COMPARISON AMONG DIFFERENT SMALL POWER PLANTS UTILIZING RENEWABLE ENERGY SOURCES

The aim of this work is the comparison of three different power plants employing renewable energy sources available in the Piedmont Region (North-West of Italy), by means of the following technologies: a mini-hydro with Archimedes' screw, a wind-turbines and a photovoltaic system with solar cells. According to the project requirements, for each of three solutions, the most suitable site was found in the Piedmont region of Italy. The mini-hydro, endless screw with asynchronous reversible generator, has been installed in a small irrigation channel near the city of Novara, where the cultivation of rice needs considerable quantities of water throughout the year. With the nominal power of the mini-hydro of 150 kW the total electric energy produced in an year results from the calculation of about 750,000 kWh. As far as the wind turbines are concerned, thanks the anemometric investigation performed by ARPA (Environmental Protection Agency in Piedmont), the most useful place resulted the Colle S. Bernardo, located between Piedmont and Ligurian Riviera at 980 m of altitude. Using the PGIS (Photovoltaic Geographical Information System), for solar cells, the best site in Piedmont, resulted instead a place in south-west of Piedmont, near the city of Cuneo. As previously said, because the total amount of electric energy has been assumed for the comparison of about 750,000 kWh, as consequence these two last solutions present different nominal power. In particular: power of 100 kW for three wind wheels and of 60 kW for one wind wheel (total power 360 kW); power of 550 kW (of peak) for solar cells. After estimating the investment costs, the operating costs and the renewable energy production incentives of the three power plants, the payback has been also evaluated for each solution. From the economical assessment that was carried out through the Net Present Value, the hydroelectric plant resulted the most profitable solution.