Alternative Energy: Solar Energy
As with hydropower, solar energy has a long history. Many pre-historic cultures used it to warm their
dwellings, dry their clothes, and cure their food. The importance of solar energy was so great that most
cultures revered the Sun and created rudimentary observatories to track its location in the sky (ex.
Stonehenge). Some found solar energy so important that they even codified its power in their laws.
Ancient Romans relied so heavily on solar energy to heat their homes and bathhouses that it was illegal
to build a house or dwelling so tall so as to block the sunlight of any neighbor1.
Ancient Rome was not the only culture to rely
heavily on the Sun for energy. The Anasazi cliff
dwellers of the ancient American Southwest also
used their knowledge of the Sun’s motion in the
sky to heat and cool their homes. They built
their dwellings into the sides of cliffs that faced
the south. In the winter, sunlight was able to
shine on their homes, while the cliffs protected
their homes from cold northern winds that might
blow. In the summer, the overhangs from the
cliffs shaded their homes from the Sun, and thus
made it cooler.
Just as with hydropower, solar energy began to
wane as a conventional energy source as fossil
fuels and nuclear energy became cheap and
reliable. The expense and variability of using sunlight has relegated its use to unusual situations where
fossils fuels and nuclear energy are not available or where they are prohibitive to use or maintain. A
perfect example of this is on satellites, which need energy to power all on board computers and
instrumentation. Using fossil fuels to power a satellite over its lifetime would require quantities of oxygen
and fuel that would be prohibitive to shoot into orbit. Nuclear material would be fine for powering the
spacecraft, but would become very problematic when the satellites life was over and it came crashing
back to Earth. An example of solar energy that