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HYDROPOWER

PRAJAPATI KAUSHIK M.ROLL NO. 064LAXMI INSTITUTE OFTECHNOLOGY,SARIGAM

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FACTS ABOUT HYDROPOWER PLANT

The Worlds hydropower plants output a combined total of 675,000 megawatts, the energy equivalent of 3.6 billion barrelsof oil.worldwide, hydro powers plant produce about 24% of worlds

electricity and supply more than one billion people withpower.hydropower provides about 10% of electricity in united states.

India produces more than 12% of its electricity with

hydropower.Norway produces more than 99% of its electricity withhydropower. New Zealand uses hydropower for 75% of itselectricity.

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World Energy Sources

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Major Hydropower Producers

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HYDROPOWER PLANTA hydropower plant uses the force of falling water to makeelectricity.

Flowing water creates energy that can be captured and turnedinto electricity. This is called hydroelectric power orhydropower .

A typical hydro plant is a system with three parts:a power plant where the electricity is produced.

a dam that can be opened or closed to control water flow.a reservoir (artificial lake) where water can be stored.

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Hydropower to Electric Power

PotentialEnergy

Kinetic

Energy

Electrical

Energy

MechanicalEnergy

Electricity

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THE POWER OF WATER Hydropower ( from hydro meaning water) is energy thatcomes from the force of moving water. The fall and movementof water is part of a continuous natural cycle called the watercycle.

The moisture eventually falls to the earth as rain or snow,replenishing the water in the oceans and rivers. Gravity drivesthe water, moving it from high ground to low ground. Theforce of moving water can be extremely powerful.

Hydropower is called a renewable energy source because thewater on the earth is continuously replenished by precipitation.As long as the water cycle continues, we wont run out of thisenergy source.

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CONCEPT OF HYDRO POWER PLANT

Hydro system makes use of falling water in a stream or riveror storage dam between two points to generate mechanicalpower through a turbine which is converted into electricalpower through a generator attached to turbine in a power

house. Power is expressed as kw or mw depending on capacityof station.Amount of water flow diverted from stream or river or dam

called discharge (q) expressed in litres /sec or cumecs or

cusecs and difference in elevation between two upstream anddownstream points called gross head (h) expressed in feet ormetres. Electricity generated in alternating current (ac) mode andgenerating voltage expressed as volts (v) or kilo volts (kv)depending on capacity of station. 9

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COMPONENT OF HYDRO POWER PLANT

In general, larger the scale of a system, more the number of components.Intake : water from the river/spring/dam/irrigation channel is

diverted from its main course. Generally weir used to divert

water through intake into open channel.Water conductor system : leads water from intake to head of penstock.De-silting basin with spillway : small tank designed to desilt

water. Provide spillway - a flow regulator for the channel.Combined with control gates to provide means of emptyingchannel. Spill flow fed back to river.Forebay tank: at head of penstock. Serves as buffer to control

sudden flow and pressure variations. 10

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COMPONENT OF HYDRO POWER PLANTcontinued..

Penstock: pipeline supplying water from forebay to turbine.Mild steel, upvc and hdpe - most commonly used materials.Power house: houses turbine generator with mechanicalcontrol valves and electrical control panels. Switch yard and

connection to distribution system.Tail race channel: leads water from turbines(s) back intostream/river/irrigation channel.Turbine and generator: hydro power in jet at end of penstock

transmitted to turbine runner - changes to mechanical power.Governor: ensures that generator is not affected when load onit changes. Hydraulic, or electronic. Depends on the generator.Generator: electricity generated when turbine drives generator

-most common type of generator produces alternative currentand known as alternator.

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HYDROPOWER PLANT

Tail water

Draft tube gate

Draft tube

TurbineMain valve

Penstock

Air inletInlet gate

Surge shaft

TunnelSand trap

Trash rack

Self closing valve

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HOW A HYDROPLANT WORKSTo generate electricity, a dam opens its gates to allow waterfrom the reservoir above to flow down through large tubescalled penstocks.At the bottom of the penstocks, the fast-moving water spinsthe blades of turbines.The turbines are connected to generators to produce

electricity.The electricity is then transported via huge transmission linesto a local utility company.

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hydrodams

A dam serves two purposes at a hydro plant. First, a damincreases the head or height of the water. Second, it controlsthe flow of water. Dams release water when it is needed forelectricity production. Special gates called spillway gatesrelease excess water from the reservoir during heavy rainfalls. Dams are built on rivers where the terrain will produce anartificial lake or reservoir above the dam. Most dams are builtfor flood control and irrigation, not electric power generation.

Its easier to build a hydro plant where there is a naturalwaterfall. Dams, which are artificial waterfalls, are the nextbest way.

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Conventional Impoundment Dam

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Schematic of Impound Hydropower

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Terminology Head

Water must fall from a higher elevation to a lower oneto release its stored energy.The difference between these elevations (the water

levels in the forebay and the tailbay) is called headDams: three categories

high-head (800 or more feet)medium-head (100 to 800 feet)

low-head (less than 100 feet)Power is proportional to the product of

head x flow

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Scale of Hydropower ProjectsLarge-hydro

More than 100 MW feeding into a large electricity gridMedium-hydro

15 - 100 MW usually feeding a gridSmall-hydro

1 - 15 MW - usually feeding into a gridMini-hydro

Above 100 kW, but below 1 MWEither stand alone schemes or more often feeding into the grid

Micro-hydroFrom 5kW up to 100 kWUsually provided power for a small community or rural industryin remote areas away from the grid.

Pico-hydroFrom a few hundred watts up to 5kW

Remote areas away from the grid.

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Ecological ImpactsLoss of forests, wildlife habitat, species.Degradation of upstream catchment areas due to inundation of reservoir area.

Rotting vegetation also emits greenhouse gases.Loss of aquatic biodiversity, fisheries, other downstreamservices.Cumulative impacts on water quality, natural flooding.

Disrupt transfer of energy, sediment, nutrients.Sedimentation reduces reservoir life, erodes turbines

Creation of new wetland habitatFishing and recreational opportunities provided by new

reservoirs

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Environmental and Social IssuesLand use inundation and displacement of peopleImpacts on natural hydrology

Increase evaporative lossesAltering river flows and natural flooding cycles

Sedimentation/siltingImpacts on biodiversity

Aquatic ecology, fish, plants, mammalsWater chemistry changes

Mercury, nitrates, oxygenBacterial and viral infection

Seismic RisksStructural dam failure risks

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Impacts of Hydroelectric Dams

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ADVANTAGESHydropowers fuel supply (flowing water) is clean and isrenewed yearly by snow and rainfall.hydro plants do not emit pollutants into the air because theyburn no fuel.With growing concern over greenhouse gas emissions andincreased demand for electricity, hydropower may becomemore important in the future.Hydropower facilities offer a range of additional benefits.Many dams are used to control flooding and regulate watersupply, and reservoirs provide lakes for recreational purposes,such as boating and fishing.Low operating and maintenance cost.

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DISADVANTAGES

Damming rivers may permanently alter river systems andwildlife habitats. Fish, for one, may no longer be able to swimupstream.

Hydro plant operations may also affect water quality bychurning up dissolved metals that may have been deposited byindustry long ago.Hydropower operations may increase silting, change watertemperatures, and lower the levels of dissolved oxygen.Degradation of upstream catchment areas due to inundation of reservoir area.High initial capital cost.

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Efficiency of Hydropower Plants

Hydropower is very efficientEfficiency = (electrical power delivered (potential energyof head water)

Typical losses are due toFrictional drag and turbulence of flowFriction and magnetic losses in turbine & generator

Overall efficiency ranges from 75-95%.

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