Energy is the ability to do work, and work is the
movement of an object by force. You do work when you write down the answers
to your math homework or kick a soccer ball. An engine does work when
it moves a motorcycle or another type of vehicle. Even the cells within
your body do work when they divide. Not to be confused with your halfway
finished math homework! The amount of work done within a given time period
is referred to as power and is measured in either horsepower (the movement
of 550 pounds one foot in one second equals one horsepower), or in watts
(746 watts equal one horsepower). Incidentally, electric output is often
measured in kilowatts (thousands) or megawatts (millions). Thats
a lot of energy!
Where does energy come from?
Energy comes from two categories of sources, primary
and secondary. Primary sources of energy such as solar radiation, tidal
energy from the earth-moon-sun system, and nuclear and thermal energy
from the earth all require no conversion process in order to be used.
Secondary sources of energy such as fossil fuels, wind, water, and hydrogen
all require other forms of energy in order to convert them for use as
fuel. Electricity, currently a charged topic, has its beginnings in
both of these two categories of energy sources.
How is electricity made?
In order to make electricity heat must be produced.
Heat can be produced by burning fossil fuels (oil, coal, or natural
gas) or trash (bioconversion). Heat can also be produced by splitting
apart atoms of uranium over and over (nuclear fission) or by gathering
the suns energy in collectors (solar energy). Typically, most
power plants use fossil fuels or nuclear energy to make heat. The heat
is used to boil huge amounts of water into steam. The steam is "pressurized"
like the steam that escapes out of the little hole in a tea kettle when
the water boils. Pressure from the steam pushes against and turns the
blades of a giant turbine. In hydroelectric plants, the force of rushing
water is used instead of steam to spin the turbine blades. The spinning
blades also turn a shaft, large metal rod, which is connected to a generator.
The generator changes the energy of the turning shaft into electrical
energy. Inside the generator is a huge magnet that turns inside a ring
of coiled copper wire. The spinning magnet causes the electrons (Negatively
charged subatomic particles that normally orbit the nucleus of atom.)
in the wire to flow through it; creating electricity. Now thats
a real live wire!
How does it get to your house?
Once electricity is produced at a power plant
it must be sent by wire every inch of the way from the generator to
the place where it will be used. Electricity travels through a complex
transmission and distribution system at the speed of light, often over
hundreds of miles. Along the way, a number of automatic operations are
performed by power grids that monitor and adjust the electrical flow
so that it reaches businesses, industries, homes, and other users at
the appropriate power levels for their particular electrical demands.
Power is literally at your fingertips because by simply flipping a switch
at home you complete the connection that puts the electricity instantly