Renewable energies: solar energy
Realization of a solar concentration panel
Between the several renewable energies the solar energy is the most important even if not more easy usable; as an example the wind energy, directed consequence of the solar energy, valued around to 1.5% - 2% of all the solar energy, is more easy usable above all in the ventilated regions, by the modern windmills with power between few tens of kw to 1,5 Mw or 2,5 Mw, and is obtained already in shape of mechanical energy, then transformed in electric power by a simple dynamo; not chance event the wind energy is expanding with the medium rhythm of 25% every year, that is the total power installed is doubling each 3 years.
Economic and philosophical considerations
Conference H2 Roma 2004 on sustainable mobility and hydrogen
However solar energy, beyond to be the most important renewable energy, allowing the existence of the life on the Earth (at least from the physical point of view, because the of the human activities impact on the environment is so strong to make necessary also the respect of moral and behavior rules and choices compatible with the environment) has some characteristics that make it interesting for numerous applications:
1) it is the most constant energy form, above all as photovoltaic energy, because photovoltaic panels supply energy also with cloudy weather, even if in reduced proportions, that is also only 10% or 20% of the maximum power, in function of the cloudiness degree;
2) it is a concentrabile energy form, by opportune reflectors, that can be constituted from simple mirrors, oriented towards a more reduced surface;
3) using opportune thermal motors, based on the Stirling cycle or the Brayton cycle, or simply heating a pressured steam (Rankine cycle) we can convert solar energy in mechanical energy and therefore in electric power;
4) the intense solar radiation, concentrated on a reduced surface, induces phenomena of photoscission of molecules and photocatalysis of chemical reactions, allowing a better carrying off of the organic or inorganic refusals and one they eventual transformation in hydrocarbons, by as an example the process of Fischer-Tropsich.
Economic and philosophical considerations
Conference H2 Roma 2004 on sustainable mobility and hydrogen
In the image is represented a version of the solar concentratore constituted by two panels of 2x1,5 meters everyone, that can be closed by two opportune electric motors; the Brayton cycle motor is placed up, in the metallic structure composed by a light metallic sheet containing thermal insulator, preferably rock wool, that isolates also a small water tank - heat exchanger, in which water enters at ambient temperature and exits heated.
This solar concentrator can therefore be closed automatically, in sun absence, either for aesthetic reasons or in order better to resist to the inclemencies (arranging to counter wind the section of minimal area).
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