Renewable energies (EnR) refer to all energies from natural sources, such as the sun, wind, water, sea, etc.
As opposed to non-renewable energies (fossil and nuclear energies) whose stocks are running out, renewable energies come from sources that are constantly renewed by nature.
Also called green energy or clean energy, renewable energy creates little waste and polluting emissions. Their exploitation therefore has a very limited impact on the environment.
There are different types of renewable energies, which vary according to the source from which they come:
1) Solar energy, produced by the sun’s rays. It produces electricity, thanks to photovoltaic solar panels, or heat thanks to solar thermal panels.
2) Wind energy that comes from the wind. From the movement of air masses, wind turbines make it possible to produce electricity. It is possible to install wind turbines on land, but also at sea.
3) Hydraulic energy, produced from water such as through dams, tides, sea currents or waves. It is the force of moving water that is harnessed to generate electricity. We also talk about marine energies.
4) Biomass is energy obtained through the transformation of animal or vegetable organic matter (plants, wood, agricultural waste, etc.) into electricity or heat. To achieve this, thermal processes (pyrolysis, gasification, combustion, etc.) or biochemical processes, such as methanation, are used.
5) Geothermal energy which comes from the extraction of the heat contained in the ground, the earth’s layers. This heat is then used to produce electricity or heat buildings. The advantage of this energy is that it is not dependent on atmospheric conditions.
The development of these energies pursues several objectives:
a) An economic objective since these energies call on nature and can therefore be produced everywhere. Their development makes it possible to avoid energy dependence by importing from other countries;
b) An environmental objective since these energies are said to be “clean” and generate almost no waste or pollutants. It is an unthinkable alternative in the fight against the reduction of greenhouse gases and the carbon footprint.
The only disadvantages result from the fact that they depend in particular on the climatic and atmospheric conditions, that their installation is expensive and long to make profitable.
Today, these energies are under discussion to become the essential alternative to the use of certain fossil fuels.