Methane Module (53_methane)


The methane module calculates methane emissions ($CH_4$) according to 1996 IPCC Guidelines of National Grennhouse Gas Inventories1.
Methane emissions before technical mitigation ($vm\_btm$) are then handed on the 57_maccs module to calculate emissions after technical mitigation.



Name Description Unit A B C
$vm\_area(j,kcr,w)$ agricultural production area mio. ha x x
$fm\_feeding\_convergence(t\_all)$ feeding convergence scenario - x x
$vm\_prod\_reg(i,k)$ regional aggregated production mio. ton DM x x
$vm\_dem\_feed(i,kli,kbio)$ regional feed demand including byproducts mio. ton DM x
$fm\_GE\_content(kbio)$ gross energy content GJ per ton DM x
$vm\_btm\_reg(i,emis\_reg)$ emissions before technical mitigation Tg N2O-N CH4 and CO2-C x x x

The last columns of the table indicate the usage in the different realizations (numbered with capital letters)

Interface plot

Figure 0: Information exchange among modules


(A) off

Methane emissions are set to zero.

vm\_btm\_reg.fx(i,emis\_ch4) = 0

CH4 emissions are fixed to zero

(B) ipcc1996 (default)

This module realization estimates $CH_4$ emissions from paddy rice cultivation, enteric fermentation from ruminant animal husbandry and from animal waste management systems. These are total $CH_4$ emissions calculated before technical mitigation ($vm\_btm\_reg$). Technical mitigation options are applied on these baseline emissions in the module 57_maccs.
Emission factors are based on the 1996 IPCC Guidelines for National Greenhouse Gas Inventories1 (IPCC 1996). Emission factors are multiplicatively connected to the cultivated area of rice $vm\_area(j,\text{"$rice\_pro$"},w)$ or on the amount of livestock production $vm\_prod\_reg(i,kli)$.
In some scenarios, it is assumed that the productivity and the management of the livestock sector changes from current practices to industrialized practices; therefore the parametrization of the regional livestock sectors are assumed to converge to the European values. The emission factors in this module converge to the European levels too.
For rice, one mitigation option would be to produce rice only on rainfed areas. Drainage would reduce methane emissions. However, paddy rice does not necessarily require blue water, but can also exclusively use green water. Moreover, LPJ does not simulate paddy rice, but irrigated normal rice, so we are not certain about the yield differential. Therefore, we only use total rice area and assume that the share of paddy rice in the world regions (from IPCC Guidelines1 (IPCC 1996)) stays constant.

CH4 emissions are calculated as follows:

enteric fermentation:

vm\_btm\_reg(i,\text{"$ent\_ferm\_ch4$"}) = \sum_{kli} (vm\_prod\_reg(i,kli)*ic53\_emis\_ch4\_liv\_1996(\text{"$ent\_ferm\_ch4$"},i,kli))

animal waste management:

vm\_btm\_reg(i,\text{"$awms\_ch4$"}) = \sum_{kli} (vm\_prod\_reg(i,kli)*ic53\_emis\_ch4\_liv\_1996(\text{"$awms\_ch4$"},i,kli))


vm\_btm\_reg(i,\text{"$rice\_ch4$"}) = \sum_{cell(i,j),w} (vm\_area(j,\text{"$rice\_pro$"},w)*f53\_emis\_ch4\_rice1996(i))

IPCC 1996 guidelines should be updated to 2006 guidelines.

(C) ipcc_1996_2006_dec14

This realization is the same as ipcc1996 realization for animal waste management and rice emissions. The $CH_4$ emissions from enteric fermentation are estimated based on the GE (energy content) in ruminant feed, the approach from IPCC 2006 Guidelines for National Greenhouse Gas Inventories, Tier II methods [2].

vm\_btm\_reg(i,\text{"$ent\_ferm\_ch4$"}) = \sum_{k} & [vm\_dem\_feed(i,\text{"$livst\_rum$"},k)*fm\_GE\_content(k)*f53\_ef\_entferm(k) \\
&+ vm\_dem\_feed(i,\text{"$livst\_rum$"},k)*fm\_GE\_content(k)*0.065] / 55.65

The factor 1/55.65 t/GJ is the energy content of methane.
The factor 0.065 is the share of GE in feed released as methane for dairy cattle.
$f53\_entferm$ is 0.035 for concentrates and 0.065 percent for fodder, pasture, scavenging, and crop residues.

$CH_4$ emissions from animal waste management may be inconsistent with $CH_4$ emissions from enteric fermentation


Name Description Unit A B C
$i53\_scen\_emis\_ch4\_liv\_1996(t,emis\_ch4,i,kli)$ $CH_4$ Emission per $t$ livestock product (methodology 1996) after feed conversion CH4/t x x
$ic53\_emis\_ch4\_liv\_1996(emis\_ch4,i,kli)$ value of $i53\_emis\_ch4\_liv\_1996$ in the current timestep CH4/t x x
$f53\_emis\_ch4\_rice1996(i)$ $CH_4$ Emission per ha (methodology 1996) CH4/ha x x
$f53\_emis\_ch4\_liv\_1996(emis\_ch4,i,kli)$ $CH_4$ Emission per $t$ livestock product (methodology 1996) CH4/t x x
$f53\_ef\_entferm(kbio)$ percentage of gross energy in feed that is released as methane for beef cattle % x

The last columns of the table indicate the usage in the different realizations (numbered with capital letters)


Benjamin Leon Bodirsky

See Also

Overview, 57_maccs, 70_livestock, 30_crop


1 * IPCC (1996) Volume 2: Workboook, Chapter 4: Agriculture, in: Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories, Institute for Global Environmental Strategies (IGES), 1996.

2 * IPCC (2006) 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 10, Table 10.12. Prepared by the National Greenhouse Gas Inventories Programme.