CGE Training Materials National Greenhouse Gas Inventories Waste Sector Version 2, April 2012...

CGE Training MaterialsNational Greenhouse Gas Inventories Waste Sector

Version 2, April 2012

Training Materials for National Greenhouse Gas Inventories

Consultative Group of Experts (CGE)

• These training materials are suitable for people with beginner to intermediate level

knowledge of national greenhouse (GHG) inventory development.

• After having read this Presentation, in combination with the related documentation, the

reader should:

a) Have an overview of how emissions inventories are developed for the waste

sector;

b) Have a general understanding of the UNFCCC and IPCC guidelines;

c) Be able to determine which methods suits their country’s situation best;

d) know where to find more detailed information on the topic discussed.

• These training materials have been developed primarily on the basis of

methodologies developed by the IPCC; hence the reader is always encouraged to

refer to the original documents to obtain further detailed information on a particular

issue.

Target Audience and Objective from Training Materials

2Training Materials for National Greenhouse Gas Inventories


Acronyms

• BOD Biochemical oxygen demand

• DOC Degradable Organic Carbon

• EFDB IPCC Emission Factor Database

• GHG Greenhouse Gas

• GPG Good Practice Guidance

• MSW Municipal Solid Waste

• SWDS Solid Waste Disposal Site



Outline of course – Waste Sector

• Introduction (slide 5)

• Definitions (slide 7)

• Revised 1996 IPCC Guidelines (slide 29)

• Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories (slide 46)



• GHG inventories for the biological sectors, such as waste, are characterized by:

• Methodological limitations

• Lack of data or low reliability of existing data

• High uncertainty.

• This presentation aims to assist non-Annex I (NAI) Parties in preparing GHG

inventories using the Revised 1996 IPCC Guidelines, particularly in the context of

UNFCCC decision 17/CP.8, focusing on:

• The need to shift to the IPCC good practice guidance (2000) and higher

tiers/methods to reduce uncertainty

• Complete overview of the tools and methods

• Use of UNFCCC inventory software and EFDB

• Review of activity data and emission factors and options to reduce uncertainty

• Use of key sources, methodologies and decision trees.

Introduction



NAI Party examples

• Examination of national communications

• 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.



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.



Definitions (cont.)

• 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.



Revised 1996 IPCC Guidelines andIPCC good practice guidance (2000)Approach and steps



• Decomposition of organic matter in wastes (carbon and nitrogen)

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

energy).

Emissions from Waste Management



Decomposition of Waste

• Anaerobic decomposition of man-made waste by methanogenic bacteria

a) Solid waste

• Land disposal sites

b) Liquid waste

• Human sewage

• Industrial waste water.

• Nitrous oxide emissions from waste-water are also produced from protein

decomposition.



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.



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.



• 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.

Methane from Land Disposal



• Highly heterogeneous

• However, relevant factors to consider:

• Waste management practices

• Waste composition

• Physical factors.

Characteristics of the Methanogenic Process



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.



Sanitary landfills

• Specially designed

• Gas and leakage control

• Scale economy

• Continued methane production.

Waste Management Practices (cont.)



• 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.

Waste Composition



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.

Physical Factors



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.

Physical Factors (cont.)



Methane Emissions

• Depend on several factors

• Open dumps require other approaches

• Availability and quality of relevant data.



Wastewater Treatment

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

• May lead to storage of carbon through eutrophication.



• 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.

Methane Emissions from Wastewater Treatment



• 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).

Factors for Methane Emissions



• Is the organic content of wastewater (“loading”)

• Represents oxygen 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.

Biochemical Oxygen Demand



Main Industrial Sources

• Food processing:

• Processing plants (fruit, sugar, meat, etc.)

• Creameries

• Breweries

• Others.

• Pulp and paper.



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.



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

• Other gases difficult to estimate:

• Nitrous oxide mainly from sludge incineration.

Emissions from Waste Incineration



Revised 1996 IPCC Guidelines

• 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.



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.



Inventory Preparation using Revised 1996 IPCC Guidelines

• Step 1: Conduct key source category analysis for waste sector where:

a) Sector is compared to other source sectors such as energy, agriculture,

LULUCF, etc.

b) Estimate waste sector’s share of national GHG inventory

c) Key source sector identification adopted by Parties that have already

prepared an initial national communication, have inventory estimates

d) Parties that have not prepared an initial national communication can use

inventories prepared under other programmes/projects

e) Parties that have not prepared any inventory, may not be able to carry out the

key source sector analysis.

• Step 2: Select the categories



Inventory Preparation using Revised 1996 IPCC Guidelines (cont.)

• 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.



• For sanitary landfills there are several methods:

a) Mass balance and theoretical gas yield

b) Theoretical first order kinetics methodologies

c) Regression approach.

• Complex models not applicable for regions or countries.

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

Calculation of Methane from Solid Waste Disposal



• 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:

a) Using empirical formulae

b) Using degradable organic content.

Mass Balance and Theoretical Gas Yield



• 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.

Empirical Formulae



• Calculated from the weighted average of the carbon content of various components

of the waste stream

• Requires knowledge of:

a) Carbon content of the fractions

b) Composition of the fractions in the waste stream

• This method is the basis for the Tier I calculation approach.

Using Degradable Organic Content (Basis for Tier 1)



Equation

• Methane emissions =

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



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.



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



Limitations

• Main:

a) No time factor

b) 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.



Default Method – Tier 1

a) 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

b) The former DOC dissimilated was reduced from 0.77 to 0.5 – 0.6, due to the

presence of lignin.



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.



• 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)

Default method – Tier 1 good practice example



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

Methane Generation Potential



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 (GDP) as an indicator of waste production rates.



IPCC Good Practice Guidance Approach



• Tier 2 considers the long period of time involved in organic matter decomposition

and methane generation.

• Main factors:

a) Waste generation and composition

b) Environmental variables (moisture content, pH, temperature and available

nutrients)

c) Age, type and time since closure of landfill.

Theoretical First Order Kinetics Methodologies (Tier 2)



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)



Good Practice Equation

• Time t is replaced by t-x, a 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).



Good Practice Equation (cont.)

• 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



• 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.

Methane Generation Rate Constant



• Is determined by type of waste and conditions

• Measurements range from 0.03 to 0.2 per year, equivalent to half lives from 23 to

3 years

• The more degradable material and humidity, the lower the half life

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

Methane Generation Rate Constant



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

Methane Generation Potential



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)



Practical Applications

• Base for Tier 2 approach

• Applied earlier in:

a) United Kingdom

b) The Netherlands

c) Canada.



Regression Approach

• From empirical models

• Statistical and regressional analysis applied.



• 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?

Uncertainties in Calculations



• 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.

Calculations of Emissions from Wastewater Treatment



• Simplified approach

• Data:

a) BOD in Gg per 1000 persons (default values)

b) Country population in thousands

c) Fraction of total waste water treated anaerobically (0.1–0.15 as default)

d) Methane emission factor(default 0.22 Gg CH4/Gg BOD

e) Subtract recovered methane.

Methane from Domestic and Commercial Wastewater



Equation

• Methane emission =

Population (103) x Gg BOD5/1000 persons x Fraction anaerobically

treated x 0.22 Gg CH4/Gg BOD – Methane recovered



• 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

Good Practice Guidance – Check Method



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



Check Method Rationale

• Emission factor is expressed in BOD; however COD is used for many purposes

• 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).



• IPCC guidelines recommends separate calculations for wastewater and sludge.

This influences the detailed approach calculation.

• Apart from 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.

Methane Conversion Factor



• Considers two additional factors:

a) Different treatment methods used and total waste water treated using each method

b) MCF for each treatment.

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

the recovered methane.

Detailed Approach



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



• Industrial wastewater 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 wastewater loading

• Most estimates used are for point sources

• Focus on key industries is required and default values are provided.

Methane Emissions from Industrial Wastewater



• Simplified approach:

• Determine relevant industries (wine, beer, food, paper, etc.)

• Estimate wastewater 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.

Emissions from Industrial Wastewater Treatment



Equation

• Industrial wastewater emissions =

(wastewater outflow by industry (Ml/yr) x kg BOD5/I

x Fraction wastewater treated anaerobically x 0.22) - Methane recovered



• Similar to the approach used for estimating methane emissions from domestic and

commercial wastewater.

• Requires knowledge of:

a) Specific wastewater treatments

b) MCF for each factor.

Detailed Approach



Equation

• Industrial wastewater Emissions =

(Wastewater outflow by industry (Ml/yr) x kg BOD5/l x

Fraction wastewater treated using method i x MCF for method i)

- Methane recovered



a) Lack of information about volumes, treatments and recycling

b) Discharge into surface waters:

• Not anaerobic (default 0%)

• Anaerobic (default 50%)

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

• Long retention of solids (default 50%)

• Short retention of solids (default 10%)

d) Open pits and latrines (default 20%)

e) Other limitations: BOD, temperature, pH and retention time.

Uncertainties in Calculations



• For carbon dioxide, only fossil fraction counts, not biomass

• Only accounted under waste sector when no energy is recovered

• IPCC good practice guidance include a simple method

a) It is good practice to disaggregate waste into waste types and take into

account burn-out efficiency of incinerator.

Emissions from Waste Incineration



CO2 emission (Gg/yr) = i(IWi*CCWi*FCFi*Efi*44/12)

Where:

i = MSW, HW, CW, SS

MSW municipal solid waste, HW hazardous waste, CW clinical waste and SS

sewage sludge

IWi = Amount of incinerated waste type i

CCWi = Fraction of carbon content in waste type i

FCFi = Fraction of fossil carbon in waste type i

EF = Burn-out efficiency of combustion of incinerators for waste type i (fraction)

44/12 = Conversion from carbon to CO2

Equation for Carbon Dioxide



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)

Equation for Nitrous Oxide



• Carbon 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%.

Emission Factors and Activity Data for Carbon Dioxide



• 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.

Emission Factors and Activity Data for Nitrous Oxide



• 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.

Reporting Framework: General Recommendations



• Transparency can be improved through clear documentation and explanations:

a) Estimate using different approaches

b) Cross-check emission factors

c) Check default values, survey data and secondary data preparation for activity

data

d) Cross-check with other countries.

• Involve industry and government experts in review processes.

Report Quality Assurance/Quality Control



a) If Tier 2 is applied, historical data and k values should be documented, and

closed landfills should be accounted for

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

documented

c) Comprehensive landfill coverage, including industrial, sludge disposal,

construction and demolition waste sites is recommended.

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).

Reporting for Methane from Solid Waste Disposal Sites



Reporting for Methane from Domestic Wastewater 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.



• 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.

Reporting for Methane from Industrial Wastewater Handling (cont.)



Reporting Nitrous Oxide Emissions from Wastewater

• Based on the Revised 1996 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.



• 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 the energy sector; may be

important for hazardous waste.

Reporting for Waste Incineration



Comparison Between Revised 1996 IPCC Guidelines and IPCC Good Practice Guidance

IPCC good practice guidance Revised 1996 IPCC Guidelines - 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



Comparison of Key Activity Data Required

IPCC good practice guidance Revised 1996 IPCC Guidelines

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



Comparison of Key Emission Factors Required

Most emission factors are common to both IPCC 1996 GL and GPG 2000:

• 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).



Link Between IPCC 1996 GL and GPG 2000

• GPG 2000 uses the same tables as were provided in IPCC 1996GL, based

on the same categories.



• Problems found by NAI experts when using IPCC 1996 GL

• Problems categorized into:

• Methodological issues

• Activity data

• Emission factors.

• GPG2000 addresses some deficiencies found in IPCC 1996 GL:

• Strategies for improvement in methodology, activity data and emission factors

• Strategy for activity data and emission factors – tier approach

• Sources of data for activity data and emission factors, including EFDB.

Problems Addressed



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.



IPCC good practice guidance approach Improvement suggested

- The GPG 2000 does not cover composting and sludge spreading, which

are common practices in NAI countries

- Burning and open dump processes are not well covered by GPG 2000 and

are frequent practices in NAI countries.

- Initiate field studies to generate methodologies, or use

approaches proposed by Annex I countries for these

categories.

- Expand the proper sections to reflect the conditions

prevailing in many NAI countries.

Lack of Waste Methodologies that Reflect National Circumstances




- The GPG 2000 does not cover conditions for tropical countries and management practices for

both solid wastes and wastewaters

- The approximation used in GPG 2000 to calculate nitrous oxide from human sewage (the

same approximation as in IPCC 1996 GL) 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

More Deficiencies in the Methodologies



Complexity of Methodology


- 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



Activity Data Problems



• Inadequate data on generated solid waste

• Inadequate time-series data for waste generation

• Non-availability of disaggregated data

• Inadequate data on composition of solid waste

• Inadequate 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

Emission Factor Problems



• Inappropriate default values given in IPCC 1996 GL

• 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 1996 GL for waste incineration (covered by GPG 2000)

• Default data commonly provides upper value, leading to overestimation

List of problems,by category



Methodological issues:

• Use of open dumps or open incineration

• Recycling, commonly of wood and paper but even of organic waste.

CH4 Emissions from Solid Waste Disposal Sites, Table 6.A



• 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

GPG 2000 is 0.2 and the one in IPCC 1996 GL 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.

Activity Data and Emission Factors



Emissions from Wastewater Handling, Table 6.B

Methodological issues

• For CH4 emissions from domestic wastewater handling, GPG2000 presents a simplified method called the “check

method” avoiding the complexities in IPCC 1996 GL.

• 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”.



• Availability of activity data and emission factors is uncommon in NAI countries for

CH4 emissions from domestic wastewater, 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.




Methodological issues

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

in GPG 2000.

• 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.

Emissions from Waste Incineration, Table 6.C



• 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.




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 .

Uncertainty Estimation and Reduction



• 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.

Reporting Uncertainties from Waste Disposal Sites



Uncertainty Estimation and Reduction

• 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.



• Uncertainties are related to industrial production, COD/unit wastewater (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.

Reporting Uncertainties from Industrial Wastewater Treatment



• 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%.

Reporting Uncertainties from Waste Incineration



Thank you!

Training Materials for National Greenhouse Gas Inventories

Consultative Group of Experts (CGE) 111

CGE Training Materials National Greenhouse Gas Inventories Waste Sector Version 2, April 2012...

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