1. Energy Needs
One of the largest uses if
energy o Earth is to produce
light. Energy is also needed to
power vehicles, run our
machies, and cool and heat
our homes and offices.

2. Energy Needs Over Time
By the late 1700s we began to use some
machines to do the work people and
animals used to do. Machines produced
clothing, and later, factories made farm
machines and automobiles. Most
machines today need electricity. Except
for lighting, electricity is not found in
nature.

3. Sources of Energy
Fossil fuels are made from the remains
of living organisms such as plants and
animals. Water from moving rivers can be
turned into electricity. Hydroelectric
power also called hydropower, is
produced by building dams across water
ways. Hydropower is a renewable
resource. It does not pollute the air. But
damming a river can be wildlife habitats.
Nuclear energy is produced by splitting
apart to atoms of the mineral uranium.
This type of energy does not pollute the
air.

4. Wind energy is used to turn
the blades of large wind
turbines. These turbines
produce energy, which
generates electricity.
Energy from the sun is
called solar energy. It
can be used directly heat
homes and buildings.
Energy from heat
inside Earth is called
geothermal energy.
This energy heats
water below Earths
surface. Geothermal
energy is a renewable
resource.
Solar energy does not
pollute the air and its also
a renewable resource.