hydroelectric power is the electricity obtained by
harnessing the power
of water flowing down from a high level. It is a timeless
Huge generators convert the potential energy of
or fast moving water into electrical energy. The potential
of the water is first converted into mechanical energy and
Water, usually stored in dams, is led down through
large pipes or tunnels to lower levels, and in the course of
the water rotates turbines. The mechanical energy produced
converted to electricity by the generators connected to it.
The structure that
houses the turbines and generators is called the powerhouse.
Transformers change the alternating current produced by the
generators into current of very high
voltage for easy transmission through long distances.
Hydropower is one of
the three principal sources of energy used to generate
the other two being fossil fuels and nuclear fuels.
has certain advantages over these other sources: it is
renewable thanks to the recurring nature of the water cycle,
and causes no pollution. Also, it is one of
the cheapest sources of electrical energy.
The Itaipú Dam
between Brazil and Paraguay, which is 190 metres high
generates more than 12,600 MW, is the largest
hydropower dam in the world. (The
185-metre Three Gorges Dam, now being constructed in China
on the upper
Yangtze River, would take its place by 2009, producing 18,200
MW of power ). The
Grand Coulee Dam, located near Spokane, Washington, is the
hydropower dam in the United States, producing 6,480 MW. The
Dam, in Russia, the tallest in the world, is 335 metres
The Oroville dam, located in California, the tallest in the
United States, is 235 metres high. Idukki
dam in India is Asia's
first and largest archdam.