Amount of energy consumed by a country depends on the living standard of its citizens and the degree of its industrialization . The average energy required for a man to maintain his daily activities require about 20kcal per day. This energy is supplied by the food he eats . In addition, man uses more energy for transportation, industrial and agricultural activities. At present, the global energy consumption per capita per day is about 2000 times the 20k calorie he needs for maintaining life. 

 At present, about 40% of the demand for energy in the world is obtained from oils. Similarly, about 20 % of the total energy consumption provided by coal, about 20% by natural gas, wood 10%, nuclear fission 7% and hydroelectric power 3%. Other energy required by the world is fulfilled by other energy sources like solar, tidal, wind energy.