Of all the energy sources available to us, the Sun is our largest source by far, dropping 970 trillion kWh worth of free energy on us every day. Enough solar energy strikes the United States each day to supply its needs for one and a half years. Put another way, the amount of solar energy the Earth receives every minute is greater than the amount of energy from fossil fuels the world uses in a year! Nearly all energy forms on Earth come from the Sun, either directly or indirectly.
To begin with, all fossil fuels are the product of organic life-forms on Earth that drew their energy from the sun. Algae and plants harvested solar energy via photosynthesis, and after accumulating and being cooked for millennia, became the substances that we know today as oil, coal, gas, shales, tar sands, and so forth—what author Thom Hartmann has called the "last hours of ancient sunlight."
Likewise, modern solar energy technologies harvest the sun's energy waves. Photovoltaic (PV) cells make electricity from photosensitive materials that respond to the visible light spectra of sunlight. Solar thermal technologies, such as solar hot-water systems and concentrating solar power (CSP) systems, directly capture heat from infrared light spectra.
Wind energy comes from the uneven heating of the planet as it spins through the day and night, being warmed and cooled by the sun. Hydropower depends on rain, which is the result of the sun warming the surface of the planet and causing ...