The different sources of energy.

Solar Energy: Solar energy is the solar radiation (from the Sun) that reaches the earth. People have devised two main types of artificial collectors to directly capture and utilize solar energy: flat plate collectors and focusing collectors.

Flat plate collectors: These collectors take less space than focusing collectors and they are comparatively cheaper although they cannot provide as much heat. Therefore, flat plate collectors can be used in households or schools in such applications as swimming pool heating. Focusing collectors: A focusing collector can provide a temperature as high as 4000 o C. The high temperature is ideal for a solar furnace that provides contaminant-free environments for research and industrial use.

Disadvantages: All the methods (except for flat plate collectors) of solar energy mentioned require large space to achieve average efficiency. Therefore, the cost of solar energy increases. Advantages: Solar energy is also pollution free. In addition, as solar energy does not use fuel, it also eliminates the problems that arise during the recovery, transportation and storage of fuels.

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Hydroelectric Energy: Hydroelectric Energy is the generation of electricity through water pressure. Hydro power is currently the world's largest renewable source of electricity, accounting for 6% of worldwide energy supply or about 15% of the world's electricity. It is one of the oldest sources of energy and was used as far back as 2000 years ago when wooden waterwheels were used to convert kinetic energy into mechanical energy.

Gravity causes water to flow downwards and this downward motion of water contains kinetic energy, that can be converted into mechanical energy, and then from mechanical energy into electrical energy in hydro-electric power stations.

Embankments usually are built to reserve water and create differences in water levels. Lakes in high altitudes are also used for the same purposes.

Advantages: The only cost...