction of treatment facilities in cities, whose wastewater is no longer replenished by the flowing Yangtze stream, as before, but by a reservoir stretching 600 km upstream, and this is a completely different ecology.
So, by the time construction began, out of 40 cities located above the site designated for the dam, only two cities had facilities for treating their wastewater, and initially the builders of the dam did not have any projects or money to change this state of affairs. Today the situation has been corrected: hence the $ 75 billion, which the Three Gorges have been estimated at in recent years.
Another cost item that makes the Three Gorges Dam the most expensive dam in the world was the cost of resettling the 1.3 million people living in the flooded area. And it is possible that $ 75 billion is not yet the limit for the largest dam in the world. Only time will tell on the fight against what consequences of global interference in nature the authors of the Three Gorges project will have to spend. It is not yet clear whether the industrial enterprises and mines flooded along with the deserted settlements will make themselves felt. But the way of life of the peasants living downstream of the Yangtze has already changed.
The fact is that any agricultural economy located in river deltas, as a rule, is fertilized in the most natural way (no, not the one you thought about). The microenvironment formed in the stream of the river and consisting of natural ingredients - animal, bird and fish droppings, dead leaves and plants, animal and fish remains and much more - is the best cocktail made by nature itself to fertilize agricultural lands. The dam restrains this stream, which as a result turns to silt underwater at the base of the dam. Instead, the peasants now have to buy fertilizers on the side.
The design of the dam provides for the discharge of silt sediment, but most of it will still accumulate on the other side of the dam. Not only did the peasants lose the natural fertilizer of their land because of this, the still accumulating silt sediment can over time complicate the operation of the hydroelectric power plant.
However, the authors of the Three Gorges project are convinced that the silt discharge system, albeit partial, guarantees uninterrupted operation (without siltation of water drains and sluices) of the dam for 100 years in advance. Nevertheless, it is possible that the development of systems for raising silt from the bottom of the reservoir and the construction of a plant for processing it into natural fertilizers are not far off. And since so far no one has heard about the technology of lifting heavy and viscous silt from the bottom of the rivers, the final potential cost of the Three Gorges project increases by an indefinite, but very significant amount.
Be that as it may, supporters of the project continue to consider it beneficial: do not forget that the Three Gorges Dam was built not only in order to save the inhabitants of the lower Yangtze from devastating floods, but also in order to ensure the developing the country's industry with electricity.
Economists were wrong with their forecasts. During construction - from 1992 to 2010 - the financial effect of the dam has slightly decreased. So in 1993, the capacity of the hydroelectric power station was sufficient to meet the all-Chinese demand for electricity by 10%. However, during this time such an industrial breakthrough has taken place in the country that today the design capacity of the Three Gorges HPP is enough to generate only 3% of all electricity consumed by the country.
Upon completion, the project will cost RMB 180 billion, which is more than RMB 20 billion less than originally planned spending of RMB 203.9 billion (less than USD 30 billion). According to China's National Development and Reform Commission, it takes 366 grams of coal to generate 1 kWh of electricity in China. Therefore, the Three Gorges Dam (Sanxia) will potentially reduce coal consumption by 31 million tons annually, while also reducing atmospheric emissions by 100 million tons of greenhouse gas, millions of tons of dust, sulfur dioxide, nitric oxide, carbon monoxide and mercury.
Over the past millennium, 215 catastrophic floods have occurred on the Yangtze River. The 1998 flood caused 4,000 deaths, 14 million people lost their homes, and economic losses totaled $ 24 million. After the construction of the dam, there will be no more floods.
During the construction of the Three Gorges, 13 cities, 140 settlements and 1300 villages were flooded. 1.3 million people fled their homes, 1,300 archaeological sites in China were destroyed, disappearing forever under water.
About 265 gallons of waste and sewage is dumped into the Yangtze every year. Previously, the river carried all emissions into the ocean, now they will settle and filter, thanks to the Three Gorges Dam project.
Several thousand factories and abandoned mines were flooded after the completion of the dam. Environmentalists warn that this could have serious consequences due to the release of waste into the water.
360 million people live on both banks of the Yangtze River downstream of the river. If a disaster strikes, then all these people will be under serious threat.
