Yunyang County ( simplified Chinese : 云阳县 ; traditional Chinese : 雲陽縣 ; pinyin : Yúnyáng Xiàn ) is a county in the northeast of Chongqing Municipality , China, bordering Hubei province to the south.
98-533: In eastern Chongqing is Yunyang County with over 1,400 years of history and a reputation as the 'Bright Pearl of Chongqing'. The county abounds with natural resources, beautiful landscapes and historical relics. The culture of Ba (the ancient name of Chongqing), salt culture and the culture of the Migrants from Three Gorges area can be learned in this area. The scenery here is rich. Mountain, river, valley, cave and ancient architecture can be seen here. Zhang Fei Temple, which
196-458: A Francis turbine . Johann Segner developed a reactive water turbine ( Segner wheel ) in the mid-18th century in Kingdom of Hungary . It had a horizontal axis and was a precursor to modern water turbines. It is a very simple machine that is still produced today for use in small hydro sites. Segner worked with Euler on some of the early mathematical theories of turbine design. In the 18th century,
294-518: A pump to fill a high reservoir during off-peak electrical hours, and then revert to a water turbine for power generation during peak electrical demand. This type of turbine is usually a Deriaz or Francis turbine in design. This type of system is used in El Hierro, one of the Canary Islands: "When wind production exceeds demand, excess energy will pump water from a lower reservoir at the bottom of
392-467: A Dr. Robert Barker invented a similar reaction hydraulic turbine that became popular as a lecture-hall demonstration. The only known surviving example of this type of engine used in power production, dating from 1851, is found at Hacienda Buena Vista in Ponce, Puerto Rico . In 1820, Jean-Victor Poncelet developed an inward-flow turbine. In 1826, Benoît Fourneyron developed an outward-flow turbine. This
490-449: A Knight Wheel, developed a Pelton wheel (double bucket design), which exhausted the water to the side, eliminating some energy loss of the Knight wheel which exhausted some water back against the center of the wheel. In about 1895, William Doble improved on Pelton's half-cylindrical bucket form with an elliptical bucket that included a cut in it to allow the jet a cleaner bucket entry. This is
588-628: A capacity of 700 MW, and two plant power generators, each with capacity of 50 MW, for a total of 22,500 MW. Among the 32 main generators, 14 are installed on the dam's north side, 12 on the south side, and the remaining six in the underground power plant in the mountain south of the dam. Annual electricity generation in 2018 was 101.6 TWh, which is 20 times more than the Hoover Dam . The main generators each weigh approximately 6,000 tonnes and are designed to produce more than 700 MW of power each. The designed hydraulic head of
686-742: A dam capable of generating 30 million horsepower (22 GW) was possible downstream of the Three Gorges . In 1932, the Nationalist government , led by Chiang Kai-shek , began preliminary work on plans in the Three Gorges. In 1939, during the Second Sino-Japanese War , Japanese military forces occupied Yichang and surveyed the area. In 1944, the United States Bureau of Reclamation 's head design engineer, John L. Savage , surveyed
784-556: A factor of 2. Along with corrosion resistance and strength, weld-ability and density are important criteria for turbine blade material selection. Greater weld-ability allows for easier and high quality repairs. Low density allows higher efficiency through easier rotation. The most common material used in Kaplan Turbine blades are stainless steel alloys (SS). The martensitic stainless steel alloys have high strength that allow thinner sections than standard carbon steel; reduced mass enhances
882-490: A flat rate of ¥250 per MWh (US$ 35.7) until July 2, 2008. Since then, the price has varied by province, from ¥228.7 to ¥401.8 per MWh. Higher-paying customers, such as Shanghai , receive priority. Nine provinces and two cities consume power from the dam. Power distribution and transmission infrastructure cost about 34.387 billion yuan. Construction was completed in December 2007, one year ahead of schedule. Power
980-427: A flood in the same area caused billions of dollars worth of damage, when 2,039 km (787 sq mi) of farmland were flooded. The flood affected more than 2.3 million people, killing 1,526. In early August 2009, the largest flood in five years passed through the dam site. During this flood, the dam limited the water flow to less than 40,000 m /s (1.4 million cu ft/s) per second, raising
1078-406: A force on the blades. Since the runner is spinning, the force acts through a distance (force acting through a distance is the definition of work ). In this way, energy is transferred from the water flow to the turbine. Water turbines are divided into two groups: reaction turbines and impulse turbines. The precise shape of water turbine blades is a function of the supply pressure of water, and
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#17328481041551176-431: A kind of elevator for vessels. The ship lift can lift ships of up to 3,000 tons. The vertical distance traveled is 113 m (371 ft), and the size of the ship lift's basin is 120 m × 18 m × 3.5 m (394 ft × 59 ft × 11 ft). The ship lift takes 30 to 40 minutes to transit, as opposed to the three to four hours for stepping through the locks. One complicating factor
1274-590: A new era of American turbine engineering. Water turbines, particularly in the Americas, would largely become standardized with the establishment of the Holyoke Testing Flume , described as the first modern hydraulic laboratory in the United States by Robert E. Horton and Clemens Herschel , the latter of which would serve as its chief engineer for a time. Initially created in 1872 by James B. Emerson from
1372-460: A spring acted directly to the valve of the turbine or the wicket gate to control the amount of water that enters the turbines. Newer systems with mechanical governors started around 1880. An early mechanical governor is a servomechanism that comprises a series of gears that use the turbine's speed to drive the flyball and turbine's power to drive the control mechanism. The mechanical governors were continued to be enhanced in power amplification through
1470-477: A total of 198 million tonnes of freight passed through the locks. The freight capacity of the river increased six times and the cost of shipping was reduced by 25%. Originally, the total capacity of the ship locks was expected to reach 100 million tonnes per year. In 2022, their cargo turnover reached 159.65 million tons, with an annual increase of 6% over the past few years. These locks are staircase locks , whereby inner lock gate pairs serve as both
1568-406: A turbine characterizes the turbine's shape in a way that is not related to its size. This allows a new turbine design to be scaled from an existing design of known performance. The specific speed is also the main criteria for matching a specific hydro site with the correct turbine type. The specific speed is the speed with which the turbine turns for a particular discharge Q, with unit head and thereby
1666-478: A volcanic cone to an upper reservoir at the top of the volcano 700 meters above sea level. The lower reservoir stores 150,000 cubic meters of water. The stored water acts as a battery. The maximum storage capacity is 270 MWh. When demand rises and there is not enough wind power, the water will be released to four hydroelectric turbines with a total capacity of 11 MW." Large modern water turbines operate at mechanical efficiencies greater than 90%. Turbine selection
1764-470: Is 181 m (594 ft) high above the rock basis. When the water level is at its maximum of 175 m (574 ft) above sea level, 110 m (361 ft) higher than the river level downstream, the dam reservoir is on average about 660 km (410 mi) in length and 1.12 km (3,675 ft) in width. It contains 39.3 km (31,900,000 acre⋅ft ) of water and has a total surface area of 1,045 km (403 sq mi). On completion,
1862-579: Is a swirl component of the water which passes energy to a spinning rotor. This additional component of motion allowed the turbine to be smaller than a water wheel of the same power. They could process more water by spinning faster and could harness much greater heads. (Later, impulse turbines were developed which didn't use swirl.) The earliest known water turbines date to the Roman Empire . Two helix-turbine mill sites of almost identical design were found at Chemtou and Testour , modern-day Tunisia , dating to
1960-407: Is able to produce unit power. Affinity laws allow the output of a turbine to be predicted based on model tests. A miniature replica of a proposed design, about one foot (0.3 m) in diameter, can be tested and the laboratory measurements applied to the final application with high confidence. Affinity laws are derived by requiring similitude between the test model and the application. Flow through
2058-549: Is an accepted version of this page The Three Gorges Dam ( simplified Chinese : 三峡大坝 ; traditional Chinese : 三峽大壩 ; pinyin : Sānxiá Dàbà ) is a hydroelectric gravity dam that spans the Yangtze River near Sandouping in Yiling District , Yichang , Hubei province, central China, downstream of the Three Gorges . The world's largest power station in terms of installed capacity (22,500 MW ),
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#17328481041552156-618: Is based on the available water head , and less so on the available flow rate. In general, impulse turbines are used for high head sites, and reaction turbines are used for low head sites. Kaplan turbines with adjustable blade pitch are well-adapted to wide ranges of flow or head conditions, since their peak efficiency can be achieved over a wide range of flows. Small turbines (mostly under 10 MW) may have horizontal shafts, and even fairly large bulb-type turbines up to 100 MW or so may be horizontal. Very large Francis and Kaplan machines usually have vertical shafts because this makes best use of
2254-529: Is distributed over multiple 500 kV transmission lines. Three direct current (DC) lines to the East China Grid carry 7,200 MW: Three Gorges – Shanghai (3,000 MW), HVDC Three Gorges – Changzhou (3,000 MW), and HVDC Gezhouba – Shanghai (1,200 MW). The alternating current (AC) lines to the Central China Grid have a total capacity of 12,000 MW. The DC transmission line HVDC Three Gorges – Guangdong to
2352-448: Is enough flow, power output is limited by plant generating capacity. The maximum power-output curves were calculated based on the average flow rate at the dam site, assuming the water level is 175 m and the plant gross efficiency is 90.15%. The actual power output in 2008 was obtained based on the monthly electricity sent to the grid. The Three Gorges Dam reached its design-maximum reservoir water level of 175 m (574 ft) for
2450-596: Is home to 6,388 plant species, which belong to 238 families and 1,508 genera. Of these species, 57 are endangered. These rare species are also used as ingredients in traditional Chinese medicines. The proportion of forested area in the region surrounding the Three Gorges Dam dropped from 20% in 1950 to less than 10% as of 2002, adversely affecting all plant species there. The region also provides habitats to hundreds of freshwater and terrestrial animal species. Freshwater fish are especially affected by dams due to changes in
2548-422: Is largely used in dam and large power plants. Impulse turbines change the velocity of a water jet. The jet pushes on the turbine's curved blades which changes the direction of the flow. The resulting change in momentum ( impulse ) causes a force on the turbine blades. Since the turbine is spinning, the force acts through a distance (work) and the diverted water flow is left with diminished energy. An impulse turbine
2646-503: Is made up of five stages, with transit time at around four hours. Maximum vessel size is 10,000 tons. The locks are 280 m long, 35 m wide, and 5 m deep (918 × 114 × 16.4 ft). That is 30 m (98 ft) longer than those on the St Lawrence Seaway , but half as deep. Before the dam was constructed, the maximum freight capacity at the Three Gorges site was 18.0 million tonnes per year. From 2004 to 2007,
2744-452: Is one in which the pressure of the fluid flowing over the rotor blades is constant and all the work output is due to the change in kinetic energy of the fluid. Prior to hitting the turbine blades, the water's pressure ( potential energy ) is converted to kinetic energy by a nozzle and focused on the turbine. No pressure change occurs at the turbine blades, and the turbine doesn't require a housing for operation. Newton's second law describes
2842-517: Is opposite the New Town of Yunyang. After years of construction, Yunyang has developed quickly and now has over 150 thousand local residences. The museum presenting the culture of the Migrants from the Three Gorges area has been built. Now, it has become a city with a good environment, well-developed communication and rich tourism resources. In 314 BC, Juren County (朐忍县) was established in Qin state . In 568 AD,
2940-652: Is regarded as a wonderful historic relic of the Yangtze River area is a must. It was built in memory of Zhang Fei, a general of the Three Kingdoms period (220–280). The temple, with over 1,700 years' of history is visited by numerous tourists from home and abroad every year. It has been a hotspot for Yangtze River Cruises. Because of the Three Gorges Dam Project , territories of Yunyang County have been submerged. The whole county and its local people have moved to
3038-462: Is that the water level can vary dramatically. The ship lift must work even if water levels vary by 12 m (39 ft) on the lower side, and 30 m (98 ft) on the upper side. The ship lift's design uses a helical gear system, to climb or descend a toothed rack. Water turbine A water turbine is a rotary machine that converts kinetic energy and potential energy of water into mechanical work. Water turbines were developed in
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3136-431: Is the first modern water turbine. It is still the most widely used water turbine in the world today. The Francis turbine is also called a radial flow turbine, since water flows from the outer circumference towards the centre of runner. Inward flow water turbines have a better mechanical arrangement and all modern reaction water turbines are of this design. As the water swirls inward, it accelerates, and transfers energy to
3234-712: The Great Leap Forward and the Cultural Revolution slowed progress. After the 1954 Yangtze River Floods , in 1956, Mao wrote " Swimming ", a poem about his fascination with a dam on the Yangtze River. In 1958, after the Hundred Flowers Campaign , some engineers who spoke out against the project were imprisoned. During China's emphasis on the Four Modernizations during its early period of Reform and Opening Up , The Communist Party revived plans for
3332-568: The Industrial Revolution , using scientific principles and methods. They also made extensive use of new materials and manufacturing methods developed at the time. The word turbine was introduced by the French engineer Claude Burdin in the early 19th century and is derived from the Greek word "τύρβη" for "whirling" or a " vortex ". The main difference between early water turbines and water wheels
3430-542: The Jingguang Railway was out of service for more than 100 days. The 1954 flood carried 50 cubic kilometres (12 cu mi) of water. The dam could only divert the water above Chenglingji, leaving 30 to 40 km (7.2 to 9.6 cu mi) to be diverted. The dam cannot protect against some of the large tributaries downstream, including the Xiang , Zishui , Yuanshui , Lishui , Hanshui , and Gan . In 1998,
3528-468: The Ministry of Environmental Protection , as of April 2007, more than 50 new plants could treat 1.84 million tonnes per day, 65% of the total need. About 32 landfills were added, which could handle 7,664.5 tonnes of solid waste every day. Over one billion tons of wastewater are released annually into the river, which was more likely to be swept away before the reservoir was created. This has left
3626-469: The National Development and Reform Commission , 366 grams of coal would produce 1 kWh of electricity during 2006. From 2003 to 2007, power production equaled that of 84 million tonnes of standard coal. Two hazards are uniquely identified with the dam: that sedimentation projections are not agreed upon, and that the dam sits on a seismic fault . At current levels, 80% of the land in
3724-531: The 1990s. This is largely due to China's large reforestation effort . This accelerated after the 1998 Yangtze River floods convinced the government that it should restore tree cover, especially in the Yangtze's basin upstream of the Three Gorges Dam. Concerns about the dam's impact on wildlife predate the National People's Congress's approval in 1992. This region has long been known for its rich biodiversity. It
3822-523: The 19th century and were widely used for industrial power prior to electrical grids . Now, they are mostly used for electric power generation. Water turbines are mostly found in dams to generate electric power from water potential energy. Water wheels have been used for hundreds of years for industrial power. Their main shortcoming is size, which limits the flow rate and head that can be harnessed. The migration from water wheels to modern turbines took about one hundred years. Development occurred during
3920-556: The South China Grid has a capacity of 3,000 MW. The dam was expected to provide 10% of China's power. However, electricity demand has increased more quickly than previously projected. Even fully operational and despite its size, on average, it supported only about 1.7% of electricity demand in China in the year of 2011, when the Chinese electricity demand reached 4,692.8 TWh. According to
4018-595: The Three Gorges Dam Construction Fund, profits from the Gezhouba Dam , loans from the China Development Bank , loans from domestic and foreign commercial banks, corporate bonds , and revenue from both before and after the dam had become fully operational. Additional charges were assessed as follows: every province receiving power from the Three Gorges Dam had to pay an extra ¥7.00 per MWh, and
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4116-550: The Three Gorges Dam directly caused the extinction of the baiji. Of the 3,000 to 4,000 remaining critically endangered Siberian crane , many spend the winter in wetlands that the Three Gorges Dam will destroy. Populations of the Yangtze sturgeon are guaranteed to be "negatively affected" by the dam. In 2022 the Chinese paddlefish was declared extinct, with the last confirmed sighting in 2003. In 2005, NASA scientists calculated that
4214-442: The Three Gorges Dam generates 95±20 TWh of electricity per year on average, depending on the amount of precipitation in the river basin. After the extensive monsoon rainfalls of 2020, the dam's annual production reached nearly 112 TWh, breaking the previous world record of ~103 TWh set by Itaipu Dam in 2016. The dam's body was completed in 2006; the power plant was completed and fully operational by 2012, when
4312-575: The United States. The design effectively combined the inward flow principles of the Francis design with the downward discharge of the Jonval turbine , with flow inward at the inlet, axial through the wheel's body, and slightly outward at the outlet. Initially performing optimally at 90% efficiency at lower speeds, this design would see many improvements in the subsequent decades in derivatives under names like "Victor", "Risdon", "Samson" and "New American," ushering in
4410-466: The area and drew up a dam proposal for a "Yangtze River Project". Some 54 Chinese engineers went to the US for training. The original plans called for the dam to employ a unique method for moving ships: the ships would enter locks at the dam's lower and upper ends and then cranes would move them from each lock to the next. Groups of craft would be lifted together for efficiency. It is not known whether this solution
4508-433: The area is eroding, depositing about 40 million tons of sediment into the Yangtze annually. Because the flow is slower above the dam, much of this sediment settles there instead of flowing downstream, and there is less sediment downstream. The absence of silt downstream has three effects: Erosion in the reservoir, induced by rising water, causes frequent major landslides that have led to noticeable disturbance in
4606-823: The available head, and makes installation of a generator more economical. Pelton wheels may be either vertical or horizontal shaft machines because the size of the machine is so much less than the available head. Some impulse turbines use multiple jets per runner to balance shaft thrust. This also allows for the use of a smaller turbine runner, which can decrease costs and mechanical losses. • Water wheel • Screw turbine • VLH turbine • Kaplan turbine • Francis turbine • Pelton wheel • Turgo turbine 0.2 < H < 4 ( H = head in m) 1 < H < 10 1.5 < H < 4.5 2 < H < 70 10 < H < 300 80 < H < 1600 50 < H < 250 The specific speed n s {\displaystyle n_{s}} of
4704-407: The controls were still done through analog systems. In the modern systems, also known as third-generation governors, the controls are performed digitally by algorithms that are programmed to the computer of the governor. A wicket gate , or guide vane , is a ring of gates (or vanes) surrounding a water turbine which control the flow of water entering it; varying the aperture between them manages
4802-845: The county has 138 schools. In 2005 there were 482 schools. In a ten-year period the number of students in the county declined by 42,000. As of 2015 there are seven schools in Jianquan Township ( 建全乡 ). Sixin Village School and one other school both have one student each; the teacher at Sixin Village ( 四新村 ) School that year was Xiang Guozheng ( 向国正 ). Around 2007 Sixin Village school had over 100 students, and its smallest class had 9 students. Students are required to attend larger schools beginning in grade 5. 30°58′25″N 108°41′53″E / 30.9736°N 108.698°E / 30.9736; 108.698 Three Gorges Dam Project This
4900-511: The county seat was moved to the site of modern Yunyang Town, and the county was renamed Yun'an (云安县). In 1283, the county was replaced by Yunyang Prefecture (云阳州). In 1373, the prefecture was downgraded to a county. In 1999, the county seat was moved from the now-submerged Yunyang Town to Shuangjiang Town (双江镇). Hong Shan Chuan Industry Ltd. Yunyang has one Yangtze River crossing , the Yunyang Yangtze River Bridge . As of 2015
4998-560: The course of the dry season. During the South China floods in July 2010 , inflows at the Three Gorges Dam reached a peak of 70,000 m /s (2.5 million cu ft/s), exceeding the peak inflow during the 1998 Yangtze River floods . The dam's reservoir rose nearly 3 m (9.8 ft) in 24 hours and reduced the outflow to 40,000 m /s (1.4 million cu ft/s) in discharges downstream, preventing any significant impact on
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#17328481041555096-466: The dam and proposed to start construction in 1986. It emphasized the need to develop hydroelectric power. The Chinese People's Political Consultative Conference became a center of opposition to the proposed dam. It convened panels of experts who recommended delaying the project. The National People's Congress approved the dam in 1992: of 2,633 delegates, 1,767 voted in favour, 177 voted against, 664 abstained, and 25 members did not vote, giving
5194-422: The dam generated an average of 97.22 TWh of electricity per year, higher than Itaipu dam's average of 89.22 TWh of electricity per year during the same period. Due to the extensive 2020 monsoon season rainfall, the annual production reached ~112 TWh that year, which broke the previous world record of annual production by Itaipu Dam equal to ~103 TWh. The State Grid Corporation and China Southern Power Grid paid
5292-484: The dam is to control flooding, which is a major problem for the seasonal river of the Yangtze. Millions of people live downstream of the dam, with many large, important cities like Wuhan , Nanjing , and Shanghai located adjacent to the river. Large areas of farmland and China's most important industrial area are situated beside the river. The reservoir's flood storage capacity is 22 km (5.3 cu mi ; 18 million acre⋅ft ). This capacity will reduce
5390-512: The designed maximum level of 175 m (574 ft) by 2010. Made of concrete and steel, the dam is 2,335 m (2,554 yd; 1.451 mi) long and 185 m (607 ft) above sea level at its top. The project used 27.2 million m (35.6 million cu yd) of concrete (mainly for the dam wall), used 463,000 tonnes of steel (enough to build 63 Eiffel Towers ), and moved about 102.6 million m (134.2 million cu yd) of earth. The concrete dam wall
5488-439: The film which improves aqueous corrosion resistance. The chromium content in these steel alloys exceed the minimum of 12% chromium required to exhibit some atmospheric corrosion resistance. Having a higher chromium concentration in the steel alloys allows for a much longer lifespan of the turbine blades. Currently, the blades are made of martensitic stainless steels which have high strength compared to austenitic stainless steels by
5586-445: The first time on October 26, 2010, in which the intended annual power-generation capacity of 84.7 TWh was realized. It has a combined generating capacity of 22.5 gigawatts and a designed annual generation capacity of 88.2 TWh. In 2012, the dam's 32 generating units generated a record 98.1 TWh of electricity, which accounts for 14% of China's total hydro generation. Between 2012 (first year with all 32 generating units operating) and 2021,
5684-420: The frequency of major downstream flooding from once every 10 years to once every 100 years. The dam is expected to minimize the effect of even a "super" flood. The river flooded in 1954 over an area of 193,000 km (74,500 sq mi), killing 33,169 people and forcing almost 18.9 million people to move. The flood waters covered Wuhan, a city of eight million people, for over three months, and
5782-402: The generator rotors have 80 poles. Rated power is 778 MVA , with a maximum of 840 MVA and a power factor of 0.9. The generator produces electrical power at 20 kV . The electricity generated is then stepped up to 500 kV for transmission at 50 Hz. The generator's stator , the biggest of its kind, is 3.1/3 m in height; the outer diameter of the stator is 21.4/20.9 m,
5880-454: The generators is 80.6 metres (264 ft). The flow rate varies between 600–950 cubic metres per second (21,000–34,000 cu ft/s) depending on the head available; the greater the head, the less water needed to reach full power. Three Gorges uses Francis turbines with a diameter of 9.7/10.4 m (VGS design/Alstom's design) and a rotation speed of 75 revolutions per minute. This means that in order to generate power at 50 Hz ,
5978-446: The gold fields, Knight developed a bucketed wheel which captured the energy of a free jet, which had converted a high head (hundreds of vertical feet in a pipe or penstock ) of water to kinetic energy. This is called an impulse or tangential turbine. The water's velocity, roughly twice the velocity of the bucket periphery, does a U-turn in the bucket and drops out of the runner at low velocity. In 1879, Lester Pelton , experimenting with
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#17328481041556076-470: The hydrodynamic flow conditions and efficiency of the water turbine. The SS(13Cr-4Ni) has been shown to have improved erosion resistance at all angles of attack through the process of laser peening . It is important to minimize erosion in order to maintain high efficiencies because erosion negatively impacts the hydraulic profile of the blades which reduces the relative ease of rotation. Turbines are designed to run for decades with very little maintenance of
6174-473: The inner diameter is 18.5/18.8 m, and the bearing load is 5,050/5,500 tonnes. Average efficiency is over 94%, with a maximum efficiency of 96.5% reached. The generators were manufactured by two joint ventures: Alstom , ABB , Kvaerner , and the Chinese company Harbin Motor; and Voith , General Electric , Siemens (abbreviated as VGS), and the Chinese company Oriental Motor. The technology transfer agreement
6272-472: The last main generator (No. 27) finished its final test on May 23, 2012, the six underground main generators were all operational, raising the capacity to 22.5 GW. After nine years of construction, installation and testing, the power plant was fully operational by July 2012. By August 16, 2011, the plant had generated 500 TWh of electricity. In July 2008 it generated 10.3 TWh of electricity, its first month over 10 TWh. On June 30, 2009, after
6370-401: The last of the main water turbines in the underground plant began production. Each of the main water turbines has a capacity of 700 MW. Combining the capacity of the dam's 32 main turbines with the two smaller generators (50 MW each) that provide power to the plant itself, the total electric generating capacity of the Three Gorges Dam is 22,500 MW. The last major component of
6468-404: The late 19th century (including water wheels ) were basically reaction machines; water pressure head acted on the machine and produced work. A reaction turbine needs to fully contain the water during energy transfer. In 1866, California millwright Samuel Knight invented a machine that took the impulse system to a new level. Inspired by the high pressure jet systems used in hydraulic mining in
6566-422: The late 3rd or early 4th century AD. The horizontal water wheel with angled blades was installed at the bottom of a water-filled, circular shaft. The water from the mill race entered the pit tangentially, creating a swirling water column which made the fully submerged wheel act like a true turbine. Fausto Veranzio in his book Machinae Novae (1595) described a vertical axis mill with a rotor similar to that of
6664-435: The legislation an unusually low 67.75% approval rate. Construction started on December 14, 1994. The dam was expected to be fully operational in 2009, but additional projects, such as the underground power plant with six additional generators, delayed full operation until 2012. The ship lift was completed in 2015. The dam raised the water level in the reservoir to 172.5 m (566 ft) above sea level by 2008 and to
6762-528: The main elements; overhaul intervals are on the order of several years. Maintenance of the runners and parts exposed to water include removal, inspection, and repair of worn parts. Normal wear and tear includes pitting corrosion from cavitation , fatigue cracking , and abrasion from suspended solids in the water. Steel elements are repaired by welding, usually with stainless steel rods. Damaged areas are cut or ground out, then welded back up to their original or an improved profile. Old turbine runners may have
6860-407: The mechanical forces of this speed. The manufacturer will supply the runaway speed rating. Different designs of governors have been used since the mid-18th century to control the speeds of the water turbines. A variety of flyball systems, or first-generation governors, were used during the first 100 years of water turbine speed controls. In early flyball systems, the flyball component countered by
6958-503: The middle and lower river. The installation of ship locks is intended to increase river shipping from ten million to 100 million tonnes annually; as a result transportation costs will be cut between 30 and 37%. Shipping will become safer, since the gorges are notoriously dangerous to navigate. There are two series of ship locks installed near the dam ( 30°50′12″N 111°1′10″E / 30.83667°N 111.01944°E / 30.83667; 111.01944 ). Each of them
7056-477: The modern fluid bearing was invented, now universally used to support heavy water turbine spindles. As of 2002, fluid bearings appear to have a mean time between failures of more than 1300 years. Around 1913, Viktor Kaplan created the Kaplan turbine , a propeller-type machine. It was an evolution of the Francis turbine and revolutionized the ability to develop low-head hydro sites. All common water machines until
7154-449: The modern form of the Pelton turbine which today achieves up to 92% efficiency. Pelton had been quite an effective promoter of his design and although Doble took over the Pelton company he did not change the name to Doble because it had brand name recognition. Turgo and cross-flow turbines were later impulse designs. Flowing water is directed on to the blades of a turbine runner, creating
7252-496: The new county of Yunyang. Located at Shuangjiang Town on the northern bank of the Yangtze River, the new county is 162 miles from the Three Gorges Dam and 223 miles from Chongqing City. It is the county that has moved the longest distance among the migrating counties and cities during the Three Gorges Project. Together with the people, Zhang Fei Temple, which is the hot scenic spot here has also been moved to Panshi Town which
7350-499: The other provinces had to pay an additional charge of ¥4.00 per MWh. No surcharge was imposed on the Tibet Autonomous Region . Power generation is managed by China Yangtze Power , a listed subsidiary of China Three Gorges Corporation (CTGC), a Central Enterprise administered by SASAC . The Three Gorges Dam is the world's largest capacity hydroelectric power station, with 34 generators: 32 main generators, each with
7448-532: The project as a monumental social and economical success, with the design of state-of-the-art large turbines and a move toward limiting greenhouse gas emissions . However, the dam has led to some ecological changes, including an increased risk of landslides, which have made it controversial domestically and abroad. Sun Yat-sen envisioned a large dam across the Yangtze River in The International Development of China (1919). He wrote that
7546-464: The project, the ship lift, was completed in 2015. In addition to generating electricity, the dam was designed to increase the Yangtze River's shipping capacity. By providing flood storage space, the dam reduces the potential for flooding downstream, which historically plagued the Yangtze Plain . In 1931, floods on the river caused the deaths of up to 4 million people. As a result, China regards
7644-411: The rate of the turbine's spin, and thereby the amount of electricity generated. Given that the turbine blades in a water turbine are constantly exposed to water and dynamic forces, they need to have high corrosion resistance and strength. The most common material used in overlays on carbon steel runners in water turbines are austenitic steel alloys that have 17% to 20% chromium to increase stability of
7742-579: The reservoir flooded a total area of 632 km (156,000 acres) of land, compared to the 1,350 km (330,000 acres) of reservoir created by the Itaipu Dam . The Chinese government estimated that the Three Gorges Dam project would cost 180 billion yuan (US$ 22.5 billion). By the end of 2008, spending had reached 148.365 billion yuan, of which 64.613 billion yuan was spent on construction, 68.557 billion yuan on relocating affected residents, and 15.195 billion yuan on financing. It
7840-503: The reservoir surface, including two incidents in May 2009 when somewhere between 20,000 and 50,000 cubic metres (26,000 and 65,000 cu yd) of material plunged into the flooded Wuxia Gorge of the Wu River . In the first four months of 2010, there were 97 significant landslides. The dam catalyzed improved upstream wastewater treatment around Chongqing and its suburban areas. According to
7938-458: The river downstream, providing fresh water for agricultural and industrial usage, and improving shipping conditions. The water level upstream drops from 175 to 145 m (574 to 476 ft), in preparation for the rainy season. The water also powers the Gezhouba Dam downstream. Since the filling of the reservoir in 2003, the Three Gorges Dam has supplied an extra 11 km (2.6 cu mi) of fresh water to downstream cities and farms over
8036-470: The river flow rate increased to over 24,000 m /s, all 28 generators were switched on, producing only 16,100 MW because the head available during flood season is insufficient. During an August 2009 flood, the plant first reached its maximum output for a short period. During the November to May dry season, power output is limited by the river's flow rate, as seen in the diagrams on the right. When there
8134-589: The runner. Water pressure decreases to atmospheric, or in some cases subatmospheric, as the water passes through the turbine blades and loses energy. In 1876, John B. McCormick , building on Francis's designs, demonstrated the first modern mixed-flow turbine with the development of the Hercules turbine, initially manufactured by the Holyoke Machine Company and subsequently improved upon by engineers in Germany and
8232-527: The shift of water mass stored by the dams would increase the total length of the Earth 's day by 0.06 microseconds and make the Earth slightly more round in the middle and flat on the poles . A study published in 2022 in the journal Open Geosciences suggests that the change of reservoir water level affects the gravity field in western Sichuan, which in turn affects the seismicity in that area. An important function of
8330-652: The testing flumes of Lowell , after 1880 the Holyoke, Massachusetts hydraulic laboratory was standardized by Herschel, who used it to develop the Venturi meter , the first accurate means of measuring large flows, to properly measure water power efficiency by different turbine models. While skepticism of certain weir calculations were held by European hydrologists, the facility allowed for standard efficiency testing among major manufacturers through 1932, by which time more modern facilities and methods had proliferated. Around 1890,
8428-510: The transfer of energy for impulse turbines. Impulse turbines are often used in very high (>300m/1000 ft) head applications. The power available in a stream is; P = η ⋅ ρ ⋅ g ⋅ h ⋅ q ˙ {\displaystyle P=\eta \cdot \rho \cdot g\cdot h\cdot {\dot {q}}} where: Some water turbines are designed for pumped-storage hydroelectricity. They can reverse flow and operate as
8526-430: The turbine is controlled either by a large valve or by wicket gates arranged around the outside of the turbine runner. Differential head and flow can be plotted for a number of different values of gate opening, producing a hill diagram used to show the efficiency of the turbine at varying conditions. The runaway speed of a water turbine is its speed at full flow, and no shaft load. The turbine will be designed to survive
8624-595: The type of impeller selected. Reaction turbines are acted on by water, which changes pressure as it moves through the turbine and gives up its energy. They must be encased to contain the water pressure (or suction), or they must be fully submerged in the water flow. Newton's third law describes the transfer of energy for reaction turbines. Most water turbines in use are reaction turbines and are used in low (<30 m or 100 ft) and medium (30–300 m or 100–1,000 ft) head applications. In reaction turbine, pressure drop occurs in both fixed and moving blades. It
8722-399: The upper gate of the chamber below and the lower gate of the chamber above. The gates are the vulnerable hinged type, which, if damaged, could temporarily render the entire flight unusable. As there are separate sets of locks for upstream and downstream traffic, this system is more water efficient than bi-directional staircase locks. In addition to the canal locks, there is a ship lift ,
8820-415: The upstream water level from 145.13 m (476.1 ft) on August 1, to 152.88 m (501.6 ft) on August 8. A full 4.27 km (1.02 cu mi) of flood water was captured and the river flow was cut by as much as 15,000 m (530,000 cu ft) per second. The dam discharges its reservoir during the dry season every year, between December and March. This increases the flow rate of
8918-419: The use of gears and the dynamic behavior. By 1930, the mechanical governors had many parameters that could be set on the feedback system for precise controls. In the later part of the twentieth century, electronic governors and digital systems started to replace the mechanical governors. In the electronic governors, also known as second-generation governors, the flyball was replaced by rotational speed sensor but
9016-534: The water stagnant, polluted and murky. In 1997, the Three Gorges area had 10% forestation, down from 20% in the 1950s. Research by the United Nations Food and Agriculture Organization suggested that the Asia-Pacific region would gain about 6,000 km (2,300 sq mi) of forest by 2008. That is a significant change from the 13,000 km (5,000 sq mi) net loss of forest each year in
9114-483: The water temperature and flow regime. Many other fish are injured in the hydroelectric plants' turbine blades. This is particularly detrimental to the region's ecosystem because the Yangtze River basin is home to 361 different fish species and accounts for 27% of China's endangered freshwater fish species. Other aquatic species have been endangered by the dam, particularly the baiji, or Chinese river dolphin , now extinct. In fact, Chinese Government scholars even claim that
9212-617: Was an efficient machine (~80%) that sent water through a runner with blades curved in one dimension. The stationary outlet also had curved guides. In 1844, Uriah A. Boyden developed an outward flow turbine that improved on the performance of the Fourneyron turbine. Its runner shape was similar to that of a Francis turbine . In 1849, James B. Francis improved the inward flow reaction turbine to over 90% efficiency. He also conducted sophisticated tests and developed engineering methods for water turbine design. The Francis turbine , named for him,
9310-570: Was considered for its water-saving performance or because the engineers thought the difference in height between the river above and below the dam too great for alternative methods. No construction work was performed because of the Nationalists' worsening situation in the Chinese Civil War. After the 1949 Communist Revolution , Mao Zedong supported the project, but began the Gezhouba Dam project nearby first, and economic problems including
9408-407: Was estimated in 2009 that the cost of construction would be fully recouped when the dam had generated 1,000 terawatt-hours (3,600 PJ) of electricity, yielding 250 billion yuan; total cost recovery was thus expected to be completed ten years after the dam became fully operational. In fact, the entire cost of the Three Gorges Dam was recovered by December 20, 2013. Funding sources include
9506-438: Was eventually achieved on October 18, 2006, after the water level reached 156 meters. On the south side, main generator No. 22 started up on June 11, 2007, and No. 15 became operational on October 30, 2008. The sixth (No. 17) began operation on December 18, 2007, raising capacity to 14.1 GW, exceeding that of Itaipu dam (14.0 GW) to become the world's largest hydro power plant by capacity. When
9604-412: Was signed together with the contract. Most of the generators are water-cooled. Some of the newer ones are air-cooled, making them simpler in design and easier to manufacture and maintain. The first north-side main generator (No. 2) started up on July 10, 2003. The north side became completely operational on September 7, 2005, with the implementation of generator No. 9. Full power (9,800 MW)
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