Electricity is a secondary energy derived from water, coal, mineral oil, natural gas and atomic minerals. It has become part of modern civilization owing to its multifarious uses in industries, transport, agriculture and home.
Electricity is mainly cheap, transportable, pollution free and renewable and hence its popularity is increasing day by day. So much so that per capita consumption of electricity is taken as an index to measure the level of material progress of a society. The per capita consumption of electricity in India though increased considerably from 16 km in 1950-51, to 102 km in 1970-71, 1 km in 1980-81 and 313 km in 1990-91 but it is s very low in comparison to developed countries like I U.S.A. 6550 km, Sweden 6434 km and U.K. 34811 km.
Depending upon its source of origin electricity is of four type, viz., (a) thermal electricity, (b) hydro electricity, (c) atomic electricity, and (d) gas and diesel electricity. Electricity can also be generated through wind energy, solar energy, bio- gas, sea waves, geothermal energy and dry batteries. Bui from commercial point of view only thermal, hydro and nuclear power are more important. Of the total installed capacity of electricity 47.82% was thermo and 26.09% was hydro in 1950-51.
During 1970-71 the percentage share was 39.26, 48.47 and 2.4J through hydro, thermal and nuclear sources respectively. During 2003-04 the contribution of hydro, thermal and nuclear sources in the total install capacity of electricity was 22.45%, 61.26% 2.05% respectively. Same year thermal sources accounted for 74.55% of the electricity generated followed by hydro (11.87%) and nuclear (2.81% ).