Emissions/Description: Difference between revisions
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==Emissions from energy production and use== | ==Emissions from energy production and use== | ||
Emission factors (EFs) (see the equation above) are used to estimate emissions from the various energy-related sources ([[Table | Emission factors (EFs) (see the equation above) are used to estimate emissions from the various energy-related sources (See the table on the additional page: ([[Atmospheric_emissions_table|Table]]). In general, the so-called Tier 1 approach from IPCC guidelines ([[IPCC, 2006]]) is used. In the energy system, emissions are calculated by multiplying energy use fluxes with time-dependent emission factors. Changes in the emission factors represent technological improvements and end of-pipe control techniques, fuel specification standards for transport, clean-coal technologies in industry, etc. | ||
The emission factors are calibrated for the historical period on the basis of the [[EDGAR database|EDGAR emission model]] as described by [[Braspenning Radu et al., 2012]]. The calibration to the EDGAR database is not always straightforward due to differences in aggregation level. The general rule is to use weighted average emission factors in the case of aggregation. However, in those cases in which this results in incomprehensible emission factors (in particular when large differences exists between the emission factors for the underlying technologies) specific emission factors were chosen. | The emission factors are calibrated for the historical period on the basis of the [[EDGAR database|EDGAR emission model]] as described by [[Braspenning Radu et al., 2012]]. The calibration to the EDGAR database is not always straightforward due to differences in aggregation level. The general rule is to use weighted average emission factors in the case of aggregation. However, in those cases in which this results in incomprehensible emission factors (in particular when large differences exists between the emission factors for the underlying technologies) specific emission factors were chosen. | ||
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The CO2 exchange between terrestrial ecosystems and the atmosphere computed by the LPJ model is described in [[Natural vegetation and carbon cycle]]. The land-use emissions model focuses on emissions of other important gases, including greenhouse gases (CH4, N2O), ozone precursors (NOx, CO, VOC), acidifying compounds (SO2, NH3) and aerosols (SO2, NO3, BC, OC). | The CO2 exchange between terrestrial ecosystems and the atmosphere computed by the LPJ model is described in [[Natural vegetation and carbon cycle]]. The land-use emissions model focuses on emissions of other important gases, including greenhouse gases (CH4, N2O), ozone precursors (NOx, CO, VOC), acidifying compounds (SO2, NH3) and aerosols (SO2, NO3, BC, OC). | ||
For many sources, the emission factor approach (see formula 1.) is used ([[Table | For many sources, the emission factor approach (see formula 1.) is used ([[Atmospheric_emissions_table|Table]]). For anthropogenic sources, the emission factors are from the EDGAR database, with time-dependent values for historical years. During the scenario period, most emission factors are constant, except for explicit climate abatement policies (see below). However, there are some important exceptions. Atmospheric N emissions are modeled in a detailed way (see below), and in several other cases, the emission factor depends on the assumptions described in other parts of IMAGE. For example, CH4 emissions from nondairy and dairy cattle are calculated on the basis of the energy requirement and feed type (see [[Livestock]]). High-quality feed such as concentrates from feed crops have a lower CH4 emission factor than feeds with lower protein and higher contents of components with lower digestibility. This implies that when the feed conversion ratio changes, the CH4 emission will automatically change as well. Feed conversion ratios are prescribed, or are calculated on the basis of the animal productivity. | ||
Constant emission factors may lead to decreasing emissions per unit of product, for example when the emission factor is specified on a per head basis. An increasing production per head may then lead to a decreasing emission per unit of product. An example is the constant CH4 emission from animal waste per animal, which leads to decreasing emissions per unit of meat or milk when the production per animal increases. | Constant emission factors may lead to decreasing emissions per unit of product, for example when the emission factor is specified on a per head basis. An increasing production per head may then lead to a decreasing emission per unit of product. An example is the constant CH4 emission from animal waste per animal, which leads to decreasing emissions per unit of meat or milk when the production per animal increases. | ||
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==Emission abatement== | ==Emission abatement== | ||
Future emissions for a number of energy and land-use related sources also vary in future years as a result of climate policy. This is described by using so-called abatement coefficients (see flowchart on the right). The values of these coefficients depend on the scenario assumptions. In scenarios in which climate change or sustainability is an important feature in the storyline, abatement will be more important than in business-as-usual scenarios. Abatement factors are used in particular for CH4 emissions from fossil fuel production and transport, N2O emissions from transport and for CH4 emissions from enteric fermentation and from animal waste, and N2O emissions from animal waste according to the IPCC method. These abatement files are calculated in the climate policy submodel of IMAGE on the basis of comparing the costs of non-CO2 abatement in agriculture against other mitigation options. | Future emissions for a number of energy and land-use related sources also vary in future years as a result of climate policy. This is described by using so-called abatement coefficients (see flowchart on the right). The values of these coefficients depend on the scenario assumptions. In scenarios in which climate change or sustainability is an important feature in the storyline, abatement will be more important than in business-as-usual scenarios. Abatement factors are used in particular for CH4 emissions from fossil fuel production and transport, N2O emissions from transport and for CH4 emissions from enteric fermentation and from animal waste, and N2O emissions from animal waste according to the IPCC method. These abatement files are calculated in the climate policy submodel of IMAGE on the basis of comparing the costs of non-CO2 abatement in agriculture against other mitigation options. | ||
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Revision as of 18:10, 23 January 2014
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