Emission ch4 solid waste

ESTIMATING EMISSIONS OF METHANE (CH4)

FINAL RESULT REPORT PREPARED TO BE PRESENTED TOTHE GHG INVENTORY PROJECT STEERING COMMITTEE

1999

July 1999

Addis Ababa

Ethiopia

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E S T I M A T I N G E M I S S I O N O F

M E T H A N E (CH4)

F R O M S O I L D W A S T E

By:

Fikru Tessema (M.Sc, B.Sc, D.Sc)

Consultant

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DEFINITION OF TERMS

1. Green House Gases (GHG): are gases like methane, carbon dioxide, nitrous

oxide, CFC-11, HCFC- & CF4 that contribute effects to the climate change.

2. Methane: is a GHG emitted from waste under anaerobic condition.

3. Landfill: is a land disposal method for solid waste.

4. Municipal Solid Waste: is a waste generated by every urban dweller.

5. Urban Center: is the urban settler with more than 2 thousand number of

population.

6. Methane Correction Factor (MCF): is a value obtained by dividing the

methane atomic weight by carbon atomic weight.

7. Degradable Organic Carbon (DOC): is the organic component in MSW that

actually degrades.

8. Disposal Rate: is the per capita based rate of disposing of the portion of

solid waste generated per person per day in kg.

9. Waste: is the unwanted material that can exist in solid or liquid form.

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ACRONYMS

1. CSA : Central Statistics Authority

2. GHG : Greenhouse Gas

3. IPCC : Intergovernmental Panel on Climate Change

4. MSW : Municipal Solid Waste

5. SWDS : Solid Waste Disposal Site

6. CH4 : Methane

7. DOC : Degradable Organic Carbon

8. CO2 : Carbon dioxide

9. Gg : Giga gram

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Executive Summary

A retrospective data based estimation of methane emissions from solid waste

disposed of in the solid waste disposal sites for urban centers of Ethiopia has been

done for GHG inventory for each year 1989-1998.

The population of Addis Ababa City accounts about 28% of the total population of

urban centers of Ethiopia and the other urban centers 72%. The work of solid waste

management is left for the Municipality in most urban centers of Ethiopia.

The solid waste generation units of per capita per day in Addis Ababa City,

according to the Norconsult 1982 study, was 0.15 kg with 1% growth rate per year

per capita based. According to the Louisberger consultant 1995 study, it was also

0.35, 0.28 and 0.17 kg/ c/ day for high, medium and low-income group respectively.

The major organic components of MSW of Addis Ababa City are paper & textiles,

(4.8%); grass, leaves & other organic putrescibles, (22.6%); food waste, (4.5%) and

wood & straw/ organic fines (35.7%).

The method employed to dispose solid waste in urban centers of Ethiopia is land

disposal called landfill. In order to complete the estimation of methane emissions

from SWDSs, the data on solid waste have been collected from Health Bureau for

Addis Ababa City and estimated using the IPCC methods for the rest of urban

centers of Ethiopia.

On the average, about 86.7 Gg MSW was disposed of in landfill for Addis Ababa

City and 387.2 Gg MSW for other urban centers per year (Table – I).

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The IPCC default methodology is divided into four parts: (1) Estimation of total

MSW generated and disposed of in SWDSs; (2) Determination of methane

correction factor; (3) Estimation of methane production rate per unit of waste and

(4) Estimation of total net annual methane emissions. There are also four steps to

complete each part, which finally gives net annual methane emissions.

The Addis Ababa City landfills methane emission accounts 18% of the total annual

emissions and the other urban centers 82%.

Methane emitted from solid waste placed in SWDSs is not recovered. Since there is

no methane recovery, the net annual emission of methane is equal to the gross and

net annual generation. On the average, about 5.3 Gg CH4 was emitted from the

landfill for Addis Ababa City and 23.8 Gg CH4 for the other urban centers per year

(Table-II).

Methane emissions from SWDSs increases by 34% of the base year (1989) emissions

for Addis Ababa City and 39% for the rest of urban centers. This implies that there is

a significant emission from landfill for Addis Ababa City.

This inventory has also quite demonstrated that a significant increase of country

methane emissions by 38% of the base year emissions from SWDSs for urban

centers of Ethiopia.

This GHG inventory, therefore, recommends that every local authority should no

longer continue to ignore methane emissions estimation that will help to design

mitigation strategies for GHG concentration reduction in the atmosphere globally

and locally.

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TABLE OF CONTENTS

CONTENTS PAGE

DEFINITION OF TERMS ..........................................................................................................................................i ACRONYMS ........................................................................................................................................................... ii Executive Summary ............................................................................................................................................ iii TABLE OF CONTENTS ............................................................................................................................................ v CHAPTER - 1 ............................................................................................................................................................ 1

1.1 INTRODUCTION ....................................................................................................................................... 1 1.2 BACKGROUND ......................................................................................................................................... 1

1.2.1 URBAN POPULATION OF ETHIOPIA: .............................................................................................. 1 1.2.2 SOLID WASTE MANAGEMENT IN URBAN CENTERS OF ETHIOPIA: ............................................. 3 1.2.3 WASTE GENERATION RATE: ........................................................................................................... 3 1.2.4 PHYSICAL COMPOSITION OF WASTE BY WEIGHT: ....................................................................... 4 1.2.5 QUANTITY OF SOLID WASTE DISPOSED TO THE SWDSs: ............................................................ 4 1.2.6 ESTIMATION OF METHANE EMISSIONS FROM SWDSs: ............................................................... 5

1.3 OBJECTIVES ............................................................................................................................................. 6 1.3.1 GENERAL OBJECTIVES .................................................................................................................... 6 1.3.2 SPECIFIC OBJECTIVES ...................................................................................................................... 6

1.4 METHODS ................................................................................................................................................ 6 1.4.1 GENERAL METHODOLOGY: ............................................................................................................ 6 1.4.2 IPCC METHODOLOGY: ..................................................................................................................... 7

CHAPTER - 2 ......................................................................................................................................................... 10 2.1 RESULTS ................................................................................................................................................ 10

CHAPTER - 3 ......................................................................................................................................................... 11 3.1 DISCUSSION .......................................................................................................................................... 11 3.2 CONCLUSION ......................................................................................................................................... 12 3.3 RECOMMENDATIONS ........................................................................................................................... 12

REFERENCES ........................................................................................................................................................ 13

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CHAPTER - 1

1.1 INTRODUCTION

The greenhouse gases are gases that exist with different concentration in the

atmosphere. Their concentration can increase in the atmosphere as a result of

some human activities and natural processes. The GHG are emitted with

different quantity of emissions from different sources. Solid waste disposal

site is one of the areas that generate the GHG like methane, carbon dioxide,

etc. Methane is the most common gas that released from solid waste under

anaerobic condition. CO2 is also released from shallow solid waste disposal

sites.

A significant quantity of methane emissions is from municipal solid waste

disposed of in the landfill for urban population (1). It is insignificant for rural

population because the amount of waste that goes to solid waste disposal

sites is very few. Estimation of methane emissions from solid waste placed in

solid waste disposal sites for urban centers is more important because it is the

urban centers that managed its waste.

Some major urban cities of Ethiopia that are found in the Northern part

Gondar, Mekele, Baherdar, and Debermarkos, in the Eastern Desie, Deriedwa,

Harar, and Asela, in the Southern Awassa, Arbamench, Jimma, Metu and

Goba, in the Western Nekement and in the Central Addis Ababa and Nazeret

(2).

1.2 BACKGROUND

1.2.1 URBAN POPULATION OF ETHIOPIA:

The urban population in Ethiopia is currently estimated at 15.4% and it is

expected to increase to 30% by the year 2020. This implies that the waste

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generation and methane emissions for urban centers will also increase

substantially by the year 2020.

Table – III Some Major Urban Cities of Ethiopia and Their Population,

1998

Se.

No.

Cities

Population

1 Mekele 114 721

2 Gondar 60 837

3 Dire Dawa 195 546

4 Dessie 115 590

5 Debre Markos 58 230

6 Bahir Dar 113 852

7 Nekemet 56 492

8 Metu 25 337

9 Jimma 108 638

10 Nazeret 181 642

11 Assela 61 011

12 Harar 90 386

13 Goba 33 895

14 Awassa 86 041

15 Arbamench 47 801

16 Addis Ababa 2 354 000

Source: CSA, 1994 Population and Housing Census Projection

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1.2.2 SOLID WASTE MANAGEMENT IN URBAN CENTERS OF ETHIOPIA:

The municipality in most urban centers of Ethiopia carries out the solid waste

management services. It involves collection and transportation of waste and

its disposal to solid waste disposal sites (1).

Addis Ababa, among the forefront growing cities of Ethiopia, has commenced

its solid waste management service over three decades ago. It was only the

Municipality that managed solid waste generated in the city. The time when

the management of solid waste was started in Addis Ababa, the collection and

disposal capacity of the Municipality was very limited. Out of many tones of

waste generated per day in the city, few portions were collected by the

municipal refuse collection system (6).

Currently, the Health Bureau is engaged to collect solid waste. The collection

efficiency is estimated to be 65% of the total waste generated in Addis Ababa

City, but it is not yet known for the rest of urban centers (7). The most

commonly used for solid waste disposal method in the urban centers of

Ethiopia is the land disposal called landfill (1).

1.2.3 WASTE GENERATION RATE:

Quantity of waste generation units of per capita per day in Addis Ababa City

was very much unclear until 1982 when a Nor consultant, a private company on

waste management, first published its findings. Gordon Sturdy, a Louisberger

consultant was also made a study on solid waste generation rate in 1994 &

1995 (4,5).

According to the Nor consultant study on the solid waste generation rate in

Addis Ababa City, the per capita per day generation was 0.150 kg and density

per cu.m was 370kg. In its conclusion, the volume growth rate of the domestic

solid waste generation has an increase of 1% per year per capita based (4).

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According to the Louisberger consultant study, based on the income level, the

unit of domestic waste generation of per capita per day is 0.35, 0.28 and 0.17

kg for high, medium and low income group respectively (5).

For other urban centers of Ethiopia, the quantity of solid waste generation

units of per capita per day is not yet clear because there is no study done on

the solid waste generation rate.

1.2.4 PHYSICAL COMPOSITION OF WASTE BY WEIGHT:

The most common and major components of solid waste in cities of

developing countries, like Ethiopia, are organic substances and fines (1).

According to the IPCC classification, the Addis Ababa City MSW has the

following composition by weight for the organic components: paper & textiles,

(4.8%); grass, leaves & other organic putrescibles, (22.6%); food waste, (4.5%);

and wood & straw waste/organic fines, (35.7%) (5).

1.2.5 QUANTITY OF SOLID WASTE DISPOSED TO THE SWDSs:

The time when Addis Ababa Municipality started refuses collection, the

disposal method employed was land disposal that was located at the border of

the city. Its surface area is estimated to be about 25 hectares with about 10

hectares in use at present. The already disposed refuse for the last 30 years is

estimated to be about six million M3 or two million tones or more than 66.7

thousand tones per year (3,7). For the last ten years (1989 – 1998), the amount

of waste disposed of in landfill was also more than 86.7 thousand tones per

year in Addis Ababa City.

The quantity of solid waste collected and disposed per year is registered in

Addis Ababa City by using the volumetric system, in M3. According to the

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Norconsult study, 1 M3 of solid waste has a weight of 370 kg or its density is 370

kg/M3. The cubic meter converted to gigagram based on these findings (4).

Since there is no data available on MSW generation rate and fraction of MSW

disposed to SWDSs for other urban centers of Ethiopia, the quantity of solid waste

disposed to SWDSs has been estimated using the IPCC default values. For the last

ten years (1989 – 1999), the estimated quantity of refuses disposed to SWDSs was

more than 387.2 thousand tones per year.

1.2.6 ESTIMATION OF METHANE EMISSIONS FROM SWDSs:

The Ministry of Mine & Energy is the first ministry that made the first GHG

Inventory at National level and reported its findings in the year 1996. Different

sectors, based on the IPCC classification, have been assessed for the year 1990 to

1993. The waste sectors in general and municipal solid waste disposal sites in

particular were the areas that have been assessed for methane emissions.

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1.3 OBJECTIVES

1.3.1 GENERAL OBJECTIVES

The main objective is to estimate methane emissions from SWDSs for urban

population for each year 1989 - 1998 and incorporate the CO2 emissions

estimation from shallow SWDSs in the GHG inventory, so as to have a GHG

inventory nationally and globally.

1.3.2 SPECIFIC OBJECTIVES

To estimate quantity of MSW landfilled for urban centers of Ethiopia,

excluding Addis Ababa.

To estimate methane emitted from MSW landfilled for Addis Ababa

(the capital city of Ethiopia) and other urban centers of Ethiopia.

1.4 METHODS

1.4.1 GENERAL METHODOLOGY:

A retrospective data based estimation of methane emissions from MSW

disposed of in landfills for urban centers of Ethiopia was designed for GHG

inventory. The year 1989 was taken as a base year to evaluate the ten years

emissions. The first GHG inventory results for methane emissions for the year

1990 –1993 have also been revised based on the IPCC default method revised in

1996.

The urban population of Ethiopia has been estimated to be about 12.6% of the

total population since 1989. Currently, it is estimated to be reached about 15.4%

of the total population.

Of the total urban population, about 28% is the population estimated to be

found in Addis Ababa City and 72% in the other Urban Centers of Ethiopia (2).

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A data for the quantity of MSW landfilled for Addis Ababa City has been

collected from Health Bureau, and for other urban centers estimated using the

IPCC default values since there is no data on the fraction of MSW disposed to

SWDSs. For CO2 emissions from portion of unmanaged waste in shallow

SWDSs, there is no available method for estimation.

The compiled data has been analyzed using the IPCC workbook and processed

using computer. The figure analysis and cross tabulations have been done for

all results using the IPCC worksheet.

1.4.2 IPCC METHODOLOGY:

The IPCC default methodology is divided into four parts: (1) Estimation of total

municipal solid waste generated and disposed of in the solid waste disposal

sites. (2) Determination of methane correction factor; (3) Estimation of

methane production rate per unit of waste and (4) Estimation of total net

annual methane emissions.

The results of each step for each part are presented in the Main Work- sheet #

6-1. The first step corresponds to part 1 (Column A), second to part 2 (Column

B), third to part 3 (Column C-H) and fourth to part 4 (Column J-N).

Step 1 begins with Column A, which is derived from data compiled by using the

supplementary work sheets. The Supplementary Worksheet 6-1A is not used

for Addis Ababa City since there is detailed data on Total Annual MSW

Disposed to SWDSs (in gig grams of MSW). It is also not used for the rest of

urban centers since there is no data on MSW per Capita Generation Rate and

Fraction of MSW Disposed to SWDSs. But, the Supplementary Worksheet 6-1B

is used for the estimation of Total Annual MSW Disposed to SWDSs (in

gigagram of MSW) for the rest of urban centers. Column A of Worksheet 6-1B

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gives Total Population per urban center, which was obtained from CSA.

Column B from the same worksheet, refers to MSW Disposal Rate to SWDS (in

kg/capita/day), which is 0.2 (default value). The value in Column C of the same

worksheet is the product of the Column A & B that gives Total Annual MSW

Disposed to SWDSs.

Step 2 begins with Column B, which refers to Methane Correction Factor

(MCF). It is also derived from information compiled by using the

Supplementary Worksheet 6-1C. Since there is no detailed data on Proportion

of Waste (by weight) for each type of SWDSs, the default value 0.6 was taken

as a Methane Correction Factor.

Step 3 begins with Column C that is the Estimation of Methane Production

Rate per Unit of Waste. Values presented in Column C are given by estimating

the Fraction of Degradable Organic Carbon (DOC) in the MSW by using Table 6-

3. It is calculated for Addis Ababa City by using data on the organic component

of MSW of the city. According to the IPCC classification of organic components

of MSW, the DOC by weight in each type of waste stream in MSW is given as:

% DOC (by weight) =(0.4x0.048)+(0.17x0.226)+(0.15x0.045)+(0.3x0.357)

Where:

0.4, 0.17, 0.15 and 0.3 are IPCC default values for % of DOC by weight

in each type of organic waste in MSW.

0.048, 0.226, 0.045 and 0.357 are country data for % composition by

weight for each type of organic waste in MSW (5).

The values can show DOC in MSW 0.2 for Addis Ababa City. Since this value

closely corresponds to the conditions in other urban centers, it is also used for

DOC in MSW for the rest of urban centers.

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It can be seen in Column D & E that the default values 0.77 & 0.5 for the

Fraction of DOC Which Actually Degrades and Carbon Released as Methane

respectively. Column F gives information on Conversion Ratio (the atomic

weight of methane is divided by carbon atomic weight). The product of the

values in Column C, D, E & F derives Column G. The product of the values in

Column B in step 2 and Column G in step 3 gives Column H for Methane

Generation Rate per Unit of MSW.

Step 4 is referred to the Estimation of the Total Net Annual Methane

Emissions. The product of values in Column H of step 3 and Column J of step 4

gives the Gross Annual Methane Generation (in Gg of CH4). Since there is no

Methane Recovery, the Gross Annual Methane Generation and Net Annual

Methane Generation (in Gg of CH4) are equal. Since One minus Methane

Oxidation Correction Factor in column M of step 4 is 1, the products of Column

L in step 4 and column M finally gives the Total Net Annual Methane Emissions

(in gigagram of methane).

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CHAPTER - 2

2.1 RESULTS

The estimated amount of total municipal solid waste disposed to solid waste

disposal sites is given in the (Table – 1 & 2) and net annual methane generation

in (Table – 3 & 4).

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CHAPTER - 3

3.1 DISCUSSION

The quantity of methane emission is influenced by the quantity and

composition of solid waste disposed to the disposal sites and the depth of

waste in the site (1).

This inventory of GHG, therefore, demonstrates that the methane emissions

increase or decrease with the increase or decrease of MSW disposed to the

disposal sites and the variation of the amount of methane emitted in each year

continue to vary with the variation of the amount of MSW landfilled.

In the last ten years (1989 – 1998), the methane emissions from landfill for

Addis Ababa City increased by 34% of the base year (1989) emission and 39% for

other urban centers.

The overall increase of methane emission has quite demonestrated that a

significant increase of methane emissions by 38% of the base year emissions

from SWDSs for urban centers of Ethiopia.

The increase of methane emissions in the past ten years for Addis Ababa City

was very close to the other urban centers of Ethiopia. This implies that there is

a significant emission from Addis Ababa City Municipal Landfill. The Addis

Ababa City landfill methane emission accounts 18% of the total country

emissions per year and the other urban centers 82%.

The revised GHG inventory in each year 1990 – 1993 also came up with results

that have no significant difference from the first GHG inventory results for

Addis Ababa City. But, there is significant difference for other urban centers

12

due to difference in the situational analysis for solid waste management in

urban centers of Ethiopia and using IPCC default values.

Some studies shew that the per capita per day generation rate for solid waste

in Addis Ababa City is estimated to be 0.27 kg (weighted mean) per person per

day. The disposal rate is also estimated to be reached about 0.2 kg/ c/d. This

implies that the disposal rate for other urban centers of Ethiopia can not go far

from this value. Therefore, the default value 0.2 kg/c/d closely corresponds to

conditions in other urban centers. Thus, the default value, (0.4 kg/c/d), that

used in the first GHG inventory does not reflect the conditions in urban centers

of Ethiopia.

3.2 CONCLUSION

The increase of methane emissions substantially from year to year is alarming

from the viewpoint of climate change globally and locally. This, therefore,

indicates that the intergovernmental in general and the local government in

particular should no longer continue to ignore the issue of mitigation of GHG

emissions in the developing countries.

3.3 RECOMMENDATIONS

1. There should be mitigation assessment to design methods that will help to reduce

the concentration of GHG in the atmosphere.

2. Since the methane emissions inventory is dependant on the MSW disposed to

SWDSs, there should be an assessment for the amount of MSW disposed of in

landfills for urban centers of Ethiopia, excluding Addis Ababa.

3. Since there is high portion of solid waste in the unmanaged shallow SWDSs, the

IPCC methodology should reconsider these sites for CO2 emissions; and

incorporate its emissions from SWDSs in the GHG inventory and develop the

methodology for its estimation.

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REFERENCES

1. H. Glas, etal, Solid Waste Disposal, Netherlands, 1994

2. CSA, The 1984 & 1994 Population and Housing Census of Ethiopia,

Addis Ababa, 1986 & 1996.

3. Kumie, A., An Overview of Addis Ababa Solid Waste and its

Management Service, Addis Ababa, 1997

4. Nor consult, Addis Ababa Solid Waste Management Study, 1982.

5. Gordon, S, Addis Ababa Solid Waste Management 3rd and 4th Study,

1994 & 1995.

6. Region 14 Health Bureau, Annual Activities Reports, Addis Ababa,

1984-1998.

7. Health Bureau, Addis Ababa, Health Sector Development Program,

A5 Year Plan (1998-2002), Addis Ababa, May 1998.