Hydropower is derived from the Earth's natural water cycle: the kinetic energy of water moving downstream. Extremely efficient, water turbines are as much as 95% effective in generating electricity. Currently 20% of all electricity in the world is generated by hydropower.

Humankind has been utilizing renewable energy for millennia. Here, we see windmills converting wind into mechanical power, which in turn is used for pumping water, grinding grain, and cutting wood.

The total power needed to run the world today is 12.5 terawatts. The renewable energy now available is 667 terawatts, more than 5,300% of our current need. We can and must move to sustainable energy in the coming decades; all that is required of us is the will to do so.

Solar cells convert the sun's energy into electricity utilizing the photovoltaic effect. When silicon is taken from just one ton of sand and used in photovoltaic solar panels, that silicon can produce as much electricity as 500,000 tons of burning coal.

Geothermal energy is the harnessing of heat stored beneath the Earth's surface. For every 100m of depth, the temperature increases 3 degrees Celsius. Translation: electric bills for a 2,000 sq. ft. home could be reduced to just $1 a day, using a simple geo-exchange system.

Turbines use wind power to create electricity. World wind generation capacity more than quadrupled between 2000 and 2006, doubling every 3 years. Studies indicate that up to 85 terawatts of readily accessible wind power can be harnessed from the Earth each year.

Studies indicate our current supply of oil will run out in as little as 30 years, with natural gas being depleted in 50. The need to utilize renewable energy opportunities throughout the world has become one of the utmost importance.