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.
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.
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.
APCp x EFp=CFp Actual CO2 emissions from primary fuel:
COp =
CFp x % FCOp x 44/12 Total CO2s+p = CO2p + … r
CO2s (CH4 - C)cdaf x 16/12 = CH4 Emissions (Gg) = … (EFabc x
Activityabc) [CH4]i,y = (EFi x POPi,y)/(106Kg/Gg) Determination of Emission Factors and Methane
Emissions from Manure Management 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.
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.
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 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:
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) 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 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: 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 = POPy x WGR x FL x FDOC x
FAD x
(GgC - CH4/GgC - biogas) x 16/12 -
MRy CH4 emissions = (POPy x
BOD5/capita-day x
365 days x EF x Fr) - MRy CH4 emissions = … {(WWO)i,y x
((BOD5)i,y x (EF)i,y x
(FWWTA)i,y)} -
MRy 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 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. Greenhouse Gas Inventory Reference Manual, IPCC
Emission 1987 1988 1989 1990 1991
1992/93
Emission 1987 1988 1989 1990 1991 1992
1993
APCs x EFs = CFs
EFQs x EFs x %CSs =
CSs
CFs - CSs = NCEs
Actual CO2 emissions from secondary fuel:
COs =
NCEs x % FCOs x 44/12
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:
(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:
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:
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.
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.
1. Daily Manure produced:
2. Yearly manure produced (Kr) from:
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
The result of the calculation shows the following emission factors for
different climate regions:
Dairy animals emission factor Nondairy animal emission
factor/head/year)
(KGCH4/head/year)
(KgCH
Cool Temperate Warm Cool Temperate Warm
1.51 1.81 2.05 0.99 1.14 1.32
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
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:
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.
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.
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:
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:
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:
CO2 EMISSIONS FROM CEMENT
FACTORIES
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.
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
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
CH4 6.55 6.54 4.87 4.68
5.18
CO2 Emissions From Cement Factories
(Gg)
Year
*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
March 1995