Skip to main content

Main principles

In the ETM the total greenhouse gas emissions for both the present and future are calculated for scenarios. This page contains extra information on the modelling principles behind carbon emissions in the ETM.

Emission categories​

The ETM makes a distinction between four 'types' of greenhouse gas emissions:

  1. Energetic CO2 emissions. These emissions are calculated by the ETM based on the energy use in your scenario. In other words, they are the result of the choices made in the Demand and Supply sections of the model.
  2. Non-energetic CO2 emissions. These emissions are given as an input to the ETM. For the future year, you can make assumptions about the growth or decline of these emissions in the Emissions section of the ETM. There are two exceptions to this category: non-energetic CO2 in the Fertilizer industry and from the use of hydrogen and ammonia feedstock (e.g. in the Chemicals industry) are calculated dynamically by the ETM based on energy demand and supply.
  3. Energetic other greenhouse gas emissions. For example methane and nitrous oxide. These emissions are given as an input to the ETM. For the future year, you can make assumptions about the growth or decline of these emissions in the Emissions section of the ETM. This means that these emissions are not adjusted automatically by the ETM if changes are made to energy supply and demand.
  4. Non-energetic other greenhouse gas emissions. For example methane and nitrous oxide. These emissions are given as an input to the ETM. For the future year, you can make assumptions about the growth or decline of these emissions in the Emissions section of the ETM.

Modelling principles​

To calculate the energetic CO2 emissions in your scenario (category 1), the ETM assumes the following principles:

  • Emissions are assigned to the sector energy is used in, rather than the location of emissions. This means that emissions related to the production of, for example, electricity are attributed to all sectors using electricity (households, industry etc.) rather than to the power sector. Read more about how emissions are calculated here. A consequence of this approach is that the ETM by default does take into account emissions of imported energy carriers (imported ammonia, electricity, heat, hydrogen etc.) and does not take into account emissions of exported energy carriers. Read more about what this means for emission factors of imported carriers on the Emission factors page.

  • In a departure from common UNFCCC standards, emissions per sector are calculated based on the primary energy that is used to supply the final energy demand of that sector. This means that any conversion and transportation losses are included in the sector's emissions. For example, transmission losses of the power grid are distributed to the demand sectors relative to their electricity demand. The primary energy demand is multiplied with the emission factor per carrier to obtain the CO2 emissions. More information can be found in the emission factors section.

  • The ETM follows international conventions regarding the scope of CO2 emissions. More precisely, this means that by default:

    • Emissions of biomass are assumed to be (net) zero. This assumption can be changed in the biomass section.
    • Emissions of international aviation and shipping are not taken into account. This assumption can be changed in the transportation sector.

  • LULUCF (Land Use, Land Use Change, and Forestry) emissions are out of scope. For more information on these definitions click here.

  • Other greenhouse gases and CO2 emissions from non-energetic processes are calculated separately. These emissions can be adjusted in the Greenhouse gases section in the ETM. As stated briefly above, there are exceptions to this:

    • The ETM does include the calculation of CO2 emissions resulting from natural gas feedstock in the fertilizer industry. This gas is used in Steam Methane Reformers to produce hydrogen feedstock. As this is closely tied to the energy system and virtually all of this CO2 is emitted, it is included in the ETM.
    • The ETM does include the calculation of emissions related to final demand of non-energetic hydrogen and ammonia. Users can make explicit assumptions about how this is produced in the hydrogen and ammonia section. As such, the ETM is able to determine the emissions related to this.

Calculation of primary CO2 emissions​

For each sector and each final demand carrier, the associated CO2 emissions are calculated by determining how much primary energy is needed to produce or supply this final demand and by multiplying this primary energy demand by the emission factor of the carrier. This means that all conversion and transportation losses are taken into account and assigned to the sector in which the final demand carriers are used.

Calculation example

Suppose the household sector has a final electricity demand of 100 [MJ]. All power is produced by coal-fired power plants with an efficiency of 50%. To supply 100 [MJ] electricity, 100 [MJ] / 50 [%] = 200 [MJ] coal is needed. The total CO2 emissions taken into account for household electricity demand equals 200 [MJ] * emission factor of coal [kgCO2/MJ].

Exception: liquid fuels​

One exception to the primary emission method is for final demand of non-biogenic liquid fuels, such as diesel, gasoline and kerosene. Instead of calculating primary emissions, the direct emissions for final demand of these fuels are calculated by multiplying final demand with the emission factors of these fuels. The reason for this is two-fold:

  • Refineries are highly complex industrial processes that are modelled in a simplified way in the ETM. More detail is required to trace back the exact energetic and feedstock inputs used to produce each refinery product, in order to determine accurate emissions with the primary emission method.
  • Using the primary emission method for refineries can result in widely varying emission factors for liquid fuels between countries with and without refineries. This reduces comparability between countries.

If additional feedstock is required in the production process for these liquid fuels, the related CO2 emissions are accounted for using the primary emissions method and allocated to the energy sector.

Calculation example

The transport sector has a final diesel demand of 100 [MJ]. Diesel is produced via pyrolysis and pyrolysis-oil fractionation, which proportionally requires 50 [PJ] of hydrogen for diesel production. This hydrogen is in turn produced via SMR, requiring 60 [PJ] of natural gas. The direct CO2 emissions for diesel demand are allocated to the transport sector and equal 100 [MJ] * emission factor of diesel [kgCO2/MJ]. The primary CO2 emissions associated with hydrogen consumption in the production process are allocated to the energy sector and equal 60 [PJ] * emission factor of natural gas [kgCO2/MJ].

The emission factors for liquid fuels are region-specific and can be consulted in the Dataset Manager. The liquid fuels for which direct emissions are calculated as an exception are the following:

  • Diesel
  • Gasoline
  • Kerosene
  • Heavy fuel oil (HFO)
  • Liquefied petroleum gas (LPG)
  • Naphtha
  • Methanol