geothermal power

Miles below your feet, scorching temperatures can get hot enough to melt rock. In some places, water heated deep underground rises to the surface in hot springs and geysers. Earth's internal heat, called geothermal power, can be an important energy source. In some places, steam released from underground is used to turn turbines, creating electricity.

Definition: heat energy from within Earth
Carbon Dioxide Emissions: very light (but does cause water and air pollution)
Cost: expensive (vs. other energy sources)
Location: near above ground and underground hot spots, where magma rises to Earth's surface.
Current Use: less than 0.5% of energy in the U.S.
Cool Fact: Geothermal plants release under 1% of the carbon dioxide released by coal-fired power plants.

Image credits: main image, courtesy DOE/NREL / Pacific Gas & Electric.