school energy&environment

Advantages and limits of wind

Wind is abundant, economical, inexhaustible, widely distributed, and wind energy is a renewable source that does not produce any polluting emissions. Therefore, specially in the sector of electric energy production, a greater diffusion of this energy can contribute significantly to a decrease in the so-called “greenhouse gas” emissions. Furthermore, compared to solar energy and geothermal energy, wind energy has the advantage  of being available in a mechanical form and is therefore easy to transform into electricity. Wind generators, furthermore, do not produce polluting chemical or radioactive substances  as these consist of metal and plastic materials only.
It must also be considered that the energy produced by a wind-generator during the course of its mean life span (approximately 20 years for onshore plants and over 25 years for the offshore plants) is about 80 times greater than the amount required for its construction, maintenance, operation, dismantling and disposal. It has been calculated that two or three months are sufficient to recover all the energy required to build the wind generator and to keep it operational.
Wind energy also has some disadvantages. First of all it is an intermittent source, it varies with the seasons and on a daily basis. For this reason installing 100MW wind turbines does not mean having 100MW power continuously, but a lesser amount. The actual annual capacity is equal to 45% of the nominal capacity in the more windy zones, and an average of 30% of the nominal capacity on a global scale. In other words, in order to obtain an actual capacity of 100MW the installed power must be 250MW.  Another problem that must be faced is related to the energy-transmission and distribution networks that the wind power plants are connected to, which must be predisposed to receive electricity with an intermittent flow, and an average tension. The distribution networks that are currently present in the industrialized countries are designed for opposite characteristics,  as they are connected to few very large power plants with a very high tension and a controlled and predictable flow of energy. Passing to a production of energy coming from many small-sized wind-energy or other plants, requires adequate and costly changes in the electricity distribution network.