Mass based fuel combustion by DEFRA

Summary

This methodology represents greenhouse gas emissions associated with the stationary combustion of fuels as measured on the basis of fuel mass. The data and calculation methodology originates from the UK government department DEFRA, as published in their most recent greenhouse gas (GHG) conversion factors documentation.

The methodology

The emissions calculation methodology is based upon emissions factors which relate a mass-based quantity of fuel, with its associated quantity of greenhouse gas emissions. These values vary, depending on factors such as the concentration of carbon and moisture within each fuel type.

Model data

Each fuel type is represented by six distinct emissions factors, which differentiate greenhouse gas emissions into the following types:

• 'direct CO₂ emissions': carbon dioxide emissions produced during fuel combustion
• 'direct CH₄ emissions': methane emissions produced during fuel combustion
• 'direct N₂O emissions': nitrous oxide emissions produced during fuel combustion
• 'total direct emissions': sum of all direct emissions, i.e. CO₂ + CH₄ + N₂O
• 'indirect emissions': emissions associated with stages in the fuel production chain such as raw material extraction and fuel delivery
• 'life cycle emissions': the total of direct and indirect emissions

Activity data required

Calculations are based on the amount of mass used during combustion of the chosen type of fuel.

Calculation and result

The following quantities are calculated on the basis of the amount of mass combusted and associated emission factors: CO₂, CH₄, N₂O, total direct CO₂e, full life cycle CO₂e.

Users should note that all quantities (including the separated CH₄ and N₂O emissions) are expressed in terms of CO₂e - the quantity of CO₂ that would exert the same atmospheric warming effect and the emissions quantity.

Related methodologies

Other DEFRA methodologies are available for fuel combustion with energy and volume based calculations.

Fuel properties, such as density and calorific values, can be found here.

Notes

Renewable Fuel Considerations

Separate Emission factors are provided for diesel, petrol, a diesel+biodiesel blend (= 4.2% by unit mass, 4.0% by unit volume, 3.7% by unit energy), and a petrol+bioethanol blend (= 3.1% by unit mass, 2.9% by unit volume, 1.9% by unit energy). Blended fuel emission factors are a weighted average of those respective fuels provided at UK public refuelling stations as a proportion of the total supply. These estimates have been made based on the most recently available reports on the Renewable Transport Fuel Obligation (RTFO).