Renewable energies are those that are obtained from virtually inexhaustible natural sources, either because of the immense amount of energy they contain, or because they are capable of regenerating themselves by natural means.
Renewable energy typically supplies energy in four major areas: power generation, air / water heating / cooling, rural (off-grid) transportation and energy services.
The term renewable energy refers to forms of energy that regenerate rapidly compared to the characteristic times of human history. The sources of these forms of energy are called renewable energy resources.
Solar energy is a source of energy of renewable origin, obtained from the use of electromagnetic radiation from the Sun.
There are three types of solar energy: passive, thermal and photovoltaic.
Solar photovoltaic energy is a source of energy that produces renewable energy, obtained directly from solar radiation using a semiconductor device called a photovoltaic cell.
A solar thermal power plant or solar thermal power plant is an industrial installation in which, from the heating of a fluid by solar radiation and its use in a conventional thermodynamic cycle, the necessary power is produced to move an alternator for the generation of electrical energy as in a classic thermal power plant. It consists of the thermal use of solar energy to transfer it and store it in a medium that carries heat, generally water.
Passive solar technology is the set of techniques aimed at harnessing solar energy directly, without transforming it into another type of energy, for immediate use or for storage without the need for mechanical systems or external energy input, although it may be supplemented by them, for example for their regulation.
Wind energy is energy obtained from the wind, that is, the kinetic energy generated by the effect of air currents, and which is converted into other useful forms of energy for human activities.
To obtain electricity, the movement of the blades drives an electric generator (alternator or dynamo) that converts the mechanical energy of the rotation into electrical energy. Electricity can be stored in batteries or directly poured into the network. The turning speed of the blade is 12 to 19 revolutions per minute.
Within this group we can highlight offshore wind energy, booming in recent times. One of its advantages is the frequency of the wind since on the high seas it usually increases by 40% and they are much more regular than on land. This implies that offshore wind energy is much more productive than onshore wind farms.
Tidal and Wave Power.
Wave power, or wave power, is the energy that enables electricity to be obtained from mechanical energy generated by the movement of waves.
Tidal energy is that obtained by taking advantage of the tides: by connecting it to an alternator, the system can be used to generate electricity, thus transforming tidal energy into electrical energy, a safer and more usable form of energy.
Hydraulic energy, hydric energy or hydro-energy is that obtained from the use of the kinetic and potential energy of the water current, waterfalls or tides.
Geothermal energy is that energy that can be obtained by harnessing the heat from the Earth’s interior. The possibilities offered by geothermal energy for homes are multiple and useful in all areas of the home. With geothermal energy you will enjoy maximum comfort while minimizing your energy and economic expenses. Its use in homes goes through heating through radiators or underfloor heating, fan coil cooling, domestic hot water or pool heating, among others.
Biomass is one of the main sources of renewable energy in many areas of the planet. Biomass has the character of renewable energy since its energy content comes ultimately from the solar energy fixed by the plants in the photosynthetic process. This energy is released to break the bonds of the organic compounds in the combustion process, giving as final products carbon dioxide and water.
Biomass is composed of organic matter such as shells, leaves, wood, sugarcane fiber, olive remains … among others. It is a fuel that can offer a significant reduction in net carbon emissions compared to fossil fuels.
It is one of the renewable energy sources with the most growth potential. Its use goes from the generation of thermal, electrical, biofuel or biogas energy.
Today, heating systems using lignocellulosic products are increasingly in demand due to:
Increased cost of fossil fuels that make them a profitable investment.
It improves the technology and efficiency of the equipment that uses pellets or chips, becoming more automated every day and generating less waste.
Increase and development of the pellet market, with many points of sale existing today. Greater social awareness of the ecological benefits of renewable energy.
The generation system is based on the simple steam or Rankine cycle.
- Transportation and treatment–
By-products such as oil production, olive pruning or cotton cultivation … reach the plant where they are separated according to their size.
- Fuel dosage–
The biomass already treated reaches the boiler through dosers that regulate the fuel inlet to always maintain to always maintain adequate combustion conditions (temperature, excess air, etc.).
The biomass is burned in the boiler raising the temperature and turning the water in the pipes into steam. This circuit first passes through an economizer that begins to heat the water before entering the boiler, optimizing the process.
- Waste disposal–
The ashes that remain from the combustion go to an ashtray located under the boiler, and from there they are reused for later use in other processes. The resulting gases are filtered to avoid air pollution.
- Water recovery–
The water, after passing through the boiler, turning into steam and moving the turbine, condenses again and reaches a tank. There the cycle begins again with the treatment of the feed water to the boiler using systems such as reverse osmosis.
- Steam turbine–
Water vapor passes through nozzles that reduce its pressure, increasing speed. This flow rotates the turbine blades and transforms the energy of the steam into mechanical energy. A generator uses this force to convert it into electricity.
- High voltage electricity–
The electrical energy from the generator passes to the transformer, which increases the voltage of the current by means of electromagnetic induction. The transformer is connected to the conventional electrical network.
Advantages and Disadvantages of Renewable Energy
All forms of energy have their advantages and disadvantages, including renewable energy. The main points in favor and against are reviewed below.
- Among the most notable advantages-
It can be said that they are the essential partner against climate change: renewables do not emit greenhouse gases in energy generation processes, which reveals them as the cleanest and most viable solution to degradation environmental.
- They are inexhaustible:
Unlike traditional energy sources such as coal, gas, oil or nuclear energy, whose reserves are finite, clean energies have the same availability as the sun where they originate and adapt to the natural cycles (that is why we call them renewable). Therefore, they are an essential element of a sustainable energy system that allows present development without jeopardizing that of future generations.
- They reduce energy dependence:
The indigenous nature of clean sources implies a differential advantage for local economies and a spur for energy independence. The need to import fossil fuels produces a subordination to the economic and political situation of the supplying country that can compromise the security of energy supply. Anywhere on the planet there is some kind of renewable resource – wind, sun, water, organic matter – that can be used to produce energy in a sustainable way.
- Increasingly competitive:
The main renewable technologies – such as wind and solar PV – are dramatically reducing their costs, so that they are already fully competitive with conventional technologies in an increasing number of locations. Economies of scale and innovation are already making renewable energy the most sustainable solution, not only environmentally but also economically, to move the world.
- Favorable political horizon:
The decisions agreed at COP21 have brought a torrent of light to the future of renewable energy. The international community has understood the obligation to strengthen the transition to a low carbon economy for the sustainable future of the planet. The climate of international consensus in favor of the decarbonisation of the economy constitutes a very favorable framework for the promotion of clean energy technologies.
Regarding the disadvantages of renewable energy, it should be noted that they are very few. In addition, it must be taken into account that although it has drawbacks, it is nothing compared to the other more damaging energies that we have been using for centuries.
The first characteristic that makes choosing this type of energy difficult is the initial investment, which involves a large movement of money and which often makes it seem unprofitable at least for time.
Availability may be a current problem, they are not always available and sufficient storage should be expected. This is closely related to the fact that they are becoming increasingly popular.
Some people find a drawback in these energies with respect to the fact that depending on their source they need a large space to develop, or they need to have large areas of land to obtain an appreciable amount of energy (this is the case for example of the solar panels, of which we will need a considerable amount if we want to generate high electrical energy).
On the other hand, it should be added that a clear problem inherent in renewable energies will be that many of them have a diffuse nature, with the exception of geothermal energy, which, however, is only accessible where the Earth’s crust is thin, such as ace hot springs and geysers.