RES Scenario in the European Union - The Sustainability of Renewable Energy in Europe - page 32

land areas and these can have a little look natural both for the shape of the compo-
nents and the visual impact.
The energy sources are grouped into two macro groups: sources relating directly
or indirectly to solar radiation and sources relating to materials or phenomena that
occur on earth independently of solar irradiation. Among the sources derived di-
rectly or indirectly from solar radiation there are the kinetic energy associated to the
flow of the winds, the kinetic energy associated with ocean currents deep, biomass,
photovoltaic (PV), energy connected to swell, and the chemical energy contained
in fossil fuels.
Among the sources derived from materials or phenomena that occur on earth
independently of solar radiation there is the energy contained in the bonds between
intra-atomic particles and the kinetic energy related to the motion of the tides and
the motion of the current surface ocean, geothermal energy.
The Directive 2001/77/EC (European Commission 2001 , 2011) states that:
• RES, renewable nonfossil energy sources (wind, solar, geothermal, wave, tidal,
hydropower, biomass, landfill gas, residual gas from sewage treatment, and bio-
gas);
• biomass, means the biodegradable fraction of products, waste, and residues from
agriculture (including vegetal and animal substances), forestry, and related in-
dustries, as well as the biodegradable fraction of industrial and municipal waste;
• electricity produced from RES, electricity produced by plants using only RES,
as well as the share of electricity produced from RES in hybrid plants also us-
ing conventional energy sources, including renewable electricity used for filling
storage systems, and excluding electricity produced as a result of storage sys-
tems;
• electricity consumption, the national electricity production, including auto-
production, plus imports, minus exports (gross national electricity consumption).
Features common to most RES that have direct implications in the power system are
the variability, the location, modularity, uncertainty on the intensity of the source,
and low operating costs since no fuel costs occur.
Here follows a brief and nontechnical description of the main sectors of inter-
vention and investment in electricity generation plants fueled by RES, by the type
of RES, particularly with regard to hydropower, geothermal, wind, solar PV, and
biomass because of their greater industrial importance compared to other RES.
The development of current wind technology began with the oil crises that hit
particularly industrial countries from 1973 onwards. Wind was considered as one
of the most promising alternatives to fossil fuels for electricity production. At the
beginning of the 1980s, current wind technology was already tested in the context
of government programs in Denmark, Britain, Germany, Sweden, and the USA,
several prototypes of wind turbines with power up to 4 MW. The progressive intro-
duction of incentives in various countries, especially in Europe, helped to keep alive
the demand. At the beginning of the 1990, European, American, and Japanese com-
panies came to produce machines with power ratings up to 300 kW. In more recent
years, machines have been placed in the market wind turbines with power ratings