Source of Energy:

       Such sources that can provide adequate amount of energy in a convenient form over a long period of time.

Characteristics of sources of energy:

      1.It should do a large amount of work per unit mass or volume - it means that the output energy must be more than the input energy. It should have high calorific value.

2.It should be easily accessible - the energy source should be able to provide energy over a long period of time. Example: coal and petroleum.

3.Should be easy to store and transport - most common sources of energy such as coal, petrol and LPG need to be transported to users from their points of production. They also need proper storage. Thus it is important to store and transport these sources safely and economically.

4.Safe and convenient to use - energy sources should be safe as it is used by a large number of people and should be convenient.

Renewable energy

1.Renewable energy is any source of energy that doesn't consume the finite resources of the Earth and can be easily and quickly replenished.

2.Renewable Energy can be regenerated in a short amount of time or is basically unlimited.

3.At present only a small proportion of the worlds energy needs come from alternative and renewable energy sources. These exist in many forms including Solar Thermal, Photovoltaic, Wind, Hydro, Tidal/Wave and Bioenergy (including Biomass, Biogas and Biofuel.

Non- renewable energy
1. The energy sources that cannot be recreated and which go on depleting as we use them are non-renewable energy sources.

2.The most extensively used non-renewable energy sources are the fossil fuels that consist of oil, natural gas, and coal.

3.The fossil fuels are formed from the dead bodies of the plants and animals buried below the deep layers of earth’s core since millions of years ago.

4.Another popular non-renewable source of energy is the radioactive elements. The energy obtained from these elements is called nuclear energy.