It is that energy which lies, embedded within earth's crust. In some places heated water comes out through the surface of earth as hot spring or steams. This hot geothermal water or steam is used to run turbines for generation of electricity.
Advantages:
1. It is most versatile and least polluting renewable energy source.
2. Power generation level is higher than solar energy.
3. It is inexpensive.
Disadvantages:
1. Withdrawal of large amount of water or steam may reduce ground water table.
2. Hazardous gages like H2S, NH3, CO2 may be released and cause pollution.
3. Noise pollution results from drilling operations.