Throughout the history of human kind, energy has been an important factor is development. The availability and exploitation of new energy sources has made possible major economic and social changes. Modern societies requiring a large amount of energy used in agricultural, industrial and transport uses. Energy sources can be classified as commercial energy sources and non-commercial energy sources. Commercial sources includes fossil fuels (coal, oil, Naturalgas) while non-commercial energy sources includes wood, animal waste agricultural waste etc.. In industrialized countries like the USA, Commercial energy sources are used. In industry less country like India commercial energy sources and non-commercial energy sources are equal.
Commercial energy sources has led to the better quality of life, but it has also created many problems. The most series problem is the harmful effect on the environment. To avoid this problem renewable energy sources are used. The renewable energy sources include solar energy, wind, ocean thermal etc. These energy sources made good economic and social growth