hydroelectrical power generation traditional methods of hydroelectric generation low head power...
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Hydroelectrical Power Generation
Traditional Methods of Hydroelectric Generation
Low Head Power Generation
Medium Head Power Generation
High Head Power Generation
Large Dams (Three Gorges, Itaipu)
Environmental Effects of Large Dams
Energy in the News
Breast Shot Wheel
Breast shot wheel:One type of traditionalWater wheel
Water wheels: sourceOf power for theIndustrial revolution
Overshot Wheel
More efficient that breast shotWheel. Some mills usingThese wheels still in operationIn rural appalachia in 1950’s
Miller: Mrs. Aarendale
Typical Hydroelectrical StationOutflow water: can be very cold. Why? (Grand Canyon)
Low Head Hydroelectrical Generators Low head:Propellor typeTurbines
Power =Change in PotentialEnergy per Unit time
= weight* Vertical drop/time
Energy = Power*time
Microhydro Installation
Small stream withHydroelectrical generator:Power for one family
(Jim Keener)
Moderate Head Hydro
Head: height differenceBetween water level inReservoir and waterLevel entering turbine
Head= height in potentialEnergy equation
Penstock: tube water flowsThrough
Francis turbine
Turbine used for moderateHead hydroelectrical powerstatiosn
Water Flow in a Francis Turbine
Left: relative to turbine blades Right: true water path
High Head Hydro
Pelton Water Wheel
Used for high head applications:(above 250 meters)Are impulse turbines.
Francis and Propeller type turbineAre reaction turbines.
Reaction turbines: run submerged.
Impulse turbines: run in normal air
Jets of Water Hitting Pelton Wheel
Jets of water are directed through a nozzle onto Pelton wheelCups on the wheel transfer kinetic energy from water to wheel.
Optimum Hydroelectric Turbine Type
Optimum waterWheel: notJust a functionOf head, alsoDepends on Water flow rate
Hydroelectrical Power Use by State
States Producing Most Hydroelectricity
Why is thereSo much Variation in theGallons of waterPer kilowatthour?
Hydropower Output by NationLure of Hydropower
Big DamsVs Rebar
Itaipu Dam
Presently world’s largest Hydroelectric plant
On Parana river betweenBrazil and Paraguay
Capacity: 12,600 MW(drought a problem recently):Provides:25% of Brazil power78% of Paraguay power
Three Gorges Area of Yangtze River
Under construction
Three GorgesDam in ChinaMoving 1.2 millionPeople
Capacity of18,600 MW
Will finish in 2009
Three Gorges Area
Great beauty
Many historicSights
Still pressingAhead on damconstruction
Gorge length;~San FranciscoTo LA
Environmental Problems with Dams
1) Silt buildup fills reservoir (Yangtze; levees)2) Fish migration disrupted (Columbia)3)Water temperature decreases (Colorado)4) Water gets more saline (Colorado)5) Water loses oxygen (Brazil)6) Water slows down, increases disease (mosquitos, schitosomiasis (Aswan))7) Water traps pollution, slows pollution flushing8) Induced seismicity may occur