Renewable energies: what they are and main types - Meanings

Renewable energies: what they are and main types - Meanings
Posted on 10-02-2022

Renewable energy

What are renewable energies?

Renewable energies are energies that are obtained in a sustainable way and from natural resources, such as the sun, wind, water, and organic matter.

These energy sources are considered inexhaustible because they are renewed faster than they are consumed.

Renewable energies are also known by the name of alternative energies to differentiate them from conventional non-renewable energies.

Non-renewable energies are those obtained from fossil fuels (coal, oil, gas) and nuclear (uranium, plutonium). These energy sources are limited and generate greenhouse gases and radioactive waste respectively.

Renewable energies must be differentiated from clean energies or green energies. Clean or green energy is that which, during its production, generates fewer polluting elements and has a reduced environmental impact compared to other types of energy.

Types of renewable energies

Solar energy

solar energy

Photovoltaic solar panels are concentrated solar power systems and thermal solar panels.

Solar energy is obtained from sunlight, the most important inexhaustible source for the amount of energy it emits. The sun originates most of the natural processes that take place on Earth and influence the rest of renewable energies.

Within solar energy we can find the following types:

  • Photovoltaic solar energy, obtained through solar panels, is made up of photovoltaic cells connected to each other. Photovoltaic cells are devices that transform solar radiation into electrical current. The electricity can be used directly or it can be stored in batteries and accumulators.
  • Concentrated solar energy, is a system that concentrates solar radiation by means of mirrors to heat a fluid and produce steam with which turbines are activated that generate electricity.
  • Thermal solar energy harnesses the sun's energy through thermal solar panels. These panels concentrate the radiation to heat a fluid that transports the heat to a tank where the water is heated. This system can be used in both domestic and industrial installations.


Wind power

Wind energy is obtained thanks to the force of the wind. The wind turns the blades of the wind turbines, activating the turbines that transform the movement into electrical energy. The energy produced can be stored in batteries, accumulators, or turned over to the electrical network.

The higher the wind speed and the size of the wind turbine blades, the greater the amount of energy obtained.

Offshore wind farms produce up to twice as much energy as onshore facilities, since the strongest and most constant winds originate in the high seas.

wind power


Hydroelectric power

Hydroelectric energy is what transforms the movement of river currents into electricity.

The system consists of a dam that retains the flow of the river by storing the water in a reservoir. The flow of water is channeled, taking advantage of its force to activate the turbines of the generator, which transform the kinetic energy into electrical current.

The electricity produced is stored in accumulators and distributed by the electrical network.

Hydroelectric power

Hydroelectric power station


sea ​​energy

The energy of the sea is produced by the movement of the masses of water in the seas and oceans and we can find the following types:

  • Wave energy is the energy obtained thanks to the oscillation of the sea waves, which starts the turbines that drive the generators responsible for producing electricity.
  • Tidal energy, this type of energy is generated from the thrusting movement produced by seawater with the alternation of the tides.
  • Salinity gradient energy, this type of system generates electricity from the difference in salinity that exists between the seawater and the water of the rivers at their mouths. Having a different density, both types of water exert a pressure that is used to generate energy.
  • Tidal thermal energy is the energy generated from the differences in temperature between the waters of the ocean depths and the surface waters.

sea energy

wave power system


Biomass is a matter of biological, animal, or vegetable origin, which can be used as a source of energy. It is renewable in nature because it is generated cyclically and can be stored and used later.

According to its origin, we can find the following types of biomass:

  • Natural biomass is generated in nature without human intervention, such as plant remains or seaweed.
  • Residual biomass comes from organic waste generated by human activities such as agricultural, forestry, urban, or industrial waste.
  • Biomass from energy crops is biomass obtained from crops intended for energy production.

There are several biomass transformation processes through which we obtain different types of fuels:

Biogas is a gas generated by the decomposition of organic matter by microorganisms in an oxygen-free environment called anaerobic digestion. It is mainly composed of methane and carbon dioxide and is used in heating and transport systems.

Liquid biofuels are obtained from the fermentation of vegetable matter rich in oils and carbohydrates. Crops such as corn, soy, or palm are used to produce biodiesel and bio alcohols such as bioethanol.

Solid biofuels come from forest residues and from the wood industry and are used to generate thermal and electrical energy through combustion. Among the most used are firewood, chips, pellets, dried fruit shells, and olive pits.

wood chips

Wood chips, firewood, and pellets (cylinders of pressed sawdust).

Geothermal energy

It is the energy that originates from the heat coming from the earth's core. This heat, on its way up to the surface, heats underground water masses and produces water vapor, giving rise to hot springs and geysers.

It is mainly used as an air conditioning and water heating system for sanitary purposes, although in areas of greater tectonic activity and temperature it is also used to generate electricity.


Images of a geyser and a hot spring


Hydrogen energy

This type of energy consists of using surplus renewable energy to obtain hydrogen, which can be stored and used to produce more energy at another time.

Two processes are used to obtain hydrogen:

  • Electrolysis is the decomposition of water molecules by an electric current to obtain pure hydrogen.
  • Reformed, is a chemical process that transforms methane from biogas into hydrogen.

Hydrogen is stored in tanks that keep it under high pressure. Hydrogen cells, which are similar to conventional batteries, use hydrogen as fuel to generate electrochemical energy for electricity.

These batteries are mainly used in electric vehicles, guaranteeing a transport system without emissions.

Advantages and disadvantages of renewable energies


The resources from which they come are considered inexhaustible because they are periodically renewed.

They do not generate greenhouse gas emissions.

Although the initial investment is high, it is compensated by the low maintenance cost and the security of its facilities.

It gives the possibility of having the energy to those who have never had access before.

advantage of renewable energy


Large extensions of land or sea are necessary for the installation of the necessary systems.

Climatic and geographical conditions affect energy production.

Renewable energies do not meet the demand for energy, that is, we can both have surpluses and situations of energy shortages.

Renewable energy plants have an impact on the environment and the landscape.

disadvantage of renewable energy

Thank You