Transcript Slide 1

Module 02
Conventional Energy Technologies
- in electricity generation from non-renewable energy sources
(coal, petroleum, natural gas and nuclear power)
- in vehicular transport
- in other primary and secondary energy consumption modes
(heating, cooling, agriculture and electronic devices)
Prof. R. Shanthini
Dec 31, 2011
1
How is electricity
generated from
non-renewable energy
sources (oil, coal or
natural gas)?
Diesel
Generator
Gas Turbine
(GT)
Prof. R. Shanthini
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Combined
Power Plant
(GT & ST)
Steam Turbine
(ST)
2
Electric Generator
We need a
rotating shaft?
Electrical
output
N
Rotating
wire loop
Magnet
S
How to rotate the
wire loop?
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http://electron9.phys.utk.edu/phys136d/modules/m8/images/gen.gif
Wind turbine gives a rotating shaft
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http://www.electricityforum.com/images/motor-eout.gif
Water turbine could also give a rotating shaft
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Diesel generator
It is a diesel engine coupled to a electric generator.
Diesel engine provides the rotating shaft.
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http://www.rkm.com.au/animations/animation-diesel-engine.html
Diesel generator
It is a diesel engine coupled to a electric generator.
Diesel engine provides the rotating shaft.
Prof. R. Shanthini
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http://www.rkm.com.au/animations/animation-diesel-engine.html
Diesel generator
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http://www.myrctoys.com/engines/ottomotor_e.swf
Gas Turbine Power Plant
fuel
compressed
air
Compressor
Combustion
Chamber
hot
gases
Gas
Turbine
Gen
fresh
air
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gases
to the
stack
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Gas turbine to produce electricity
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Gas turbine driving a jet engine
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Gas Turbine Power Plant
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Gas Turbine Power Plant
(QCC)
in
fuel
compressed
air
Combustion
Chamber
Compressor
hot
gases
(WGT)
out
Gas
Turbine
(WC)
in
fresh
air
Prof. R. Shanthini
Dec 31, 2011
Gen
gases
to the
stack
13
Gas Turbine Power Plant
(QCC)
in
fuel
compressed
air
Combustion
Chamber
hot
gases
Compressor
(WGT)
out
Gas
Turbine
(WC)
in
fresh
air
Prof. R. Shanthini
Dec 31, 2011
Useful work output = ?
Total heat input = ?
Total energy loss = ?
Gen
gases
to the
stack
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Gas Turbine Power Plant
Useful work output = (WGT)
(WC)
in
out
Total heat input = (QCC)
goes to
electricity
generation
in
comes with the fuel
Thermal efficiency of the GT power plant
ηthermal =
Prof. R. Shanthini
Dec 31, 2011
(WGT)
out
- (WC)
(QCC)
in
in
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Gas Turbine Power Plant
ηthermal =
(WGT)
out
(QCC)
Energy wasted:
= (QCC)
- (WC)
in
-
in
= 22 – 28%
in
[ (W
GT)
out
- (WC) in
]
= 72 – 78% of heat released by the fuel
Prof. R. Shanthini
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for 50 to 100 MW plant
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Heat engine converts heat into work
Hot reservoir at TH K
Qin
Wout
Qout
ηthermal
Wout
=
Qin
ηCarnot = 1 -
TC
TH
ηthermal < ηCarnot
Cold reservoir at TC K
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Gas Turbine Power Plant
Carnot efficiency of the GT power plant
ηCarnot = 1 -
TC
TH
Lowest temperature
(exhaust gas temperature)
Highest temperature
(combustion chamber temperature)
ηCarnot =
Maximum possible work output
Total heat input
Maximum possible work output =
Prof. R. Shanthini
Dec 31, 2011
ηCarnot (QCC)
in
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Gas Turbine Power Plant
Second-law efficiency of GT power plant
=
Useful work output
Maximum possible work output
ηthermal (QCC)
=
ηCarnot (QCC)
in
ηthermal
= η
Carnot
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in
<1
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Steam turbine
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http://www.bizaims.com/files/generator.JPG
Steam Turbine Power Plant
Steam
Turbine
Gen
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Steam Turbine Power Plant
hot gases
compressed Steam Generator
water
superheated
steam
Steam
Turbine
Pump
C
Gen
Condenser
saturated
water
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cooling water
saturated
steam
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Steam turbine to produce electricity
Oil could be used
instead of coal.
R. Shanthini
15
Aug
Prof.
R.2010
Shanthini
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Steam engines are also used to power the train.
(QSG)
Steam Turbine Power Plant
in
hot gases
compressed Steam Generator
water
Pump
C
WP
in
superheated
steam
(WST)
out
Steam
Turbine
Gen
Condenser
saturated
water
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cooling water
saturated
steam
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Steam Turbine Power Plant
ηthermal =
(WST)
out
(QSG)
- (WP)
in
= 30 – 40%
in
Energy wasted:
= (QSG) in-
[ (W
ST)
out
- (WP)
in
]
= 60 – 70% of heat released by the fuel
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for 200 to 800 MW plant
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Combined Power Plant
fuel
GT
atmospheric
air
hot gases
gases
to the
stack
ST
C
cooling water
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Combined Power Plant
fuel
GT
atmospheric
air
hot gases
gases
to the
Stack ST
ST
C
cooling water
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Combined Power Plant
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Combined Power Plant
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Combined Power Plant
ηthermal = Useful work output at GT & ST
Heat released by fuel
= 36 – 50%
Energy wasted:
= 50 – 64% of heat released by the fuel
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for 300 to 600 MW plant
Containment
CORE
Pressurized water
C
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Nuclear Power Plant
Control
rods
PWR
ST
cooling water
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Nuclear power plant to produce electricity
R. Shanthini
15
Aug
Prof.
R.2010
Shanthini
Dec 31, 2011
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Nuclear Power Plant
ηthermal =
Useful work output at ST
Heat released by fuel
= 31 – 34%
Energy wasted:
= 66 – 69% of heat released by the fuel
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for 500 to 1100 MW plant
According to the
2nd Law of Thermodynamics
when heat is converted into work,
part of the heat energy must be wasted
Power generation
type
Diesel engine
Unit size
(MW)
Energy Wasted
(MW)
10 - 30
7 – 22
Gas Turbine
50 - 100
36 – 78
Steam Turbine
200 - 800
120 – 560
Combined (ST & GT)
300 - 600
150 – 380
Nuclear (BWR & PWR)
500 - 1100
330 – 760
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50% - 70% lost
in producing
electricity
2% - 20% lost
in transmitting
electricity
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Generation, transmission
and end-use losses
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Electric
power sector
Typical energy losses in an
industrialised country
70% energy losses
Transportation
sector
80% energy losses
Residential
& Commercial
sector
25% energy losses
Industrial
sector
20% energy losses
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Discussion Point:
Why oil, coal, natural gas and nuclear fuel
are unsustainable?
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Sustainable energy
is energy which is replenishable within a
human lifetime and causes no long-term
damages to the environment.
Source: http://www.jsdnp.org.jm/glossary.html
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Global Consumption (in Million
tonnes oil equivalent)
Nuclear Energy
Oil
Hydroelectric
4000
Coal
Nuclear
3500
Natural gas
3000
2500
2000
1500
1000
500
0
1965
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1975
1985
Year
1995
2005
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Source: BP Statistical Review of World Energy June 2008
Global Consumption (in Million
tonnes oil equivalent)
Nuclear Energy
800
600
Nuclear
400
200
0
1965
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1975
1985
Year
1995
2005
40
Source: BP Statistical Review of World Energy June 2008
Nuclear Energy
Technological status mature
Average growth
0.7% per year
Total share of global 16% of electricity in 2007
energy mix
10% of electricity in 2030 (potential)
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Nuclear Energy
An isotope of Uranium, 235U, is used as the reactor fuel.
A neutron striking a 235U nucleus gets absorbed into it and 236U
is created.
236U
is unstable and this causes the atom to fission.
The fissioning of 236U can produce over twenty different
products.
Eg:
235U + 1 neutron
3 neutrons + 89Kr + 144Ba + ENERGY
Examples of fission products:
90Sr and 137Cs (half-life 30 years)
126Sn (half-life of 230,000 years, but low yield)
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Nuclear Energy
Heat to Work
paradigm
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Source: http://www.cameco.com/uranium_101/uranium_science/
nuclear_reactors/
Nuclear Energy
Nuclear fission provides 16% of the world electricity
production and 7% of the total energy consumption.
Current usage of uranium is about 65,000 t/yr.
The world's present measured resources of uranium in
the cost category somewhat below present spot prices
is about 5.5 Mt.
They could last for over 80 years at the current usage
rate.
Nuclear energy is therefore not a renewable energy
source.
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Source: http://www.world-nuclear.org/info/inf75.html
Nuclear Energy
Nuclear waste and the retired nuclear plants could remain
radioactive for hundreds of future generations.
Uranium is available on earth only in limited quantities.
Uranium is being converted during the operation of the
nuclear power plant so it won't be available any more for
future generations.
Therefore nuclear power is not a sustainable source of
energy.
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Fusion Energy
The D-T Fusion Reaction
Nuclei of two isotopes of hydrogen, naturally occuring
deuterium (2H) and synthetically produced tritium (3H) react to
produce a helium (He) nucleus and a neutron (n).
In each reaction, 17.6 MeV of energy (2.8 pJ)
is liberated
2H
+
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3H
4He
(3.5 MeV) + n (14.1 MeV)
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Fusion Energy
Sun energy comes
from the fusion of
hydrogen into
helium.
It happens at very
high temperatures
generated owing
to the massive gas
cloud shrinking
under its own
gravitational force.
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Fusion Energy
Technological status research phase
Major challenge
make ITER (International
Thermonuclear Experimental Reactor)
a success
Major barrier
immense investments in research and
development are needed
Total share of global
energy mix
0% of electricity in 2007
Possible adverse
effects
worn-out reactors will be radioactive for
50-100 years, but there is no long-lived
radioactive waste
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Combustion Engine
The combustion engine is used to power
nearly all land vehicles and
many water-based and air-based vehicles.
In an internal combustion engine,
a fuel (gasoline for example) fills a chamber,
then it is compressed to heat it up, and
then is ignited by a spark plug,
causing a small explosion which generates work.
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Combustion Engine
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Vehicles mostly uses Internal Combustion Engines
EffCarnot = 1 - TC
TH
TH
TC
= Flame temperature (800oC)
= Exhaust Temperature (40oC)
313 K
EffCarnot = 1 1073 K
≈ 71%
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A user of a car always asks for some minimum
requirements while using a car.
- The drive should be smooth and easy.
- The car should maintain a good speed so as to cope up
with other cars in traffic.
- Easy and fast refuelling of cars.
- A good mileage
- Less pollution
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A Typical Car:
63 kJ
Fuel
Energy
Engine losses in fuel energy conversion,
In engine cooling and with exhaust gases
6 kJ
Driveline losses
18 kJ
100 kJ
2.5 kJ
Aerodynamic
drags
4 kJ
Rolling
resistance
5.5 kJ
Braking
12 kJ
17 kJ
2 kJ
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Urban Driving
Standby Idle
Energy for
accessories
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Source: http://www.fueleconomy.gov/feg/atv.shtml
A Typical Car:
69 kJ
Fuel
Energy
Engine losses in fuel energy conversion,
In engine cooling and with exhaust gases
5 kJ
Driveline losses
25 kJ
100 kJ
11 kJ
Aerodynamic
drags
7 kJ
Rolling
resistance
2 kJ
Braking
20 kJ
4 kJ
2 kJ
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Dec 31, 2011
Highway Driving
Standby Idle
Energy for
accessories
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Source: http://www.fueleconomy.gov/feg/atv.shtml
Electric Car:
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Electric Car:
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http://www.esb.ie/electric-cars/environment-electric-cars/how-green-are-electric-cars.jsp
Hybrid Car:
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Hybrid Car:
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Hybrid Car:
Advantages Of Hybrid Cars
• Better mileage (claimed).
• More reliable and comfortable (claimed).
• Lesser GHG emissions.
• Batteries need not be charged by an external source.
• Warranties available for batteries as well as motors.
• Less dependence on fuels.
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Hybrid Car:
Disadvantages Of Hybrid Cars
• The initial cost is higher.
• Car is heavier (110%).
• Risk of shock during an accident.
• The vehicle can be repaired only by professionals.
• Spare parts will be very costly and rare.
• Uses more rare metals (nickel metal hydride batteries and more
copper wires)
• Highway driving works the IC engine and not on the battery.
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Bio-ethanol as an alternative fuel
Bioethanol is produced from plants
that harness the power of the sun
to convert water and CO2 to sugars
(photosynthesis),
therefore it is a renewable fuel.
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Bio-ethanol as an alternative fuel
Bioethanol is produced from plants
that harness the power of the sun
to convert water and CO2 to sugars
(photosynthesis),
therefore it is a renewable fuel.
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A growing number of cars and trucks
designated as FlexFuel Vehicles (FFV)
can use ethanol blended up to
85% with petrol (E85 fuel).
Today there are more than 6 million FFV's on
U.S. roads alone.
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Prof. R. Shanthini
Dec 31, 2011
Source: http://www.distill.com/World-Fuel-Ethanol-A&O-2004.html
64
Bioethanol from simple sugars:
Sugar cane and sugar beets store the energy as
simple sugars, glucose (C6H12O6)
yeast
2 CH3CH2OH + 2 CO2
this simple-looking reaction is a
bioreaction and thus very complex
glucose molecule
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Dec 31, 2011
impure cultures of yeast produce
glycerine and various organic acids
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Yeast can be replaced by the
bacterium Zymomonas mobilis
- gives up to 98% yields
- minimal by-products
- simple fermentation requirements
- several-fold the production rates of yeast
Z. mobilis industrial strain CP4,
originating from Brazil,
vigorously fermenting glucose.
Photo courtesy Katherine M. Pappas
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Dec 31, 2011
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sugar
cane
yeast
sugar cane crushed and
soluble sugar washed out
fermentation of sugars
produces 5 - 12% ethanol
distilled to concentrate to
80 – 95% ethanol
used as a petrol
replacement
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Dec 31, 2011
sugar cane
residue
CO2
wet
solids
dehydrate to
100% ethanol
used as a petrol
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additive
Bioethanol from starch:
Corn, wheat and cassava store the energy as
more complex sugars, called starch
}
starch
(glucose polymer)
α-amylase
dextrins
amyloglucosidase
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Dec 31, 2011
glucose monomer
68
cassava flour + water +
alpha-amylase enzyme
Liquification
(at 90 – 95 deg C;
pH = 4 - 4.5; 400 rpm)
Saccharification with
glucosidase enzyme
(at 55 - 65 deg C, pH = 4 - 4.5)
Fermentation with
yeast (40 – 50 hrs)
Distillation
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Dec 31, 2011
80-95% ethanol
Cooling (32 deg C)
Dehydration
100% ethanol 69
Bioethanol from Biomass
(except sugars and starches):
Rice straw
Paddy husks
Saw dust
Grasses
Bagasse
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Bioethanol from Biomass
(except sugars and starches):
Cellulose (40 to 60% by weight of the biomass)
made from the six-carbon sugar, glucose.
Its crystalline structure makes it resistant to
hydrolysis (the chemical reaction that releases simple,
fermentable sugars).
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Currently, bioethanol yields 25% more energy
output than input to produce it.
Because fossil fuel is required
- for the tractor planting the corn
- for the fertilizer put in the field
- for the energy needed at the processing plant
Bioethanol also requires land and water.
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Is bioethanol a
sustainable energy source?
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Bioethanol will be used in engines that
convert heat into work
Engines that convert heat
into work are very
inefficient
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Biofuels, such as US corn bioethanol, Brazilian sugar cane
bioethanol, Brazilian soy biodiesel and Malaysian palm-oil
biodiesel, have greater total environmental impacts than fossil
fuels.
Andy Tait of Greenpeace said "It is clear that what government
and industry are trying to do is find a neat, drop-in solution
that allows people to continue business as usual. If you are
looking at the emissions from the transport sector, the first
thing you need to look at is fuel efficiency and massively
increasing it. That needs to come before you even get to the
point of discussing which biofuels might be good or bad."
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Heating
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Cooling: air conditioning
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Cooling: refrigeration
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Agricultural machinery
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