Environmental Engineering Reference
In-Depth Information
Transformer
h
u
Grid
SG
Generator
H h
u -
h
l
h
l
~
G
Gear
(if necessary)
Flow rate Q
in m
3
/s
Rake
Turbine
Figure 1.15
Principle of a Hydro-electric Power Plant
Electricity generation from hydro power started at the end of the 19th century
and has achieved technical sophistication. A weir creates a height (or
'potential') difference (also called a 'head') between the water before and after
the weir (see Figure 1.15). This potential difference can be utilized by a power
plant. The water flows through a turbine, which transforms the potential
energy into mechanical energy. An electric generator converts this into
electricity. Depending on the head height and flow rate, different turbines are
used. Common turbines are the Pelton, Francis or Kaplan turbines. Finally, a
transformer converts the generator voltage to the grid voltage.
The power output:
P
=
G
T
W
•
g
•
Q
•
H
(1.6)
•
•
of the power plant can be calculated from the efficiency of the generator
G
W
~
1000 kg/m
3
), the head
H
(in m), the gravitation constant
g
(
g
= 9.81 m/s
2
) and the flow rate
Q
(in m
3
/s).
and the turbine
T
, the density
W
of the water (
Table 1.8
Contribution of Hydro-electricity to the Net Electricity
Generation in Different Countries
Country
Paraguay
Norway
Brazil
Iceland
Venezuela
Austria
Canada
Share (%)
100
99
89
83
75
71
60
Country
Russia
China
Australia
US
Germany
UK
Netherlands
Share (%)
19
17
8
7
4
1.4
0.1
Source:
DOE, 2003
