Energy - põhjalik referaat energiast
turbine that generates electricity. Nuclear power was used to generate 19.4% of all the
country's electricity in 2007.
Hydropower, the source for 5.8% of U.S. electricity generation in 2007, is a process in
which flowing water is used to spin a turbine connected to a generator. There are two basic
types of hydroelectric systems that produce electricity. In the first system, flowing water
accumulates in reservoirs created by the use of dams. The water falls through a pipe called
a penstock and applies pressure against the turbine blades to drive the generator to produce
electricity. In the second system, called run-of-river, the force of the river current (rather
than falling water) applies pressure to the turbine blades to produce electricity.
Geothermal power comes from heat energy buried beneath the surface of the earth. In
some areas of the country, enough heat rises close to the surface of the earth to heat
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