This methodology provides data and a calculation methodology for calculating CO2 emissions associated with the consumption of transport fuels (e.g. motor gasoline, diesel, kerosene, compressed natural gas (CNG), liquefied natural gas (LNG), liquid petroleum gas (LPG)). The methodology is sourced from the 2006 IPCC Guidelines for National Greenhouse Gas Inventories.

The methodology

Emissions model

Greenhouse gas emissions associated with transport arise from the combustion of fuels. According to this methodology, CO2 emissions are directly related to the quantity of carbon which is oxidised during combustion and therefore directly proportionate to the quantity of fuel burned and the concentration of carbon within the particular fuel type.

Model data

The IPCC provides the following fuel property data for several types of transport fuel:

  • CO2 emissions factor: emissions factors expressed in terms of quantities of CO2 emitted per unit of energy (kg per TJ)
  • Heating value: 'heating' or 'calorific' values (net) describing the energy content of the fuel (TJ per Gg)

Thus, CO2 emissions can be calculated in two ways using these data: (1) on the basis of energy consumption by simply multiplying a quantity of energy by the mass CO2 per energy emission factor; or (2) according to a mass of fuel by converting a mass-based fuel quantity (e.g. kg, tonnes) into its corresponding energy quantity using the heating value, and multiplying by the energy-based emission factor.

A third method of calculating is on the basis of a volumetric quantity of fuel (e.g. litres, barrels), which can be achieved by specifying a volumetric quantity together with value for fuel density (i.e. mass per unit volume) which enables the conversion of volumetric quantities into their corresponding mass-based quantity and, in-turn, into energy and CO2 quantities.

Related methodologies

Other IPCC transport categories are available which represent transport fuel consumption in specific offroad, ship and train contexts, as well as vehicular emissions for European road vehicles and both 'conventionally' and 'alternatively' (cng, lpg, lng, ethanol) fuelled vehicles in the US.

Using this methodology

Choosing a specific activity type

To use this methodology, the particular type of fuel which best represents the users emissions scenario must be specified by selecting from the fuel drill down choice.

Activity data required

Calculations can be made on the basis of either: (1) energy consumed; (2) mass of fuel consumed; or (3) volume of fuel consumed.

Specifying energy consumption: Set the energy consumed using the energy profile item value.

Specifying fuel mass: Set the mass of fuel consumed using the mass profile item value.

Specifying fuel volume: Set the volume of fuel consumed using the volume profile item value. In this case the fuel density must also be specified using the density profile item value.

Calculation and result

The returned quantity for this methodology represents the CO2 emissions associated with the fuel consumption specified.

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