All sources of energy divided into two groups:
- Conventional sources of energy.
- Non- Conventional sources of energy.
- The fuel like wood, coal and petroleum are major conventional sources of energy. Wood and coal convert chemical energy into heat energy. Petroleum converts chemical energy into mechanical energy to run automobiles.
- The solar energy, wind energy, water energy, bio-gas energy etc. are non-conventional sources of energy.
- The energy from the sun is called solar energy. It is the main source of energy on earth. In the presence of sunlight plants make food for themselves. Solar energy is used in solar cookers, solar water heater etc.
- From centuries, the man is using the power of strong winds to sail ships. Even today wind mills use the kinetic energy of wind to generate electricity.
- In a water dam, large quantity of water is stored at some height and its potential energy is used to run the turbine of electric generator. The fiscal waste of animal is used to produce bio-gas. This gas works as fuel and produce heat energy to cook food in homes. The energy released from breaking of the nucleus is called nuclear energy. This energy is used to produce electric energy.