geothermal

Explains how geothermal energy, natural heat from inside the earth, can be used as a source of heat or to provide electricity.

Describes how heat beneath Earth's surface and plants and animals can be used as sources of power, how using this power affects the environment, and what the future significance of geothermal power and bio-energy may be.

Defines geothermal and bio-energies, and explains their advantages and disadvantages.