水能的历史与未来.doc

The History and Future of waterpowera) Who founded this type of energy?b) When was it invented,developed,or first used?Early uses of waterpower date back to Mesopotamia and ancient Egypt, where irrigation has been used since the 6th millennium BC and water clocks had been used since the early 2nd millennium BC. Other early examples of water power include the Qanat system in ancient Persia and the Turpan water system in ancient China.Hydropower has been used since ancient times to grind flour and perform other tasks. In the mid-1770s, French engineer Bernard Forest de Blidor published Architecture Hydraulique which described vertical- and horizontal-axis hydraulic machines. By the late 19th century, the electrical generator was developed and could now be coupled with hydraulics.2 The growing demand for the Industrial Revolution would drive development as well.3 In 1878 the worlds first hydroelectric power scheme was developed at Cragside in Northumberland, England by William George Armstrong. It was used to power a single arc lamp in his art gallery.4 The old Schoelkopf Power Station No. 1 near Niagara Falls in the U.S. side began to produce electricity in 1881. The first Edison hydroelectric power plant, the Vulcan Street Plant, began operating September 30, 1882, in Appleton, Wisconsin, with an output of about 12.5 kilowatts.5 By 1886 there were 45 hydroelectric power plants in the U.S. and Canada. By 1889 there were 200 in the U.S. alone.At the beginning of the 20th century, many small hydroelectric power plants were being constructed by commercial companies in mountains near metropolitan areas. Grenoble, France held the International Exhibition of Hydropower and Tourism with over one million visitors. By 1920 as 40% of the power produced in the United States was hydroelectric, the Federal Power Act was enacted into law. The Act created the Federal Power Commission to regulate hydroelectric power plants on federal land and water. As the power plants became larger, their associated dams developed additional purposes to include flood control, irrigation and navigation. Federal funding became necessary for large-scale development and federally owned corporations, such as the Tennessee Valley Authority (1933) and the Bonneville Power Administration (1937) were created.3 Additionally, the Bureau of Reclamation which had began a series of western U.S. irrigation projects in the early 20th century was now constructing large hydroelectric projects such as the 1928 Hoover Dam.6 The U.S. Army Corps of Engineers was also involved in hydroelectric development, completing the Bonneville Dam in 1937 and being recognized by the Flood Control Act of 1936 as the premier federal flood control agency.7Hydroelectric power plants continued to become larger throughout the 20th century. Hydropower was referred to as white coal for its power and plenty.8 Hoover Dams initial 1,345 MW power plant was the worlds largest hydroelectric power plant in 1936; it was eclipsed by the 6809 MW Grand Coulee Dam in 1942.9 The Itaipu Dam opened in 1984 in South America as the largest, producing 14,000 MW but was surpassed in 2008 by the Three Gorges Dam in China at 22,500 MW. Hydroelectricity would eventually supply some countries, including Norway, Democratic Republic of the Congo, Paraguay and Brazil, with over 85% of their electricity. The United States currently has over 2,000 hydroelectric power plants which supply 49% of its renewable electricity.c) How has the function of this energy source changed throughout history?Different today from the past?Waterwheels, turbines, and millsHydropower has been used for hundreds of years. In India, water wheels and watermills were built; in Imperial Rome, water powered mills produced flour from grain, and were also used for sawing timber and stone; in China, watermills were widely used since the Han Dynasty. The power of a wave of water released from a tank was used for extraction of metal ores in a method known as hushing. The method was first used at the Dolaucothi gold mine in Wales from 75 AD onwards, but had been developed in Spain at such mines as Las Medulas. Hushing was also widely used in Britain in the Medieval and later periods to extract lead and tin ores. It later evolved into hydraulic mining when used during the California gold rush.In China and the rest of the Far East, hydraulically operated pot wheel pumps raised water into irrigation canals. At the beginning of the Industrial revolution in Britain, water was the main source of power for new inventions such as Richard Arkwrights water frame.1 Although the use of water power gave way to steam power in many of the larger mills and factories, it was still used during the 18th and 19th centuries for many smaller operations, such as driving the bellows in small blast furnaces (e.g. the Dyfi Furnace)2 and gristmills, such as those built at Saint Anthony Falls, which uses the 50-foot (15 m) drop in the Mississippi River.In the 1830s, at the early peak in U.S. canal-building, hydropower provided the energy to transport barge traffic up and down steep hills using inclined plane railroads. About the same time and later, as railroads overtook canals for transportation, canal systems were modified and developed into hydropower systems; the history of Lowell, Massachusetts is a classic example of commercial development and industrialization, built upon the availability of water power.During this time also, technological advances had moved the water wheel to a turbine, and in 1848 James B. Francis, while working as head engineer of Lowells Locks and Canals company, improved on these designs to create a turbine with 90% efficiency. Applying scientific principles and testing methods he produced a very efficient turbine design, but more importantly, his mathematical and graphical calculation methods improved turbine design and engineering. His analytical methods allowed confident design of high efficiency turbines to exactly match a sites specific flow conditions. The Francis reaction turbine is still in wide usage today, with few changes in either design or methods. In the 1870s and deriving from uses in the California mining industry, Lester Allan Pelton developed the high efficiency Pelton wheel impulse turbine, which utilized hydropower with very different conditions of flow and pressure.editHydraulic power-pipe networksHydraulic power networks also developed, using pipes to carrying pressurized water and transmit mechanical power from the source to end users elsewhere locally; the power source was normally a head of water, which could also be assisted by a pump. These were extensive in Victorian cities in the United Kingdom. A hydraulic power network was also developed in Geneva, Switzerland. The world famous Jet dEau was originally designed as the over-pressure relief valve for the network.3editCompressed air hydroWhere there is a plentiful head of water it can be made to generate compressed air directly without moving parts. In these designs, a falling column of water is purposely mixed with air bubbles generated through turbulence at the high level intake. This is allowed to fall down a shaft into a subterranean, high-roofed chamber where the now-compressed air separates from the water and becomes trapped. The height of falling water column maintains compression of the air in the top of the chamber, while an outlet, submerged below the water level in the chamber allows water to flow back to the surface at a slightly lower level than the intake. A separate outlet in the roof of the chamber supplies the compressed air to the surface. A facility on this principal was built on the Montreal River at Ragged Shutes near Cobalt, Ontario in 1910 and supplied 5,000 horsepower to nearby mines.d) What is the latest research taking palce with this energy source?Will it have new potential uses in the future?I think the water clock is the latest research taking palce with this energy source.In China,The water-powered mechanism of Su Songs astronomical clock tower, featuring a clepsydra tank, waterwheel, escapement mechanism, and chain drive to power an armillary sphere and 113 striking clock jacks to sound the hours and to display informative plaquesIn China, as well as throughout eastern Asia, water clocks were very important in the study of astronomy and astrology. The oldest reference dates the use of the water-clock in China to the 6th century BC.16 From about 200 BC onwards, the outflow clepsydra was replaced almost everywhere in China by the inflow type with an indicator-rod borne on a float.16Huan Tan (40 BC AD 30), a Secretary at the Court in charge of clepsydrae, wrote that he had to compare clepsydrae with sundials because of how temperature and humidity affected their accuracy, demonstrating that the effects of evaporation, as well as of temperature on the speed at which water flows, were known at this time.17 In 976, Zhang Sixun addressed the problem of the water in clepsydrae freezing in cold weather by using liquid mercury instead.18 Again, instead of using water, the early Ming Dynasty engineer Zhan Xiyuan (c. 1360-1380) created a sand-driven wheel clock, improved upon by Zhou Shuxue (c. 1530-1558).19The use of clepsydrae to drive mechanisms illustrating astronomical phenomena began with Zhang Heng (78-139) in 117, who also employed a waterwheel.20 Zhang Heng was the first in China to add an ex