2. What is HEP.... :-
HEP (Hydroelectric Power) is an
environmentally friendly way to generate
electricity.
3. Hydroelectric Energy :-
The hydroelectric energy, is the most important and
widely used renewable source of energy. It represents the 19%
of the total production of electricity.Today all over the world
exist roughly 45.000 big hydroelectric dams in operation. The
country with the bigger production of hydroelectricity is
Canada and follows the U.S.A and Brazil.
It emanates from the exploitation of waters of rivers. The
hydroelectric energy does not produce damaging gases and as
a result has perceptibly smaller effect in atmosphere.
4. Hydroelectric units of less 30 Mw in size are characterized small scale and are
considered as renewable sources. Fast moved water which is led through
tunnel to turn turbines, creates thus mechanic energy. A generator changes
this energy in electric . By contrast with what happens with mining fuels, the
water is not made useless at the production of electric energy and it can be
also used for other aims. Naturally, only in regions with important waterfalls,
rich sources and suitable geological configuration it is possible to manufacture
water tank . Usually the energy that is finally produced, is used only additionally
with other conventional sources of energy, in hours of peak. In our country the
hydroelectric energy satisfies the 10% of our energy needs.
5. Where is the best place for a HEP
station?
The best place for a hydro-electric power
station is up in the mountains.This is
because it doesn’t get too hot so the water
doesn’t evaporate and stays in the
dam.Also there is a lot of rain in the
mountains ensuring the reservoir is always
full.The land also needs to be impermeable
so that the water doesn’t infiltrate through
the rocks below.
6. How it works.....?
A dam is built to trap water, usually in a valley
where there is an existing lake. Water is
allowed to flow through tunnels into the dam ,
to turn turbines and thus drive generators.
Notice that the dam is much thicker at the
bottom than at the top , because the pressure
of the water increases with depth.
7. Small Hydroelectric power
station :-
The hydraulic energy, the energy of water, is a
renewable, and decentralised source of energy that
served and serves man loyally in his course of
progress . Many hydraulic wheels, watermills, sawmills,
and other mechanisms of hydro movement continue even
today to use the force of water, contributing considerably
in the progress of the local economy of many regions, in
an absolutely friendly to the environment way. In many
parts the of Greek country certain traditional, but also
modern installations of Small Hydroelectric Work continue
developing the energy of water for the production of
mechanic work but mainly for the production of electric
current nowadays. The exploitation of small
hydrodynamic sources of mountainous Greece passes
from the concretisation decentralised, developed small
hydroelectric power stations of multiple expediency, that
can function and for the simultaneous cover watering
irrigatory and other local needs.
Small Hydroelectric power
station :-
The hydraulic energy, the energy of water, is a
renewable, and decentralised source of energy that
served and serves man loyally in his course of
progress . Many hydraulic wheels, watermills, sawmills,
and other mechanisms of hydro movement continue even
today to use the force of water, contributing considerably
in the progress of the local economy of many regions, in
an absolutely friendly to the environment way. In many
parts the of Greek country certain traditional, but also
modern installations of Small Hydroelectric Work continue
developing the energy of water for the production of
mechanic work but mainly for the production of electric
current nowadays. The exploitation of small
hydrodynamic sources of mountainous Greece passes
from the concretisation decentralised, developed small
hydroelectric power stations of multiple expediency, that
can function and for the simultaneous cover watering
irrigatory and other local needs.
8.
9. Operation of Hydroelectric units:-
The hydroelectric units use the energy of water and by using a simple method
change this energy into electric current. This units are based on the movement of
water that turns a turbine which brings in operation a generator. Most hydroelectric
units use a dam which retains a big quantity of water creating thus a big reservoir.
Certain doors in the dam open and because of the gravity the water passes in a
driver which leads it to a turbine. As it passes from the driver it creates a big
pressure. The water falls on the propeller s of a turbine and makes it turn. This
movement is transported in the generator which is connected with the turbine with
an axis.
10. Most hydroelectric units function in this way. However ,another type
of hydroelectric unit exists. In a conventional hydroelectric unit the
water from the reservoir passes from the turbine and leads again to
the river. The new hydroelectric units use two reservoirs. The higher
reservoir which assembles the water that retains the dam and is
used for the production of electric current. The lower reservoir which
assembles the water that leaves from the turbines, send it behind in
the river. A reverse turbine channels this water again behind in the
higher reservoir. Returning the water behind the unit has more water
for use in periods of peak.
12. The most usual type of turbine for
hydroelectric units
is the turbine Francis which resembles to a
big disk with convex . Such a turbine can
weigh up to 172 tons and make 90 rotations
per minute. While the propellers of the
turbine are turning, the magnets of the
generator are turned round an inductor
placing in movement electrons and creating
the alternating electric current. The
transformer takes the alternating current and
changes it into current of high potential.
Outside each hydroelectric unit exist four
cables: the three phases of current that are
created simultaneously plus the neutral for
the three.
13. Advantages of HEP :-
Once the dam is
built,the energy is
virtually free
Water can be stored
above the dam ready
to cope with peaks in
demand
Much more reliable
than wind,solar or
wave power
No waste or pollution
produced
Electricity can be
generated constantly
Hydro-electric power
stations can increase
to full power very
quickly unlike other
power stations
14. MORE advantages from the use of hydroelectric energy are:
The hydroelectric power stations are possible to be placed in operation as soon as
it is asked more electric energy, contrary to the thermo stations of (coals, oil), that
requires time of preparation
Also through the water tanks is given the possibility to be satisfied other needs, as
water supply, irrigation, interception of torrents, creation of wetlands, recreation,
sports. In 140 countries, the dams provide cheap hydroelectric energy. In world
scale, provide the 19% of produced energy and through the irrigation, the 16% of
world feeding. Certain dams continue their function after 30-40 years, providing
current and water. The hydroelectric energy plays a serious role in the reduction of
the emission of gases that they create the" greenhouse effect" at 13%,as it
produces the equivalent of energy which in a different case would be produced in
another way that would create greenhouse gases
15. Disadvantages of HEP :-
The dams are very
expensive to
build,however many
dams are also used for
flood control or
irrigation,so building
costs can be shared
Building a large dam will
flood a very large area
upstream,causing
problems for animals that
used to live there
Finding a suitable site
can be difficult - the
impact on residents and
the environment may be
unacceptable.
Water quality and
quantity downstream can
be affected, which can
have an impact on plant
life.
16. The disadvantages that usually are presented
are:
The big cost of the manufacture of dams and the equipment of the
stations of generation of electricity, as well as, the time that is
required up to the completion of work
The intense environmental alteration in the region of tank (potential
locomotion of populations, areas revalorization, change in the use
of the ground, in the flora and fauna of the regions but also local
climate, fulfillment of tanks with brought matters, increase of
seismic danger, etc)..
The disadvantages that usually are presented
are:
The big cost of the manufacture of dams and the equipment of the
stations of generation of electricity, as well as, the time that is
required up to the completion of work
The intense environmental alteration in the region of tank (potential
locomotion of populations, areas revalorization, change in the use
of the ground, in the flora and fauna of the regions but also local
climate, fulfillment of tanks with brought matters, increase of
seismic danger, etc)..
17. Is it renewable..?
Hydro-electric power is renewable.The
Sun provides the water by evaporation
from the sea,and will keep on doing so
The Sun evaporates water
from the sea and lakes,
which forms clouds and falls
as rain in the mountains,
keeping the dam supplied
with water.
