co2 emission rate per mwh of energy generated from coal fired plants
TRANSCRIPT
COCO22 Emission Rate per MWh of Energy Emission Rate per MWh of Energy
Generated from Coal-Fired Plants Generated from Coal-Fired Plants
© Copyright 2008 David Palmer
CoalCoal
Coal is one type of Coal is one type of
fossil fuelfossil fuel
It is the largest single It is the largest single
source of:source of:
fuel for the fuel for the
generation of generation of
electricityelectricity
carbon dioxide carbon dioxide
emissionsemissions
© Copyright 2008 David Palmer
Complete Combustion of CoalComplete Combustion of Coal
OHy
xCOOy
xHC yx 222 )2
()4
( +⇒++
WaterCO heat oxygen fuel 2++⇒+
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The Energy Density of CoalThe Energy Density of Coal
Energy density ‘Q’ is also referred to fuel Energy density ‘Q’ is also referred to fuel content or heating ability (MJ / kg) content or heating ability (MJ / kg)
1000
93)8
(1442337 SO
HCQ
+−+=
where; C is the mass percent of carbon, H is the mass percent of hydrogen, O is the mass percent of oxygen, and S is the mass percent of sulfur in the coal
The energy density of coal is roughly 24 kgMJ
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Various Types of CoalVarious Types of Coal
ASTM classASTM class ASTM groupASTM group MJ/kgMJ/kg
LigniteLignite Lignite ALignite A <14.6<14.6
Lignite BLignite B 14.6-19.314.6-19.3
Sub-bituminousSub-bituminous Sub-bituminous CSub-bituminous C 19.3-22.119.3-22.1
Sub-bituminous BSub-bituminous B 22.1-24.422.1-24.4
Sub-bituminous ASub-bituminous A 24.4-26.724.4-26.7
High volatile CHigh volatile C 24.4-30.224.4-30.2
BituminousBituminous High Volatile BHigh Volatile B 30.2-32.530.2-32.5
High Volatile AHigh Volatile A >32.5>32.5
Medium volatileMedium volatile >32.5>32.5
Low volatileLow volatile >32.5>32.5
AnthraciteAnthracite Semi-anthrciteSemi-anthrcite >32.5>32.5
AnthraciteAnthracite >32.5>32.5
Meta-anthraciteMeta-anthracite >32.5>32.5
© Copyright 2008 David Palmer
As mentioned earlier the energy density of As mentioned earlier the energy density of coal is 24 , this converts to coal is 24 , this converts to from,from,
Energy Density of CoalEnergy Density of Coal
kg
hkW ⋅kgMJ
kg
hkW
MW
kWh
sJ
Ws
kg
MJ ⋅=×××× 67.61000min6060
min24
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Thermodynamic Efficiency Thermodynamic Efficiency of Coal-Fired Plantsof Coal-Fired Plants
Typical thermodynamic efficiency of coal Typical thermodynamic efficiency of coal
plants is about 30%.plants is about 30%.
Coal has 6.67 kW·h of energy per Coal has 6.67 kW·h of energy per
kilogram and approximately 30% can kilogram and approximately 30% can
successfully be turned into electricity – the successfully be turned into electricity – the
remaining energy is heat waste. remaining energy is heat waste.
Coal power plants obtain approximately Coal power plants obtain approximately
2.0 kW·h per kg of burned coal.2.0 kW·h per kg of burned coal.
© Copyright 2008 David Palmer
Energy Consumption ExampleEnergy Consumption Example
As an example, running one 100 watt light bulb for As an example, running one 100 watt light bulb for one year requires 876 kW·h. one year requires 876 kW·h.
(100 W × 24 h/day × 365 {days in a year} (100 W × 24 h/day × 365 {days in a year}
= 876000 W·h = 876000 W·h
= 876 kW·h = 876 kW·h
Converting this power usage into physical coal Converting this power usage into physical coal consumption: consumption:
coal of lbs 966coal of kg 438kghkW 2.0
hkW 876 ==⋅
⋅
© Copyright 2008 David Palmer
COCO22 Production Production
Coal is at least 50% carbon (by mass), then 1 kg Coal is at least 50% carbon (by mass), then 1 kg of coal contains at least 0.5 kg of carbon.of coal contains at least 0.5 kg of carbon.Carbon has an atomic weight of 12 kg / kmol, Carbon has an atomic weight of 12 kg / kmol, where 1 mol is equal to NA (Avogardo’s where 1 mol is equal to NA (Avogardo’s Number)Number)Therefore, 0.5 kg of carbon is,Therefore, 0.5 kg of carbon is,
Carbon reacts with oxygen during combustion, Carbon reacts with oxygen during combustion, producing carbon dioxide, COproducing carbon dioxide, CO22, which has an , which has an atomic weight of (12 + 16 × 2 = 44 kg / kmol) atomic weight of (12 + 16 × 2 = 44 kg / kmol)
kmol24
1
12
5.0 =⋅ kmolkg
kg
© Copyright 2008 David Palmer
Kilograms of COKilograms of CO22 Produced Produced
per Kilogram of Coalper Kilogram of Coal
As mentioned earlier,As mentioned earlier,
The same number of ‘x’carbon atoms are found in coal (CxHy) The same number of ‘x’carbon atoms are found in coal (CxHy) before combustion as seen in carbon dioxide CObefore combustion as seen in carbon dioxide CO22 after after
combustion then,combustion then,
1 / 24 kmol of CO1 / 24 kmol of CO22 is produced from the 1 / 24 kmol present in is produced from the 1 / 24 kmol present in
every kilogram of coal, which weighs approximately,every kilogram of coal, which weighs approximately,
OHy
xCOOy
xHC yx 222 )2
()4
( +⇒++
kg 1.83 kmol
kg 44kmol
24
1 ≈⋅
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Carbon Cost of Energy Carbon Cost of Energy with the use of Coal Powerwith the use of Coal Power
Variables: Variables:
Thermodynamic efficiency of coal fired plant = 30% Thermodynamic efficiency of coal fired plant = 30%
Energy density = 6.67 kW·h of energy per kilogram of coalEnergy density = 6.67 kW·h of energy per kilogram of coal
Energy produced = 2.0 kW·h/kg (coal)Energy produced = 2.0 kW·h/kg (coal)
As calculated earlier,As calculated earlier,
1 kg of coal produces roughly 1.83 kg C01 kg of coal produces roughly 1.83 kg C022, then using electricity from coal , then using electricity from coal
produces COproduces CO22 at a rate of, at a rate of,
or,or,hkW
kg915.0
kghkW 2.0
kg 1.83
⋅=
⋅
MJ
kg254.0
MJ
kJ1000
kJ
kWs
60s
min
60min
h
hkW
kg915.0 =××××
⋅
© Copyright 2008 David Palmer
Comparison with Comparison with U.S Energy ReportU.S Energy Report
This estimate compares with the U.S Energy Information This estimate compares with the U.S Energy Information
Agency’s Report on COAgency’s Report on CO22 emissions for energy emissions for energy
generation, which quotes a production rate of generation, which quotes a production rate of
By comparison COBy comparison CO22 generation from oil was generation from oil was
and natural gas was and natural gas was
hkW
kg950.0
⋅
hkW
kg0.890
⋅
hkW
kg600.0
⋅
© Copyright 2008 David Palmer
SummarySummary
Using electricity from coal produces COUsing electricity from coal produces CO22
at a rate of, , which is also equal to,at a rate of, , which is also equal to,hkW
kg915.0
⋅
hMW
kg915
MW
kW1000
hkW
kg915.0
⋅=×
⋅
© Copyright 2008 David Palmer
Ontario’s Five Coal-Fired PlantsOntario’s Five Coal-Fired Plants
Lambton Nanticoke
Atikokan
Thunder BayLennox
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Ontario’s Lambton Coal-Fired PlantOntario’s Lambton Coal-Fired Plant
The following table shows the COThe following table shows the CO22 emission rates, in kilograms per emission rates, in kilograms per
megawatt-hour (kg / MWh) of each of the Lambton Generating megawatt-hour (kg / MWh) of each of the Lambton Generating Station’s coal-fired boilers, (results from 2005).Station’s coal-fired boilers, (results from 2005).
EmissionRates
kg / MWh
LambtonUnit 1
LambtonUnit 2
LambtonUnit 3
LambtonUnit 4
CarbonDioxide
CO2
927.80 927.35 926.87 926.57
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Resistance and Heating Resistance and Heating in the Power Linesin the Power Lines
One should also take into account transmission and One should also take into account transmission and distribution losses caused by resistance and heating in distribution losses caused by resistance and heating in the power lines. Which is in the order of 5–10%, the power lines. Which is in the order of 5–10%, depending on the distance from the power station and depending on the distance from the power station and other factors.other factors.
If this was taken into account our earlier calculation of If this was taken into account our earlier calculation of
would equal,would equal,hkW
kg915.0
⋅
hkW
kg960.005.1
hkW
kg915.0
⋅=×
⋅
© Copyright 2008 David Palmer
Other Types of COOther Types of CO22 Production Production
Steel-making Steel-making 1.97 ton CO1.97 ton CO22 / ton of steel produced / ton of steel produced
Cement makingCement making 0.87 to 0.97 ton CO0.87 to 0.97 ton CO22 / ton of cement produced / ton of cement produced
AutomobliesAutomoblies 165 g CO165 g CO22 / km driven or, / km driven or,
2.5 kg CO2.5 kg CO22 / Litre of gasoline consumed / Litre of gasoline consumed
© Copyright 2008 David Palmer