HYDROPOWER
Energy from Moving Water
HYDROPOWER GENERATES ELECTRICITY
Of the renewable energy sources that generate
electricity, hydropower is the most often
used. It accounted for 7 percent of total
U.S. electricity generation and 73 percent
of generation from renewables in 2005.
It is one of the oldest sources of energy
and was used thousands of years ago to turn
a paddle wheel for purposes such as grinding
grain. Our nation’s first industrial
use of hydropower to generate electricity
occurred in 1880, when 16 brush-arc lamps
were powered using a water turbine at the
Wolverine Chair Factory in Grand Rapids,
Michigan. The first U.S. hydroelectric power
plant opened on the Fox River near Appleton,
Wisconsin, on September 30, 1882. Until
that time, coal was the only fuel used to
produce electricity. Because the source
of hydropower is water, hydroelectric power
plants must be located on a water source.
Therefore, it wasn’t until the technology
to transmit electricity over long distances
was developed that hydropower became widely
used.
HOW HYDROPOWER WORKS
Understanding the water cycle is important
to understanding hydropower. In the water
cycle -
Solar energy heats water on the surface,
causing it to evaporate.
This water vapor condenses into clouds and
falls back onto the surface as precipitation.
The water flows through rivers back into
the oceans, where it can evaporate and begin
the cycle over again.
Mechanical energy
is derived by directing, harnessing, or
channeling moving water. The amount of available
energy in moving water is determined by
its flow or fall.Swiftly flowing
water in a big river, like the Columbia
River
along
the border between Oregon and Washington,
carries a great deal of energy in its flow.
So, too,with water descending rapidly from
a very high point, like Niagara Falls in
New York. In either instance, the water
flows through a pipe, or penstock,then
pushes against and turns blades in a turbine
to spin a generator to produce electricity.
In a run-of-the-river system, the
force of the current applies the needed
pressure, while in a storage system,
water is accumulated in reservoirs created
by dams, then released when the demand for
electricity is high. Meanwhile, the reservoirs
or lakes are used for boating and fishing,
and often the rivers beyond the dams provide
opportunities for whitewater rafting and
kayaking.
Hoover Dam,
a hydroelectric facility completed in 1936
on the Colorado River between Arizona and
Nevada, created Lake Mead, a 110-mile-long
national recreational area that offers water
sports and fishing in a desert setting.
WHERE HYDROPOWER IS GENERATED
Over one-half of the total U.S. hydroelectric
capacity for electricity generation is concentrated
in three States (Washington, California
and Oregon) with approximately 27 percent
in Washington, the location of the Nation’s
largest hydroelectric facility – the Grand
Coulee Dam.
It is important to note that only a small
percentage of all dams in the United States
produce electricity. Most dams were constructed
solely to provide irrigation and flood control.
HYDROPOWER AND THE ENVIROMENT
Some people regard hydropower as the ideal
fuel for electricity generation because,
unlike the nonrenewable fuels used to generate
electricity, it is almost free, there are
no waste products, and hydropower does not
pollute the water or the air. However, it
is criticized because it does change the
environment by affecting natural habitats.
For instance, in the Columbia River, salmon
must swim upstream to their spawning grounds
to reproduce, but the series of dams gets
in their way. Different approaches to fixing
this problem have been used, including the
construction of "fish ladders" which help
the salmon "step up" the dam to the spawning
grounds upstream.
Last Revised: May 2007
Sources: Energy Information
Administration, Electric Power Monthly,
March 2007.
National Energy Education Development Project,
Intermediate Energy Infobook, 2004-2005.
