Introduction hydroelectric Power what is it?

part of a system, or a piece of equipment. It is expressed in 
kilowatts, kilovolt amperes, or other suitable units at a given 
instant or averaged over any designated period of time. The 
primary source of "demand" is the power-consuming equipment of 
the customers. 
Direct Current 
Electric current going in one direction only. 
Distribution System
The portion of an electric system that is dedicated to delivering 
electric energy to an end user. The distribution system "steps 
down" power from high-voltage transmission lines to a level that 
can be used in homes and businesses. 
Energy 
The capacity for doing work as measured by the capability of 
doing work (potential energy) or the conversion of this capability 
to motion (kinetic energy). Energy has several forms, some of 
which are easily convertible and can be changed to another form 
useful for work. Most of the world's convertible energy comes 
from fossil fuels that are burned to produce heat that is then used 
as a transfer medium to mechanical or other means in order to 
accomplish tasks. Electrical energy is usually measured in kilowatt 
hours and represents power (kilowatts) operating for some time 
period (hours), while heat energy is usually measured in British 
thermal units.
Generation (Electricity)
The process of producing electric energy by transforming other 
forms of energy; also, the amount of electric energy produced, 
expressed in watthours (Wh). 
Generator 
A machine that converts mechanical energy into electrical energy. 
Head 
The difference in elevation between the headwater surface above 
and the tailwater surface below a hydroelectric powerplant under 
specified conditions. 
Horsepower 
A unit of rate of doing work equal to 33,000 foot pounds per 
minute or 745.8 watts (Brit.), 746 watts (USA), or 736 watts 
(Europe). 
Hydroelectric Power 
Electric current produced from water power. 
Hydroelectric Powerplant 
A building in which turbines are operated, to drive generators, by 
the energy of natural or artificial waterfalls. 

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Kilowatt (kW) 
Unit of electric power equal to 1,000 watts or about 1.34 
horsepower. For example, it's the amount of electric energy 
required to light ten 100-watt light bulbs. 
Kilowatt-Hour (kWh) 
The unit of electrical energy commonly used in marketing electric 
power; the energy produced by 1 kilowatt acting for one hour. Ten 
100-watt light bulbs burning for one hour would consume one 
kilowatt hour of electricity. 
Kinetic Energy 
Energy which a moving body has because of its motion, dependent 
on its mass and the rate at which it is moving. 
Load (Electric) 
The amount of electric power delivered or required at any specific 
point or points on a system. The requirement originates at the 
energy-consuming equipment of the consumers. 
Megawatt
A unit of power equal to one million watts. For example, it's the 
amount of electric energy required to light 10,000 100-watt bulbs. 
Ohm 
The unit of measurement of electrical resistance. The resistance of 
a circuit in which a potential difference of one volt produces a 
current of one ampere. 
Peakload 
The greatest amount of power given out or taken in by a machine 
or power distribution system in a given time. 
Power 
Mechanical or electrical force or energy. The rate at which work 
is done by an electric current or mechanical force, generally 
measured in watts or horsepower. 
Pumped-Storage 
A plant that usually generates electric energy during peak-load 
Hydroelectric Plant
periods by using water previously pumped into an elevated storage 
reservoir during off-peak periods when excess generating capacity 
is available to do so. When additional generating capacity is 
needed, the water can be released from the reservoir through a 
conduit to turbine generators located in a power plant at a lower 
level. 
Rated Capacity 
That capacity which a hydro generator can deliver without 
exceeding mechanical safety factors or a nominal temperature rise. 
In general this is also the nameplate rating except where turbine 
power under maximum head is insufficient to deliver the 
nameplate rating of the generator. 

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Reservoir 
An artificial lake into which water flows and is stored for future 
use. 
Turbine 
A machine for generating rotary mechanical power from the 
energy of a stream of fluid (such as water, steam, or hot gas).
Turbines convert the kinetic energy of fluids to mechanical energy 
through the principles of impulse and reaction, or a mixture of the 
two. 
Volt (V) 
The unit of electromotive force or potential difference that will 
cause a current of one ampere to flow through a conductor with a 
resistance of one ohm. 
Watt (W) 
The unit used to measure production/usage rate of all types of 
energy; the unit for power. The rate of energy transfer equivalent 
to one ampere flowing under a pressure of one volt at unity power 
factor. 
Watthour (Wh) 
The unit of energy equal to the work done by one watt in one hour. 

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Document Outline

• INTRODUCTION
• Low-head Hydropower
• Peaking with Hydropower
• Hydropower, the Environment, and Society
  • GLOSSARY