2. Introduction
It is a form of energy … a renewable resource. Hydropower
provides about 96 per cent of the renewable energy in the
United States.
Hydroelectric power comes from flowing
water … winter and spring runoff from
mountain streams and clear lakes. Water,
when it is falling by the force of gravity, can
be used to turn turbines and generators that
produce electricity
3. HOW HYDROPOWER WORKS 2
11
In the hydrologic cycle, atmospheric water reaches the earth is surface
as precipitation. Water from rain and melting snow eventually reaches
ponds, lakes, reservoirs, or oceans where evaporation is constantly
occurring.
4. Water from the reservoir
flows due to gravity to
drive the turbine.
Turbine is connected to a
generator.
Power generated is
transmitted over power
lines.
5.
6. Hydro power is available by creating dams in stream and
river flows. Hydro power generation is an established
technology and maybe as much as one fifth of the world's
electricity is generated this way, which is slightly more than
by nuclear generation.
9. In electricity generation, an
electrical generator is a device
that converts mechanical energy
to electrical energy, generally
using electromagnetic induction.
The source of mechanical energy
may be a reciprocating or turbine
steam engine, water falling
through a turbine or waterwheel,
an internal combustion engine, a
wind turbine, a hand crank,
compressed air or any other
source of mechanical energy.
10. Pumped Storage
At night when customer
demand for energy is
lower, water is pumped
to storage pool above the
dam
11. At Day
When demand and heavy
load is placed on the
system is allowed to flow
back through the turbine
– generator
12.
13. ADVANTAGES
1. Once a dam is
constructed, electricity
can be produced at a
constant rate.
14. 2 - Economics
The major advantage of hydroelectricity is elimination of the cost
of fuel. The cost of operating a hydroelectric plant is nearly
immune to increases in the cost of fossil fuels.
15. 3. If electricity is not
needed, the sluice gates
can be shut, stopping
electricity generation. The
water can be saved for
use another time when
electricity demand is high.
16. 4. When in use, electricity produced by dam systems do not
produce green house gases. They do not pollute the
atmosphere.
5. The lake's water can be used for irrigation
purposes
Although dams prevent the natural flushing out of a
river during a flood, they also control flooding
downstream in times of high rainfall and snowmelt.
17. Disadvantages
. Dams are extremely expensive to build and must be
built to a very high standard.
Usually a large area of land
has to be flooded to ensure
a continuous flow of water
to the turbine. In some
cases when a dam is built,
large populations have to be
relocated. In China, the
Three Gorges Dam Project
on the Yangtze River
will displace more than 1
million people.
18. Disadvantages
Environmental damage
Hydroelectric projects can be disruptive to surrounding
aquatic ecosystems. For instance, studies have shown that
dams along the Atlantic and Pacific coasts of North America
have reduced salmon populations by preventing access to
spawning grounds upstream, even though most dams in
salmon habitat have fish ladders installed.
19. Population relocation
Another disadvantage of
hydroelectric dams is the
need to relocate the people
living where the reservoirs
are planned. In many cases,
no amount of
compensation can replace
ancestral and cultural
attachments to places that
have spiritual value to the
displaced population. Such
problems have arisen at the
Three Gorges Dam project
in China.
20. Dam failures
Failures of large dams,
while rare, are potentially
serious — the Banqiao Dam
failure in Southern China
resulted in the deaths of
171,000 people and left
millions homeless. Dams
may be subject to enemy
bombardment during
wartime, sabotage and
terrorism. Smaller dams
and micro hydro facilities
are less vulnerable to these
threats.
