This module calculates methane emissions according to 2006 IPCC Guidelines of National Greenhouse Gas Inventories. See also IPCC (2006). Further, using the IPCC 2019 revision, this module calculations CH4 emissions from the burning of agricultural residues.
| Description | Unit | A | B | |
|---|---|---|---|---|
| fm_attributes (attributes, kall) |
Conversion factors - where X is ton N P K C DM WM or PJ GE | \(X/tDM\) | x | |
| im_maccs_mitigation (t, i, emis_source, pollutants) |
Technical mitigation of GHG emissions | \(percent\) | x | |
| vm_area (j, kcr, w) |
Agricultural production area | \(10^6 ha\) | x | |
| vm_dem_feed (i, kap, kall) |
Regional feed demand including byproducts | \(10^6 tDM/yr\) | x | |
| vm_emissions_reg (i, emis_source, pollutants) |
Regional emissions by source and gas after technical mitigation N CH4 C | \(Tg/yr\) | x | x |
| vm_manure (i, kli, awms, npk) |
Calculation of manure excreted in confinements | \(10^6 t X\) | x | |
| vm_res_ag_burn (i, kcr, attributes) |
Regional residues burned on fields in respective attribute units DM GJ Nr P K WM C | \(10^6 tX\) | x |
This module realization calculates methane from different agricultural sources based on the IPCC (2006). Methane emission sources considered in the module are enteric fermentation, animal waste management, and rice. Further, methane emissions from the burning of agricultural residues is incorporated, with emissions factors taken from the IPCC 2019 revision.
We calculate methane emissions in each regions (reg) (vm_emissions_reg) from the aforementioned four sources of emissions step-by-step in the following four equations.
The first equation describes how CH4 emission from enteric fermentation is calculated. The equation shows that total methane from enteric fermentation depends on the animal feed demand type (vm_dem_feed) and the purpose of raising livestock - either for meat (livst_rum) and/or milk (livst_milk). The factor 1/55.65 t/GJ in the equation is the energy content of methane. The other scalars - 0.065 and 0.03 - refer to the share of gross energy (ge) in feed released as methane for dairy cattle and ruminants respectively.
\[\begin{multline*} vm\_emissions\_reg(i2,"ent\_ferm","ch4") = \frac{ 1}{55.65 } \cdot \left(\sum_{k\_conc53}\left( vm\_dem\_feed(i2,"livst\_rum",k\_conc53) \cdot fm\_attributes("ge",k\_conc53) \cdot 0.03\right) + \sum_{k\_conc53}\left( vm\_dem\_feed(i2,"livst\_milk",k\_conc53) \cdot fm\_attributes("ge",k\_conc53) \cdot 0.065\right) + \sum_{k\_noconc53,k\_ruminants53}\left(vm\_dem\_feed(i2,k\_ruminants53,k\_noconc53) \cdot fm\_attributes("ge",k\_noconc53) \cdot 0.065\right) \right) \cdot \left(1-\sum_{ct} im\_maccs\_mitigation(ct,i2,"ent\_ferm","ch4")\right) \end{multline*}\]
As such, methane from enteric fermentation depends on the feed quality and the purpose of livestock farming. The feed quality (measured by energy content of the feed type) can be k_conc53 (with high energy contents, for example, temperate and tropical cereals, maize,pulses) or k_noconc53 (for example, pasture, fodder,crop residues). The purpose of livestock raising k_ruminants53 can be either for meat (livst_rum) or for milk (livst_milk). The parameter fm_attributes in MAgPIE captures a content of some thing (e.g. gross energy-ge, dry matter-dm, reactive nitrogen-nr) in a given commodity. These attributes or coefficients are then used in content conversions in many modules of the model.
The second equation of this realization is meant to calculate CH4 emission from animal waste management (AWM). In general, AWM depends on the amount of manure excreted in confinements (such as stables or barns) (see 55_awms) and its subsequent storage. We calculate the CH4 emission per unit of nitrogen in manure based on IPCC (2006) and Manure Management Emissions from FAOSTAT (2016). See the module for more on calculation of methane from animal waste(or manure).
\[\begin{multline*} vm\_emissions\_reg(i2,"awms","ch4") = \sum_{kli}\left( vm\_manure\left(i2, kli, "confinement", "nr"\right) \cdot \sum_{ct} f53\_ef\_ch4\_awms(ct,i2,kli)\right) \cdot \left(1-\sum_{ct} im\_maccs\_mitigation(ct,i2,"awms","ch4")\right) \end{multline*}\]
The third equation of this realization calculates methane emissions from rice cultivation. As presented below CH4 from rice is a function of harvested area of rice and th CH4 emission intensity of rice (measured as CH4 per hectare of rice). The calculation is based on IPCC (2006) and Rice Cultivation Emissions from FAOSTAT (2016).
\[\begin{multline*} vm\_emissions\_reg(i2,"rice","ch4") = \sum_{cell(i2,j2),w}\left( vm\_area(j2,"rice\_pro",w) \cdot \sum_{ct}f53\_ef\_ch4\_rice(ct,i2)\right) \cdot \left(1-\sum_{ct} im\_maccs\_mitigation(ct,i2,"rice","ch4")\right) \end{multline*}\]
The fourth equation calculates emissions from burning crop residues for CH4. This calculation follows the 2019 Refinement to the 2006 IPPC Guidelines for National Greenhouse Gas Inventories, Eq. 2.27.
\[\begin{multline*} vm\_emissions\_reg(i2,"resid\_burn","ch4") = \sum_{kcr} vm\_res\_ag\_burn(i2,kcr,"dm") \cdot s53\_ef\_ch4\_res\_ag\_burn \end{multline*}\]
Limitations CH4 emissions from animal waste management may be inconsistent with CH4 emissions from enteric fermentation.
No representation of methane emissions within the model. While unrealistic, this realization may be useful for comparisons and completeness. When used, this realization sets all emissions from enteric fermentation, animal waste management, rice cultivation, and agricultural residue burning to 0.
Methane emission from agricultural sources equals to zero.
vm_emissions_reg.fx(i,emis_source,"ch4") = 0;Limitations It is unrealistic to consider zero methane emissions and to ignore it from a model such as MAgPIE which is meant to assess impacts of agricultural production on environment.
| Description | Unit | A | B | |
|---|---|---|---|---|
| f53_ef_ch4_awms (t_all, i, kli) |
CH4 emission per livestock products | \(CH4/tDM\) | x | |
| f53_ef_ch4_rice (t_all, i) |
CH4 emission per ha rice | \(CH4/ha\) | x | |
| q53_emissionbal_ch4_awms (i) |
Detailed ch4 constraint for animal waste management systems before technical mitigation | \(tCH4\) | x | |
| q53_emissionbal_ch4_ent_ferm (i) |
Detailed ch4 constraint for enteric fermentation before technical mitigation | \(tCH4\) | x | |
| q53_emissionbal_ch4_rice (i) |
Detailed ch4 constraint for rice before technical mitigation | \(tCH4\) | x | |
| q53_emissions_resid_burn (i) |
Estimates ch4 emissions from the burning of agricultural residues | \(Mt X-N\) | x | |
| s53_ef_ch4_res_ag_burn | CH4 emissions from the burning of agricultural residues | \(tCH4/tDM\) | x |
| description | |
|---|---|
| attributes | Product attributes characterizing a product (such as weight or energy content) |
| awms | animal waste management systems |
| cell(i, j) | number of LPJ cells per region i |
| ct(t) | Current time period |
| emis_source | Emission sources |
| emis_source_methane53(emis_source) | emission sources |
| i | all economic regions |
| i2(i) | World regions (dynamic set) |
| j | number of LPJ cells |
| j2(j) | Spatial Clusters (dynamic set) |
| k_conc53(kall) | feedstuff with high energy content |
| k_noconc53(kall) | non-concentrates |
| k_ruminants53(kli) | ruminant subset |
| kall | All products in the sectoral version |
| kap(k) | Animal products |
| kcr(kve) | Cropping activities |
| kli(kap) | Livestock products |
| npk(nutrients) | Plant nutrients |
| pollutants(pollutants_all) | subset of pollutants_all that can be taxed |
| t_all(t_ext) | 5-year time periods |
| t(t_all) | Simulated time periods |
| type | GAMS variable attribute used for the output |
| w | Water supply type |
Benjamin Leon Bodirsky
16_demand, 18_residues, 30_crop, 55_awms, 56_ghg_policy, 57_maccs, 70_livestock