EDUCATION: GLOBAL METHANE INVENTORY

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Appendix III: Default Values for Calculating Methane Emissions from Landfills

The IPCC methodology for calculating methane emissions from landfills was based on estimates of the factors influencing methane production in solid waste. Among these is the degradable organic carbon (DOC) content of the waste. The percent of DOC is based on the composition of the waste. Since the composition can vary widely between developed and developing countries, data on the amount and composition of solid waste from various regions were collected. From this, default values for the per capita production of solid waste, the fraction to landfill and the fraction of DOC may be calculated for various countries. Where data for specific countries are sparse, assumptions are made based on regional data available.

Calculating methane emissions from landfills requires data on the urban and rural population and the per capita solid waste production of a country from which the total amount of municipal solid waste (MSW) can be calculated. Methane emissions can then be calculated by applying the IPCC default values for the fraction of the total MSW to landfill and the fraction of DOC in that landfill that undergoes anaerobic decay and multiplying that by the methane potential. Population statistics are supplied by students and can be found in the FAO database. Data for per capita solid waste production, municipal solid waste (MSW) and other factors necessary for the calculation of methane emissions from landfills is supplied by IPCC.

This procedure is as follows:

Step 1 - Calculate the Total Municipal Solid Waste in Tg (10⁹g)

Total Municipal Solid Waste

=

[(Urban Population × Urban MSW generated Factor kg/capita/day × 365 days)

+

(Rural Population × Rural MSW generated Factor in kg/capita/day × 365 days)]

/

1×106 (to convert 103 kg to 1012 g = Teragrams)

Step 2 - Calculate the methane emissions in Tg 10¹²g)

Methane Emission

=

Total MSW Generated (from part 1)

×

Fraction Going to Landfill

×

Fraction Undergoing Anaerobic Decay

×

Methane Potential Factor

×

.001372 (to convert to Teragrams)

Example:

State	Urban Population (in 1000s)	Urban MSW Factor (kg/capita/day)	Rural Population (in 1000s)	Rural MSW Factor (kg/capita/day)	Fraction Going to Landfill	Fraction Undergoing Anaerobic Decay	Methane Potential Factor
Alabama	2440	1.9	1601	1.9	0.7	1.0	57

Step 1 - Calculate the Total Municipal Solid Waste in Tg (10¹² g)

Total Municipal Solid Waste	=	[(Urban Population × Urban MSW generated Factor kg/capita/day × 365 days)	+	(Rural Population × Rural MSW generated Factor in kg/capita/day × 365 days)]	/	1×106 (to convert 103 kg to 1012 g = Teragrams)
	=	[(2440 × 1.9 × 365)	+	(1601 × 1.9 × 365)]	/	1×106	=	2.802 Tg/yr

Step 2 - Calculate the methane emissions in Tg (10¹² g)

Methane Emission

=

Total MSW Generated (from part 1)

×

Fraction Going to Landfill

×

Fraction Undergoing Anaerobic Decay

×

Methane Potential Factor

×

.001372 (to convert to Teragrams)

=

2.802 Tg/yr

×

0.7

×

1.0

×

57

×

0.001372

=

0.153 Tg/yr

Although this calculation seems complicated, it is fairly simple and logical. People (population) make trash (solid waste) and some of it goes to landfills. Some of it will decay to produce methane. It is simply a matter of plugging values into an equation and doing the calculations. Using a spreadsheet for this can make it much easier.

Note: Where values for a particular country are not given, You may use values for a country which is in the same region. You do, however, need to document which country is used.

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