CHAPTER: 1 1. 0 Introduction: Electricity is one of the most important energy resources for modern development. But due to the high cost production as well as the high cost of establishment of national grid, the third world country like Bangladesh can not provide electricity to all over the country. Due to the above causes the supply of electricity, i. e, national grid, covers only a few areas, especially the urban and suburban regions where only 20% of the total population of Bangladesh live (BBS, 2004) [Ref. 1].
So, the maximum portion of the population who lives in the rural area is not getting the advantages of using electricity. It is a matter of appreciation that Rural Electrification Board has taken initiatives to provide electricity for advantages less rural people since 1977, but yet to provide the facility for the people who are living in suburban region. Hydro electric power, whereby a difference in water level is used to extract power, is well established technology. Most hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator.
In this case the energy extracted from the water depends on the volume and on the difference in height between the source and the waters outflow. This height difference is called the head. The amount of potential energy in water is proportional to the head. However, it is generally only considered for locations where there is more than 10m of head. In low head situations, the low velocity implies the need for large flow rates and hence large machines to recover a modest amount of power. Hydro power is an eco-friendly clean power generation method.
Unfortunately, the scope of hydro power generation is very limited in Bangladesh because of its plain lands with exceptions in some hilly regions in the northeast and southeast parts of the country. The lone hydropower plant of the country is located at Kaptai of Chittagong Hill Tracts With an installed capacity of 230 MW. In 1981 the Water Development Board and Power Development Board [Ref. 2] carried out a study on the assessment of Small/Mini hydropower potential in the country. It identified 12 potential rivers/charas with an estimated annual production of 1. GWh in Chittagong Bandarban area, 6. 3 GWh in Sylhet and Moulavi Bazar area, 8. 6 MWh in Mymensing-Sherpur area and 1. 8 GWh in the Dinajpur-Rangpur area. Recently LGED [Ref. 3] has taken up a project at Bamer chara in Bashkhali of Chittagong District and BCSIR [Ref. 4] in Sailopropat, Bandarban and in Madhobkundu, Moulovibazar. The BCSIR has estimated that these two sites have the potential for annual energy production of 43. 8 MWh and 1. 3 GWh respectively. Tidal power is not a new concept and has been used in Britain and France since at least the 11th century for milling grains.
Ocean cover over 70% of the earth surface & the energy contained in waves & tidal movements is enormous. It has been estimated that if less than 0. 1% of the renewable energy available within the oceans could be converted into electrical it would satisfy the present world demand for energy more than five times over (Wavegen, 1999). However, tidal power remains well bellow its potential in terms of application. Presently, tidal plants exists only in France since 1967 (La Rance), Canada since 1984 (Annapolis Royal). Many tidal projects one being considered today including the seven projects in England.
Derby Hydro power of Western Australia: (48 MW); Corova , South coast of Alaska; Southern portion of Chile; Gujarat ; India: (1000 MW); Mexico: (500 MW); the Philippines: (2200 MW) and China: (20000 MW) (Tidal Electric Inc. 1999; Green Energy,1999;ACRE,1999). The usual technique in harnessing the tide is to dam a tidally-affected estuary or inlet, allowing the incoming tide to enter the inlet unimpeded and using the impounded water to generate power. The main barriers to uptake of the technology are environmental concerns and high capital costs.
In recent years, these problems have been initigated considerably by design, by involvement of experts and local communities in the identification and installation of new plant, and by a growing understanding of how to achieve more sustainable energy development. Generally speaking, it is quite possible to harness energy from the tides; however the technology is not yet practically and commercially available; there are also environmental concerns. Therefore, until now, tidal power generating issues have not been substantively addressed.
The other major problem of high capital costs will also be addressed. Like hydro schemes, tidal power has high capital costs due to the large scale of engineering involved, but involved low operating costs. Tidal power has the extra problem of having to be located in a coastal environment where engineering is likely to be even more costly due to the changeability of the coast. However, there is no research that has been conducted yet where the coastal engineering infrastructure is already present (like Bangladesh coastal Islands).
A comparative study of low head hydropower projects reveals that the former one is more capital intensive and involves major political decisions causing difficulties in different implementation phases. On the other hand low head-hydro projects are low cost, small sized and can be installed to serve a small community making its implementation more appropriate in the socio-political context of Bangladesh. So there is a scope for harnessing the low head hydro potentiality by identifying proper sites and designing appropriate power generation system. . 1 Objectives: •Investigation about low head hydropower. •Feasibility Study. •Economic Analysis. •Prospects of low head hydropower in Bangladesh. CHAPTER: 2 2. 0 Historical Background: What is hydropower’s history? The mechanical power of falling water is an age old tool. It was used by the Greeks to turn water wheels for grinding wheat into flour, more than 2,000 years ago. The availability of cheap slave and animal labor, however, restricted its widespread application until about the 12th century.
During the Middle Ages, large wooden waterwheels were developed with a maximum power output of about 50 hp. Modern large-scale water-power owes its development to the British civil engineer John Smeaton, who first built large waterwheels out of cast iron. Water-power played an important part in the Industrial Revolution. It gave impetus to the growth of the textile, leather, and machine-shop industries in the early 19th century. Although the steam engine had already been developed, coal was scarce and wood unsatisfactory as a fuel.
Water-power helped to develop early industrial cities in Europe and the United States until the opening of the canals provided cheap coal by the middle of the 19th century. Dams and canals were necessary for the installation of successive waterwheels when the drop was greater than 5 m (16 ft). Large storage-dam construction, however, was not feasible, and low water flows during summer and autumn, coupled with icing during the winter, led to the replacement of nearly all waterwheels by steam when coal became readily available.
The earliest hydroelectric plant was constructed in 1880 in Cragside, Northumberland, England. The rebirth of water-power came with the development of the electric generator, further improvement of the hydraulic turbine, and the growing demand for electricity by the turn of the 20th century. By 1920 hydroelectric plants already accounted for 40 per cent of the electric power produced in the United States. The basic principle of operation of most major installations has remained the same since then.
Plants depend on a large water-storage reservoir upstream of a dam where water flow can be controlled and a nearly constant water level can be assured. Water flows through conduits, called penstocks which are controlled by valves or turbine gates to adjust the flow rate in line with the power demand. The water then enters the turbines and leaves them through the so-called tailrace. The power generators are mounted directly above the turbines on vertical shafts. The design of turbines depends on the available head of water, with so-called Francis turbines used for high heads and propeller-turbines used for low heads.
In contrast to storage-type plants, which depend on the impounding of large amounts of water, a few examples exist where both the water drop and the steady flow rate are high enough to permit so-called run-of-the-river installations; one such is the joint US-Canadian Niagara Falls power project. In the 1700’s, Americans recognized the advantages of mechanical hydropower and used it extensively for milling and pumping. By the early 1900’s, hydroelectric power accounted for more than 40 percent of the United States’ supply of electricity.
In the 1940’s hydropower provided about 75 percent of all the electricity consumed in the West and Pacific Northwest, and about one third of the total United States’ electrical energy. With the increase in development of other forms of electric power generation, hydropower’s percentage has slowly declined and today provides about one tenth of the United States’ electricity. The early hydroelectric plants were direct current stations built to power arc and incandescent lighting during the period from about 1880 to 1895.
The years 1895 through 1915 saw rapid changes occur in hydroelectric design and a wide variety of plant styles built. Hydroelectric plant design became fairly well standardized after World War I with most development in the 1920’s and 1930’s being related to thermal plants and transmission and distribution. 2. 1. 0 History of Hydropower in United State: By using water for power generation, people have worked with nature to achieve a better lifestyle. The mechanical power of falling water is an age-old tool.
It was used by the Greeks to turn water wheels for grinding wheat into flour, more than 2,000 years ago. In the 1700’s mechanical hydropower was used extensively for milling and pumping. By the early 1900’s, hydroelectric power accounted for more than 40 percent of the United States’ supply of electricity. In the 1940’s hydropower provided about 75 percent of all the electricity consumed in the West and Pacific Northwest, and about one third of the total United States’ electrical energy.
With the increase in development of other forms of electric power generation, hydropower’s percentage has slowly declined and today provides about one tenth of the United States’ electricity. Niagra Falls was the first of the American hydroelectric power sites developed for major generation and is still a source of electric power today. The early hydroelectric plants were direct current stations built to power arc and incandescent lighting during the period from about 1880 to 1895. When the electric motor came into being the demand for new electrical energy started its upward spiral.
The years 1895 through 1915 saw rapid changes occur in hydroelectric design and a wide variety of plant styles built. Hydroelectric plant design became fairly well standardized after World War I with most development in the 1920’s and 1930’s being related to thermal plants and transmission and distribution The Bureau of Reclamation became involved in hydropower production because of its commitment to water resource management in the arid West. The waterfalls of the Reclamation dams make them significant producers of electricity. Hydroelectric power generation has long been an integral part of
Reclamation’s operations while it is actually a byproduct of water development. In the early days, newly created projects lacked many of the modern conveniences, one of these being electrical power. This made it desirable to take advantage of the potential power source in water. Power plants were installed at the dam sites to carry on construction camp activities. Hydropower was put to work lifting, moving, and processing materials to build the dams and dig canals. Power plants ran sawmills, concrete plants, cableways, giant shovels, and draglines.
Night operations were possible because of the lights fed by hydroelectric power. When construction was complete, hydropower drove pumps that provided drainage of conveyed water to lands at higher elevations than could be served by gravity-flow canals. Surplus power was sold to existing power distribution systems in the area. Local industries, towns and farm consumers benefited from the low-cost electricity. Much of the construction and operating costs of dams and related facilities were paid for by this sale of surplus power, rather than by the water users alone.
This proved to be a great savings to irrigators struggling to survive in the West. Reclamation’s first hydroelectric power plant was built to aid construction of the Theodore Roosevelt Dam on the Salt River about 75 miles northeast of Phoenix, Arizona. Small hydroelectric generators, installed prior to construction, provided energy for construction and for equipment to lift stone blocks into place. Surplus power was sold to the community, and citizens were quick to support expansion of the dam’s hydroelectric capacity.
A 4,500 kilowatt power plant was constructed and, in 1909, five generators were in operation, supplying power for pumping irrigation water and furnishing electricity to the Phoenix area. Power development, a byproduct of water development, had a tremendous impact on the area’s economy and living conditions. Power was sold to farms, cities, and industries. Wells pumped by electricity meant more irrigated land for agriculture, and pumping also lower water tables in those areas with water logging and alkaline soil problems.
By 1916, nine pumping plants were in operation irrigating more than 10,000 acres. In addition Reclamation supplied all of the residential and commercial power needs of Phoenix. Cheap hydropower, in abundant supply, attracted industrial development as well. A private company was able to build a large smelter and mill nearby to process low-grade copper ore, using hydroelectric power. The Theodore Roosevelt Power plant was one of the first large power facilities constructed by the Federal Government.
Its capacity has since been increased form 4,500 kW to over 36,000 kW. Power, first developed for building Theodore Roosevelt Dam and for pumping irrigation water, also helped pay for construction, enhanced the lives of farmers and city dwellers, and attracted new industry to the Phoenix area. During World War I, Reclamation projects continued to provide water and hydroelectric power to Western farms and ranches. This helped to feed and clothe the Nation, and the power revenues were a welcome source of income to the Federal Government.
The Depression of the 1930’s, coupled with widespread floods and drought in the West, spurred the building of great multipurpose Reclamation projects such as Grand Coulee Dam on the Columbia River, Hoover Dam on the lower Colorado River, and the Central Valley Project in California. This was the “big dam” period, and the low-cost hydropower produced by those dams had a profound effect on urban and industrial growth. With the advent of World War II the Nation’s need for hydroelectric power soared. At the outbreak of the war, the Axis Nations had three times more available power than the United States.
The demand for power was identified in this 1942 statement on ” The War Program of the Department of the Interior:” “The war budget of $56 billion will require 154 billion kWh of electric energy annually for the manufacture of airplanes, tanks, guns, warships, and fighting material, and to equip and serve the men of the Army, Navy and Marine Corps. ” Each dollar spent for wartime industry required about 2-3/4 kWh of electric power. The demand exceeded the total production capacity of all existing electric utilities in the United States.
To produce enough aluminum to meet the President’s goal of 60,000 new planes in 1942 alone required 8. 5 billion kWh of electric power. Hydropower provided one of the best ways for rapidly expanding the country’s energy output. Addition of more powerplant units at dams throughout the West made it possible to expand energy production, and construction pushed ahead to speed up the availability of power. In 1941, Reclamation produced more than 5 billion kWh, resulting in a 25 percent increase in aluminum production.
By 1944 Reclamation quadrupled its hydroelectric power output. During the war, Reclamation was the major producer of power in the West where needed resources were located. The supply of low-cost electricity attracted large defense industries to the area. Shipyards, steel mills, chemical companies, oil refineries, and automotive and aircraft factories all needed vast amounts of electrical power. Atomic energy installations were located at Hanford, Washington, to make use of hydropower from Grand Coulee.
While power output of Reclamation projects energized the war industry, it was also used to process food, light military posts, and meet needs of the civilian population in many areas. With the end of the war, power plants were put to use in rapidly developing peacetime industries. Hydropower has been vital for the West’s industries which use mineral resources or farm products as raw materials. Many industries have depended wholly on Federal hydropower. In fact, periodic low flows on the Columbia River have disrupted manufacturing in that region.
Farming was tremendously important to America during the war and continues to be today. Reclamation delivers 10 trillion gallons of water delivered to more than 31 million people each year and provides 1 out of 5 Western farmers (140,000) with irrigation water for 10 million farmland acres that produce 60% of the nation’s vegetables and 25% of the its fruits and nuts Hydropower directly benefits rural areas in three ways: •It produces revenue which contributes toward repayment of irrigation facilities, easing the water user’s financial burden. It makes irrigation of lands at higher elevations possible through pumping facilities. •It makes power available for use on the farm for domestic purposes. Reclamation is second only to the Corps of Engineers in the operation of hydroelectric power plants in the United States. Reclamation uses some of the power it produces to run its facilities, such as pumping plants. Excess hydropower is sold first to preferred customers, such as rural electric power co-ops, public utility districts, municipalities, and state and Federal agencies.
Any remaining power may be sold to private electric utilities. Reclamation generates enough hydropower to meet the needs of millions of people, and power revenues exceed $900 million a year. Power revenues are returned to the Federal Treasury to repay the cost of constructing, operating, and maintaining projects. An excellent book detailing the history of hydroelectricity is the two volume set of “Hydroelectric Development in the United States 1880 – 1940” prepared for the Task Force on Cultural Resource Management, Edison Electric Institute, Duncan Hay, New York State Museum, 1991.
This book details American hydroelectric development from the first use of hydroelectric power around 1880 up to 1940. The following time line includes data from the above referenced book highlighting a chronology of American hydroelectric development. 1879 First commercial arc lighting system installed, Cleveland, Ohio. 1879Thomas Edison demonstrates incandescent lamp, Menlo Park, New Jersey. 1880Grand Rapids Michigan: Brush arc light dynamo driven by water turbine used to provide theater and storefront illumination. 881Niagra Falls, New York; Brush dynamo, connected to turbine in Quigley’s flour mill lights city street lamps. 1882 Appleton, Wisconsin; Vulcan Street Plant, first hydroelectric station to use Edison system. 1883Edison introduces “three-wire” transmission system. 1886Westinghouse Electric Company organized. 1886Frank Sprague builds first American transformer and demonstrates use of step up and step down transformers for long distance AC power transmission in Great Barrington, Massachusetts. 188640 to 50 water powered electric plants reported on line or under construction in the U. S. nd Canada. 1887San Bernadino, California; High Grove Station, first hydroelectric plant in the West. 1888Rotating field AC alternator invented. 1889American Electrical Directory lists 200 electric companies that use waterpower for some or all of their generation. 1889Oregon City Oregon, Willamette Falls station, first AC hydroelectric plant. Single phase power transmitted 13 miles to Portland at 4,000 volts, stepped down to 50 volts for distribution. 1891Ames, Colorado; Westinghouse alternator driven by Pelton waterwheel, 320 foot head. Single phase, 3000 volt, 133 cycle power transmitted 2. miles to drive ore stamps at Gold King Mine. 1891Frankfort on Main, Germany; First three-phase hydroelectric system used for 175 km, 25,000 volt demonstration line from plant at Lauffen. 189160 cycle AC system introduced in U. S. 1892Bodie, California; 12. 5 mile, 2,500 AC line carried power from hydroelectric plant to ore mill of Standard Consolidated Mining Co. 1892San Antonio Creek, California; Single phase 120 kW plant, power carried to Pomona over 13 mile 5,000 volt line. Voltage increased to 10,000 and line extended 42 miles to San Bernadino within a year.
First use of step up and step down transformers in hydroelectric project. 1892General Electric Company formed by the merger of Thomson-Houston and Edison General Electric. 1893Mill Creek, California; First American three-phase hydroelectric plant. Power carried 8 miles to Redlands on 2,400 volt line. 1893Westinghouse demonstrates “universal system” of generation and distribution at Chicago exposition. 1893Folsom, California; Three-phase, 60 cycle, 11,000 volt alternators installed at plant on American River. Power transmitted 20 miles to Sacramento. 889-93Austin, Texas; First dam designed specifically for hydroelectric power built across Colorado River. 1895Niagra Falls, New York; 5,000 horsepower, 60 cycle, three-phase generators go into operation. 1897Mechanicville, New York; Hudson River Power Transmission Company completes 5,250 kW, 38 cycle plant and 17 mile line to Schenectady. 1897Minneapolis, Minnesota; Lower Dam hydroelectric plant completed at St. Anthony’s Falls on the Mississippi. 1898Los Angeles, California; 83 mile line built from Santa Anna River No. 1 hydroelectric plant. 899Nevada City, California; power from Nevada City, Yuba, and Colgate hydroelectric plants sold to Sacramento Power & Light Co. over 62 mile line to Folsom. 1899Kalamazoo, Michigan; 24-mile, 22,000 volt line built from Trowbridge Dam hydroelectric plant. 1901Oakland, California; 142 mile line built from Colgate hydroelectric plant by Bay Counties Power Company. 1901First Federal Water Power Act 1901Trenton Falls, New York; First installation of high head reaction turbines designed and built in the U. S. 1889-1902Massena, New York; Dam and powerhouse built at confluence of St. Lawrence & Grasse Rivers.
Power primarily used for smelting by Aluminum Corporation of America (ALCOA) 1902Reclamation Act of 1902 establishes the Reclamation Service which later becomes the U. S. Bureau of Reclamation. Included in the act is the authority to develop the hydropower potential of Reclamation projects. 1897-1903Sault Ste. Marie, Michigan; Michigan, Lake Superior Power Company Plant, 80 horizontal shaft units delivered 40,000 horsepower. 1905Sault Ste. Marie, Michigan; First low head plant with direct connected vertical shaft turbines and generators. 1906Ilchester, Maryland; Fully submerged hydroelectric plant built inside Ambursen Dam. 906Town Sites and Power Development Act – Authorized Secretary of the Interior to lease surplus power or power privileges. 1907Hauser Lake, Montana: Short lived steel dam built across Missouri River by Wisconsin Bridge & Iron Co. for Helena Power & Transmission Co. 1910Federal Water Power Act revised. 1910Big Creek, California; Construction begins on a hydroelectric system that would eventually include eight powerhouses, over a 6,200 foot fall, rated at 685,000 kW. 1905-1911Roosevelt Dam, Salt River, Arizona; Largest, and last, masonry dam ever built by U. S. Bureau of Reclamation.
Mixed use irrigation/hydroelectric project. 1911R. D. Johnson invents differential surge tank and Johnson hydrostatic penstock valve. 1912Holtwood, Pennsylvania; First commercial installation of Kingsbury vertical thrust bearing in hydroelectric plant. 1910-1913Keokuk, Iowa; Mississippi River Power Transmission Plant. 1913Tallulah Falls, Georgia; Highest head hydroelectric plant in the East. 1913Nolenchucky, Tennessee; First use of W. M. White’s plate steel spiral turbine case. 1914S. J. Zowski develops high specific speed reaction (Francis) turbine runner for low head applications. 914Argo, Michigan; Streamline draft tube introduced. 1916First commercial installation of fixed-blade propeller turbine designed by Forrest Nagler. 1917Hydracone draft tube patented by W. M. White. 1917National Defense Act authorizes construction of government dam and powerplant at Muscle Shoals, Alabama. 1919Viktor Kaplan demonstrates adjustable blade propeller turbine runner at Podebrady, Czechoslovakia. 1920Federal Power Act establishes Federal Power Commission with authority to issue licenses for hydroelectric development on public lands. 1922First hydroelectric plant built specifically for peaking power. 922Organization representing the power industry and manufacturers met to standardize voltages 1924First World Power Conference, London. 1929Del Rio, Texas; First Kaplan turbines installed in the U. S. — Lake Walk plant. 1929Rocky River Plant, New Milford, Connecticut; First major pumped storage hydroelectric plant. 1930Federal Power Act revised, independent full-time Federal Power Commission established. 1931Construction begins, Boulder (later Hoover) Dam, Colorado River, Arizona-Nevada. 1933Tennessee Valley Authority Act. 1933Construction begins, Grand Coulee Dam, Columbia River, Washington. 935Federal Power Commission authority extended to all hydroelectric projects built by utilities engaged in interstate commerce. 1933-1937Bonneville Dam, Columbia River, Washington/Oregon. 1937First power generated at Hoover Dam, Arizona/Nevada. 1937Bonneville Project Act – Created BPA (Bonneville Power Administration) 1940Over 1500 hydroelectric facilities produce about one third of the United States’ electrical energy. 1941First power generated at Grand Coulee Power plant, Washington – Presently the third largest hydroelectric plant in the world at 6,800 megawatts installed capacity. 944First power generated at Shasta Dam in California. 1964First power generated at Glen Canyon Dam in Arizona. 1968Wild and Scenic Rivers Act – Protects rivers in their natural state by excluding them from consideration as hydroelectric power sites. 1969National Environmental Policy Act – Ensures that environmental considerations are systematically taken into account by Federal agencies. 1974Fish and Wildlife Coordination Act – Ensures equal consideration of fish and wildlife protection in the activities of Federal agencies. 978Public Utility Regulatory Policies Act – Encourages small-scale power production facilities; exempted certain hydroelectric projects from Federal licensing requirements, and required utilities to purchase – at “avoided cost” rates – power from small production facilities that use renewable resources 1979First power generated at New Melones Dam in California. Built by the Corps of Engineers and turned over to the Bureau of Reclamation, this is the last of the larger power plants (over 30 megawatts) in the Bureau of Reclamation’s power program. 1980Energy Security Act –
Exempted small-scale hydroelectric power from some licensing requirements. 1980Crude Oil Windfall Profit Tax – Provided tax incentives to small-scale hydropower producers. 1983First power generated at Itaipu power plant, Brazil/Paraguay – Presently the largest hydroelectric power plant in the world at 12,600 megawatts installed capacity. 1986Electric Consumers Protection Act – Amended the Federal Power Act to remove public preference for relicensing actions; gives equal consideration to non-power values (e. g. , energy conservation, fish, wildlife, recreation, etc. as well as to power values when making license decisions. 1986First power generated at Guri (Raul Leoni) power plant, Venezuela – Presently the second largest hydroelectric power plant in the world at 10,300 megawatts installed capacity. 1992The top five electric generating countries in order are Canada, the United States, Brazil, Russia, and China. 1992Energy Policy Act of 1992 – An act to provide for improved energy efficiency. Includes provisions to allow for greater competition in energy sales and amendments to section 211 of the Federal Power Act. 994National Hydropower Association establishes the Hydropower Research Foundation to facilitate research and to promote educational opportunities on the value of hydropower. 1994The Federal Energy Regulatory Commission has authorized, through its licensing authority under the Federal Power Act, almost 1,700 hydroelectric projects. These projects include about 2,300 dams and multi-purpose water resource developments that provide about 55,000 MW of hydroelectric generating capacity (about one-half of the nation’s hydro capacity). 1997Hydroelectric generation provides about 10 percent of the United States’ electricity. . 1. 1 Hydropower in Uganda: Table: 2. 0 Major Sites on River Nile: NoSiteHydro Capacity (MW)RiverRemarks 1Nalubaale (Owen Falls)180NileIn Service 2Kiira (Owen Falls Extension)200Nile80MW in service, 40MW expected by June 2002 3Bujagali250NileConstruction to start by June 2002 4Kalagala225NileTo be developed into a leisure/tourist centre 5Busowoko**230NileNot developed 6Karuma(Kamdani)300-350Nile -do- 7Ayago(North)310-400Nile-do- 8Ayago(South)230-250Nile-do- 9Murchison Falls450-550Nile-do- TOTAL (max)2,635 In table 2. 0 ** This site is less economically viable with the development of neighboring sites. *** This site is ready for development but its development is dependant on what happens on the Bujagali project (development delayed by the environmental issues) Mini Hydro Sites elsewhere in Uganda: Successive Governments have not taken Minihydro development as an immediate and easily achievable solution to some of the countries power problems. Investment in these small sites may not need external financing especially in cases where local communities can be served with power without constructing HV transmission lines. In most cases progress stops once studies are concluded.
Only one hydro site was built at Maziba gorge (1 MW) in. The other developed site is at Mubuku (5MW) and this is a private station which sells most of the power to the Transmission (grid) Company. Table 2. 1 Tidal power in Uganda: No. SiteHydro Capacity (MW)River (District)Remarks 1. Paidha10Nyagak (Nebbi)Studies done awaiting funding 2. Ishasha5Ishasha (Rukungiri)- do – 3. Muzizi20Muzizi (Kibale)Not developed 4. Nyamabuye1. 5 – 4. 0Kaku (Kisoro)- do – 5. Biseruka10Ntungu (Rukungiri)- do – 6. Nsongezi54Kagera (Mbarara) – do – 7. Bugoye7. 5Mubuku (Kasese)5MW in service TOTAL122. 5 2. 1. 2 History of Hydropower in China:
In China small hydropower (SHP) refers to those SHP stations with installed capacity below 50 MW and power grids mainly with SHP. The classification of SHP is as follows: micro, mini and small hydropower. The micro hydropower refers to those stations below 100kW. The hydropower stations with installed capacity between 100 and 500 kW is called mini hydro power. The hydropower stations with installed capacity between 500 and 50000kW is called small hydro power. There has been tremendous SHP development in China. The history has witnessed the use of pine resin for lighting to the present electric lighting at the rural electrification stage.
In 1996, the electrification coverage ratio for township, village and household reached 96. 6% 94. 3% and 91. 7% respectively, greatly increasing the living standards of the local people, protecting the environment and booming the local economy in the vast hilly areas. By the end of 2000,al together 49278 SHP stations have been built, the SHP installed capacity amounted to 24. 85 GW, with annual power generation 79. 98 bil kWh. There were 19545 MHP stations with installed capacity amounted to 696 MW, with annual power generation 1. 68 bil kWh. Much has been also scored in R+D, planning, equipment manufacturing, Operation and maintenance etc.
According to the statistics, half of the total land, 1/3 of the Chinese counties (800 counties) and 1/4 of the Chinese population mainly depend on SHP. It has a special role to play in rural energy supply, environmental protection and poverty alleviation. Currently, there are over 40 MHP equipment manufacturers widely adopting simplified, generalized and standardized principles. The units include tubular, impulse, Francis and axial types, heads range from 1 to 100 m. Not long ago, special research was conducted to the MHP of 3 kW, 5kW and 8kW. The equipment and technology have the trend of commercialization.
Both the technology and product are easy to obtain, with the manuals easily to be mastered like electric appliance. The farmers may purchase, install and maintain by themselves. It is cheap in price and easy to use, welcome by the farmers. Table: 2. 2 Hydropower Project in China (Completed) NameYear of completionTotal capacityMaximum annual electricity production Three Gorges Dam200422500 MW84. 7 TW-hours Ertan Dam19993300 MW17. 0 TW-hours Gezhouba Dam19883115 MW17. 01 TW-hours Table: 2. 3 Hydropower Project in China (Under Construction) NameMaximum capacityConstruction startedScheduled completionComments Three Gorges Dam22400 MWDecember 14 9942009Largest power plant in the world. First power in July2003,with 10500 MW installed by June 2007 Xiluodu Dam12600 MWDecember 26 20052015 Baihetan Dam12000 MW20092015Still in planning Wudongde Dam7000 MW 20092015Still in planning Longtan Dam6300 MWJuly 1 2001December 2009 Xiangjiba Dam6000 MWNovember 26 20062009 Jinping 2 Hydrpower Station4800 MWJanuary 30 20072014To build this dam, only 23 families and 129 local residents need to be moved. It works with Jinping 1 Hydropower Station as a group Laxiwa Dam4200 MWApril 18 20062010 Xiaowan Dam4200 MWJanuary 1 2002December 2012 Jinping 1 Hydrpower Station3600 MWNovember 11 0052014 Pubugou Dam3300 MWMarch 30 20042010 Goupitan Dam3000 MW November 8 20032011 Guandi Dam2400 MW20072012 2. 1. 3 Hydropower Project in Canada: Table: 2. 4 Hydropower Project in Canada (Completed) NameYear of completionTotal capacityMaximum annual electricity production Robert-Bourassa19815616 Churchill Falls1971542935 TW-hours La grande-419862779 W. A. C. Bennett19682730 La Grande-319842418 La Grande-2-A19922106 2. 1. 4 Hydropower Project in Russia: Table: 2. 5 Hydropower Project in Russia (Completed) NameYear of completionTotal capacityMaximum annual electricity production Sayano Shushenskaya19836721 MW23. 6 TW-hours
Krasnoyarskaya19726000 MW20. 4 TW-hours Bratskaya19674500 MW22. 6 TW-hours Ust llimskya19804320 MW21. 7 TW-hours Volzhskaya(Volgogradskaya)19612541 MW12. 3 TW-hours Zhiguliovskaya(Samarskaya)19572300 MW10. 5 TW-hours Table: 2. 6 Hydropower Project in Russia (Under Construction) NameMaximum capacityConstruction startedScheduled completion Boguchan Dam3000 MW19802012 Bureya Dam2010 MW19782009 2. 1. 5 Hydropower in UK: There are very many hydropower generators in the UK ranging from a couple of hundred Watts up to hundreds of Kilowatts. Below are listed details of some of the largest (80MW+) hydro power stations in the United Kingdom.
All are located in Scotland with the exception of the largest of all, Dinorwig, which is in North Wales and is the largest in the UK. Biggest Hydropower Stations in the UK: Dinorwig Power Station (1,728MW): The Dinorwig Power Station in Wales was commission in 1984 and has a huge 1. 7GW power rating. 10 miles of underground tunnels buried beneath Elidir mountain carry water down from Marchlyn Mawr to the six 288MW turbine generators situated in Europe’s largest man-made cavern. During construction 12 million tonnes of material was excavated and 1 million tonnes of concrete and 4,500 tonnes of steel used.
A schematic diagram is displayed below: Ben Cruachan Power Station (400MW): This unique Scottish hydro power station is actually built inside a mountain. In 1965 a dam across Loch Cruachan was opened by the Queen. The loch’s water is then carried by two massive pipes through the mountain to turbine generators hidden in a man made cavern in the centre of the mountain. At night time when less power is needed across the UK, the turbines are reversed and water is pumped back up to the reservoir storing energy to be used in the day time. Foyers Power Station (305MW):
The Foyers hydro-electric power scheme is located on the Southeast corner of Loch Ness in Scotland. During off-peak times surplus electricity from the National Grid is used to pump water from Loch Ness up to Loch Mhor (a man-made reservoir linking two natural lochs). This water can then be released to turn turbines and generate electricity at times of peak usage. 100 cubic metres of water pass through each of two huge turbine generators during generation giving a total capacity of over 300MW. Lochaber Hydroelectric Power (84MW): The power generated by the Lochaber hydroelectric turbine is used by the aluminium smelter at Fort William.
Constructed before WWII, a 15 mile 4. 5m wide conduit (for 50 years the world’s longest water supply tunnel) from Loch Laggan to Loch Treig and on to Ben Nevis takes water down to the aluminium smelter power house where it generates over 80MW of electricity. Mossford Power Station(247MW): In the 1950’s the Vaich Dam was constructed creating Loch Vaich. From here and Loch Droma water is taken to another man-made loch, Lock Glascarnoch which is situated behind the Glascarnoch Dam. From there a 5 mile long tunnel takes water to the Mossford power station generating almost 250MW of electricity.
Sloy Power Station (160MW): The Loch Sloy hydro scheme was build just after WWII taking water down from Loch Sloy to Loch Lomond and generating electricity for the city of Glasgow. It is another pumped storage system used to generate electricity at peak periods from the kinetic energy held by water pumped up to Loch Sloy during the night. 2. 1. 6 Hydropower in India: SHP Potential • Potential – 15,000MW. • Identified Potential – 11,356MW (4554 sites). • Installed Capacity – 1975MW (602 projects). • Under Implementation – 649MW (219 projects) 10th Plan Target – 600MW Achievement – 537MW Target for 2007-08 – 200MW Over 2600MW capacity SHP sites offered/allotted to private sector by the States to set up SHP projects Over 110 Small Hydro Power projects aggregating 450 MW commissioned by the private sector. • Karnataka – 280MW • Andhra Pradesh – 110MW • Himanchal Pradesh – 28. 5MW • Maharashtra – 6. 00MW • Uttaranchal – 6. 00MW • Punjab – 7. 75MW • West Bengal – 6. 00MW Top Ten SHP potential States: State Sites (No) Potential in MWAchievement in MW Himanchal Pradesh 323 1624 141. 61 Uttaranchal 354 1478 75. 67 J 201 1207 111. 83 Karnataka 258 652 416. 50 Maharastra 234 1160 209. 33 Kerala 252 514 98. 12 Tamil Nadu 147 338 89. 70 MP 85 336 51. 16 U.
P 211 267 25. 10 A. P 286 254 — Low head mini hydel schemes: The overall capital cost for low head mini hydel schemes is generally high compared to that of the conventional hydel schemes. However in many low head schemes, the release of water is for a long period in a year which improves the plant load factor and enhances the generation of energy. Hence taking up such low head mini hydel schemes could to be financially viable. TCE’s experience on low head, mini hydel schemes: TCE has recently taken up feasibility studies to establish techno-economic viability of four projects in Punjab wherein the head is less than 4 m (a) Khanpur – Head 2. m, Capacity – 3 x 500 kW (b) Gholian – Head 3 m, Capacity – 2 x 500 kW (c) Channowal- Head 3. 9 m, Capacity – 2 x 500 kW (d) Kunjar- Head 2. 8 m, Capacity – 1 x 750 kW These four projects are good examples of low head mini hydel schemes wherein siphon intake type turbines are considered. They are techno economically viable and have been recommended for implementation. As per the delivery list of manufacturers available, there are some low head mini hydel schemes with head and capacity as listed below operating satisfactorily in India. •? Range of head – 1. 8 m to 4 m •? Range of Output – 400 kW to 1200 kW 2. 1. 7 HYDROPOWER IN SRILANKA:
The south-western quarter of Sri Lanka is characterised by persistent rainfall that lasts for nearly nine months in some parts of the hill country. The mean annual rainfall varies from about 5500 mm, in the wettest parts of the island, to around 3000 mm in most parts of the central and south-west mountain ranges. Geologically, these mountain ranges are characterised by steeply dissected hilly and rolling terrain. This geo-climatic combination causes a large number of streams to radiate from the upper reaches of mountains. They merge downstream to form some of Sri Lanka’s major rivers, such as Kelani Ganga, Mahaweli Ganga and Kalu Ganga.
Small streams in the upper catchments as well as major rivers offer considerable potential to generate hydroelectric power. Colonial planters, who established large-scale plantations in the south-western quarter of the island, were the first to tap hydro power in small streams to generate electricity and motive power for their plantation industries. It is estimated that around 500 such micro-hydro plants had been in operation in the early part of the 20th century. This paper presents a preliminary assessment of the small hydro potential in Sri Lanka, focussing largely on the plantation sector.
It is based on a two-year research study conducted by the Sri Lanka Country Office of the Intermediate Technology Development Group. Table: 2. 7 Numbers of Sites Utilized Capacity and Exploitable Potential in Old Estate Sites. Classification of SitesNo. of SitesUtilized Capacity (KW)Exploitable Potential (KW) In operation49334310367 Not in operation145442555 Abandoned74222810746 Total137611523668 Table 2. 8 Distribution of New Estate Sites by District: DistrictNumber of Sites Exploitable Potential (KW)Average Site Potential (KW) Nuwara Eliya3712496338 Kegalle72888412
Ratnapura82451307 Kandy91697188 Badulla91093121 Galle19292 Total71207231458 Table 2. 9 Distribution of Non Estate Sites by District: DistrictNumber of Sites Capacity (KW)% Composition of Capacity Ratnapura222680051 Kegalle11997219 Kandy5685013 Nuwara Eliya8584710 Badulla130676 Matara24791 Total4753016100 2. 1. 8 Low head Hydro Power in the South-East of England: The low head hydro resource in the SE of England has been utilized for many centuries. For example, the region is festooned with a myriad of old mills which historically used water power to grind corn to make flour.
Use of such a natural resource is a part of our Heritage. Using it again to produce energy can make environmental and economic sense providing real benefits to local communities and the region. The study explores the various sources of low head hydro power available, namely from old mill sites and from weirs. It concludes that there are an enormous number of potential sites that might technically be used for energy generation (electricity). The technical resource is estimated to be more than 13MWe assuming a minimum size of 3kWe or an equivalent likely head of at least one meter.
This is based on 525 sites considered across the region and uses information gleaned from a subset of 50 sites analyzed in great detail following more than 100 individual site visits and appraisals. Bearing in mind the effect of non-technical constraints such as sites where the environmental impact is likely to be an over riding issue, planning, poor economic potential and site access then this potential is reduced to a practical resource of 6. 28MWe based on 157 potential sites. A further estimate is given of the likely short term realizable resource that might be mobilized to meet the 2010 regional renewable target.
This takes into account the likelihood of owners of sites progressing with projects. 2. 1. 9 Hydropower in South Korea: South Korea to Build World’s Largest Tidal Power Plant Sihung City, South Korea [RenewableEnergyAccess. com] Plans are well underway for a tidal energy power plant off the South Korean coast that developers say will be the largest such project in the world. Known as the Sihwa Tidal Power Plant, the project would generate 260 MW from the constant flow of water in and out of a seaside bay. The plant will generate electric power by using the head between the high tide and the reservoir level.
The tidal power plant, with a total project cost of approximately USD $250 million, would be the first of its kind in South Korea and the largest in the world, according to the developers and companies involved. The project will consist of a powerhouse for 10 “bulb-type” turbines with direct driven generators including gates and other equipment. The output of each turbine and generator will be 26 MW (total 260 MW installed capacity). The power plant is designed to be operated in one direction from the sea to the Sihwa Lake, allowing up to 60 billion tons of seawater to be circulated annually.
In doing so the plant will generate electric power by using the head between the high tide and the reservoir level. Equipment contracts are already underway for the project’s main components. VA Tech Hydro, an international supplier of equipment and services for hydropower plants, was awarded an order from Daewoo Engineering & Construction for engineering and delivery of the electromechanical main components for the world’s largest tidal power plant – the Sihwa Tidal Power Plant – in South Korea.
The Korea Water Resources Corporation (KOWACO) is the governmental water authority of South Korea and acts as the project developer / owner. Daewoo, as leader of the Korean joint venture with other civil companies, is the project’s main contractor. VA Tech Hydro will carry out the detailed design for the turbine / generator equipment as technology provider while at the same time being responsible for supplies and services with respect to the electro-mechanical portion as sub-contractor of Daewoo.
Additionally, the company will supply all the major equipment for the turbines and generators. Not only will the project generate power, but VA Tech Hydro said the existing water quality of the Sihwa Lake will be significantly improved. Due to industrial facilities taking process water out of the lake and releasing waste water into it, the zone has over and over again been the subject matter of discussions during the past years. Regularly flushing the Sihwa Lake with sea water was identified as an acceptable method of remediation, according to the company.
It was obvious that such an investment would only be cost-effective, if the operator simultaneously gained profit out of the energy production of a tidal power plant. The Sihwa Lake Tidal Power Plant is set to open up a new chapter in the domestic alternative energy development as South Korea plans to significantly increase spending on alternative energy sources in the coming years. The country expects their share of alternative energy to be increased from 1. 4 percent to 5 percent by 2011.
The project expected to be completed by 2009. 2. 2 Low Head Plants in Egypt: Naga Hammadi The existing Naga Hammadi Barrage is located on the River Nile in Upper Egypt 360 km downstream of Aswan Dam and 135 km north of the city of Luxor. It was commissioned in 1930 and forms together with the barrages in Esna (193 km upstream) and Assiut (185 km downstream), a series of structures in the River Nile to provide rised river water levels for irrigation of the areas downstream of each barrage.
A conceptual study comparing rehabilitation of the existing barrage at Naga Hammadi and construction of a New Barrage resulted in a New Barrage with inclusion of a hydropower plant being the most economic alternative. The New Barrage will be located some 3,500 m downstream of the existing structure in a confined reach of the river and where geologic conditions enable the establishment of a large construction pit in the river with a depth of 25 m below river water level. The New Barrage consists of a navigation lock, a sluiceway with 7 vents and a run-of-river hydropower plant with bulb turbines and an installed capacity of 64 MW.
For the feasibility design, comprehensive geotechnical investigations including geophysical surveys and pumping tests were carried out, flood release capacities of the High Aswan Dam and the emergency release capability of the Toshka spillway were assessed, river hydraulics during diversion and operation were simulated by two-dimensional mathematical flow modelling followed by physical hydraulic model tests and economic and financial analysis for the hydropower component were finally carried out.
A full Environmental Impact Assessment was performed, comprising detailed surveys in the fields of agriculture, irrigation and drainage, wildlife and fisheries, land tenure, groundwater, upstream infrastructure, public health, sanitation and water supply. A three-dimensional Finite- Element-Groundwatermodel was applied to simulate present and future groundwater levels in the upstream project area. Client: Ministry of Water Resources and Irrigation, Cairo Ministry of Electricity and Energy, Cairo Main Data: No. of bulb turbines: 4 Rated turbine discharge: 320 m /s
Maximum turbine discharge: 460. 5 m /s Net head range: 7. 97 m / 2. 40 m Installed capacity: 64 MW Annual energy output: 462 GWh Sluiceway capacity: 7,000 m /s Navigation locks usable length/width: 170 m / 17 m Execution: since 1992 Table 2. 2 the main characteristics of the existing Tidal energy sites and examples of others that have been studied. SiteMean Tidal Range (m)Basin Area (km2)Installed Capacity (MW)Design output (Gwh/year)In-Service Date or Status Rance (France)8. 0172405401966 Kislogubsk (Russia)2. 420. 411968 Jiangxia (China)7. 123. 2111980 (1st unit) Annapolis (Canada)6. 620501984 Severn (UK)8. 3520860014400Studied A8 Bay Fundy (Canada)9. 29014003420Studied B6 Bay Fundy (Canada)11. 0240486414004Studied Garolin (Korea)5. 185400800Studied Kachch (India)5. 01706001600Studied Secure Bay (Australia)5. 2947401400Studied Walcott (Australia)5. 526417503310Studied Mersey (UK)6. 5607003310Studied Chapter: 3 3. 0 LOW HEAD HYDRO POTENTIAL IN BANGLADESH Several studies have reported the micro hydro potentials in different regions of the country. Table 3. 1 shows some of these data. The head varies from 2m to 10m whereas the flow rate varies from 40 to 1000 l/s.
Again there is a seasonal variation both in flow rates and available head. The output power is calculated as P = 5 Q Ho (kW), Where Q is the flow rate in m /s and Ho is the available head in meter and assuming 50% system efficiency. Table: 3. 1 Hydro power potential: Site EstimatedAverage Discharge(l/s)Available Head, Ho (m)Output Power(KW) Sailopropat, Banderban [ Ref. 3] 10063 Madhabkundu,Moulouvibazar [ Ref. 3]150107. 5 Faizlake[Ref. 5]42. 5122. 5 Chota Karina Chara[Ref. 5]31169. 3 Ringuli Chara[Ref. 5]3404. 67. 8 Sealock[Ref. 5]113295. 1 Longi Chara[Ref. 5]42536. Budia Chara[Ref. 5]1707. 66. 5 Nikhari Chara[Ref. 5]4806. 816. 3 Madhab Chara[Ref. 5]9969. 949 Table 3. 2 Tidal levels in Coastal Bangladesh (BIWTA, 1999). [Ref. 6] StationLATMLWSMLWNMLMHWNMHWSHATTD(AT) Hiron Points-0. 2560. 2250. 9051. 7002. 4953. 1753. 6563. 912 Sundarikota-0. 5530. 0360. 6361. 8293. 0223. 6944. 2114. 764 Mongla-0. 2610. 3251. 1942. 3103. 4274. 2964. 8825. 143 Khal no. 10-0. 4440. 2611. 2312. 6644. 0975. 0675. 7726. 216 Sadarghat-0. 4230. 2391. 1002. 4813. 8614. 7225. 3855. 808 Cox’s Bazar-0. 3390. 2051. 0231. 9952. 9673. 7854. 3294. 668 S. Island-0. 3480. 911. 0451. 8742. 7033. 5574. 0964. 444 Sandwip-0. 5830. 2381. 6343. 2434. 8516. 2487. 0707. 653 Char Changa-0. 3750. 2561. 0602. 0373. 0143. 8184. 4494. 824 Khepupara-0. 3230. 1951. 0252. 0603. 0963. 9254. 4454. 768 C. Ramdaspur-0. 2610. 1890. 7632. 0363. 3093. 8834. 3334. 594 Barisal+0. 1340. 4340. 6921. 5392. 3862. 6442. 9442. 810 Chandpur+0. 0190. 2560. 4932. 1723. 8524. 0884. 3264. 307 Nalmuri+0. 0780. 3700. 7222. 1953. 6694. 0214. 3134. 235 Narayanganj+0. 4580. 5850. 6972. 7704. 8444. 9565. 0834. 625 Galachipa-0. 1590. 2830. 9371. 7642. 5923. 2453. 6893. 848 Patuakhali-0. 430. 2420. 7401. 5752. 4092. 9073. 2933. 436 Explanation: MLWS = Mean Low Water Spring, MHWS = Mean High Water Spring, MHWN = Mean High Water Neap, MLWN = Mean Low Water Neap, ML = Mean Level, AT = Astronomical Tide, LAT = Lowest Astronomical Tide, HAT = Highest Astronomical Tide, TD = Difference between lowest and highest tidal height in “m”. Table 3. 3 Potential Small Hydro Sites identified by BPTB and BWDB Engineers [BPDB]. SI. NO. DistrictRiver/ Chara /StreamPotentiality of Electrical Energy. (kw) 1ChittagongFaiz Lake 4 2ChittagongChota Kumira15 3ChittagongHinguli Chara12 Chittagong Hill TracksSealock81 5ChittagongLungichara10 6ChittagongBudichara10 7SylhetNikhan Chara26 8SylhetMadhab Chara78 9SylhetBanga Pani Gung616 10JamalpurBhugai-Kangsa60 kw for 10 months 48 kw for 2 months 11JamalpurMarisi35 kw for 10 months 20 kw for 2 months 12DinajpurBadul24 13DinajpurChawai 32 14DinajpurTalma 24 15DinajpurPathraj 32 16DinajpurTangon 48 17DinajpurPunarhaba 11 18RangpurBari Khora32 19RangpurFulkumar48 Chapter: 4 4. 1 HYDROPOWER BASICS: 4. 1. 1 Head and Flow: Hydraulic power can be captured wherever a flow of water falls from a higher level to a lower level.
This may occur where a stream runs down a hillside or a river passes over a waterfall or man-made weir, or where a reservoir discharges water back into the main river. 4. 2 Details about Head: (according to British Hydropower Association) 4. 2. 1 Definition of Head: Electricity is produced from the potential energy in water moving from a high point to a lower one. This distance is called “head” and is measured in units of distance: meters (or feet) or in units of pressure. Classification of Head: Low head: Sites where the gross head* is less than 10m would normally be classed as “low head”.
Medium head: sites where the gross head is 10-50m would typically be called “medium head”. High head: sites where the gross head is above 50m would be classed as high head. *The Gross Head (H) is the maximum available vertical fall in the water, from the upstream level to the downstream level. The actual head seen by a turbine will be slightly less than the gross head due to losses incurred when transferring the water into and away from the machine. This reduced head is known as the Net Head. Sites where the gross head is less than 10 m would normally be classed as “low head”.
From 10-50 m would typically be called” medium head”. Above 50 m would be classed as “high head”. The Flow Rate (Q) in the river is the volume of water passing per second, measured in m3/sec. For small schemes, the flow rate may also be expressed in liters/second where 1000 liters/sec is equal to 1m3/sec. 4. 2. 2Head measurements: The head of water available at any one site can be determined by measuring the height difference between the water surface at the proposed intake and the river level at the point where the water will be returned.
A number of reference books can provide details of basic survey techniques to measure or estimate the available head. The most common methods are summarized as follows. An initial estimate for a high-head site (; 50m) can be taken from a large-scale map, simply by counting the contours between the inlet and discharge points: the distance between contours on standard Ordnance Survey maps is 10 m. Altimeters can also be useful for high-head pre-feasibility studies. Surveying altimeters in experienced hands will give errors of as little as 3% in 100m. Atmospheric pressure variations need to be corrected readings. 4. 2. Hydropower Potential: There are two main factors that determine the generating potential at any specific site: the amount of water flow per time unit and the vertical height that water can be made to fall (head). Head may be natural due to the topographical situation or may be created artificially by means of dams. Once developed, it remains fairly constant. Water flow on the other hand is a direct result of the intensity, distribution and duration of rainfall, but is also a function of direct evaporation, transpiration, infiltration into the ground, the area of the particular drainage basin, and the field-moisture capacity of the soil.
Runoff in rivers is a part of the hydrologic cycle in which -powered by the sun – water evaporates from the sea and moves through the atmosphere to land were it precipitates, and then returns back to the sea by overland and subterranean routes. Hydro power potential can be estimated with the help of river flows around the world. The results show that this total resource potential is 50 000 TWh per year – only a quarter of the world precipitation, but still over four times the annual output of all the world present power plants.
Realistic resource potential which is based on local conditions of world rivers is in range 2 – 3 TW with an annual output of 10 000 – 20 000 TWh (UN 1992). But the important question remains : how much of hydro potential can we afford to use (see the chapter on environmental aspects). A theoretical yearly production potential of 10. 000 TWh of electrical energy means that the same amount of electrical energy produced in thermal plants with oil as fuel would require approximately 40 million barrels of oil per day. If this is compared to the world consumption of petroleum products, which amounted to around 80 million barrels per day in 1995.
For developing countries, who together possess almost 60% of the installed potential, the magnitude is striking. 4. 2. 6 Problems of Hydropower: The main reasons that hydro power plants are not build everywhere are that they are costly and require large bodies of water relatively close to inhabitants. According to the World Bank, “developing countries will need to raise an estimated USD 100 billion by the year 2000 for hydroelectric plants currently in the planning stage. ” Another arising problems are the effects of dams on river ecosystems and social problems related to relocation of inhabitants. . 2. 6. 1 Environmental Aspects of Hydropower Plants: A watercourse is an ecological system where changes within one component may create a series of spread-effects. For instance, changes in the water flow may affect the quality of the water and the production of fish downstream. Dam barriers may greatly change the living conditions for fish. Environmental changes may be traced far downstream, at times even out into the sea. In the tropics there may be great seasonal variations as to the amount of precipitation, and in dry periods evaporation from lakes and reservoirs may be considerable.
This may affect the water level of the reservoirs more dramatically than in temperate areas. The watercourse and its watershed mutually influence each other. The watercourse, for example, may affect the local climate and the ground-water level in surrounding areas. The sedimentation taking place in a reservoir can often lead to increased erosion downstream, i. e. an increase in the total erosion. Changes in water flow and water level will also lead to changes in the transportation of sediments. During the construction phase the transport of mud and sediments will be especially large downstream from the construction area.
Excavation and tunnelling may lead to greatly reduced water quality and problems for those dependent on the water. 4. 2. 6. 2 Groundwater: The groundwater level is important for the ecosystem‘s composition and development of plant and animal species. Groundwater is particularly important as a drinking-water source in most countries. The filling of a reservoir of hydro power plant and the flow of a watercourse are of great importance to the groundwater level and for the feeding of the groundwater reservoirs.
A reservoir, together with the changes and variations of the water level caused by its operation, will change the groundwater level in surrounding areas. These areas may in turn influence the quality of the water and the sediment transport of the watercourse as a result of area run-off and erosion. 4. 2. 6. 3 Excessive Fertilization: Whenever nutrients are trapped in a reservoir, the result may be excessive fertilisation – eutrophication – in the reservoir. It may lead to an increased growth of algae or large amounts of higher-order aquatic plants.
A substantial production of organic matter in the reservoir, or the supply of external organic matter, may cause anaerobic conditions – lack of oxygen – in the deep water layers. On the whole, shallow lakes with a large surface area are most at risk, partly because the reserve of oxygen in the deep-water layers is limited in proportion to the productive area in the top layers. In deep, narrow lakes the oxygen content in the deep-water layers will be sufficient to recycle organic matter sinking down, provided there is a regular circulation of the waters. This is not always the case in the tropics.
If the watercourse is initially rich in nutrients, the risk of eutrophication will increase. Evaporation may cause a concentration of nutrients, leading to excessive fertilization or eutrophication. Tropical soil normally has-low humus content. This combined with the great seasonal variations as to the amount of precipitation, and the fact that precipitation often comes in heavy showers, may cause considerable erosion. The transportation of eroded sediments will be halted and deposited in a reservoir. The reservoir’s lifetime may in this way be reduced.
Transport of sediments and nutrients tends to play a crucial role in the ecosystem of a watercourse. The population’s utilization of nature and natural resources may be completely dependent on floods and waterborne sediments and nutrients. 4. 2. 6. 4 Transport of Nutrients: A reservoir serves as a trap for nutritious elements and mud flowing in, possibly leading to a considerable reduction of the total transport of nutrients downstream. In addition, the annual variations in supply downstream may undergo changes. This may reduce the biological production all the way to the sea.
There are grave examples of marine fishing being impaired in the wake of a major dam development. 4. 2. 6. 5 Fish: The composition of fish species may be altered, since reproduction for some species may be hindered if the operation involves changes in the water level during the spawning period. Artificial reservoir tends to contain a less varied composition of species than a natural lake. Changes in the water flow and water-flow pattern may radically alter nutrient and spawning conditions downstream. The primary production as well as the direct accessibility of nutriment for fish will change.
Changes made to the downstream floods, as a result of water control, may be decisive. At dam and turbine outlets a surfeit of gas may occur, principally of nitrogen, which can cause death among fish. 4. 2. 6. 6 Population Movement: Large hydro power plants with dams require large reservoir and discharge areas. Many people have to be evacuated to make room for these areas. This could lead to a completely new situation for people who have lived in a relatively small, protected environment. Housing, land distribution, working conditions and way of life may change radically. The impacts will depend upon the size and location of the project.
Social consequences are likely to arise if the population concerned should be pressured into settling down in, or exploiting, more marginal and ecologically vulnerable areas than the ones they have traditionally utilized. These impacts may further aggravate their situation. Such indirect environmental effects can cause considerable ecological problems. Indigenous groups affected by hydropower development may be particularly deprived. Their principle socio-cultural conditions together with their traditional connection to land, water and other natural resources tend to m
