What are renewable energies?
The Sun is the main source of energy on the planet. It produces a series of natural phenomena whose exploitation yields renewable energies. Since the Sun is considered to be an inexhaustible energy source, at human level, we may consider that renewable energies also are. Another advantage of Renewable Energies is that they are basically used wherever they are generated.
Kinds of renewable energies
The direct light from the Sun can be exploited both for generating electricity and heating up fluids (like for example, water). Two different kinds of technology stem from this principle to exploit solar light: photovoltaic energy, which produces electricity, and solar thermal energy, which generates hot water.
The Sun heats up the air on the surface of the Earth originating wind. Wind energy exploits wind speed to generate electric power.
The Sun heats up the seas and oceans evaporating water, which transformed into clouds, comes back to the Earth as rain. The accumulation of river waters in dams is used to generate electric power through waterfalls.
The Sun generates life. Basically, the exploitation of organic forest and agriculture waste (remains from pruning, sowing, forest cleaning, etc.) used as fuel is what we call Biomass.