# Hydro-electric power plant

pattern of a hydro-electric power plant equipped with a Kaplan turbine

a hydro-electric power plant or a hydroelectric power plant is a power station, which converts the mechanical energy of the water into electric current. Thus water power for humans is made usable.

## function mode

Water is back held by a water retaining structure. The energy of the movement of the flowing off water will transfer to a water turbine or a water wheel, whereby this is shifted in rotating motion. This again becomes direct or over a transmission to the wave of the Generator further led. The generator converts the mechanical energy into electric current.

Further construction units depend, on size and design of the power station:

## achievement

the achievement P depends on the water flow Q and the head of h as well as on the efficiencies [itex] \ eta< /math> the inlet, the water turbine, the transmission and the generator </br>

Approach computation ( g [itex] \ /math <cdot> ρ [itex] \ cdot \ eta = 7 kN /m ^3 [/itex])

< math>

P \ left [KW \ right] = Q \ left [m^3 of /s \ right] \ cdot h \ left [m \ right] \ cdot 7 \ left [kN /m ^3 \ right] [/itex]

The width of the installed achievement lies between few KW and 18.000 Megawatt (three-ravine dam in China).

Hydro-electric power plants obtain a high efficiency. Their turbines and generators can convert up to 90% of usable water power into electric current.

## types from hydro-electric power plants

### organization according to Nutzgefälle

 A typical hydro-electric power plant, here at the Ruhr hydro-electric power plant “Grand Coulee Dam” in the USA

the Nutzgefälle or the head is the difference in height between the water level above the turbine (upper water) and the water level behind the turbine (underwater).

• Niederdruckkraftwerke
flow: largely
kinds of turbine: Kaplan turbine, Durchströmturbine
designs: River-run power plants, tidal power stations, wave power station
• of medium pressure power stations
flow: means - large
kinds of turbine: Francis water turbine, Kaplan turbine, Durchströmturbine
designs: River-run power plants, Storage power stations
• of high pressure power stations
flow: small
kinds of turbine: Francis water turbine, pelton turbine
designs: Organization according to extent of utilization the produced
quantity of electricity (rule work ability

### ) those results in

storage power stations, pump-fed power stations, underground power houses [work on] in relation to the rated output Extent of utilization of a power station.

extent of utilization: > 50%
designs:River-run power plants, tidal power stations, wave power station
extent of utilization: 30 - 50%
designs: River-run power plants with swelling enterprise, storage power stations
extent of utilization: < 30%
designs: Storage power stations, pump-fed power stations, underground power houses

### organizationafter design

with a run hydro-electric power plant is accumulated a river and produced with the flowing off water electric current.
stored with a storage power station the water during one period (several hours until several months), over if necessary valuable point energy tooproduce.
a pump-fed power station is a storage power station, with which with surplus river water from a low situation is pumped to lain artificial lake a more highly.
an underground power house uses artificially created cavities (Kavernen) as energy storage or as locationfor power station components.
a tidal power station uses the energy from the constant change of ebb-tide and tide.
in wave power stations is used, in contrast to a tidal power station, not the Tidenhub, but the energy of the continuous sea waves themselves.
Sea flow power station uses the kinetic energy of Meeresströmungen.
a glacier power station is a special variant of a storage power station, whereby a meltwater lake serves as memory.

## economic meaning

world-wide are produced for scarcely 18 per cent of the electricity with hydro-electric power plants. Norway coversnearly its entire electricity need with water power, Brazil approximately 80 per cent. </br> in Germany amounts to the water power ratio approximately 5 per cent (4,215 MW would install achievement, 18.6 TWh rule work abilities). In Austria annually approximately 36 TWh river are produced by hydro-electric power plants, that are round55% of the total production.

The costs of the investments of hydro-electric power plants lie much high and load the profitability of the plant. Therefore the electric current produced in hydro-electric power plants is first of all more expensive than in comparable steam power plants. The Kostenlosigkeit that almost for an unlimited periodthe available becomes resources water power only apparent if proceeds of the sold river covered the costs of the establishment of the power station . For this reason hydro-electric power plants are laid out for a high life span, around this effect as for a long time as possible use toocan.

Hydro-electric power plants are established preferentially in the central and high mountains as well as at large rivers, over by large difference in height and/or. To increase flow economy.

## ecological effect

the landscape consumption when putting on hydro-electric power plants, particularly with the building by new Artificial lakes or barriers can to conflicts lead, with which the disadvantages and advantages, also compared with other solutions, must be weighed out in individual cases.

• renewable form of energy in large yardstick (restriction: Pump-fed power stations)
• no emissions of greenhouse gases (restriction:Pump-fed power stations, as well as methane missions with artificial lakes, under which before the flow the vegetation was not removed (S. Tucuruí))
• Channel regulation, flood protection (water is held back in water-rich times and delivered proportioned)
• improved navigability of rivers
• cleaning of the rivers (driving property becomes from the rakethe power station held back and disposed)
• irrigation (water is available also in water-poor times)

• resettlement of the inhabitants
• ecological changes, impairment of nature and landscape, destruction of the natural running waters regime
• over congestion and destruction of cultural properties
• dam knowsEarthquakes release (“reservoir induced being SMI town center”)
• dam failure

## history

the technical predecessor of the hydro-electric power plant were the Wassermühle, whereby the estimated number of 100.000 to in 20. Century in Germany of existing water wheels on approximately 8,000 water turbines decreased/went back. Thosewith the century-long use of the Wassermühlen developed pilot rights remained existing and be able against it in many cases today with modern water wheels to be re-activated.