RES Scenario in the European Union - The Sustainability of Renewable Energy in Europe - page 34

north-central EU), the average cost of energy may be much lower, even in the order
of 50-60 €/MWh.
The production of wind energy has mainly two controversial aspects. First, the
average cost of wind power generation is still above the EU average revenues ob-
tained from the sale of the wind power in the electricity market. It then explains
how the wind power production still needs some incentives (it follows a detailed
description of incentive mechanisms in Chap. 3).
Second, the development of RES, in particular wind energy, introduces elements
of landscape transformation, thus an evolution of the ratio between the population
and perception that they have of the landscape itself. The plants powered by RES
are deeply rooted in the territory in which they are installed and from which they
receive their raw material, making it more visible energy production and transform-
ing the relationship with the natural environment. The presence of environmental
impacts related to RES imposes the need for a shared scenario and an integrated
approach to the comparison of the overall benefits and the changes induced locally.
The wind power capacity installed worldwide during 2012 is 44,184 MW, cor-
responding to a cumulative capacity of 281,052 MW worldwide (Table 2.1 ).
Wind continues to be used mainly by wind power plants of significant power,
connected to high-voltage power grids and wind turbines mainly between 1 and
3 MW of power per unit on the mainland and between 2 and 6 MW offshore.
Concerning the PV technology, it allows to directly convert solar energy into
electricity through the PV effect, that is the property of some semiconductor ma-
terials to generate electricity when struck by light radiation. The silicon element is
widespread in nature, is the basic material for the PV cell, and is the elementary
device that can produce about 1.5 W in direct current, normally insufficient for
common uses. More cells are electrically connected and encapsulated in a structure
to form the module-based component which is commercially available.
Several modules are connected in series and in parallel, forming sections of a
plant whose power can reach thousands of kilowatt. Downstream of PV modules is
placed the inverter that converts the direct current into alternating current generated
by the cell, directly usable by users or with the possibility of being fed into the grid.
The modules can be oriented towards the sun on fixed structures, or structures able
to follow the movement in order to increase solar collection.
Each kilowatt peak 2 installed requires an area of about 8-10 m 2 net for crystal-
line silicon modules coplanar to the roofs of buildings; it is necessary instead of
a broader space for modules arranged in several rows on a flat surface to reduce
shading.
The main applications of PV systems are:
• Systems with storage system for isolated users from the network; such systems
are independent type and they are indicated in the case of the absence of electrical
connection (such as mountains, in agricultural areas not served by the network,
2 The kilowatt peak is used to measure the maximum power delivered by a photovoltaic generator.