The amount of solar energy converted into mechanical power by the wind is equal to about 0.2%. In order to exploit kinetic energy from the air it is necessary to build a wind farm and this depends on certain parameters determined by a wind gauge. The amount of wind power available depends on wind speed, the passage section and air density. The difficulty in evaluating the amount of wind power available is in the unreliability of the wind source: wind intensity heavily depends on both the weather and location. There are also significant differences relating to wind farm sites in terms of orographic features and the distance of wind turbines from the ground. In order to evaluate potential wind power, an average wind speed is taken over regular intervals. Daily surveys show that in most places wind is more intense during the day than at night. Indeed, the highest values are recorded in the early afternoon. The fact that there is more wind during the day is extremely useful for the production of electricity.

The speed of the wind varies according to differences in wind volume. In fact obstacles or rugged soil can reduce the amount of wind, producing a lower value than that of uninterrupted wind flow. In a wind gauge evaluation different areas are classified according to the ruggedness of the earth.

How a wind farm works

Wind turbine generators are used to produce electricity from the wind and there are various types. In particular, there are vertical-axis wind turbines and horizontal-axis turbines.Horizontal-axis turbines are made up of a rotor shaft, a brake assembly, a tower structure, blades, an electrical generator, a gearbox, a rotor yaw mechanism and a nacelle. The size of horizontal-axis turbines determines the amount of downward pressure generated on the blade tips. The power extracted from a wind turbine is referred to by values that relate to capacity and production. These values are expressed as a percentage of the theoretical maximum capacity of a turbine to extract power, based on the rotor speed achieved and consequent energy production from uninterrupted wind flow. Indeed, the function of wind turbines, typically those of horizontal-axis design, is to produce as much electricity as possible by converting kinetic energy into mechanical energy.

The biggest and most powerful turbines today are horizontal axis with three-blade rotors, which are adjustable for the harnessing of both electric and hydraulic power by using epoxy resin strengthened with fiber glass. The best combination for small-scale wind farms is a horizontal-axis turbine with multi-blade rotor, the tips of which are angled for centrifugal strength.


Renexia is involved in a number of projects in the wind power sector both in Italy and abroad.

Onshore wind farms

Onshore wind farms are positioned near the coast or in other windy places, in open areas or on hills and mountains. In Italy, Renexia has an extensive portfolio of projects in Puglia (Foggia, Lucera, Troia, Alberona) and in Campania (Santa Croce del Sannio, Castelfranco e Casalduni), with installed power equal to 300MW and an expected productive capacity of the equivalent of 2.400 hours a year. Abroad, the company operates in the USA and North Africa. In particular, in Tunisia Renexia is involved in two important projects for a total of about 150MW and an average expected productive capacity of the equivalent of 3.500 hours a year.

Offshore wind farms

Offshore sites are found in large bodies of water, in the sea or lakes, in order to exploit the strong wind currents in these areas. Here, Renexia focuses on the American market where it has been awarded the right to exploit a stretch of water in the states of New Jersey and Massachusetts. The potential of these two projects is over 1.500MW. Other projects are also underway in northern Europe and particularly in Germany.


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