ABSTRACT
It is fitting to begin our discussion of the various kinds of renewable energy with the sun-the medium-sized star that symbolizes life, power, strength, force, clarity, and, yes, energy. The sun nourishes our planet. Solar energy is a renewable resource because it is continuously supplied to the Earth by the sun. When we consider the sun and solar energy, we quickly realize that there is nothing new about renewable energy. The sun was the first energy source; it has been around for 4.5 billion years, as long as anything else we are familiar with. On Earth, without the sun there would be nothing-absolutely nothing, zilch. The old 5-5-5 rule sums up the essence of life on Earth: We can survive 5 minutes without oxygen, 5 days without water, and 5 weeks without food. Without the sun, though, the 5-5-5-rule has no validity. Without the sun, nothing related to life has validity. Without the sun, there is nothing: no air, no water, no food…no life. The sun, the ultimate energy source, provided light and heat to the first humans. During daylight, people searched for food. They hunted and gathered and probably stayed together for their safety. When nightfall arrived, we can only imagine that they huddled together for warmth and reassurance under the light of the stars and moon, waiting for the sun and its live-giving and life-sustaining light to return.
