Solar energy: To use solar energy is to generate electricity from sun light. For this purpose special chemical substances which are sensitive to light have been developed.
When light falls on these substances small chemical current is generated in large amounts. This can be stored and used when needed. Watches, calculators, street lamps have been invented which use the current produced by light falling on light sensitive material.
Wind Energy: Wind mills are in use for centuries especially for pumping water from wells. In wind mills, wind rotates the blades of windmill and is used to move the piston and lift the water from the well.
Wind energy is being used to pump water and to run turbines for the production of electricity.
Tidal energy (Kinetic energy) : Large amount of energy (Kinetic energy) la stored In the waves especially In seas.
Special devices have been made to rotate as the water passes through them by the wave action. This Is used to generate electricity.
Water power: Dams are constructed across the rivers water from the reservoir falls from a height on the turbines. This water falls Is used to drive turbines to generate electricity. These are called hydro electric projects.
