Emission factors
(Carbon) emission factors describe the amount of CO2 emissions emitted as a result of energy use. The following page displays all emission factors used in the calculation of (total) energetic CO2 emissions in the ETM, as well as examples on how these emissions are calculated. For the calculation of non-energetic emissions and other greenhouse gases, please check the Greenhouse gases article.
Overview
The emission factors for energy carriers may vary per region. For example, the (organic) composition of coal or waste depends on where these carriers are sourced and hence so does their CO2 content. The ETM supports this by specifying emission factors per country in the ETDataset country analysis.
If no 'custom' emission factor is specified, the following 'default' emission factors are used:
| Primary energy carrier | Emission factor (kg CO2 per MJ) |
|---|---|
| Coal | 0.096 |
| Crude oil | 0.0755 |
| Lignite | 0.1012 |
| Natural gas | 0.0564 |
| Uranium (nuclear energy) | 0 |
| Non-biogenic waste | 0.0835 |
| Biomass (solid, liquid, gaseous, waste) | 0 |
| Renewable electricity (wind, solar etc.) | 0 |
| Renewable heat (ambient heat, solar thermal, geothermal) | 0 |
Source: EU Joint Research Centre
The emission factors for electricity, hydrogen and (collective) heat depend on the installed production technologies, which vary per ETM scenario. E.g. a scenario with lots of coal-fired power plants will have a more carbon-intensive power supply than a scenario with nuclear power plants. If carbon capture is applied to energy production technologies using biomass as input, a carrier may have a negative emission factor. This means that any sector using this carrier will see a decrease in its emissions. This, for example, applies to:
- Coal-fired power plants with biomass co-firing
- Gas-fired power plants using green gas
- Hydrogen production with biomass gasification technology
The emission factors of imported ammonia, electricity, hydrogen and heat can be set in the model. See the import and export article for more information. The following default factors are used in case no country-specific data has been specified:
| Energy carrier | Emission factor (kg CO2 per MJ) |
|---|---|
| Imported ammonia | 0.097 |
| Imported electricity | 0.146 |
| Imported heat | 0.078 |
| Imported hydrogen | 0.04 |
Source: Mixed
Calculation of 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.
Example: Suppose the household sector has a final electricity demand of 100 PJ. Also suppose that all power is produced using gas-fired power plants with an efficiency of 50%. Power transmission losses are assumed to be 5%. To supply 100 PJ electricity to the household sector, 105.3 PJ electricity needs to be produced: 105.3 * 5% transmission losses leaves 100 PJ final demand. To produce this electricity, 210.6 PJ natural gas is needed (105.3 / 50% power plant efficiency). The total CO2 emissions taken into account for household electricity demand equals 210.6 PJ * the emission factor of natural gas.
Exception: Refinery products and emission factors
One exception to this rule is the final demand of 'refinery products' in the transportation sector, such as diesel, gasoline and kerosene. To calculate the emissions associated with this final demand, the ETM simply multiplies the final demand of these carriers directly with fixed emission factors, rather than tracing back the primary energy demand. The reason for this is two-fold:
- Energetic demand of refineries, e.g. electricity and heat used in refinery processes, is already included in the final demand of the industry sector, and hence CO2 emissions. To avoid double-counting, these emissions should not be taken into account when calculating the emissions of refinery products in transportation.
- 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. Using fixed factors avoids (slight) inconsistencies with emission factors typically found in the literature.
For refinery products, the following default emission factors are used. Again note that these values may be overwritten with country-specific data.
| Energy carrier | Emission factor (kg CO2 per MJ) |
|---|---|
| Diesel | 0.0743 |
| Gasoline | 0.072 |
| Heavy fuel oil | 0.0774 |
| Kerosene | 0.0715 |
| LPG | 0.0667 |
Source: EU Joint Research Centre