Subject:- Renewable Energy Sources

Topic:- Introduction to Energy Sources

Difficulty:- Medium

1) Wind Energy :-

• A small portion of total solar radiation reaching on earth’s surface causes wind due to following two factors.
• Heating up of earth’s surface due to absorb of solar radiations and cooling at night.
• Rotation of earth and its motion around the sun.
• The wind power which is indirect source of solar energy can be utilized for generation of electric power with the help of wind mills.

2) Tidal Energy :-

• Tides are generated due to gravitational pull between the earth and the moon and sun.
• The difference in head of high tide and low tide could be utilized to operate a hydraulic turbine.
• The mechanical power generated by the turbine can be used to run a generator to produce electric power.

3) Wave energy :-

• The wave energy is developed due to winds interacting with the surface of the ocean. Wind’s get 1% to 5% of sun’s energy and part of this energy is transfered to the waves. The wave energy can be used to develop electric power.

4) Ocean Thermal Energy :-

• Ocean serves a big store house of solar energy. In tropical regions, the water surface temperature is about 250 C which can be used as source while the temperature of water at a depth of about 100m is 50c which can be used as sink.
• This temperature differential can be used to run a heat engine to produce power using working fluids having low boiling points like NH3 , R-12, propane gas etc.

5) Bio-mass and Bio-gas :-

• Bio-mass is an organic matter produced by plants both grown on land and in water and their derivatives and animal manure.
• Biomass can be considered a from of solar energy as it is used indirectly to grow these plants by photosynthesis.
• Bio-gas is a gaseous fuel which obtained by fermenting the biomass an aerobically in absence of oxygen. Its main constituent is methane (55% to 65%) and carbon- dioxide (30% to 40%) and rest impurities like N2 H2s, H2 etc.
• This biogas can be used to generate electric power in a heat engine or to run water pumps or for cooking purposes etc.

6) Hydrogen Cells :-

• Hydrogen gas is probably the fuel for future as substitute to fossil fuels & other energy sources. It is clean energy fuel.
• Hydrogen can be produced through solar powered electrolysis process of water. It can also be produced by coal gasification or by methane gas and natural gas reformation.

7) Fuel Cells :-

• Fuel cell is an emerging technology. It is an electrochemical device that continuously converts the chemical energy of fuel directly into electricity and heat without intermediate state of combustion.
• It generates dc power. At present the cost of production of fuel cells is high with low life therefore the application of fuel cells is limited.