Prof. R. Shanthini Dec 31, 2011 1 Module 02 Conventional Energy Technologies - in electricity...
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Prof. R. Shanthini Dec 31, 2011
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
2
How is electricity generated from
non-renewable energy sources (oil, coal or
natural gas)?
Diesel Generator
Gas Turbine (GT) Steam Turbine
(ST)
Combined Power Plant
(GT & ST)
Prof. R. Shanthini Dec 31, 2011
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http://electron9.phys.utk.edu/phys136d/modules/m8/images/gen.gif
Magnet
Rotating wire loop
Electrical output
S
N
How to rotate the wire loop?
Electric Generator
We need a rotating shaft?
Prof. R. Shanthini Dec 31, 2011
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http://www.electricityforum.com/images/motor-eout.gif
Wind turbine gives a rotating shaft
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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.
http://www.rkm.com.au/animations/animation-diesel-engine.html
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Diesel generator
It is a diesel engine coupled to a electric generator.
Diesel engine provides the rotating shaft.
http://www.rkm.com.au/animations/animation-diesel-engine.html
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Diesel generator
http://www.myrctoys.com/engines/ottomotor_e.swf
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Comp-ressor
fresh air
Combustion Chamber
fuel
GasTurbine
gasesto the stack
Gen
compressed air
hot gases
Gas Turbine Power Plant
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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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Comp-ressor
fresh air
Combustion Chamber
fuel
GasTurbine
gasesto the stack
Gen
compressed air
hot gases
Gas Turbine Power Plant
(WGT)out
(WC)in
(QCC)in
Prof. R. Shanthini Dec 31, 2011
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Comp-ressor
fresh air
Combustion Chamber
fuel
GasTurbine
gasesto the stack
Gen
compressed air
hot gases
Gas Turbine Power Plant
(WGT)out
(WC)in
(QCC)in
Useful work output = ?
Total heat input = ?
Total energy loss = ?
Prof. R. Shanthini Dec 31, 2011
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Gas Turbine Power Plant
Useful work output =
Total heat input =
Thermal efficiency of the GT power plant
(WGT)out
(WC)in
(QCC)in
-
(QCC)in
(WGT)out
(WC)in
-ηthermal =
goes to electricity generation
comes with the fuel
Prof. R. Shanthini Dec 31, 2011
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= = 22 – 28%
Energy wasted:
- [ ]=
=
72 – 78% of heat released by the fuel
for 50 to 100 MW plant
(QCC)in
(WGT)out
(WC)in
-
(QCC)in
(WGT)out
(WC)in
-
ηthermal
Gas Turbine Power Plant
Prof. R. Shanthini Dec 31, 2011
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= TC
1 - TH
Hot reservoir at TH K
Heat engine converts heat into work
Cold reservoir at TC K
ηthermal = Wout
Qin
Wout
Qin
Qout
< ηthermal
ηCarnot
ηCarnot
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ηCarnot =
Carnot efficiency of the GT power plant
Gas Turbine Power Plant
TC
TH
1 -Lowest temperature(exhaust gas temperature)
Highest temperature(combustion chamber temperature)
ηCarnot =
= (QCC)in
Maximum possible work output
Total heat input
Maximum possible work output ηCarnot
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Gas Turbine Power Plant
Second-law efficiency of GT power plant
(QCC)in
ηCarnot
= Maximum possible work output
Useful work output
= (QCC)
inηthermal
ηCarnot
= ηthermal
< 1
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Steam turbine
http://www.bizaims.com/files/generator.JPG
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SteamTurbine
Gen
Steam Turbine Power Plant
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C
saturated water
hot gases
SteamTurbine
Gen
compressed water
superheated steam
Condenser
Pump
cooling watersaturatedsteam
Steam Generator
Steam Turbine Power Plant
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R. Shanthini 15 Aug 2010
Steam turbine to produce electricity
Oil could be used instead of coal.
Steam engines are also used to power the train.
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Steam Turbine Power Plant
C
saturated water
Gen
compressed water
superheated steam
cooling water
(WST)out
Pump
SteamTurbine
Condenser
Steam Generator
saturatedsteam
(QSG)in
hot gases
WPin
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ηthermal = (WST)
out (WP)
in
(QSG)in
-= 30 – 40%
Energy wasted:
(QSG)in
- [ (WST)out
- (WP)in]
=
=
60 – 70% of heat released by the fuel
for 200 to 800 MW plant
Steam Turbine Power Plant
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atmosphericair
fuel
GT
gasesto the stack
C
hot gases
ST
cooling water
Combined Power Plant
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atmosphericair
fuel
GT
gasesto the Stack ST
C
hot gases
ST
cooling water
Combined Power Plant
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Combined Power Plant
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Combined Power Plant
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ηthermal = Heat released by fuel
Useful work output at GT & ST
= 36 – 50%
Energy wasted:
= 50 – 64% of heat released by the fuel
for 300 to 600 MW plant
Combined Power Plant
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Nuclear Power Plant
C
Pressurized water
ST
cooling water
CORE Control rods
Containment
PWR
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R. Shanthini 15 Aug 2010
Nuclear power plant to produce electricity
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= 31 – 34%
Energy wasted:
= 66 – 69% of heat released by the fuel
for 500 to 1100 MW plant
Nuclear Power Plant
ηthermal = Heat released by fuel
Useful work output at ST
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According to the 2nd Law of Thermodynamics
when heat is converted into work, part of the heat energy must be wasted
Power generation
type
Unit size (MW)
Energy Wasted (MW)
Diesel engine 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
Generation, transmission and end-use losses
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Electric power sector 70% energy losses
Transportationsector
Industrialsector
Residential & Commercial
sector
80% energy losses
25% energy losses
20% energy losses
Typical energy losses in an industrialised country
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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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0
500
1000
1500
2000
2500
3000
3500
4000
1965 1975 1985 1995 2005
Year
Glo
ba
l Co
nsu
mp
tion
(in
Mill
ion
to
nn
es
oil
eq
uiv
ale
nt)
Oil Hydroelectric
Coal Nuclear
Natural gas
Source: BP Statistical Review of World Energy June 2008
Nuclear Energy
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0
200
400
600
800
1965 1975 1985 1995 2005
Year
Glo
bal C
onsu
mpt
ion
(in M
illio
n to
nnes
oil
equi
vale
nt)
Nuclear
Source: BP Statistical Review of World Energy June 2008
Nuclear Energy
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Technological status mature
Average growth 0.7% per year
Total share of global energy mix
16% of electricity in 2007
10% of electricity in 2030 (potential)
Nuclear Energy
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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)
Prof. R. Shanthini Dec 31, 2011
43Source: http://www.cameco.com/uranium_101/uranium_science/nuclear_reactors/
Nuclear Energy
Heat to Work paradigm
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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.
Source: http://www.world-nuclear.org/info/inf75.html
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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.
Prof. R. Shanthini Dec 31, 2011
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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 + 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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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
Fusion Energy
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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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EffCarnot =
TC 1 -
TH
TC
TH = Flame temperature (800oC)
= Exhaust Temperature (40oC)
EffCarnot =
313 K1 -
1073 K
71%≈
Vehicles mostly uses Internal Combustion Engines
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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:
100 kJ
63 kJ
18 kJ
17 kJ
2 kJ
Engine losses in fuel energy conversion, In engine cooling and with exhaust gases
Energy for accessories
Standby Idle
Fuel Energy
6 kJ
12 kJ
Driveline losses
2.5 kJ
4 kJ
5.5 kJ
Aerodynamic drags
Rolling resistance
Braking
Source: http://www.fueleconomy.gov/feg/atv.shtml
Urban Driving
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A Typical Car:
100 kJ
69 kJ
25 kJ
4 kJ
2 kJ
Engine losses in fuel energy conversion, In engine cooling and with exhaust gases
Energy for accessories
Standby Idle
Fuel Energy
5 kJ
20 kJ
Driveline losses
11 kJ
7 kJ
2 kJ
Aerodynamic drags
Rolling resistance
Braking
Source: http://www.fueleconomy.gov/feg/atv.shtml
Highway Driving
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Electric Car:
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Electric Car:
http://www.esb.ie/electric-cars/environment-electric-cars/how-green-are-electric-cars.jsp
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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 plantsthat harness the power of the sun
to convert water and CO2 to sugars (photosynthesis),
therefore it is a renewable fuel.
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Bioethanol is produced from plantsthat harness the power of the sun
to convert water and CO2 to sugars (photosynthesis),
therefore it is a renewable fuel.
Bio-ethanol as an alternative 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.
Prof. R. Shanthini Dec 31, 2011
64Source: http://www.distill.com/World-Fuel-Ethanol-A&O-2004.html
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glucose molecule
Bioethanol from simple sugars:
Sugar cane and sugar beets store the energy as simple sugars, glucose (C6H12O6)
2 CH3CH2OH + 2 CO2
yeast
impure cultures of yeast produce glycerine and various organic acids
this simple-looking reaction is a bioreaction and thus very complex
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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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sugar cane sugar cane crushed and
soluble sugar washed out
sugar cane residue
fermentation of sugars produces 5 - 12% ethanol
yeast
distilled to concentrate to 80 – 95% ethanol
used as a petrol replacement
dehydrate to 100% ethanol
used as a petrol additive
CO2
wet solids
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68
Bioethanol from starch:Corn, wheat and cassava store the energy as
more complex sugars, called starch
dextrins
α-amylase
amyloglucosidase
glucose monomer
}starch(glucose polymer)
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Liquification Liquification (at 90 – 95 deg C; (at 90 – 95 deg C;
pH = 4 - 4.5; 400 rpm)pH = 4 - 4.5; 400 rpm)
Saccharification with Saccharification with glucosidase enzymeglucosidase enzyme
(at 55 - 65 deg C, pH = 4 - 4.5)(at 55 - 65 deg C, pH = 4 - 4.5)
Cooling Cooling (32 deg C)(32 deg C)Fermentation with Fermentation with yeast yeast (40 – 50 hrs)(40 – 50 hrs)
Distillation Distillation Dehydration Dehydration
80-95% ethanol 80-95% ethanol 100% ethanol 100% ethanol
cassava flour + water + cassava flour + water + alpha-amylase enzymealpha-amylase enzyme
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Bioethanol from Biomass (except sugars and starches):
Rice strawPaddy husksSaw dustGrasses Bagasse
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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).
Bioethanol from Biomass (except sugars and starches):
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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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74
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