Suited for high head, low flow sites.
The largest units can be up to 200 MW.
Can operate with heads as small as 15 meters
and as high as 1,800 meters.
• Combined action of pressure and moving
• Runner placed directly in the water stream
flowing over the blades rather than striking each
•L ower head and higher flows than compared
with the impulse turbines.
The inlet is a scroll-shaped tube that wraps
around the turbine's wicket gate.
Water is directed tangentially, through the
wicket gate, and spirals on to a propeller
shaped runner, causing it to spin.
The outlet is a specially shaped draft tube that
helps decelerate the water and recover kinetic
The inlet is spiral shaped.
Guide vanes direct the water tangentially to the
This radial flow acts on the runner vanes,
causing the runner to spin.
The guide vanes (or wicket gate) may be
adjustable to allow efficient turbine operation
for a range of water flow conditions.
Nuclear Reactor works
• 235U fissions by absorbing a neutron and producing 2 to 3 neutrons, which
initiate on average one more fission to make a controlled chain reaction
•Normal water is used as a moderator to slow the neutrons since slow
neutrons take longer to pass by a U nucleus and have more time to be
•The protons in the hydrogen in the water have the same mass as the neutron
and stop them by a billiard ball effect
•The extra neutrons are taken up by protons to form deuterons
•235U is enriched from its 0.7% in nature to about 3% to produce the reaction,
and is contained in rods in the water
•Boron control rods are inserted to absorb neutrons when it is time to shut
down the reactor
•The hot water is boiled or sent through a heat exchanger to produce steam.
The steam then powers turbines.
Nucleons more tightly bound in Fission Product Nuclei – Gives
200 Mv Energy per Fission
How Does it Work
•Carnot Efficiency (T1-T2)/T1: in
transferring heat to do work, the
greater the spread in temperature
between the heat source and the heat
sink, the greater the efficiency of the
•As long as the temperature between
the warm surface water and the cold
deep water differs by about 20°C
(36°F), an OTEC system can produce
a significant amount of power with a
maximum Carnot Efficiency of about
•Low Environmental Impact
The distinctive feature of OTEC energy systems is that the end products
include not only energy in the form of electricity, but several other synergistic
The first by-product is fresh water. A small 1 MW OTEC is capable of
producing some 4,500 cubic meters of fresh water per day, enough to supply a
population of 20,000 with fresh water.
A further by-product is nutrient rich cold water from the deep ocean. The cold
"waste" water from the OTEC is utilised in two ways. Primarily the cold water is
discharged into large contained ponds, near shore or on land, where the water
can be used for multi-species mariculture (shellfish and shrimp) producing
harvest yields which far surpass naturally occurring cold water upwelling
zones, just like agriculture on land.
The energy is free – no fuel needed, no waste produced
Not expensive to operate and maintain
Can produce a great deal of energy
Depends on the waves – sometimes you’ll get
loads of energy, sometimes almost nothing
Needs a suitable site, where waves are
Some designs are noisy. But then again, so
are waves, so any noise is unlikely to be a
Must be able to withstand
Environmental Impact•Noise pollution
•Displace productive fishing sites
•Change the pattern of beach sand nourishment
•Alter food chains and disrupt migration patterns
•Offshore devices will displace bottom-dwelling organisms where they
connect into the
•Earth emits some 44TW of energy. Not
•As a rough rule, 1 km3 of hot rock cooled
by 1000C will yield 30 MW of electricity
over thirty years.
•The heat flux from the center of the Earth
can fulfill human energy demands (Joules
are there, by techniques….)
Geothermal Energy Sources
Hot Water Reservoirs: hot underground water. Large number, but best suited
for space heating
Natural Steam Reservoirs: Steam comes to the surface. This type of
resource is rare in the US.
Geopressured Reservoirs: Brine saturated with natural gas (overpressurized).
This type of resource can be used for both heat and for natural gas.
DRY STEAM: steam moves
through turbine and condenses to
form water which acts as heat
FLASH STEAM: extremely hot
water is turned or “flashed” into
steam from a decrease in pressure,
steam drives turbine to produce
BINARY CYCLE: hot water goes
through heat exchanger, heats up
another fluid such as isobutane in a
closed loop system, second fluid
now boils at lower temperature than
hot water and turns to steam much
faster, steam drives turbine
=> most commonly used
(steam = rare)
Need of MHDs
Principle Of MHD Power Generation
Types of MHD SYSTEM
Open Cycle MHD System
Closed Cycle MHD System
Diffrence between Open Cycle and
Closed Cycle MHD System
8. Advantages OF MHD System
9. Disadvantages of MHD System
Magneto HydroDynamic (MHD) system is a nonconventional source of energy which is based upon
Faraday’s Law of Electromagnetic Induction, which
states that energy is generated due to the movement of
an electric conductor inside a magnetic field.
Concept given by Michael Faraday in
1832 for the first time.
MHD System widely used in advanced
Under construction in INDIA.
Need of MHDs
At present a plenty of energy is needed
to sustain industrial and agricultural
production, and the existing conventional
energy sources like coal, oil, uranium etc
are not adequate to meet the ever
increasing energy demands. Consequently,
efforts have been made for harnessing
energy from several non-conventional
energy sources like Magneto Hydro
Principle Of MHD Power
Faraday’s law of electromagnetic induction : When an
electric conductor moves across a magnetic field, an
emf is induced in it, which produces an electric current .
the charged particle
F = q(v × B)
v = velocity of the particle
q= charge of the particle
B = magnetic field (vector)
Comparison between a Turbo
generator and a MHD generator
(1)Open cycle System
(2)Closed cycle System
(i)Seeded inert gas systems
(ii) Liquid metal systems
DIFFERENCE BETWEEN OPEN
CYCLE AND CLOSED CYCLE
Open Cycle System
Working fluid after generating
electrical energy is
discharged to the
atmosphere through a stack
Operation of MHD generator
is done directly on combustion
Temperature requirement :
2300˚C to 2700˚C.
Working fluid is recycled to
the heat sources and thus is
Helium or argon(with cesium
seeding) is used as the
Temperature requirement :
NEED FOR FURTHER
The MHD channel operates on extreme
conditions of temperature, magnetic and electric
So, numerous technological advancements are
needed prior to commercialization of MHD
Search is on for better insulator and electrode
materials which can with stand the electrical,
thermal, mechanical and thermo-chemical
stresses and corrosion.
ADVANTAGES OF MHD
Conversion efficiency of about 50% .
Less fuel consumption.
Large amount of pollution free power generated
Ability to reach full power level as soon as
Plant size is considerably smaller than
conventional fossil fuel plants .
Less overall generation cost.
No moving parts, so more reliable .
Suffers from reverse flow (short circuits) of
electrons through the conducting fluids
around the ends of the magnetic field.
Needs very large magnets and this is a
High friction and heat transfer losses.
High operating temperature.
Coal used as fuel poses problem of molten
ash which may short circuit the electrodes.
Hence, oil or natural gas are much better
fuels for MHDs. Restriction on use of fuel
makes the operation more expensive.
Power generation in space craft.
Hypersonic wind tunnel experiments.
The MHD power generation is in advanced stage
today and closer to commercial utilization. Significant
progress has been made in development of all critical
components and sub system technologies. Coal
burning MHD combined steam power plant promises
significant economic and environmental advantages
compared to other coal burning power generation
technologies. It will not be long before the
technological problem of MHD systems will be
overcame and MHD system would transform itself
from non- conventional to conventional energy