Introduction hydroelectric Power what is it?

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INTRODUCTION 
Hydroelectric Power -- what is it? 
It
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s a form of energy … a renewable resource. Hydropower provides about 96 percent of the 
renewable energy in the United States. Other renewable resources include geothermal, wave 
power, tidal power, wind power, and solar power. Hydroelectric powerplants do not use up 
resources to create electricity nor do they pollute the air, land, or water, as other powerplants 
may. Hydroelectric power has played an important part in the development of this Nation's 
electric power industry. Both small and large hydroelectric power developments were 
instrumental in the early expansion of the electric power industry. 
Hydroelectric power comes from flowing water … winter and spring runoff from mountain 
streams and clear lakes. Water, when it is falling by the force of gravity, can be used to turn 
turbines and generators that produce electricity. 
Hydroelectric power is important to our Nation. Growing populations and modern technologies 
require vast amounts of electricity for creating, building, and expanding. In the 1920's, 
hydroelectric plants supplied as much as 40 percent of the electric energy produced. Although 
the amount of energy produced by this means has steadily increased, the amount produced by 
other types of powerplants has increased at a faster rate and hydroelectric power presently 
supplies about 10 percent of the electrical generating capacity of the United States. 
Hydropower is an essential contributor in the national power grid because of its ability to 
respond quickly to rapidly varying loads or system disturbances, which base load plants with 
steam systems powered by combustion or nuclear processes cannot accommodate. 
Reclamation
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s 58 powerplants throughout the Western United States produce an average of 42 
billion kWh (kilowatt-hours) per year, enough to meet the residential needs of more than 14 
million people. This is the electrical energy equivalent of about 72 million barrels of oil.
Hydroelectric powerplants are the most efficient means of producing electric energy. The 
efficiency of today's hydroelectric plant is about 90 percent. Hydroelectric plants do not create 
air pollution, the fuel--falling water--is not consumed, projects have long lives relative to other 
forms of energy generation, and hydroelectric generators respond quickly to changing system 
conditions. These favorable characteristics continue to make hydroelectric projects attractive 
sources of electric power.