I PARCHI EOLICI. ANALISI DI UN CASO STUDIO: SEDINI (SS)

One of the instruments identified for realizing a sustainable development model is the wider use of renewable sources of energy,as they can guarantee a less environmental impact than the ones given by the fossil fuels.The aerogenerators put into effect the conversion of the mechanical energy of the wind into a direct and alternating current.The energy supplied by wind basically consists in kinetic energy possessed by an air mass in movement.The basic component of a modern system of conversion of wind energy is the rotor,formed by a certain number of vanes fixed on a shaft that has the job to convert the power and the kinetic energy of the wind into mechanical energy.The transformation in electric energy is completed by an electric generator (alternator). The wind power plant of Sedini, the subject of this study,is located in the North-West of Sardinia and is formed by 36 large size aerogenerators,connected to the national grid, each of them with a nominal power up to 1550 kW,reaching a overall maximum power of 54 MW. The estimate of the average annual potential production of the plant is about 90 million kWh (90 GWh),enough to cover the energy requirements of 30.000 families,avoiding the inlet in the atmosphere of 60.000 tons of carbon dioxide and the consumption of about 17.000 tons reduction of oil (toe) per year. The final report examines first of all the production of energy of the different months of the year,beginning from 2005 (the starting year of the wind power plant of Sedini) up to 2008.The year 2005,except the only month of December (with a production of 10 GWh),is the year with the lowest production (on average less than 4 GWh month),because the aerogenerators just started to work. Excluding 2005,through the data analysis,we had an idea of the average monthly production of the later 3 years.Except 2007,the month with the largest production was March (upper to 12 GWh), while June and October were lower than 4 GWh.Generally we could observe a better productivity during the winter months and at the beginning of Spring. As regards to 2008,having precise data,we did a detailed analysis of the production of energy concerning each of the 36 aerogenerators.We could do this analysis because all the aerogenerators of the plant,with a total area of 2 square kilometres,have different locations and exposures and then are interested by a different speed of the wind.From the analysis of the owned data, we could deduce that the wind power plant studied presents a very irregular but,at the same time satisfactory,trend production resulting from the speed of the wind blowing in the area (on average from 3 to7 m/s).As a matter of fact,even if we could verify in different cases a high number of hours of stop engines, due to routine maintenance or sometimes due to fault parts of the engines (hours fault),is evident that a good and continuous speed of the wind can balance this deficit.Actually,if the wind is present and blows constantly and continuously,the aerogenerators work and produce electric energy.It is clear that the exploitation of the wind for the production of electric energy, through the realization of wind power plants which the one in Sedini is a significant choice,it is a strong alternative to the use of the traditional fuel fossils,especially if it is combined with other systems of production of energy,starting from the renewable sources(e.g. in Sedini we can think a photovoltaic power plant).