Friday 11 November 2016

Combustion of Fuels - Carbon Dioxide Emission


Environmental emission of carbon dioxide CO2 when combustion fuels like coal, oil, natural gas, LPG and bio energy


To calculate the CO2 emission from a fuel the carbon content of the fuel must be multiplied with the ratio of molecular weight CO2 (44) to the molecular weight Carbon 12 -> 44 / 12 = 3.7
Carbon Dioxide emission can be calculated as
qCO2 = cf / hf  CCO2/Cm         (1)
where
qCO2 = specific CO2 emission (CO2/kWh)
cf = specific carbon content in the fuel (kgC/kgfuel)
hf = specific energy content (kWh/kgfuel)
Cm = specific mass Carbon (kg/mol Carbon)
CCO2 = specific  mass Carbon Dioxide (kg/mol CO2)
Emission of Carbon Dioxide - CO2 - when combustion some common fuels are indicated in the table below.
Note! Heat loss - 55-75% - in power generation is not included in the numbers.  
FuelSpecific Carbon Content
(kgC/kgfuel)
Specific Energy Content
(kWh/kgfuel)
Specific CO2 Emission
(kgCO2 /kgfuel)
Specific CO2 Emission
(kgCO2/kWh)
Coal (bituminous/anthracite) 0.75 7.5 2.3 0.37
Gasoline 0.9 12.5 3.3 0.27
Light Oil 0.7 11.7 2.6 0.26
Diesel 0.86 11.8 3.2 0.24
LPG - Liquid Petroleum Gas 0.82 12.3 3.0 0.24
Natural Gas, Methane 0.75 12 2.8 0.23
Crude Oil    
0.26
Kerosene    
0.26
Wood 1)    
0.39
Peat 1)    
0.38
Lignite    
0.36
Bio energy 0 -
02)
1) Commonly viewed as a Bio fuel
2) Bio Energy is produced from biomass derived from any renewable organic plant, including
  • dedicated energy crops and trees
  • agricultural food and feed crops
  • agricultural crop wastes and residues
  • wood wastes
  • aquatic plants
  • animal wastes
  • municipal wastes and other waste materials
Emissions of CO2 can contribute to climate change. Combustion of bio energy don't add to the total emission of carbon dioxide as long as the burned bio mass don't exceed the renewed production. The recycling of carbon from wood combustion is virtually instantaneous and continuous and it is also common to regard the net supply of CO2 to the atmosphere from combustion of wood close to zero.
A variety of bio fuels can be made from biomass resources, including
  • ethanol
  • methanol
  • biodiesel
  • Fischer-Tropsch diesel
  • gaseous fuels like hydrogen or methane

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