Ethiopia: Greenhouse Gas Emissions and Sources

Asress Wolde Giorgis

Ethiopian Energy Authority

SUMMARY: This paper deals with greenhouse gas emissions (GHG) inventoried from different emission sources in Ethiopia. This inventory of greenhouse gas emissions is phase I of the Ethiopian Climate Change Country Study Project which is partially financed by the United States Government.

INTRODUCTION

Although, it was planned to undertake a GHG emissions inventory for all sources recommended by IPCC, only emissions from the following sources are considered:

The inventory was limited to these sources because statistics for the above sources were available. Further, these sources are believed to be the most significant based on Ethiopia's economic level of development. Five gases (CO2, CO, CH4, N2O, and NOx) were inventoried for the abovementioned emission source categories.

The Ethiopian Energy Authority has a plan to undertake GHG emission inventories for anthropogenic activities (especially from the energy sector) through the year 1999. Therefore, it is hoped that in due course more information will be collected, in order to quantify the emission of gases which are not mentioned here (e.g., NMVOCs) and to quantify emissions from all sources recommended by the IPCC.

INVENTORY METHODS

The inventory of the greenhouse gases has been conducted in accordance with international guidelines, in order to facilitate comparison with similar works undertaken in other countries. IPCC default values provided in the greenhouse gas reference manual have been utilized whenever local statistics where unavailable. Methodologies utilized to quantify the GHG emission from each source category are briefly stated below.

EMISSIONS FROM THE ENERGY SECTOR

CO2 Emissions from Fossil Fuels

Except for liquid fossil fuels, solid fossil fuels like coking coal, steam coal, lignite, subbituminous coal, and peat (primary solid fossil fuels) and coke (secondary solid fossil fuel) are not used for energy supply in Ethiopia. Therefore, only CO2 emissions from liquid fossil fuels have been quantified.Prior to the calculation of carbon emissions from each fossil fuel type, fuels used as raw materials for nonenergy use were identified. According to the observations of fuel characteristics and utilization methods in Ethiopia, bitumen and lubricants are the only important fuels used as raw materials for nonenergy use. Bitumen is used as asphalt for road construction and as lubricants for locomotive parts. Therefore, except for the abovementioned two fuels, all other fuel types are not considered to store carbon since they are used for energy production. The CO2 emissions from each liquid fossil fuel is calculated based on the following relationship (see list of symbols at the end of this paper:

APCp x EFp=CFp
APCs x EFs = CFs
EFQs x EFs x %CSs = CSs
CFs - CSs = NCEs

Actual CO2 emissions from primary fuel: COp = CFp x % FCOp x 44/12
Actual CO2 emissions from secondary fuel: COs = NCEs x % FCOs x 44/12

Total CO2s+p = CO2p + … r CO2s

GHG Emissions from Traditional Fuels

The main traditional biomass fuels burned for energy in Ethiopia are wood, agricultural residues, charcoal, and dung. The CH4, CO, N2O, NOx emission calculation methodologies utilized for the above fuels (including charcoal production) are presented below:

(CH4 - C)cdaf x 16/12 = CH4
(CO - C)cdaf x 28/12 = CO
[FCcdaf x FFOcdaf x CFFcdaf] x (N-C x N2O -N)cdaf x 44/28 = N2O
(N-C x NOx-N)cdaf x 30/14 = NOx

GHG Emissions From Bagasse

Sugar cane residue is a byproduct of sugar production in large agro- industries. Therefore, it is logical to treat bagasse as an industrially made residue compared to other agri-residues. The emissions from bagasse have been calculated using the following formula:

Emissions (Gg) = … (EFabc x Activityabc)

GHG EMISSIONS FROM THE AGRICULTURAL SECTOR

Methane Emissions from Enteric Fermentation and Animal Manure

Methane Emissions from Enteric Fermentation
Herbivorous animals produce CH4 during the digestion process by which carbohydrates are broken down by microorganisms into simple molecules for absorption into the blood stream. The quantity of CH4 produced during this process has been calculated as follows:

[CH4]i,y = (EFi x POPi,y)/(106Kg/Gg)
ACH4 = … (CH4)i,y
Enteric fermentation emission factors utilized are dairy cattle = 36; nondairy cattle = 32; sheep = 5; goat = 5; horse = 18; mules and asses = 10.

Determination of Emission Factors and Methane Emissions from Manure Management
The amount of manure produced from ruminant and non-ruminant animals and the portion of the manure that decomposes anaerobically is the primary determinant of the amount of CH4 produced.

Manure management systems in Ethiopia may differ from other countries. Animal manure, especially cattle manure, is collected and is made into dung cakes. After drying it is used as a fuel. An attempt has been made to modify the emission factors for cattle because the management of manure from cattle in Ethiopia is unique. The following calculation has been carried out to determine the factors.

1. Daily Manure produced:
a) Dairy cattle A = 2.01 (Kg/h/d dry)
b) Nondairy cattle B = 2.27 (Kg/h/d dry)
2. Yearly manure produced (Kr) from:
Dairy cattle X = A x DCy x 365 days
Nondairy cattle Y = B x NDCy x 365 days
Total Manure produced: X + Y

The Ethiopian Energy Authority has been collecting data on the amount of dung utilized for energy for a number of years. Therefore, the fraction of manure handled in a dung form to that of manure produced is as shown below.

                                               Year

87-88 88-89 89-90 90-91 91-92 92- 93
Dung 3,647.25 3,743.12 3,841.45 3,767.59 4,046.10 4,152.43 (utilized Kt)
Manure 17,705.52 17,273.73 17,319.16 17,970.81 17,777.52 17,861.68 produced (Kr)
MS percent 20.60 21.70 22.20 21.00 22.80 23.30
Note: MS percent is manure management usage. The average ratio of dung to manure produced from cattle is 22 percent. This ratio has been used to derive/modify management emission factors.
Dairy Nondairy
Climate Slurry Pasture Fuel Slurry Pasture Fuel MS percent 0 percent 83 percent 22 percent 0 percent 95 percent 22 percent

In order to modify the manure management emission factor, the manure management system methane conversion factors, the maximum CH4 producing capacity, the daily VS excreted (from IPCC manual) and the manure management usage (MS percent to 22 percent) calculated above have been inserted in the manure management emission factor equation shown below.

EFi = VSi x 365 days/yr x Boi x 0.67Kg/M3 x …jkMCFjk x MS%ijk
The result of the calculation shows the following emission factors for different climate regions:


     Dairy animals emission factor        Nondairy animal emission 
factor
(KgCH4/head/year) (KGCH4/head/year)
Cool Temperate Warm Cool Temperate Warm 1.51 1.81 2.05 0.99 1.14 1.32

Based on the above emission factors and percentage distribution of animals according to climate, the average manure management emission factor has been calculated as follows:

AEFi = EFi (A %C + B %T + C %W)

Animal distribution and manure management emission factors calculated are presented in the following table:

                     Climate Region            Average Manure Management
                    Cool        Temp.           Warm      Emission Factor
Animal Species    (percent)    (percent)      (percent)   
(Kg/head/year)
Dairy cattle 46.00 42.50 11.50 1.70 Nondairy cattle 46.00 42.50 11.50 1.09 Sheep 34.88 43.97 21.15 0.15 Goats 48.40 28.94 12.66 0.16 Horses 31.52 46.08 22.40 0.58 Mules 42.83 44.15 13.02 0.81 Asses 42.07 38.50 19.43 0.81 Poultry 30.64 28.70 40.66 0.02

Therefore, the CH4 emission from manure management has been determined by applying:

(MMCH4)i,y = (AEFi x POPi,y)/106Kg/Gg

(AMCH4 = … (MMCH4)i,y

The total annual emission from livestock has been determined by applying:

CH4 (Gg) = … (ACH4 + AMCH4)

Non-CO2 Trace Gas Emissions From Field Burning of Agricultural Residues

Crop residue burning is a significant net source of CH4, CO, NOx and N2O. Burning of crop residues in fields is not considered to be a net source of CO2, because the carbon released to the atmosphere from the crop residues burning at the end of harvest is usually absorbed during the next growing season. Total agri-residues produced annually in Ethiopia can be mathematically represented as follows:

TOTAL = AF + EU + CO + BF + DE

The Ethiopian Energy Authority has been recording the amount of residues used in energy consumption for a number of years. Therefore, what is unknown here is the amount burned in fields and left to decay. The amount burned could be determined by calculating the difference between the total agri-residue produced, the amount used for various purposes, and the decayed part in the field as follows.

BF = TOTAL - (EU + CO + DE)

However, since the decayed amount is not known and the decay process may not be completed within one year, it is not easy to obtain the amount of residues burned in fields from the above relationship. Therefore, the following IPCC recommended relationship has been utilized to determine the emission of the non- CO2 gases from the residues burned onsite.

Total Carbon Released = AP x R/C RATIO x ADMC x FABF x CE x CF

Therefore, CH4 Emissions = Total carbon release x Emission ratio of CH4 x16/12

CO Emissions = Total carbon released x Emission ratio of CO x 28/12

N2O Emissions = Total carbon released x N/C x N2O Emission ratio x 44/28

NOx Emissions = Total carbon released x N/C x NOx Emission Ratio x 30/14

EMISSIONS FROM FOREST COMBUSTION

Fire is a natural component of all forest ecosystems, including those which occur in Ethiopia. The IPCC/OECD methodology was employed to estimate fire emissions from forests. The equations used in these estimates are referenced in the IPCC/OECD methods manual.

Given this background and based on available local data and assumptions, it is estimated that about 23 percent of the total natural forest biomass (Fr) is burned onsite annually. The carbon released from natural forests is initially determined as follows in order to calculate the GHG emission quantities.

ANFC x NCB x f x CE x CFAGB = Carbon released

Therefore, the gases emitted are determined from:
CO2 Emissions = Carbon released x 44/12
CO Emissions = Carbon released x emission ratio x 28/12
CH4 Emissions = Carbon released x emission ratio x 16/12
N2O Emissions = Carbon released x (N/C ratio) x Emission ratio x 44/28
NOx Emissions = Carbon released x (N/C ratio) x Emission Ratio x 30/14

METHANE EMISSIONS FROM WASTE

Methane Emissions From Municipal Solid Waste (Landfills)

Except in Addis Ababa there is not any record of solid waste collected from Ethiopian cities and towns. The solid waste of Addis Ababa is disposed of by the municipality office at Repi. The present solid waste collection efficiency of the city office is 60 percent, in other words, the municipality of the city office has the capacity to collect about 60 percent of the solid waste produced in the city. The remaining 40 percent is collected and burned by individuals around their respective residences.

Therefore, methane emissions from the waste collected by the municipality office is considered important, because it is well developed landfill. The quantity of net methane emission from Addis Adaba is therefore obtained by carrying out the following formula:

CH4 emissions = MSWRE x FDOC x FAD x (GgC - CH4/Ggc - biogas) x 16/12 - MRy
Since the other towns' solid waste production is not usually recorded. The quantity of solid waste is initially calculated based on the population, waste generation rate, and fraction landfilled. Therefore, the equation used to determine the methane emission from other Ethiopian landfills is:

CH4 emissions = POPy x WGR x FL x FDOC x FAD x (GgC - CH4/GgC - biogas) x 16/12 - MRy

Methane Emissions from Municipal Liquid Waste

In this submodule, only methane emissions from Addis Ababa have been calculated as there are statistics on the parameters useful to determine CH4 emission from this source. About 70 percent of the inhabitants of Addis Ababa population have toilets in their houses and the rest (30 percent) have no toilets. Therefore, they defecate anywhere. Fifty-eight percent, 11 percent, and 1 percent of the population of Addis Ababa uses pit latrines, septic tanks, and sewerage lines, respectively. In general, the total fraction of the city waste water treated anaerobically is (0.11 + 0.01) 0.12 percent. Therefore, the annual CH4 emissions is calculated applying the following formula:

CH4 emissions = (POPy x BOD5/capita-day x 365 days x EF x Fr) - MRy

Methane Emissions from Industrial Waste Water

Methane emissions from industrial waste water treatment are dependent on waste water outflow from industry. In Ethiopia, there are many small and large scale industries which produce waste water containing concentrations of organic material likely to produce significant quantities of CH4 emission. The methane emission from all Ethiopian industries waste water has been computed applying the following formula:

CH4 emissions = … {(WWO)i,y x ((BOD5)i,y x (EF)i,y x (FWWTA)i,y)} - MRy

CO2 EMISSIONS FROM CEMENT FACTORIES

Cement production is the most notable example of an industrial transformation process that releases a significant amount of CO2. CO2 released from cement factories is produced during the production of clinker, an intermediate product from which cement is produced. The basic formula used to compute CO2 emission is:

CO2 emissions = Physical unit of production (t) x Emission Factor (tCO2/t product)

INVENTORY RESULTS AND DISCUSSION

Input statistical data used to calculate GHG emissions from consumption of fossil fuels, traditional fuels, bagasse and animal population, amount of agri-residues and Addis Ababa landfills were collected between the first of July (Ethiopian fiscal year) and the end of June for each year. Therefore, GHG emissions released annually from the above sources are reported for those years where sufficient data were available for calculating emissions.

Inventory output from the abovementioned sources show that in all the years reported the major emissions were carbon monoxide from traditional fuels, carbon dioxide from fossil fuels, methane emissions from livestock enteric fermentation, carbon monoxide from agri-residues, and methane from traditional fuels. Although very low in quantity compared to the abovementioned emissions, significant quantities of emissions like oxides of nitrogen emitted from traditional fuels, methane emissions from manure, carbon dioxide from bagasse, methane emissions from agri-residues, nitrous oxide from agri-residues, and traditional fuels have been released from 1987-88 to 1992-93.

Information used to calculate emissions from onsite burning of natural forests, savanna burning, municipal solid and liquid waste, industrial waste water, and cement factory has been collected between January and December of the mentioned years. Inventory output from the above sources shows that carbon dioxide from onsite burning of natural forests, carbon monoxide from savanna burning, methane from municipal liquid waste of Addis Ababa, carbon monoxide from natural forests, and carbon dioxide from cement factories, respectively, were the gases with the highest emissions in the years mentioned.



SYMBOLS DEFINITION OF SYMBOLS AND UNITS

ACH4 Annual CH4 emission from enteric fermentation [Gg] ADMC Agri-residue dry matter content [percent] AEF Average emission factor [KgCH4/head/yr] AF Agri-residue used for animal feed [Kt] AGBD Above-round biomass density [Kt dm/ha] AMCH4 Annual CH4 emission from animal manure [Gg] ANFC Annual natural forest cleared [Kt dm] AP Annual production [Kt] APC Apparent consumption [Gj] AS Area of savanna [Kha] ASB Area of savanna burned annually [Kha] A%C Animal population ratio living in cool climate region [percent] BB Biomass burned [Kt dm] BF Biomass quantity burned in fields [Kt dm] BO CH4 producing potential [M3 CH4/Kg of VS] BOD Biochemical oxygen demand [GgBOD5/cap./day] Bs Natural forest biomass burned onsite [Kt dm] B%T Animal population ratio living in temperate climate region[percent] CCDB Carbon content of dead biomass [t C/ t dm] CCLB Carbon content of living biomass [t C/ t dm] CE Combustion efficiency [percent] CF Carbon fraction [percent] CFAGB Carbon fraction of above-ground biomass [percent] CH4-C Methane carbon ration [percent] CFF Carbon fraction of fuel [percent] CO-C Carbon monoxide carbon trace gas emission ratio [percent] CRD Carbon released from dead biomass [Kt C or Gg C] CRL Carbon released from living biomass [Kt C or Gg C] CS Carbon stored [percent] C%W Animal population ratio living in warm climate region [percent] DC Dairy cattle [103 head] DE Decay [Kt dm] EF Emission factor [Gg CH4/ GgBOD5] EFQ Estimated fuel quantity consumed [MT] Used to determine carbon stored En Natural forest biomass used for energy [Kt dm] EU Agri-residue utilized for energy supply [Kt dm] f Fraction [percent] FAB Fraction actually burned [percent] FABF Fraction of agri-residue burned in fields [percent] FAD Fraction actually degrades [percent] FB Fraction burned annually [percent] FC Fuel consumption [Kt dm] FFO Fraction of oxidized [percent] %FCO Fraction of carbon oxidized [percent] FD Fraction that is dead [percent] FDOC Fraction of degradable organic carbon [CgDOC/GgMSW] FL Fraction that live [percent] Fr Quantity of biomass cleared annually from natural forests [Kt dm] Fr (In methane emissions from municipal liquid waste) Fraction of liquid waste treated anaerobically FWWTA Fraction of waste water treated anaerobically [GgBOD - percent] MCF Methane conversion factor [percent] MMCH4 Methane emitted from animal manure [Gg]g MR Methane recovery [Gg] MSW Municipal solid waste [Gg or Kt] N-C Nitrogen carbon ratio [percent] NCB Net change of biomass [Kt dm] NCE Net carbon emission [Gg] NDC Nondairy cattle [10 head] N2O-N Nitrous oxide nitrogen trace gas emission ration [percent] NOx-N Nitrogen oxides nitrogen trace gas emission ration [percent] POP Population [10 head] R/C Residue Crop ration [percent] VS Average manure volatile solids [Kg] WGR Waste generation rate [Gg MSW/10 head/yr] WWO Waste water outflow [10 litre]

SUBSCRIPTS

a: Fuel type
b: Sector activity
c: Technology type, Charcoal consumption (depends on the area of discussion)
d: dung
e: Charcoal production
f: Fuel wood
i: Animal species, Industry (depends on the area of discussion)
j: Manure management system
k: Climate region
p: primary, Re: recorded
s: secondary
y: year

REFERENCES

Greenhouse Gas Inventory Reference Manual, IPCC
National Energy Balance, Ethiopian Energy Authority, 1990-91
National Energy Balance, EEA, 1991
Greenhouse Gas Inventory Workbook, IPCC
Estimation of Greenhouse Gas Emission and Sources, OECD/OCDE, Aug. 1991, pp. 2-34
Ethiopian Statistical Abstract, 1988 and 1990
Assistance to Landuse Planning Thiopia, FAO, ROME, 1984
Natural Biomass Data for Leap Preliminary Report, EEA, 1992
Ethiopian Forestry Action Program, May 1992
African Compendium of Environment Statistics, 1993
Energy Database Sources and Methods, June 1991




Fossil Fuel CO2 (Gg) Emissions
                                             Year

87-88 88-89 89-90 90-91
CO2 (Gg) 2,543.10 2,906.12 2,620.00 2,102.00
Greenhouse Gas Emissions From Traditional Fuels (Gg) Year CH4 CO N2O NOx
1987-88 272.96 2,177.37 1.00 38.21 1988-89 279.46 2,232.62 1.00 38.55 1989-90 287.42 2,295.59 1.00 40.30 1990-91 297.72 2,367.59 1.00 41.60 1991-92 306.28 2,440.42 1.00 42.84 1992-93 2,498.58 1.00 43.89
Emission From Bagasse
Year
87-88 88-89 89-90 90-91
CO (Gg) 7.50 7.80 8.00 8.10 NOx (Gg) 0.38 0.40 0.00 0.42
CH4 Emissions From Agriculture (Gg)
                                             Year
Emission Source 87-88 88-89 89-90 90-91
Enteric Ferm. 898.47 879.40 881.41 910.18 Manure Man. 29.53 28.79 29.00 29.87 Total 928.00 908.37 910.41 940.05
GHG Emissions From Agri-Residues (Gg) CH4 CO N2O NOx
1987-88 5.00 111 0.00 2.98 1988-89 4.00 9 0.00 2.64 1989-90 5.00 111 0.00 3.11 1990-91 5.00 124 0.00 3.46 1991-92 6.00 133 0.00 3.75 1992-93 6.00 142 0.00 4.04
GHG Emissions From Savanna Burning (Gg) Year Emission 1987 1988 1989 1990 1991 1992 1993
CH4 190.39 183.73 177.00 171.09 16.00 159.33 153.80 CO 4,997.80 4,822.90 4,654.10 4,491.20 4,334.00 4,182.30 4,036.00 N2O 2.36 2.27 2.19 2.12 2.04 1.97 1.90 NOx 55.08 53.15 51.08 4.00 47.76 46.09 44.48
GHG Emission From Onsite Burning of Natural Forests (Gg) Year Emission 1987 1988 1989 1990 1991 1992 1993
CO2 6,713.00 6,612.50 6,513.20 6,415.00 6,319.40 6,225.90 6,132.00 CH4 29.29 28.85 28.42 27.99 27.58 27.17 26.76 CO 256.32 252.48 248.69 244.94 241.29 237.72 234.10 N2O 0.18 NOx 4.75 4.68 4.61 4.54 4.47 4.34
CH4 Emissions From Wastes (Gg) Year Emission 1987 1988 1989 1990 1991 1992 1993
*MSW (Excluding Addis) 36.52 38.69 40.12 41.59 4.00 44.75 *MLW of Addi 551.81 58.00 626.69 657.43 689.00 723.56 759.10 *Industrial waste water 9.96 10.91 10.17 10.13 10.10
CH4 Emissions From Addis Ababa Landfill Year

Emission 1987 1988 1989 1990 1991 1992/93


CH4 6.55 6.54 4.87 4.68 5.18
CO2 Emissions From Cement Factories (Gg) Year

Emission 1987 1988 1989 1990 1991 1992 1993


*From Muger factory 155.65 155.66 140.18 191.16 117.85 171.4 *From Addis factory 26.08 2.00 18.14 14.74 12.12 16.53 Total CO2 181.73 183.26 159.32 205.00 129.97 188.00


INTERIM REPORT ON CLIMATE CHANGE COUNTRY STUDIES
March 1995

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