7. ELECTRIC POWER PLANTS
In most electric power plants,heat is
produced when coal,oil or natural gas is
burned or nuclear power plants undergo
fission to release huge amounts of energy.
This heat turns water to steam,which
in turn spins turbines to produce
electrecity.
8. • After doing ,the spent steam must be cooled and
condensed back into water.
To condense the team ,cool water is brought into the
plant and circulated next to the hot stream.
In this process,the water used for cooling warms 5 to
10 degree celsius.
After this it may be dumped back into the water body
from where it came.
10. NUCLEAR POWER PLANTS
Hot effluents from nuclear power plants
and nuclear fuel processing units,the
drainage from nuclear research institutes
and emissions from nulear experiments
and explosions dicharge large amount of
undesirable heat and radionucleotides into
the nearby water bodies.
This is perhaps the most serious type of
12. Coal-fired power plants
Some thermal power plants use coal as
the fuel.
The condenser coils of such thermal
power plants are coded and the resulting
hot water is discharged into water bodies.
This results in the increase of water
temperature thus resulting in thermal
pollution.
14. ENVIRONMENTAL IMPACTS OF WARM
WATER
Elevated temperature decreases the level of dissolved
oxygen in water.
This cause harm to aquatic animals such as fish,
amphibians etc.
Oxygen dispersion into deeper water will be limited
contributing anaerobic conditions.
This can lead to increased bacterial levels.
Many aquatic species will not be able to reproduce.
A large increase in temperature can lead to denaturing
of life supporting enzymes.
15. ENVIRONMENTAL EFFECTS OF COLD
WATER
Release of cold water into water
bodies from reservoirs can damage
fish population.
Macro invertebrate fauna will be
effected.
Effects river productivity
18. VERMONT YANKEE NUCLEAR POWER
PLANT
The discharge of warm water from Vermont
Yankee nuclear power plant poses a serious threat
to river ecology.
Heating up the river weakens and disrupts fish
which look to changes in water temperature to
migrate or breed.
Vermont Yankee has been allowed to raise the
temperature of river Connecticut up to 13 degree
Celsius during winter and up to 5 degrees in
summer.
19. The nuclear power plants sends up to 543
million gallons of heated water.
In 2006 the Vermont Agency of Natural
Resources allowed the power plants to
increase water temperature.
Although CRWC fought the increase all
the way to the Vermont Supreme Court,
Entergy was ultimately allowed to raise
the river temperature during the summer
season when American Chad are
vulnerable to warm conditions.
21. DIABLO CANYON POWER PLANT
It is a nuclear power plant that is used for
generating electricity
It is located in Avila Beach in San Luis Obispo
County
The power plant has been in operation since 1985.
People have protested saying the power plant is
causing harm to the environment.
The plant species surrounding the power plant has
been effected.
22.
23. CONTROL OF THERMAL POLLUTION
FROM POWER PLANTS
Heated water from thermal power plants can be controlled
with cooling ponds, man-made bodies of water designed
for cooling by evaporation,convection and radiation
cooling towers which transfer waste heat to the
atmosphere through evaporation or heat
transfercogeneration a process where waste heat is
recycled for domestic or industrial purposes.
Instead of discharging heated water into water bodies
power plants can pass the heated water into cooling ponds
where evaporation cools the water before it is discharged
24. Alternatively power plants can designed or
refitted to be more efficient and to produce less
waste heat in the first place.
In cogeneration the excess heat energy from
generating electricity can be used in another
manufacturing process that needs such energy.
Where homes or other buildings are located
near industrial plants, waste hot water can be
used for heating.
This arrangement is found in Scandinavian
countries and is proposed for use in China.
25. COOLING PONDS
It is a pond or lake especially constructed to provide a
source of cooling water and a closed sink to which to
return it after use.
The pond must be sufficiently large that evaporation
and other heat transfer to the air from its surface can
keep the average water temperature low enough to
provide a continous source of cooling water.
The pond outlet is usually located as far as possible
from the hot water return to minimize the time
allowed for cooling.
26. Unfortunately from 1 to 2 acres of
cooling pond are required per Mwe
plant and their use is restricted to
regions where land is both cheap and
available.
27. COOLING TOWERS
It allows the efficient contact of ambient air with
heated water, resulting in the rapid cooling of the
water without returning it to its source, or before it is
returned to its source.
When a cooling tower is used it is possible to use the
same water for power plant cooling again by adding a
small fraction of fresh water to make up for
evaporation lesser “blow down” and drift.
Water withdrawal rates can be reduced to 2-4% or less
of these required for once through cooling.
28. Cooling towers are classified by design as either “wet” or “dry”
and as being “natural” or “mechanical draft”
In a wet tower the heated water is broken into a fine spary
which falls through moving ambient air.
The water is cooled by the evaporation of a few percent of its
weight approaching a low temperature which is dependent on
the ambient temperature and humidity.
Dry cooling towers functions much like large auto radiators in
which the heated water passes through closed coils over which
ambient air moves.
heat is transferred through the coils by conduction and into the
air by convection.
29. No water is lost by evaporation and
the lowest temperature attainable by
the water is the ordinary dry bulb
temperature which is higher than the
wet bulb temperature and is the
temperature recorded by an ordinary
thermometer.
