Introduction hydroelectric Power what is it?

HOW HYDROPOWER WORKS
Hydroelectric power comes from water at work, water in motion. It can be seen as a form of 
solar energy, as the sun powers the hydrologic cycle which gives the earth its water. In the 
hydrologic cycle, atmospheric water reaches the earth
=
s surface as precipitation. Some of this 
water evaporates, but much of it either percolates into the soil or becomes surface runoff. Water 
from rain and melting snow eventually reaches ponds, lakes, reservoirs, or oceans where 
evaporation is constantly occurring. 

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Moisture percolating into the soil may become ground water (subsurface water), some of which 
also enters water bodies through springs or underground streams. Ground water may move 
upward through soil during dry periods and may return to the atmosphere by evaporation. 
Water vapor passes into the atmosphere by evaporation then circulates, condenses into clouds, 
and some returns to earth as precipitation. Thus, the water cycle is complete. Nature ensures 
that water is a renewable resource. 
Generating Power
In nature, energy cannot be created or destroyed, but its form can change. In generating 
electricity, no new energy is created. Actually one form of energy is converted to another form. 
To generate electricity, water must be in motion. This is kinetic (moving) energy. When 
flowing water turns blades in a turbine, the form is changed to mechanical (machine) energy.
The turbine turns the generator rotor which then converts this mechanical energy into another 
energy form -- electricity. Since water is the initial source of energy, we call this hydroelectric 
power or hydropower for short. 
At facilities called hydroelectric powerplants, hydropower is generated. Some powerplants are 
located on rivers, streams, and canals, but for a reliable water supply, dams are needed. Dams 
store water for later release for such purposes as irrigation, domestic and industrial use, and 
power generation. The reservoir acts much like a battery, storing water to be released as needed 
to generate power. 

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The dam creates a 
A
head
@
or height from which water flows. A pipe (penstock) carries the water 
from the reservoir to the turbine. The fast-moving water pushes the turbine blades, something 
like a pinwheel in the wind. The waters force on the turbine blades turns the rotor, the moving 
part of the electric generator. When coils of wire on the rotor sweep past the generator
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s 
stationary coil (stator), electricity is produced. 
This concept was discovered by Michael Faraday in 1831 when he found that electricity could be 
generated by rotating magnets within copper coils. 
When the water has completed its task, it flows on unchanged to serve other needs.