Over the next twenty years a rise of fifty percent or more is expected in the world energy consumption. It is possible to counter this demand by the use of 'green' power sources. Environment friendly and clean renewable types of energy such as the solar energy, tidal energy, wind energy, biomass energy and geothermal energy should be used. The use of these non conventional sources will reduce the dependence of the world population on the conventional energy resources that are limited. Thus the ever increasing demand for additional energy from the conventional sources can be met by 'green' power sources.