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TOPIC 2: BASIC EMISSION PROCESSES  

The carbon content of a fuel is an inherent chemical property (i.e., mass of carbon atoms relative to total mass of the fuel). The carbon content of crude oil is often measured in degrees using the API gravity scale. Using an estimate of world average API gravity of 32.5 +/-2 degrees, the global average carbon composition of crude oil would be about 85 +/-1 percent. A summary of default carbon content factors from the Revised 1996 IPCC Guidelines is given in the following table.

Table 2: IPCC default carbon content factors for major primary and secondary fossil fuels.
Liquid
(t C/TJ)
 Solid
(t C/TJ)
 Gaseous
(t C/TJ)
Primary Fuels
Primary Fuels
 Natural Gas (Dry)
15.3
Crude Oil
20.0
 Anthracite
26.8
 
Orimulsion
22.0
 Coking Coal
25.8
  
N. Gas Liquids
17.2
 Other Bit. Coal
25.8
  
Secondary Fuels Sub-bit. Coal
26.2
  
Gasoline
18.9
 Lignite
27.6
  
Jet Kerosene
19.5
 Oil Shale
29.1
  
Other Kerosene
19.6
 Peat
28.9
  
Shale Oil
20.0
 Secondary Fuels
  
Gas/Diesel Oil
20.2
 BKB & Patent Fuel
25.8*
  
Residual Fuel
21.1
 Coke Oven/Gas Coke
29.5
  
LPG
17.2
 
  
Ethane
16.8
 
  
Naphtha
20.0*
 
  
Bitumen
22.0
 
  
Lubricants
20.0*
 
  
Petroleum Cole
27.5
 
  
Refinery Feedstocks
20.0*
 
  
Other Oil
20.0*
 
  

*Preliminary values identified by the IPCC. Parties should only use these values when no other data are available. Reference: Table 1.1 in the Revised 1996 IPCC Guidelines, vol. 3. Note: Energy units expressed in terms of net calorific values (NCVs).