Fossil fuels are a non-renewable source of energy. As a result of growing demand fossil fuels are being depleted at a rate of 100,000 times faster than they are being formed. At the present rate of usage, the coal reserves are likely to last for about 200 years. Similarly, at the present rate of usage, the world’s crude oil reserves would be exhausted in just 50 years. These resources are non-renewable and take millions of years to form. It is essential, therefore, to reduce dependence on such energy resources and explore and exploit the enormous potential of alternative sources of energy like solar energy, tidal energy, wind energy, geothermal energy, and biomass-based energy. They are not only renewable sources of energy but are environmentally clean and safe to use.