International electricity by DEFRA

Note: Although DEFRA presents data for the UK separately from those of other countries/regions, the data for the UK is included herein for completeness.

The methodology

Emissions model

Emissions are calculated, according to this methodology, on the basis on emissions factors which relate a quantity of grid electricity electricity with an associated quantity of greenhouse gas emissions. These emissions factors are based on the average annual emissions intensity of grid electricity in each country (or other region), as specified on a per kWh basis. By multiplying a quantity of electricity by the appropriate factor, the total quantity of emissions are calculated.

Model data

The comprehensive dataset included within methodology differentiates several aspects of electricity-associated emissions, including: (1) the activities of generation, transmission and consumption; (2) direct, indirect and life cycle emissions; (3) historical (raw annual or annual rolling average) data.

Activity type: Separate data are available for greenhouse gas emissions attributable to electricity generation, electricity transmission and distribution, and electricity consumption. All greenhouse gas emissions are ultimately associated with the generation phase, being a consequence of fuel/energy consumption (direct emissions) and related activities (indirect: e.g. fuel sourcing, transport) at the power plant. However, since there are usually losses associated with the distribution and transmission of electricity, the quantity of emissions per unit of electricity generated (e.g. kWh) usually differs from the corresponding per unit emissions at the point of consumption. The DEFRA dataset provides values for greenhouse gas quantities which are attributable to the intermediate transmission phase, although these should be understood to be an accounting convenience reflecting transmission (in)efficiency rather than actual emissions caused during this phase. The emissions associated with electricity consumption are simply the sum of those attributable to generation and transmission. In most cases - i.e. those in which the final, end-point of electricity usage is under consideration - the values for consumption should be used.

Emission type: The DEFRA dataset differentiates between direct and indirect greenhouse gas emissions. 'Direct' emissions are limited to those associated with activities at the power plant, while 'indirect' emissions refer to those which derive from other stages in the production chain such as raw material extraction and fuel delivery. The combination of these two types of emission represents full life cycle emissions for electricity. The importance of these emissions types will vary depending on how the user attributes the various portions of the life cycle emissions to the various agents involved (e.g. supplier, producer, consumer). It is most common to use direct emissions only when considering electricity consumption. Indirect and life cycle emissions are expressed in terms of CO₂e.

Historical values: The greenhouse gas emissions produced per unit of electricity generated/consumed varies through time as the mix of fuels used by power stations supplying a national or regional grid changes. These changes may reflect variations in electricity demand or the relative prices of different fuel types. DEFRA publishes annual emissions factors based on the average quantity of emissions per unit of electricity across the grid during each calendar year. These values cover the period 1990-2006. In addition to the raw annual values, DEFRA provides 'rolling average' emissions factors which represent the average of the previous 5 years for each given year. These are suggested as being more suitable for inter-annual comparisons by DEFRA.

How to use this category

Choosing an emissions scenario

To use this category, choose the country or region by using the country drill down choice and the type of activity using the type drill down choice. For the latter, the following options are available:

• electricity generation
• electricity distribution and transmission
• electricity consumption

Specifying activity data

The quantity of electricity under consideration is specified by setting the energyConsumed profile item value.

DEFRA publishes historical annual data for direct CO₂ emissions for each country/region within this category. If calculating using the direct and annual options, users can specify start- and end-dates in association with their electricity consumption and CarbonKit will use its data item value history functionality to apply the appropriate emissions factor(s). If no profile dates are set, the most recent (i.e. 2006) data are used.

Result

The returned quantity represents the emissions associated with the energy quantity (and dates) specified. The following discrete amounts are returned:

• directCO2AnnualBasis: Direct CO₂ emissions calculated on the basis of annual emissions factors
• directCO2RollingBasis: Direct CO₂ emissions calculated on the basis of rolling average emissions factors
• indirectCO2e: Indirect CO₂ emissions
• lifeCycleCO2e: total life cycle CO₂e emissions

Additional data item values

This category also contains data item values representing the mix of electricity and heat production from which the emissions data are derived for each country/region - these are available from the CarbonKit data API under the following paths:

• percentElectricity: Percentage of total energy production represented by electricity
• percentHeat: Percentage of total energy production represented by heat
• percentLossesElectricity: Percentage of losses attributable to electricity production
• percentLossesHeat: Percentage of losses attributable to heat production