There are two sources of energy. sources of energy which have been in common use for a long time and can be depleted, and sources of energy which are being used only recently and cannot be depleted. Firewood and fuels are limited. The fuels were made by dead vegetation and wildlife. They are likely to be exhausted soon. The three fossil fuels are , and . Electricity generated from coal is called power. is also referred to as buried sunshine. It is used as a domestic fuel as well as in industries. and its derivatives are called black gold. CNG whose full form is , is a form of natural gas stored in high pressure. It is found with petroleum.
As these resources are limited and are getting depleted fast, we need to switch to cleaner fuels and other sources on energy. energy is the energy which we tap from the sun. It has vast uses. Wind energy is produced by action of . power is obtained from atoms of radio active elements. energy is heat energy obtained from the earth. is made by decomposing organic wastes. energy is energy generated from tides. We need to use these sources more in order to reduce depletion of ehaustible sources.