many times more than all of the energy we use. For this reason, we consider solar energy
a renewable form of energy. For as long as sunlight continues to warm the Earth, we will
never run out of this resource. One problem with solar energy is that it cannot be used
at night, unless a special battery stores extra energy during the day for use at night. The
technology for most uses of solar energy is still expensive. Until this technology becomes
more affordable, most people will prefer to get their energy from other sources. As you
learned earlier, most of the Earth’s energy comes from the sun. Other renewable resources
also come from the sun originally. You will be learning about these resources later in this
lesson.
Figure 5.7: This experimental car is one example of the many uses that engineers have found
for solar energy. ( 7 )
Figure 5.8: This solar power plant uses mirrors to focus sunlight on the tower in the center.
The sunlight heats a liquid inside the tower to a very high temperature, producing energy
to make electricity. ( 9 )