Make a list of conventional and non-conventional sources of energy. Give a brief description of harnessing one nonconventional source of energy.

Hint:Conventional sources of energy are those sources existing in our nature which will get deplete and one day will become extinct. Contrary to these non conventional sources are those sources of energy which get replenished and will never become extinct with the passage of time.

Complete answer:
Conventional sources of energy: Some of the notable examples are the Coal, petrol, natural gas, compressed natural gas, fissionable materials like uranium, polonium, radium etc.
Non-conventional sources of energy: Some of the notable examples are the Wind, the power of water, the Sun, Ocean Tidal Energy, Interior of the Earth, Biogas, Plants, Vegetables, animal waste and left-over food and other waste etc.

Additional information:
Biomass is one of the most promising sources of energy in far flung rural areas. Slurry of animal dung or other sorts of bio-waste and water is formed within the mixing tank then fed into the digester. The digester is usually a closed underground tank. In digester, the action of microorganisms decomposes the complex compounds of the biomass within the slurry. Anaerobic microorganisms, the presence of water, degrade the biomass in the digester. As anaerobic microorganisms don't require oxygen, the digester is meant sort of a sealed chamber. The complete degradation process takes a few days, during which bio gases are produced. Now the bio gas is often supplied to consumers through pipes. Periodically the slurry, that is left behind in the digester, is removed and it serves as an excellent manure.

Note: While we have divided the available sources into two different categories but we should be very careful while using the available resources and must do it judiciously. The burning of fossil fuels is an important source of air pollution and if the AQI is greater than the permissible limit then it possesses a grave health hazard.