Prior to the discovery of fossil fuels, humanity’s only sources of energy were natural, or what we like to refer to as “renewable” or alternative energy. Before we were heating our homes with electricity, we were using light from the sun. Our predecessors learned to use the wind, sun, and water to create energy and new technologies for themselves. Evidence of solar power being used in previous centuries can be seen in the architecture of the Parthenon. The Egyptians invented the sail as early as 3200 BC to use the wind as energy to propel ships, and not soon after, the Chinese invented the wind mill. But it wasn’t just wind and the sun, hydroelectricity was also being used very early on in our history. During the classical period, the Greeks employed wheels being turned by water to grind wheat into flour. Coal was introduced as an alternative to wood as early as the medieval ages, and in 1917 Alexander Graham Bell proposed we use alcohol instead of fossil fuels. During the 1970′s, the United States experienced its first energy crisis. This prompted Americans to search for renewable and alternative energy sources on a more widespread basis, despite previous attempts in history.