Renewable energy is the energy renewed or regenerated naturally on a wide scale for the benefit of humanity. The sun is the best source of renewable energy. Its radiation is in itself a very powerful source of reusable energy. This radiation also gives rise to other forms of energy: the water cycle helps create hydroelectricity, and the wind is also exploited as an energy source.

Photosynthesis is also originated by sun light and it created different materials for usable energy, but photosynthesis not always renewable. The internal heat of the Earth is also a source of renewable energy, for example, geothermal energy. The rotation of the stars, for example, the Earth-Moon movement causing water movements on the Earth's surface which can be a form of usable energy through tidal power.

The renewable energy depends not on the speed at which the source is regenerated, but the speed at which it is consumed. Oil and all fossil fuels are not renewable and these resources are being consumed at a rate well above the speed at which these resources are naturally created. This will cause such natural resources to deplete soon. Hence, there is a need to find alternate renewable energy resources that can be produced easily on a very large scale.

The different types of renewable energy are:

Solar energy

Solar energy directly to the origin of the Sun. The sun emits electromagnetic radiation in which we include cosmic rays, gamma, X-ray, visible light, infrared, microwaves and radio waves according to frequency. All these types of radiation emit electromagnetic energy. The level of irradiance (energy flux) reaching the earth's surface depends on the wavelength of sunlight.

Solar thermal energy

In terrestrial conditions, the thermal radiation is between 0.1 and 100 micrometers. It is characterized by the emission of radiation at the expense of heat energy from the body transmitter. Thus, a body emitting thermal radiation is the heat energy and reduce body heat radiation receiving its heat energy is increasing.

The Sun emits radiation mainly in the visible, between 0.4 and 0.8 micro-meters. Thus, returning to a body contact with solar radiation increases the temperature of the body. We are talking about solar thermal energy. This energy source is known for a very long time, especially by virtue of position in a sunny spot to warm up.

Today, solar thermal energy is used in different applications such as solar heating (hot water for housing), solar cookers, and solar thermodynamics or helio-thermodynamics.

Photovoltaic energy

The photovoltaic energy is based on the photoelectric effect to create a continuous electrical current from an electromagnetic radiation.

Wind energy

Solar activity is the main cause of weather. These are characterized by displacement of air mass within the atmosphere. It is the mechanical energy of the displacement of air mass that is the basis of wind energy. Wind energy is converted to the mechanical energy easily.

Sailboats have been used since antiquity, as evidenced by the Solar Barque of Khufu. Until the mid-nineteenth century, most of the displacement watercraft that traveled middle and long distance over waterways were using the wind energy.

Wind power has been quickly exploited by using windmills with blade-shaped sails, like those that can be seen in the Netherlands or those mentioned in Don Quixote. These mills use mechanical energy to operate various equipment.

The mills of the Netherlands operate directly pumps whose aim is to dry the water clogged lands. Millers mills were used to turn a grain grinder. Today, the wind turbines take the place of windmills. Wind turbines convert mechanical energy into electrical energy.

Hydro-power

Like wind energy, hydro-power has its origins in the weather and therefore the Sun. The use of dams to stop the water and then use its directed flow to produce electrical energy has been used successfully on large scale by most nations.

Before the advent of the electricity, power of the water was used to capture this energy and cause mechanical tools to work easily. The water mills are the best example of the hydro-power used in the ancient times. Later, with the invention of electricity, it has transformed this mechanical energy into electrical energy, and this energy is still being used widely all over the world.

Study Source: Renewable Energy