5.1

CGEGreenhouse Gas Inventory

Hands-on Training Workshop

WASTE SECTOR

5.2

Overview Introduction IPCC 1996GL (Revised 1996 IPCC Guidelines for National

Greenhouse Gas Inventories) and GPG2000 (Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories)

Reporting framework Key source category analysis and decision trees Tier structure, selection and criteria Review of problems

Methodological issues Activity data Emission factors

IPCC 1996GL category-wise assessment and GPG2000 options Examination and assessment of activity data and emission

factors: data status and options Uncertainty estimation and reduction

5.3

Introduction

5.4

Introduction

COP2 adopted guidelines for preparation of initial national communications (decision 10/CP.2)

IPCC guidelines used by 106 NAI Parties to prepare national communications

New UNFCCC guidelines adopted at COP8 (decision 17/CP.8) provided improved guidelines for preparing GHG inventory

UNFCCC User Manual for guidelines on national communications to assist NAI Parties in using latest UNFCCC guidelines

Review and synthesis reports of NAI inventories highlighted several difficulties and limitations of using IPCC 1996GL (FCCC/SBSTA/2003/INF.10)

GPG2000 addressed some of the limitations and provided guidelines in order to reduce uncertainties

5.5

Purpose of this Handbook

GHG inventories are mostly biological sectors, such as Waste, and characterized by:

methodological limitations lack of data or low reliability of existing data high uncertainty

This handbook aims at assisting NAI Parties in preparing GHG inventories using the IPCC 1996GL, particularly in the context of UNFCCC decision 17/CP.8, focusing on:

the need to shift to GPG2000 and higher tiers/methods to reduce uncertainty

complete overview of the tools and methods use of IPCC inventory software and EFDB review of AD and EF and options to reduce uncertainty use of key sources, methodologies and decision trees

5.6

Target groups

NAI inventory experts

National GHG inventory focal points

5.7

NAI country examples Review of national communications: Argentina,

Colombia, Chile , Cuba and Panama GHG inventories show that the Waste sector

may be significant in NAI countries Commonly a significant source of CH4

In some cases a significant source of N2O Solid waste disposal sites (SWDS) frequently a

key source of CH4 emissions

5.8

Definitions Waste emissions – Includes GHG emissions

resulting from waste management activities (solid and liquid waste management, excepting CO2 from organic matter incinerated and/or used for energy purposes).

Source – Any process or activity that releases a GHG (such as CO2, N2O, CH4) into the atmosphere.

5.9

Definitions (2) Activity Data – Data on the magnitude of human

activity, resulting in emissions during a given period of time (e.g. data on waste quantity, management systems and incinerated waste).

Emission Factor – A coefficient that relates activity data to the amount of chemical compound that is the source of later emissions. Emission factors are often based on a sample of measurement data, averaged to develop a representative rate of emission for a given activity level under a given set of operating conditions.

5.10

IPCC 1996GL andGPG2000

Approach and steps

5.11

Emissions from waste management

Decomposition of organic matter in wastes (carbon and nitrogen)

Waste incineration (these emissions are not reported when waste is used to generate energy)

5.12

Decomposition of waste Anaerobic decomposition of man-made waste by

methanogenic bacteria Solid waste

Land disposal sites Liquid waste

Human sewage Industrial waste water

Nitrous oxide emissions from waste water are also produced from protein decomposition

5.13

Land disposal sites Major form of solid waste disposal in

developed world Produces mainly methane at a diminishing

rate taking many years for waste to decompose completely

Also carbon dioxide and volatile organic compounds produced

Carbon dioxide from biomass not accounted or reported elsewhere

5.14

Decomposition process Organic matter into small soluble molecules

(including sugars) Broken down to hydrogen, carbon dioxide

and different acids Acids are converted to acetic acid Acetic acid with hydrogen and carbon

dioxide are substrate for methanogenic bacteria

5.15

Methane from land disposal

Volumes Estimates from landfills: 20–70 Tg/yr Total human methane emissions: 360 Tg/yr From 6% to 20% of total

Other impacts Vegetation damage Odours May form explosive mixtures

5.16

Characteristics of the methanogenic process

Highly heterogeneous However, relevant factors to consider:

Waste management practices Waste composition Physical factors

5.17

Waste management practices

Aerobic waste treatment Produces compost that may increase soil carbon No methane

Open dumping Common in developing regions Shallow, open piles, loosely compacted No control for pollutants, scavenging frequent Anecdotal evidence of methane production An arbitrary factor, 50% of sanitary land filling, is

used

5.18

Waste management practices (II)

Sanitary landfills Specially designed Gas and leakage control Scale economy Continued methane production

5.19

Waste composition

Degradable organic matter can vary Highly putrescible in developing countries In developed countries, due to higher paper

and card content, less putrescible This affects stabilization and methane

production Developing countries: 10–15 years Developed countries: more than 20 years

5.20

Physical factors

Moisture essential for bacterial metabolism Factors: initial moisture content, infiltration

from surface and groundwater, as well as decomposition processes

Temperature: 25–40°C required for a good methane production

5.21

Physical factors (II)

Chemical conditions Optimal pH for methane production: 6.8 to 7.2 Sharp decrease of methane production below 6.5 pH Acidity may delay the onset of methane production

Conclusion Data availability is too poor to use these factors for

national or global methane emissions estimates

5.22

Methane emissions

Depend on several factors Open dumps require other approaches Availability and quality of relevant data

5.23

Waste-water treatment

Produces methane, nitrous oxide and non-methane volatile organic compounds

May lead to storage of carbon through eutrophication

5.24

Methane emissions from waste-water treatment

From anaerobic processes without methane recovery

Volumes 30–40 Tg/yr About 8%–11% of anthropogenic methane

emissions Industrial emissions estimated at 26–40 Tg/yr Domestic and commercial estimated at 2 Tg/yr

5.25

Factors for methane emissions

Biochemical oxygen demand (BOD) (+/+) Temperature ( >15°C) Retention time Lagoon maintenance

Depth of lagoon ( >2.5 m, pure anaerobic; less than 1 m, not expected to be significant, most common facultative 1.2 to 2.5 m – 20% to 30% BOD anaerobically)

5.26

Biochemical oxygen demand

Is the organic content of waste water (“loading”)

Represents O consumed by waste water during decomposition (expressed in mg/l)

Standardized measurement is the “5-day test” denoted as BOD5

Examples of BOD5: Municipal waste water 110–400 mg/l Food processing 10 000–100 000 mg/l

5.27

Main industrial sources

Food processing: Processing plants (fruit, sugar, meat, etc.) Creameries Breweries Others

Pulp and paper

5.28

Waste incineration

Waste incineration can produce: Carbon dioxide, methane, carbon

monoxide, nitrogen oxides, nitrous oxides and non-methane volatile organic compounds

Nevertheless, it accounts for a small percentage of GHG output from the waste sector

5.29

Emissions from waste incineration

Only the fossil-based portion of waste to be considered for carbon dioxide

Other gases difficult to estimate Nitrous oxide mainly from sludge

incineration

5.30

IPCC 1996GL Basis of inventory methodology for waste sector

is: Organic matter decomposition Incineration of fossil origin organic material

Does not include concrete calculations for the latter

Organic matter decomposition covers: Methane from organic matter in both liquid and solid

wastes Nitrous oxide from protein in human sewage Emissions of non-methane volatile organic

compounds are not covered

5.31

IPCC default categories

Methane Emissions from Solid Waste Disposal Sites

Methane Emissions from Wastewater treatment Domestic and Commercial Wastewater Industrial Wastewater and Sludge Streams

Nitrous oxide from Human Sewage

5.32

Inventory preparation using IPCC 1996GL

Step 1: Conduct key source category analysis for Waste sector where:

Sector is compared to other source sectors such as Energy, Agriculture, LUCF, etc.

Estimate Waste sector’s share of national GHG inventory Key source sector identification adopted by Parties that have

already prepared an initial national communication, have inventory estimates

Parties that have not prepared an initial national communication can use inventories prepared under other programs/projects

Parties that have not prepared any inventory, may not be able to carry out the key source sector analysis

Step 2: Select the categories

5.33

Inventory preparation using IPCC 1996GL (2)

Step 3: Assemble required activity data depending on tier selected from local, regional, national and global databases, including EFDB

Step 4: Collect emission/removal factors depending on tier level selected from local/regional/national/global databases, including EFDB

Step 5: Select method of estimation based on tier level and quantify emissions/removals for each category

Step 6: Estimate uncertainty involved Step 7: Adopt quality assurance/control procedures and report

results Step 8: Report GHG emissions Step 9: Report all procedures, equations and sources of data

adopted for GHG inventory estimation

5.34

Calculation of methane from solid waste disposal

For sanitary landfills there are several methods: Mass balance and theoretical gas yield Theoretical first order kinetics methodologies Regression approach

Complex models not applicable for regions or countries

Open dumps considered to emit 50%, but should be reported separately

5.35

Mass balance and theoretical gas yield

No time factors Immediate release of methane Produces reasonable estimates if amount

and composition of waste have been constant or slowly varying, otherwise biased trends

How to calculate: Using empirical formulae Using degradable organic content

5.36

Empirical formulae

Assumes 53% of carbon content is converted to methane

If microbial biomass is discounted it reduces the amount emitted

234 m3 of methane per tonne of wet municipal solid waste

5.37

Using degradable organic content (Base of Tier 1)

Calculated from the weighted average of the carbon content of various components of the waste stream

Requires knowledge of: Carbon content of the fractions Composition of the fractions in the waste

stream This method is the basis for the Tier I

calculation approach

5.38

Equation

Methane emission = Total municipal solid waste (MSW) generated

(Gg/yr) x

Fraction landfilled x

Fraction degradable organic carbon (DOC) in MSW x

Fraction dissimilated DOC x

0.5 g C as CH4/g C as biogas x

Conversion ratio (16/12) ) – Recovered CH4

5.39

Assumptions Only urban populations in developing countries

need be considered; rural areas produce no significant amount of emissions

Fraction dissimilated was assumed from a theoretical model that varies with temperature: 0.014T + 0.28, considering a constant 35°C for the anaerobic zone of a landfill, this gives 0.77 dissimilated DOC

No oxidation or aerobic process included

5.40

Example

Waste generated 235 Gg/yr % landfilled 80 % DOC 21 % DOC dissimilated 77 Recovered 1.5 Gg/yr Methane =

(235*0.80*0.21*0.77*0.5*16/12) – 1.5 =19 Gg/yr

5.41

Limitations Main:

No time factor No oxidation considered

DOC dissimilated too high Delayed release of methane under increasing waste

landfilled conditions leads to significant overestimations of emissions

Oxidation factor may reach up to 50% according to some authors, a 10% reduction is to be accounted

5.42

Default method – Tier 1

Includes a methane correction factor according to the type of site (waste management correction factor). Default values range from 0.4 for shallow unmanaged disposal sites (> 5m) to 0.8 for deep (<5m) unmanaged sites; and 1 for managed sites. Uncategorized sites given a correction factor of 0.6

The former DOC dissimilated was reduced from 0.77 to 0.5 - 0.6, due to the presence of lignin

5.43

Default method – Tier 1

The fraction of methane in landfill gas was changed from 0.5 to a range between 0.4 and 0.6, to account for several factors, including waste composition

Includes an oxidation factor. Default value of 0.1 is suitable for well managed landfills

It is important to remember to subtract recovered methane before applying an oxidation factor

5.44

Default method – Tier 1 Good Practice

Emissions of methane (Gg/yr) =[(MSWT*MSWF*L0) -R]*(1-OX) where

MSWT= Total municipal solid waste

MSWF= Fraction disposed at SWDS

L0 = Methane generation potential

R = Recovered methane (Gg/yr)

OX = Oxidation factor (fraction)

5.45

Methane generation potential

L0 = (MCF*DOC*DOCF*F*16/12 (GgCH4/Gg waste))

where:MCF = Methane correction factor (fraction)

DOC = Degradable organic carbon

DOCF = Fraction of DOC dissimilated

F = Fraction by volume of methane in landfilled gas

16/12 = Conversion from C to CH4

5.46

Other approaches

Include a fraction of dry refuse in the equation

Consider a waste generation rate (1 kg per capita per day for developed countries, half of that for developing countries)

Use gross domestic product as an indicator of waste production rates

5.47

GPG2000 Approach

5.48

Theoretical first order kinetics methodologies (Tier 2)

Tier 2 considers the long period of time involved in the organic matter decomposition and methane generation

Main factors: Waste generation and composition Environmental variables (moisture content, pH,

temperature and available nutrients) Age, type and time since closure of landfill

5.49

Base equation

QCH4 = L0R(e-kc - e-kt)

QCH4 = methane generation rate at year t (m3/yr)

L0 = degradable organic carbon available for

methane generation (m3/tonne of waste)

R = quantity of waste landfilled (tonnes)

k = methane generation rate constant (yr-1)

c = time since landfill closure (yr)

t = time since initial refuse placement (yr)

5.50

Good practice equation Time t is replaced by t-x, normalization factor

that corrects for the fact that the evaluation for a single year is a discrete time rather than a continuous time estimate

Methane generated in year t (Gg/yr) = x [(A*k*MSWT(x)*MSWF(x)*L0(x)) * e-k(t-x) ] for x = initial year to t

Sum the obtained results for all years (x)

5.51

Good practice equation Where:

t = year of inventory

x = years for which input should be added

A = (1-e-k)/k; normalisation factor which corrects the summation

k = Methane generation rate constant

MSWT (x)= Total municipal solid waste generated in year x (Proportional to total or urban population if no rural waste collection)

L0(x) = Methane generation potential

5.52

Methane generation rate constant

The methane generation rate constant k is the time taken for the DOC in waste to decay to half its initial mass (half-life)

k = ln2/t½

This requires historical data. Data for 3 to 5 half lives in order to achieve an acceptable result. Changes in management should be taken into account

5.53

Methane generation rate constant

Is determined by type of waste and conditions Measurements go from 0.03 to 0.2 per year,

equivalent to half lives from 23 to 3 years More degradable material and humidity lower

half life Default value: 0.05 per year, or a half life of 14

years

5.54

Methane generation potential

L0(x) = (MCF(x)*DOC(x)*DOCF*F*16/12 (GgCH4/Gg waste))

where:MCF(x) = Methane correction factor in year x (fraction)

DOC (x) = Degradable organic carbon in year x

DOCF = Fraction of DOC dissimilated

F = Fraction by volume of methane in gas generated from landfill

16/12 = Conversion from C to CH4

5.55

Methane emitted Methane generated minus methane recovered

and not oxidized Equation:

Methane emitted in year t (Gg/yr) = (Methane generated in year t (Gg/yr) - R(t))*(1 - Ox)

Where:

R(t) = Methane recovered in year t (Gg/yr)

Ox = Oxidation factor (fraction)

5.56

Practical applications

Base for Tier 2 approach Applied earlier in:

United Kingdom The Netherlands Canada

5.57

Regression approach

From empirical models Statistical and regressional analysis applied

5.58

Uncertainties in calculations

Methane actually produced Are old landfills covered?

Quantity and composition of landfilled waste Is there historical data on waste

composition? Methane actually produced

Are landfill and waste management practices well known?

5.59

Calculations of emissions fromwaste-water treatment

Calculations for industrial and domestic and commercial waste water are based on biochemical oxygen demand (BOD) loading

Standard methane conversion factor 0.22 Gg CH4/Gg BOD is recommended

For nitrous oxide and methane it is possible to base calculation on total volatile solids and apply the simple method used in the agriculture sector

5.60

Methane from domestic and commercial waste water

Simplified approach Data:

BOD in Gg per 1000 persons (default values) Country population in thousands Fraction of total waste water treated anaerobically

(0.1–0.15 as default) Methane emission factor

(default 0.22 Gg CH4/Gg BOD Subtract recovered methane

5.61

Equation

Methane emission =

Population (103) x

Gg BOD5/1000 persons x

Fraction anaerobically treated x

0.22 Gg CH4/Gg BOD –

Methane recovered

5.62

GPG 2000 Approach

5.63

Good practice guidance – Check method

WM = P*D*SBF*EF*FTA*365*10-12 , where:WM = country’s annual methane emissions from domestic

waste water

P = population (total or urban in developing countries)

D = organic load (default 60 g BOD/person/day)

SBF = fraction of BOD that readily settles, default = 0.5

EF = emission factor (g CH4/ g BOD), default =0.6 or 0.25 g CH4/ g COD (chemical oxygen demand) when using COD

FTA = part of BOD anaerobically degraded, default = 0.8

5.64

Check method rationale

SBF is related to BOD from non-dissolved solids, which account for more than 50% of BOD. Settling tanks remove 33% and other methods 50%

Fraction of BOD in sludge that degrades anaerobically (FTA) is related to the processes, aerobic or anaerobic. Aerobic processes and sludge non-methane producing procedures may lead to FTA = 0

5.65

Check method rationale

Emission factor is expressed in BOD, however COD is used in many places

COD is 2 to 2.5 times higher than BOD, so the default values are 0.6 g CH4/ g BOD or 0.25 g CH4/ g COD

Emission factor is calculated from the methane producing factor stated above and the weighted average of methane conversion factor (MCF)

5.66

Methane conversion factor

IPCC guidelines recommends to separate calculations for waste water and sludge. This influences the detailed approach calculation

Excepting sludge sent to landfills or for agriculture, this is not necessary

If no data are available, expert judgement of sanitation engineers may be incorporated: Weighted MCF = Fraction of BOD anaerobically degrades

5.67

Detailed approach

Considers two additional factors: Different treatment methods used and total

waste water treated using each method MCF for each treatment

The final result is the sum of the fractions calculated by the simplified approach, less the recovered methane

5.68

Equation

Domestic and commercial waste-water emissions =

(Methane calculated by simplified approach x

Fraction waste water treated using method i x MCF for method i) - methane recovered

5.69

Methane emissions from industrial waste water

Industrial waste water may be treated in domestic sewer systems or on site

Only on-site calculations are covered in this section, the rest should be added to domestic waste-water loading

Most estimates used are for point sources Focus on key industries is required and default

values are provided

5.70

Emissions from industrial waste-water treatment

Simplified approach: Determine relevant industries (wine, beer, food,

paper, etc.) Estimate waste-water outflow (per tonne of product,

or default) Estimate BOD5 concentration (or default) Estimate the fraction treated Estimate methane emission factor (default 0.22 Gg

CH4/Gg BOD ) Subtract any methane recovered

5.71

Equation

Industrial waste-water emissions =

(waste-water outflow by industry (Ml/yr) x

kg BOD5/I x

Fraction waste water treated anaerobically x 0.22) - Methane recovered

5.72

Detailed approach Similar to the used for estimating methane

emissions from domestic and commercial waste water

Requires knowledge of: Specific waste-water treatments MCF for each factor

5.73

Equation

Industrial waste-water Emissions =

(Waste-water outflow by industry (Ml/yr) x

kg BOD5/l x

Fraction waste water treated using method i x MCF for method i) - Methane recovered

5.74

Uncertainties in calculations

Lack of information about volumes, treatments and recycling

Discharge into surface waters: Not anaerobic (default 0%) Anaerobic (default 50%)

Septic tanks (long retention times: more than 6 months)

Long retention of solids (default 50%) Short retention of solids (default 10%)

Open pits and latrines (default 20%) Other limitations: BOD, temperature, pH and retention

time

5.75

GPG2000 Approach

5.76

Emissions from waste incineration

For carbon dioxide, only fossil fraction counts not biomass

Only accounted under waste sector when no energy is recovered

IPCC guidelines include a simple method It is good practice to disaggregate waste into waste

types and take into account burn-out efficiency of incinerator

5.77

Equation for carbon dioxide

CO2 emission (Gg/yr) = i(IWi*CCWi*FCFi*Efi*44/12)where i = MSW, HW, CW, SSMSW municipal solid waste, HW hazardous waste,

CW clinical waste and SS sewage sludge

IWi = Amount of incinerated waste type i

CCWi = Fraction of C content in waste type i

FCFi = Fraction of fossil C in waste type iEF = Burn-out efficiency of combustion of

incinerators for waste type i (fraction)

44/12 = Conversion from C to CO2

5.78

Equation for nitrous oxide

N2O emission (Gg/yr) = i(IWi*Efi)*10-6 where

IWi = Amount of incinerated waste type i (Gg/yr)

EFi = Aggregate emission factor for waste type i (kg N2O/Gg) or

N2O emission (Gg/yr) = i(IWi*ECi*FGVi)*10-9

IWi = Amount of incinerated waste type i (Gg/yr)

ECi = N2O emission concentration in flue gas from waste of type i (mg N2O /Mg)

FGVi = Flue gas volume by amount of incinerated waste type i (m3/Mg)

5.79

Emission factors and activity data for carbon dioxide

C content varies: sewage sludge, 30%; municipal solid waste, 40%; hazardous waste, 50%; and clinical waste, 60%.

It is assumed that there is very little <<virtually no>> fossil carbon in sewage sludge, 0%; high content in clinical and municipal, 40%; and very high content in hazardous waste, 90%

The efficiency of combustion is 95% for all waste streams, except hazardous, which is 99.5%

5.80

Emission factors and activity data for nitrous oxide

Emission factors differ with facility type and type of waste

Default factors can be used Consistency and comparability are difficult

due to heterogeneous waste types across countries

5.81

Reporting framework

5.82

General reporting recommendations

It is good practice to document and archive all information required to produce the national inventory estimates

See GPG2000, Chapter 8, Quality Assurance and Quality Control, Section 8.10.1, Internal Documentation and Archiving

Transparency in activity data and the possibility to retrace calculations are important

5.83

Report quality assurance/quality control Transparency can be improved through clear

documentation and explanations Estimate using different approaches Cross check emission factors Check default values, survey data and

secondary data preparation for activity data Cross check with other countries

Involve industry and government experts in review processes

5.84

Reporting for methane from solid waste disposal sites

If Tier 2 is applied, historical data and k values should be documented, and closed landfills should be accounted for

Distribution of waste (managed and unmanaged) for MCF should be documented

Comprehensive landfill coverage, including industrial, sludge disposal, construction and demolition waste sites is recommended

5.85

Reporting for methane from solid waste disposal sites

If methane recovery is reported an inventory is desirable. Flaring and energy recovery should be documented separately

Changes in parameters should be explained and referenced

Time series should apply the same methodology; if there are changes it is required to recalculate the entire time series to achieve consistency in trends (See GPG2000, Chapter 7, 7.3.2.2, Alternative recalculation techniques)

5.86

Reporting for methane from domestic waste-water handling

Function of human population and waste generation per person, expressed as biochemical oxygen demand

If in rural areas, only aerobical disposal; only urban population is accounted for

COD*2.5 = BOD Recalculate whole time series Calculations need to be retraced, particularly

if there are changes to MCFs

5.87

Reporting for methane from industrial waste-water handling

Industrial estimates are accepted if they are transparent and consistent with QA/QC

Recalculations need to be consistent over time

Default data for industrial waste water is in GPG2000, Chapter 5, Table 5.4

Sectoral tables and a detailed inventory report are necessary to provide transparency

5.88

Reporting nitrous oxide emissions from waste water

Based on IPCC Guidelines, Chapter 4, Agriculture, Section 4.8, Indirect N2O emissions from nitrogen used in agriculture

Future work on data, approaches and calculations is needed

5.89

Reporting for waste incineration

All waste incineration is to be included Avoid double counting with energy recovery,

even when waste is used as a substitute fuel (e.g. cement and brick production)

Default ranges for emission estimates are provided in GPG2000, Chapter 5, Tables 5.6 and 5.7

Support fuel, generally little, shall be reported in Energy sector; maybe important for hazardous waste

5.90

Key source category analysis and decision

trees

5.91

Comparison

5.92

Comparison betweenIPCC 1996GL and GPG2000

GPG2000 IPCC 1996GL - default approach

First Order Decay Method for Solid Waste Disposal Sites based on real- world conditions of decomposition

Based on last year’s waste entering the disposal sites. Good approximation only for long-term stable conditions. First Order Decay is mentioned without specific calculations

Includes a “check method” for countries with difficulties to calculate the emissions from domestic waste-water handling

Keeps a separation between: Domestic waste water Industrial waste water

Human sewage is indicated as an area for further development and no improvement over IPCC 1996GL is presented

Calculation made on the basis of an approximation developed for the Agriculture sector (see chapter on Agriculture sector)

New section including emissions from waste incineration covers: CO2 emissions N2O emissions

Contains no detailed methodologies <<correct?>>

5.93

Key activity data required for GPG2000 and IPCC 1996GL

GPG2000 IPCC 1996GL

Disposal activity for solid waste for several years

Less requirements with the check method for CH4 emissions from domestic waste

water Top-down modification of IPCC 1996GL

recommended due to high costs Incineration amounts, composition (carbon

content and fossil fraction) required for CO2

Emission measurements recommended for N2O

Disposal activity for current year, default values or a per capita approach

Waste-water flows and waste-water treatment data required

Very detailed, industry specific data required

No specific methodology

5.94

Key emission factors required for IPCC 1996GL and GPG2000

Most emission factors are common to both: Methane generation potential for

SWDS Human sewage conversion factor Methane conversion factor

New emission factors related to: Tier 2 for SWDS, particularly k value Waste incineration (lack of some default

values)

5.95

Link between IPCC 1996GL and GPG2000

GPG2000 uses the same tables as were provided in IPCC 1996GL, based on the same categories

5.96

List of problems

5.97

Problems addressed

Problems found by NAI experts in using IPCC 1996GL

Problems categorized into: Methodological issues Activity data (AD) Emission factors (EF)

GPG2000 addresses some deficiencies found in IPCC 1996GL

Strategies for improvement in methodology, AD and EF Strategy for AD and EF – tier approach Points to sources of data for AD and EF, including EFDB

5.98

Methodological issues Methodologies that are not covered :

Sludge spreading and composting, Use of burning under conditions not reflected

properly in the waste incineration section Tropical conditions of many NAI Parties vis-à-vis

methane generation Use of open dumps instead of landfills Lack of a proper calculation method for human

sewage in the case of island countries or countries with prevailing coastal populations, and complexity of the methodology.

5.99

Lack of waste methodologies that

reflect national circumstances

GPG2000 approach Improvement suggested

- The GPG2000 does not cover composting and sludge spreading, which are common practices in NAI countries

- Burning and open dump processes are not well covered by GPG2000 and are frequent practices in NAI countries.

- Initiate field studies to generate methodologies, or use approaches proposed by Annex 1 countries for these categories.

- Expand the proper sections to reflect the conditions prevailing in many NAI countries.

5.100

More deficiencies in the methodologies

GPG2000 approach Improvement suggested

- The GPG2000 does not cover conditions for tropical countries and management practices for both solid wastes and waste waters

- The approximation used in GPG2000 to calculate nitrous oxide from human sewage (the same approximation as in IPCC 1996GL) does not reflect properly the situation of coastal/island areas

- Initiate field studies to expand the methodology

- Adopt the proposed methodologies covered in the Agriculture chapter differentiating according to geographical reality

5.101

Complexity of methodology

GPG2000 approach Improvement suggested

- The methodologies presented for Solid Waste Disposal Sites and Waste Incineration require data that are not commonly available in NAI countries

- Methods similar to the Check method for waste water should be provided to enhance completeness of reporting

5.102

Activity data problems

Lack of data on generated solid waste

Lack of time-series data for waste generation

Lack of availability of disaggregated data

Lack of data on composition of solid waste

Lack of data on oxidation conditions

Extrapolations based on past data used to apply Tier 2 for Solid Waste Disposal Sites CH4 generation

Low reliability and high uncertainty of data

5.103

Emission factor problems

Inappropriate default values given in IPCC 1996GL

Default data not suitable for national circumstances

Lack of emission factors at disaggregated level

Lack of availability of methane conversion factors for certain NAI regions

Low reliability and high uncertainty of data

Lack of emission factors in IPCC 1996GL for waste incineration (covered by GPG 2000)

Default data commonly provides upper value, leading to overestimation

5.104

List of problems(Category wise)

5.105

CH4 Emissions from Solid Waste Disposal Sites

Table 6.A

5.106

Methodological issues

Use of open dumps or open incineration Recycling, commonly of wood and paper

but even of organic waste

5.107

Activity data and emission factors

Lack of activity data, both for the present and the required time series, for the waste flows and their composition

Default activity data for only 10 NAI countries Values reflected for k parameter for the application

of the First Order Decay method do not reflect tropical conditions of temperature and humidity. The higher k value in GPG2000 is 0.2 and the one in IPCC 1996GL is 0.4

The proposed Methane Correction Factor, even using the lesser value, 0.4, may lead to overestimations, due to shallowness and the frequent practice of burning as a pretreatment at disposal sites

5.108

Emissions from Wastewater Handling

Table 6.B

5.109

Methodological issues For CH4 emissions from domestic waste-water handling,

GPG2000 presents a simplified method called the “check method” avoiding the complexities in IPCC 1996GL

In NAI countries, national methods or parameters, or even activity data, may by available only infrequently

For CH4 emissions from industrial waste-water handling, GPG2000 presents a “best practice” for cases where these emissions represent a key source, recommending the selection of 3 or 4 key industries

For emissions of N2O from human sewage, no improvements were made in GPG2000 over IPPC 1996 GL. This methodology has several limitations that have caused several NAI countries to declare it “inapplicable”

5.110

Activity data and emission factors

Availability of activity data and emission factors is uncommon in NAI countries for CH4 emissions from domestic waste water, and the “check method” may help to overcome this issue. In any case, GPG 2000 is an improvement in that it identifies potential CH4 emissions

For CH4 emissions from industrial waste water, in cases where it is a key source, it is feasible to work only with the largest industries

For N2O emissions from human sewage, the activity data needed are relatively simple and easy to obtain

5.111

Emissions from Waste Incineration

Table 6.C

5.112

Methodological issues

This source category was only briefly introduced in the IPCC 1996GL, but is fully developed in the GPG2000

In NAI countries, incineration of waste (other than clinical waste) is uncommon due to high costs

Differentiation is made between CO2 and N2O because the former is calculated with a mass balance approach and the latter depends on operating conditions

5.113

Activity data and emission factors

GPG2000 recognizes the difficulties in finding activity data to differentiate the four proposed categories (municipal, hazardous, clinical and sewage sludge)

Do not request differentiation if data are not available when it is not a key source category

5.114

Review and assessment of activity data and

emission factors: data status and options

5.115

Status of EFDB for the Waste sector

EFDB is an emerging database All experts are expected to contribute to EFDB. Currently it contains only limited information on

Waste sector emission factors In future, with contributions from experts around

the world, EFDB should become a reliable source of data for emission factors for GHG inventory

5.116

EFDB – Waste sector status

IPCC 1996GL category Emission factor records

Solid Waste Disposal on Land (6A) 115

Wastewater Handling (6B) 191

Waste Incineration (6C) 47

Other (6D) 0

Total (as at October 2004) 353

5.117

Uncertainty estimation and reduction

5.118

Uncertainty estimation and reduction

The good practice approach requires that estimates of GHG inventories be accurate they should neither be over- nor underestimated

as far as can be judged Causes of uncertainty could include:

unidentified sources lack of data quality of data lack of transparency

5.119

Reporting uncertainties from solid waste disposal sites

Main uncertainty sources: Activity data (total municipal waste MSWT and

fraction sent to disposal sites MSWF) Emission factors (methane generation rate

constant) Other factors listed in GPG2000, Table 5.2:

Degradable organic carbon, fraction of degradable organic carbon, methane correction factor, fraction of methane in landfill gas

Possibly also methane recovery and oxidation factor

5.120

Reporting uncertainties from domestic waste-water handling

Uncertainties are related to BOD/person, maximum methane producing capacity and fraction treated anaerobically (data for population has little uncertainty (+5%))

Default ranges are: BOD/person and maximum methane

producing capacity (+ 30%) For fraction treated anaerobically use expert

judgement

5.121

Reporting uncertainties from industrial waste-water treatment

Uncertainties are related to industrial production, COD/unit waste water (from -50% to +100%), maximum methane producing capacity and fraction treated anaerobically

Default ranges are: industrial production (+ 25%) maximum methane producing capacity (+ 30%)

For fraction treated anaerobically use expert judgement

5.122

Reporting uncertainties from waste incineration

Activity data uncertainty on amount of incinerated waste assumed to be low (+5%) in developed countries. Some wastes, such as clinical waste, may be higher

Major uncertainty for CO2 is fossil carbon fraction

For N2O default values, uncertainty is as high as 100%