RES Scenario in the European Union - The Sustainability of Renewable Energy in Europe - page 37

Table 2.2 Global photovoltaic cumulative installed capacity (MW). (Source: EurObserv'er and
ENEA 2013)

Cumulative capacity
(2011)

Cumulative capacity
(2012)

Installed capacity in
2012

Europe 52,884.0 70,043.0 17,159.0

Asia Pacific 7628.0 12,397.0 4769.0

Americas 4959.0 8717.0 3758.0

China 3300.0 8300.0 5000.0

Middle East and
Africa

192.0 601.0 409.0

Rest of the world 2098.0 2098.0 0.0

Total 71,061.0 102,156.0 31,095.0

(7.8 GW) and Japan (6.9 GW). Some countries that have a huge potential, as Africa,
the Middle East, South East Asia and Latin America, are beginning to appear on PV
market.
At the global level, nine of the top ten markets for PV in 2012 have installed at
least 1 GW of PV systems (Table 2.2 ).
Concerning the hydroelectric technology, hydroelectric power plant converts the
hydraulic energy of a watercourse, natural or artificial, into electrical energy. In
general, the functional scheme includes the work of the barrage, a dam, or a cross-
bar, which intercepts the course of water creating a reservoir which may be a tank,
or basin, where it is kept in an almost constant level of water.
Through the works of water supply, canals, and tunnels, water is then piped into
tanks and cargos and through penstocks, it flows in turbines via the inlet valves
(safety) and regulatory bodies of the range (distributors) according to energy de-
mand. The water, which puts into action the turbines, then flows out of the discharge
channel through which it is returned to the river. The alternator is directly connected
to the turbine and is mounted in an arrangement with a vertical axis or horizontal
axis. It is essentially a rotating electrical machine capable of transforming mechani-
cal energy into electrical energy by the turbine. The electricity thus obtained must
be transformed in order to be transmitted over long distances.
Therefore, before being conveyed in transmission lines, electrical energy passes
through the transformer that lowers the intensity of the current produced by the al-
ternator; however, by raising the voltage to thousands of volts. Arrived at the place
of use, before being used, the energy passes back into a transformer that this time
raises the intensity of current and lowers the voltage so as to make it suitable for
domestic use.
The power of a hydraulic system depends on two factors that are the jump (height
difference between the height at which the water resource is available flared and the
level at which the same shall be refunded after the passage through the turbine) and
the rate of flow (the mass of water flowing through the machine expressed per unit
of time).