2. Energy exists freely in nature. Some of them exist infinitely (never run out, called RENEWABLE), the rest which have finite amounts (they took millions of years to form, and will run out one day, called non renewable)

4. Wind energy, natural, renewable, clean, and is a source of infinite power of the sun. Wind turbines, wind power plants is the main structural element of the kinetic energy of moving air, and at first it is converted into mechanical energy and then into electrical energy.

5. Biomass resources are specially grown plants like corn, wheat and grass, seaweed, algae, droppings, industrial waste, all organic house waste (waste of fruit and vegetables) As a basement of plants and living orgnanisms, biomassis called as plantal organism which store solar energy by photosynthesis

6. Water energy is obtained from flowing water which pass over wheels or similar devices.

7. Geothermal energy is renewable, sustainable, inexhaustible, inexpensive, reliable, environmentally friendly and green energy. There are three main components of geothermal resources: 1- The heat source, 2- Fluid carries the heat from underground to the surface, 3- Rock permeability is sufficient to provide water circulation.

9. The general name of the light and heat energy emitted from the sun is Solar energy. To produce solar energy we need technological materials.

10. Wave energy is obtained directly from the surface wave or under surface wave pressures. The waves are generated by winds blowing from the surface of the sea or ocean. Wind up in many parts of the world regularly and continuously works to create permanent waves. There is a lot of energy in the waves of the sea and the ocean. Wave machines produce energy directly from the movement of surface waves and wave pressures.