• Electricity is a common source of energy.energy pole image by Soja Andrzej from Fotolia.com
  
  As of 2007, the world uses a total of 483.597 Quadrillion British Thermal Units (BTU) of energy -- of which the United States uses about 21 percent, according to the Energy Information Administration. Ultimately, almost all of Earth's energy comes from the sun, but there are five principal sources of energy that come from solar power.
  
  

Climate Derived Energy

• Climatic energy comes from natural weather patterns, mostly wind and ocean currents, according to the "Encyclopaedic Dictionary of Environment." Wind power is well developed, but only 1.8 percent of U.S. energy consumption comes from windmills, according to the Energy Information Administration. A standard windmill uses blades to catch wind that turns a turbine, which moves an electrical generator. Society has used windmills before the discovery of electricity. In ancient times, farmers would use windmills to grind grain. As of 2010, ocean current technology is still in the development phase, with a few prototype systems in place, according to Argonne National Laboratory. The most likely grid-connected ocean current system will be turbines turned by currents. Currents, or the movement of water, occurs because of wind gusts, temperature variations and sometimes differences in water density or salinity.
  
  

Hydroelectric

• As of 2010, hydroelectric power is the most used renewable source of energy -- accounting for 6 percent of U.S. energy production, according to the EIA. Hydropower is generated because of the natural movement of water, such as ocean current power. The water cycle -- the evaporation of water, condensation into clouds and then precipitation falling to Earth -- generates most hydropower. Potential energy -- water moving from a high point to a lower one -- also creates hydropower.
  
  

Photosynthetic

• About 80 percent of the energy sold in the world comes from oil derived from the photosynthetic production of energy, according to ChemistryExplained. Photosynthesis occurs in plants, which use sunlight to convert water and carbon dioxide into an energy carrying molecule called adenosine triphosphate (ATP), according to Maricopa College. After plants break down, they decompose into fossil fuels, such as coal, natural gas and oil within a few million years. Wood is another photosynthesis-derived source of energy.
  
  

Photovoltaic Solar Energy

• Straight solar is a common source of heat, such as sunlight heating a sidewalk, and society is beginning to convert sunlight into electricity. The conversion of solar energy usually occurs with a photovoltaic system. PV systems capture sunlight, which knocks out negatively charged electrons. Electrons from the bottom of the PV cell move to the front. The differential in electrons from the front and back of the PV cell creates an electrical charge, according to the EIA.
  
  

Passive Solar

• Passive solar energy systems capture and concentrate sunlight, usually with mirrors, to boil water and create steam, which turns a turbine. Some passive solar systems are built into the architecture of a building, such as increasing window space to let in more sunlight, according to the EIA.