Renewable energy is defined as the source which, unlike fossil fuels and nuclear energy, can be considered practically inexhaustible: wind, solar thermal, photovoltaic, hydroelectric, geothermal or biomass.

Its importance lies in the fact that it minimizes or completely reduces the emissions of greenhouse gases, in particular carbon dioxide, into the atmosphere.

Renewable sources are increasing every day, every year, by leaps and bounds.

But What is electrical energy?

Electric energy, force is the electrical attraction or repulsion between charged particles.

The movement of charged particles through a wire or other medium is called current or electricity.

Renewable energies.

Wind power.

Wind turbines and cows
Image: guitar photographer Shutterstock

Wind power today is arguably the most competitive of all renewable energy sources. To be able to produce electricity, the wind must have a speed greater than about 3-5 m / second, but it must not exceed 20-25 m / second: in the first case the blades do not even move, in the second turbulence This could create problems for machines which, for this same reason, are ready to stop automatically.

Wind towers have no environmental impact, but the same cannot be said about the landscape and its visual effect. One solution could be not to install them in natural parks or in areas of exceptional cultural and monumental value. In addition, they can be dangerous to birds, especially raptors: however, installing “acoustic scarecrows” tuned to an appropriate frequency would easily solve this problem.

Photovoltaic solar energy.

The photovoltaic modules of a solar power plant are made up of individual cells, arranged in chains a few tens of meters long which can remain fixed, oriented towards the Sun, or rotate according to the best inclination with respect to our star.

Solar energy is not distributed evenly during the day or during the seasons and is strongly affected by latitude: at night it cannot be used and even in cloudy weather it reduces its efficiency.

In fact, today’s photovoltaic panels work even in low light conditions. Electrical energy is produced by photons which are absorbed by the material of the cell (which is a semiconductor) where a pair of electric charges of opposite sign is created.

There are small impurities in cells that can change the electrical properties of the semiconductor by inducing the potential difference which is used to generate an electric current. As for silicon (by far the most used element in cells), the impurities are made up of phosphorus or boron. The manufacture of industrial photovoltaic elements generates a little pollution, but to a much lesser extent than what is necessary for the manufacture of systems for converting energy from other sources.

Solar thermal energy.

Photo Shutterstock

We can use the heat of the sun to heat or produce hot water that can reach 70 ° C in summer, well above the 40 ° -45 ° required for a shower.

A solar thermal panel (or collector) is composed of a radiator capable of absorbing heat from the sun’s rays and transferring it to the water tank. The water is moved from the tank to the domestic tap by natural or forced circulation: in the latter case, the panel incorporates an electric current pump.

The length of time required varies greatly depending on sun exposure, season of the year, weather conditions and latitude. The main questions asked by those interested in installing this technology are: “What happens when it rains, when is it cloudy?” Technology has long overcome these drawbacks. The domestic hot water is kept in insulated tanks (that is to say insulated so as not to exchange heat between them) to guarantee an autonomy of several hours. One could not explain otherwise why many European countries with a level of insolation much lower than Spain have already invested in thermal solar panels…. Much more than our land of the Sun!

Solar thermal panels, or thermal collectors, have become a daily reality in Germany and Austria. Greece is another very advanced European country in this area. The growth of the European solar market contributes to a rapid reduction in the purchase prices of the panels thanks to the increased competition between manufacturers and installers. The price can vary considerably depending on the technology of the panel.

Hydro-electric power.

The Hydro-electric power It takes advantage of the transformation of gravitational potential energy (property of water masses at altitude) into kinetic energy to overcome a level difference, which is transformed, thanks to an alternator coupled to a turbine, into electrical energy.

Hydroelectric power is obtained from the course of rivers and lakes through the creation of dams and pipelines.

There are several types of dams. The jump plants take advantage of the great heights of fall available in mountainous regions. In the case of running water hydropower plants, large amounts of river water are used, which overcomes small differences in height.

Hydroelectric power is a clean (emission-free) and renewable source, but the construction of dams and large reservoirs, along with the inundation of vast natural spaces, can cause the alteration of the ecosystem of the area with enormous environmental damage: excessive sedimentation upstream of the dam, erosion of water downstream, reduction in fishing along the river, interruption of the ascent paths of certain species of fish.

Geothermal energy.

The internal heat of the Earth is a resource that can be exploited conveniently and without environmental impact and, in regions characterized by volcanic phenomena, it is possible to exploit this heat by obtaining renewable and clean energy: the first condition is the presence of heat (from the base layers of the mantle and crust), there must be a porous and permeable rock (“reservoir rock”) above the underground heat source, and the reservoir must have a “Cover” capable of preventing the dissipation of fluid and its heat.

Geothermal energy is practically inexhaustible and does not produce greenhouse gas emissions, and it is not only electricity, but also and above all heat.

The biomass

The term biomass was introduced to identify all materials of organic origin (plant or animal) which have not undergone any fossilization process and which are used for energy production. Therefore, not all fossil fuels can be considered such.

Biomass is a renewable source because the CO2 emitted for energy production does not represent an increase in carbon dioxide in the environment.

The oldest biomass used for energy production is wood. There are problems: biomass is produced in large areas, produces a large amount of pollutants and has low energy efficiency.

The choice of energy cannot simply be a matter of economic convenience: there are environmental, health and safety issues behind it. The problem is to know to what extent the economy of a country can incur additional costs to have increasingly clean and secure energy, both for the environment and for health. This is why it must be a coordinated global energy transition.

Do you know of other sources of renewable energy?