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Transcript of hydropower final
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HYDROPOWER
Presented By:
GURPREET SINGH(500902014)
GURVINDER SINGH
(500902015)
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FACTS ABOUT HYDROPOWER PLANT
The Worlds hydropower plants output a combined total of
675,000 megawatts, the energy equivalent of 3.6 billion barrels
of oil.
worldwide, hydro powers plant produce about 24% of worlds
electricity and supply more than one billion people with
power.
hydropower provides about 10% of electricity in united states.
India produces more than 12% of its electricity with
hydropower. Norway produces more than 99% of its electricity with
hydropower. New Zealand uses hydropower for 75% of its
electricity.
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World Energy Sources
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World hydro production
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Major Hydropower Producers
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HYDROPOWER PLANT
A hydropower plant uses the force of falling water to make
electricity.
Flowing water creates energy that can be captured and turned
into electricity. This is called hydroelectric power or
hydropower.
A typical hydro plant is a system with three parts:
a power plant where the electricity is produced.
a dam that can be opened or closed to control water flow.
a reservoir (artificial lake) where water can be stored.
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Hydropower to Electric Power
PotentialEnergy
Kinetic
Energy
Electrical
Energy
MechanicalEnergy
Electricity
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THE POWER OF WATER
Hydropower (from hydro meaning water) is energy that
comes from the force of moving water. The fall and movement
of water is part of a continuous natural cycle called the water
cycle.
The moisture eventually falls to the earth as rain or snow,
replenishing the water in the oceans and rivers. Gravity drives
the water, moving it from high ground to low ground. The
force of moving water can be extremely powerful.
Hydropower is called a renewable energy source because thewater on the earth is continuously replenished by precipitation.
As long as the water cycle continues, we wont run out of this
energy source.
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Hydrologic Cycle
http://www1.eere.energy.gov/windandhydro/hydro_how.html
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CONCEPT OF HYDRO POWER PLANT
Hydro system makes use of falling water in a stream or river
or storage dam between two points to generate mechanical
power through a turbine which is converted into electrical
power through a generator attached to turbine in a power
house. Power is expressed as kw or mw depending on capacityof station.
Amount of water flow diverted from stream or river or dam
called discharge (q) expressed in litres /sec or cumecs or
cusecs and difference in elevation between two upstream anddownstream points called gross head (h) expressed in feet or
metres.
Electricity generated in alternating current (ac) mode and
generating voltage expressed as volts (v) or kilo volts (kv)
depending on capacity of station.10
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CONCEPT OF HYDRO POWER PLANT
continued..
After flow and gross head between two points measured -
hydraulic power calculated as below.
Power = qxhx9.81 watts; q in liters per second and h gross
head in meters.
Net head after allowing for frictional losses in water conductor
system and penstocks calculated using formulae.
In case of micro hydel projects, friction loss taken as 25% of
gross head. NET HEAD (h) = GROSS HEAD FRICTION LOSSES.
Used to calculate net hydraulic power. Mechanical power calculated using turbine efficiency. For
small shp - 65%.
Useful electrical power calculated using generator efficiency -
generally 80% for small size generators (induction generatorssuitable for direct drive .
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COMPONENT OF HYDRO POWER PLANT
In general, larger the scale of a system, more the number of
components.
Intake: water from the river/spring/dam/irrigation channel is
diverted from its main course. Generally weir used to divert
water through intake into open channel.
Water conductor system : leads water from intake to head of
penstock.
De-silting basin with spillway : small tank designed to desilt
water. Provide spillway - a flow regulator for the channel.Combined with control gates to provide means of emptying
channel. Spill flow fed back to river.
Forebay tank: at head of penstock. Serves as buffer to control
sudden flow and pressure variations. 12
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COMPONENT OF HYDRO POWER PLANT
continued..
Penstock: pipeline supplying water from forebay to turbine.
Mild steel, upvc and hdpe - most commonly used materials.
Power house: houses turbine generator with mechanical
control valves and electrical control panels. Switch yard and
connection to distribution system.
Tail race channel: leads water from turbines(s) back into
stream/river/irrigation channel.
Turbine and generator: hydro power in jet at end of penstock
transmitted to turbine runner - changes to mechanical power. Governor: ensures that generator is not affected when load on
it changes. Hydraulic, or electronic. Depends on the generator.
Generator: electricity generated when turbine drives generator
-most common type of generator produces alternative currentand known as alternator.
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HYDROPOWER PLANT
Tail water
Draft tube gate
Draft tube
Turbine
Main valve
Penstock
Air inlet
Inlet gate
Surge shaft
TunnelSand trap
Trash rack
Self closing valve
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HOW A HYDROPLANT WORKS
To generate electricity, a dam opens its gates to allow water
from the reservoir above to flow down through large tubes
called penstocks.
At the bottom of the penstocks, the fast-moving water spins
the blades of turbines.
The turbines are connected to generators to produce
electricity.
The electricity is then transported via huge transmission lines
to a local utility company.
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STORING ENERGY
One of the biggest advantages of a hydropower plant is its
ability to store energy. The water in a reservoir is, after all,
stored energy. Water can be stored in a reservoir and released
when needed for electricity production.
During the day when people use more electricity, water can
flow through a plant to generate electricity. Then, during the
night when people use less electricity, water can be held back
in the reservoir.
Storage also makes it possible to save water from winter rains
for summer generating power, or to save water from wet years
for generating electricity during dry years.
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hydrodams
A dam serves two purposes at a hydro plant. First, a dam
increases the head or height of the water. Second, it controls
the flow of water. Dams release water when it is needed for
electricity production. Special gates called spillway gates
release excess water from the reservoir during heavy rainfalls.
Dams are built on rivers where the terrain will produce an
artificial lake or reservoir above the dam. Most dams are built
for flood control and irrigation, not electric power generation.
Its easier to build a hydro plant where there is a natural
waterfall. Dams, which are artificial waterfalls, are the next
best way.
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Conventional Impoundment Dam
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Schematic of Impound Hydropower
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Terminology
Head
Water must fall from a higher elevation to a lower oneto release its stored energy.
The difference between these elevations (the water
levels in the forebay and the tailbay) is called head
Dams: three categories
high-head (800 or more feet)
medium-head (100 to 800 feet)
low-head (less than 100 feet) Power is proportional to the product of
head x flow
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Scale of Hydropower Projects
Large-hydro More than 100 MW feeding into a large electricity grid
Medium-hydro 15 - 100 MW usually feeding a grid
Small-hydro 1 - 15 MW - usually feeding into a grid
Mini-hydro Above 100 kW, but below 1 MW
Either stand alone schemes or more often feeding into the grid
Micro-hydro From 5kW up to 100 kW
Usually provided power for a small community or rural industryin remote areas away from the grid.
Pico-hydro From a few hundred watts up to 5kW
Remote areas away from the grid.
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Ecological Impacts
Loss of forests, wildlife habitat, species.
Degradation of upstream catchment areas due to inundation of
reservoir area.
Rotting vegetation also emits greenhouse gases. Loss of aquatic biodiversity, fisheries, other downstream
services.
Cumulative impacts on water quality, natural flooding.
Disrupt transfer of energy, sediment, nutrients. Sedimentation reduces reservoir life, erodes turbines
Creation of new wetland habitat
Fishing and recreational opportunities provided by new
reservoirs
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Environmental and Social Issues
Land use inundation and displacement of people
Impacts on natural hydrology
Increase evaporative losses
Altering river flows and natural flooding cycles
Sedimentation/silting
Impacts on biodiversity
Aquatic ecology, fish, plants, mammals
Water chemistry changes
Mercury, nitrates, oxygen Bacterial and viral infection
Seismic Risks
Structural dam failure risks
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Impacts of Hydroelectric Dams
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ADVANTAGES
Hydropowers fuel supply (flowing water) is clean and is
renewed yearly by snow and rainfall.
hydro plants do not emit pollutants into the air because they
burn no fuel. With growing concern over greenhouse gas emissions and
increased demand for electricity, hydropower may become
more important in the future.
Hydropower facilities offer a range of additional benefits.
Many dams are used to control flooding and regulate water
supply, and reservoirs provide lakes for recreational purposes,
such as boating and fishing.
Low operating and maintenance cost.
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DISADVANTAGES
Damming rivers may permanently alter river systems and
wildlife habitats. Fish, for one, may no longer be able to swim
upstream.
Hydro plant operations may also affect water quality bychurning up dissolved metals that may have been deposited by
industry long ago.
Hydropower operations may increase silting, change water
temperatures, and lower the levels of dissolved oxygen.
Degradation of upstream catchment areas due to inundation of
reservoir area.
High initial capital cost.
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Efficiency of Hydropower Plants
Hydropower is very efficient
Efficiency = (electrical power delivered (potential energy
of head water)
Typical losses are due to
Frictional drag and turbulence of flow
Friction and magnetic losses in turbine & generator
Overall efficiency ranges from 75-95%.
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Hydropower Calculations
P = power in kilowatts (kW)
g= gravitational acceleration (9.81 m/s2)
L = turbo-generator efficiency (0
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Calculation of head loss
g2
ch
2
!
Where:
hf = Head loss [m]
f = Friction factor [ - ]
L = Length of pipe [m]
D = Diameter of the pipe [m]
c = Water velocity[m/s]
g = Gravity [m/s2]
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