Thermal solar panels utilize solar energy, which is captured by a solar collector, to produce thermal power that is subsequently transferred towards an accumulator for subsequent use. Therefore it is a device with a panel, with a heat exchanger where the fluid utilized for energy transfer circulate, and with a tank in which the power is cumulated.

Natural and forced circulation

The system can have either natural or forced circulation. In the natural circulation option the vectorial fluid, once got hot, floats - differently from the cold fluid - and it heads towards the exchanger where it releases heat. This method is fairly cheap, also considering that with no pump, which wouldbe used to let the fluid move, there is no extra-electric energy expenditure.

In forced circulation, instead, fluid circulation occurs by the pump when the water inside the panels has a temperature superior to the fluid contained in tank. This system makes panels slightly more efficient; but obviously its cost is higher. The hot water, therefore, can be used either as health hot water or in small environments, for houses and small housing complexes.

Panels for thermal energy

Hardly, however, it substitutes entirely the traditional methods of eating; this happens because of the solar energy unsteadiness, whose flux is influenced by seasons and other meteorological factors: for example, in cloudy weather the power produced is low. Such an inconvenient, however, using new panels is going to disappear as heat will be absorbed also from solar rays’ infrared radiations. Panels will produce thermal energy even without sun reflecting directly on them.

Electric energy with panels

In addition to hot water, solar panels can be used to produce electric power. When water starts boiling, its steam activates a thermoelectric heat pump that produces electric power. This device requires ample spaces, high investments and the continuous presence of the sun. Some of these power stations are already in desert, and in Italy one is under construction.
Domestic solar panels are a very worthwhile investment in medium-long period, so that its costs write off within 10 years and the device lasts also 20 years. What is more, there are more and more fiscal reductions for those choosing this renewable energy, in addition to the environmental benefits deriving from a lower fossil fuel use.

Bookmark to:

The solar energy is a renewable power produced by the sun, a star around which the earth moves. The sun is the gravitational centre and the only thermal energy source of our solar system. This form of energy can be converted into both thermal and electrical power.

If this enormous quantity of energy was adequately exploited, it could guarantee economic savings as well as less pollution. It is, in fact, an ideal clean and renewable power source, since it has a limited environmental impact, compared to fossil fuel such as petroleum and coal.

Thermal and Photovoltaic energy

The thermal energy, which is absorbed from the sun’s rays by a solar collector, can be used to meet various energetic needs, such us the production of both hot water - for heating as well as sanitary use – and electric as well as mechanic power. The main difference between the thermal and photovoltaic energy is that the first uses the Solar Power produced by a solar collector to heat fluid circulation, while the second produces electric power.

The energy derived from the sun is 15 000 times bigger than the energy currently in use. But there are some problems: the not constant sun’s rays of lights and the law concentration for surface unit make the power stations very expensive. But in a near future, research investments could improve this form of energy production with tangible benefits to the community.

More efficient Photovoltaic Cells

Nowadays most of the studies aim to the production of more efficient and less expensive photovoltaic cells. More ambitious studies aim to the building of orbiting solar stations, which should be constituted of photovoltaic cells that convert the light of the sun into electric power to be conveyed, afterwards, through an antenna, on earth. These solar stations should have strong rays influx not interrupted from atmospheric or seasonal agents. To make the research on this type of applications slower are the high prices of them and the few funds addressed to this purpose. According to the current projects, these solar stations will be installed not in the near future, and surely not before the year 2040.

The biggest photovoltaic Italian station is near Salerno; it has been working from 1995. Another one, always from ENEL, will be launched in 2008 in Montalto di Castro (Vt): ten hectares of solar panels. In Brindisi, the biggest European photovoltaic park will be probably built on the ex-petrochemical pole area. It should be finished by the year 2010 and it is supported by University of Puglia.

Bookmark to:

Wind Power exploits the kinetic energy of wind in wind turbines to generate other forms of power, especially mechanical power and electricity. It is considered one of the most used forms of renewable energies: the term Wind Power describes the power generated from no-fossil sources, whose use has a very significant environmental importance by assuring both minor air pollution and reduction of gas carbon emission rate. Another positive aspect related to its use is the exceptional cost/production ratio.

Wind and Aeolic Generators

Air generators, the technical name for pinwheel, divide into various categories according to: the Aeolian generator that can be either on horizontal or on vertical axis, the number of shovels (from one to three) and the lengths of shovels (from fifty centimetres to thirty meters). Air generators are constituted by: a rotor (a pivot on which are inserted shovels), a stopping system for shovels block; a turns’ multiplier to increase shovels’ speed, a generator that enables to convert mechanical power into electricity; and a control system that manages the pinwheel functionality (and that, in overloaded or malfunctioning eventuality, blocks it); some air generators, generally the bigger ones, have also a system that provides a constant alignment between the rotor axis and the wind direction.

Wind Farms

The “Wind Farms” are real power stations: they originate from the connection of several air generators located within a fixed distance from each other in order to avoid dangerous interferences among them. Some Wind Farms, named Off-Shore, are located into the sea, near coasts and lakes; they are a valuable option also in densely populated countries. The history of wind plants in Italy is almost recent; the first air generator, installed in Sardinia, dates back to 1989; up to now we can say that the Wind Power use is considerably increased: the number of wind plants is raised up to around forty.

Air Generators

Anyway, it is of note that this form of energy has some negative aspects: from an environmental point of view, even if they reduce the gas emissions rates, they have a negative landscape/visual impact. In addition, because air generators are fairly noisy, the noise pollution can annoy persons and animals that take also other risks: birds can be killed while flying across shoves, even if this rarely happens; there is also the problem of interferences, and of the magnetic fields creation, but this can be avoided by using small expedients.

To finish with, it is worth saying that Wind Power considerably reduces both gas and polluters emissions, which is on the contrary avoidable from normal power stations.

Bookmark to:

In nature nothing is destroyed and nothing is created

First, let’s see what the renewable energies are and how they can be classified: renewable energies are a form of energy derived from unlimited energy sources, whose use does not jeopardize the availability of natural resources for future generations; but we have to be careful: these statements are worth only from both a social and a political point of view, as according to the first principle of dynamics in nature nothing is destroyed and nothing is created; but if we consider that the regeneration both of fossils, such as coal, natural gas and petroleum, and of chemical elements, such as plutonium and uranium, take millions of years, we have to consider these sources exhaustible, as in the near future they will be limited.

Sustainable development

Can be considered as renewable energy: the geothermal energy (the heat derived from geological sources), the hydroelectric energy (energy of tides, of sea heat and sea waves), the Wind Power, the solar energy (photovoltaic and thermal), the energy derived from Biomass (such as vegetable oils, biogas, biodiesel and chips), and the waste thermovalorization. The renewable energy has a very limited environmental impact; it allows having a sustainable development by not wasting the natural sources, thus preserving their availability for future generations.

In our country, the energy is mostly produced using very old techniques of petroleum or coal combustion; but the science has taken giant steps forward and, now, it is time for Italy to develop the use of renewable energy resources.

Bookmark to: