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1 Chapter 10 SMALL SCALE HYDROELECTRIC POWER 10.1 Introduction Through the ages the force of falling water has been mankind’s important source of power and energy. Hydropower has been harnessed to do useful work – to grind grain, saw lumber and provide power to do other tasks. Power was transferred to a variety of rotary motion machines via shafts, pulleys, cables and gears. The Greeks used vertical axis water wheels as early as 85 BC and horizontal axis wheels from about 15 BC. The origins of water wheels can also be traced back to ancient Egypt, Persia and China where these were used for irrigation as well as grinding grain or flour. Hydropower was the only source of mechanical energy (other than wind) until the development of the steam engine in the nineteenth century. The early hydraulic units were relatively small and their outputs rarely exceeded few hundred kilowatts. Small hydropower provided the early settlers in the United States with mechanical power to drive looms and lathes. The invention and development of electric generator in nineteenth century have led to generation of electricity using hydropower as a primary source of energy. Hydropower converts potential energy into kinetic energy by virtue of elevation changes. While rivers with widely varying rates of flow were found to be unsuitable for installation of generators, dams in rivers provided an easy means of adjusting the flow of water to meet varying demands for electricity. The first hydroelectric generation facility was built in Appleton, Wisconsin in 1882, and it was rated as 125 kilowatts. The generator produced direct current primarily for local industries. Tremendous strides have been made in the field of hydro-dynamics in order to develop and improve equipment to meet increasing complex requirements of larger and larger hydroelectric power plants. The earlier waterwheels have been refined to modern turbines for providing mechanical shaft power to the generator. Even today hydropower remains a significant source of electricity in all parts of the world. At present (2011) about a fifth of the world’s entire electricity demand is met through hydropower. Large scale hydroelectric generation remains one of the cheapest and most reliable sources of electricity. However, the best sites for hydroelectricity in many countries have been used up, and the remaining ones are coming under stringent environmental scrutiny. The golden age of hydropower was the first half of the 20th century when hydropower provided much of the energy for the industrial development around the world. However, its contribution in electricity generation mix steadily declined after 1940’s in United States and many industrialized countries. The advent of abundant and inexpensive fossil fuels, first coal then oil, and finally natural gas coupled with generation technology which led to the economy of scale, resulted in large scale development of thermal
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2 power plants. The perceived economy and low cost of nuclear power plants convinced many such
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